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Effects of heliox on respiratory mechanics and sensory responses during exercise in endurance-trained.. Wilkie, Sabrina Shirley 2012

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    EFFECTS OF HELIOX ON RESPIRATORY MECHANICS AND SENSORY RESPONSES DURING EXERCISE IN ENDURANCE-TRAINED MEN AND WOMEN  by  Sabrina Shirley Wilkie  B.H.K., The University of British Columbia, 2010     A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF  THE REQUIREMENTS FOR THE DEGREE OF  MASTER OF SCIENCE  in     THE FACULTY OF GRADUATE STUDIES  (Kinesiology)     THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver)  September 2012  © Sabrina Shirley Wilkie, 2012 ii  ABSTRACT   Mechanical ventilatory constraints have been shown to develop in healthy endurance-trained (ET) men, and both ET and untrained women due to structural and functional sex-based differences with respect to the pulmonary system.  The purpose of this study was to compare the effects of unloading the respiratory system using a heliox (He-O2) inspirate on expiratory flow limitation (EFL), the work of breathing (WOB), operational lung volumes and sensory responses (leg and breathing discomfort) between men and women.  It was hypothesized that He-O2 would reduce EFL, operational lung volumes, the WOB and sensory responses while increasing airflow rates, minute ventilation (V’E) and exercise performance.  The aforementioned changes would occur to a greater extent in women and those developing EFL breathing room air (RA).  Endurance trained men (n = 11) and women (n = 11) competitive cyclists completed two 5 km time trials (TT), breathing either RA or He-O2.  The maximum expiratory flow-volume (MEFV) curve method was used to determine EFL.  An esophageal balloon catheter was used to measure the WOB as determined by transpulmonary pressure (the difference between esophageal and mouth pressures).  Sensory responses were recorded throughout the TTs.  Both sexes had a small (albeit non-significant) 2.3% improvement in power output breathing He-O2.  During the RA TT, 60% of women and 36% of men developed EFL.  Heliox significantly increased the MEFV curve for both sexes however 40% of women and 45% of men still developed EFL.  The magnitude of EFL was variable throughout both TT’s for all subjects due to alterations in end expired lung volume and expiratory flow rates, as subjects utilized the He-O2 induced enhanced ventilatory reserve.  Despite significantly lower V’E, women had similar WOB and operational lung volumes as men.  Sensory responses were not affected by sex, inspirate, or presence of EFL.  Collectively these findings suggest that EFL occurs to various extents throughout endurance exercise in both sexes and may limit endurance performance.  Sex-based differences in pulmonary structure and function predispose women to mechanical ventilatory constraints breathing RA and increase women’s relative cost of breathing compared to men.         iii   PREFACE Research ethics was approved by the UBC Clinical Research Ethics Board, CREB Number H11-02521.     iv  TABLE OF CONTENTS  Abstract ...................................................................................................................................................... ii  Preface ...................................................................................................................................................... iii  Table of Contents ...................................................................................................................................... iv  List of Tables .............................................................................................................................................. v  List of Figures .......................................................................................................................................... vii  List of Abbreviations ................................................................................................................................ ix  Acknowledgements ................................................................................................................................... xi  Introduction ................................................................................................................................................. 1  Review of Literature ................................................................................................................................... 3  Hypotheses ................................................................................................................................................ 19  Methods  .................................................................................................................................................. 20  Results  .................................................................................................................................................. 27  Discussion ................................................................................................................................................. 52  Conclusion ................................................................................................................................................ 63  References ................................................................................................................................................. 64  Appendices    Appendix A: Individual Data – Tables .................................................................................................. 70    Appendix B: Individual Data – Figures ................................................................................................. 98    Appendix C: Questionnaires ................................................................................................................ 142                v  LIST OF TABLES Table 1 Descriptive and anthropometric data ..................................................................................... 27 Table 2 Pulmonary function data ....................................................................................................... 27 Table 3 Cycling background experience ............................................................................................ 28 Table 4 Maximal values from the incremental cycle test to exhaustion  ............................................ 29 Table 5 Summary of 5 km time trial performance data ...................................................................... 32 Table 6 Time trial performance improvement - power ...................................................................... 32 Table 7 Average speed, power and cadence throughout the room air and heliox 5 km time trials .... 33 Table 8 Room air time trial metabolic data ........................................................................................ 36 Table 9 Heliox time trial metabolic data ............................................................................................ 37 Table 10 Maximal expiratory flow rates .............................................................................................. 39 Table 11 Room air operational lung volumes ...................................................................................... 40 Table 12 Heliox operational lung volumes .......................................................................................... 40 Table 13 Expiratory flow limitation susceptibility ............................................................................... 42 Table 14 Magnitude of expiratory flow limitation ............................................................................... 43 Table 15 Expiratory flow limitation at 5 km ........................................................................................ 43 Table 16 Total work of breathing - men and women combined........................................................... 45 Table 17 Total work of breathing - men and women separate ............................................................. 45 Table 18 Inspiratory elastic work of breathing - men and women combined ...................................... 48 Table 19 Inspiratory elastic work of breathing - men and women separate ......................................... 48 Table 20 Expiratory total work of breathing - men and women combined .......................................... 49 Table 21 Expiratory total work of breathing - men and women separate ............................................ 49 Table 22 Rating of perceived exertion at time trial completion ........................................................... 51 Table 23 Individual descriptive and anthropometric data ................................................................... 70  Table 24 Individual pulmonary function data ...................................................................................... 71 Table 25 Individual cycling experience ............................................................................................... 72 Table 26 Individual Day 1 maximal exercise data  .............................................................................. 73 Table 27 Individual overall time trial performance data ...................................................................... 74 vi  Table 28 Individual room air time trial performance data .................................................................... 75  Table 29 Individual heliox time trial performance data ....................................................................... 76 Table 30 Individual room air time trial metabolic data ........................................................................ 77  Table 31 Individual heliox time trial metabolic data ............................................................................ 80  Table 32 Individual expiratory flow rates ............................................................................................ 83  Table 33 Individual room air time trial operational lung volumes ....................................................... 84  Table 34 Individual heliox time trial operational lung volumes........................................................... 86  Table 35 Room air time trial individual expiratory flow limitation susceptibility and magnitude ...... 88  Table 36 Heliox time trial individual expiratory flow limitation susceptibility and magnitude .......... 89  Table 37 Individual room air time trial work of breathing data ........................................................... 90  Table 38 Individual heliox time trial work of breathing data ............................................................... 93  Table 39 Individual room air time trial ratings of perceived exertion .................................................. 96  Table 40 Individual heliox time trial ratings of perceived exertion ..................................................... 97   vii  LIST OF FIGURES Figure 1 Men and women time trial performance ............................................................................... 30 Figure 2 Time, cadence, power and speed throughout the time trials ................................................. 34 Figure 3 Time trial ventilatory responses ............................................................................................ 38 Figure 4 Operational lung volumes ..................................................................................................... 41 Figure 5 Average ventilatory reserve throughout the time trials ......................................................... 44 Figure 6 Total work of breathing and minute ventilation .................................................................... 46 Figure 7 Inspiratory resistive work of breathing.................................................................................. 47 Figure 8 Sensory responses.................................................................................................................. 50 Figure 9 Representative subject demonstrating increasing end expired lung volumes ....................... 56 Figure 10 104 – Total work of breathing and operational lung volumes ............................................... 98  Figure 11 105 – Total work of breathing and operational lung volumes ............................................... 99 Figure 12 106 – Total work of breathing and operational lung volumes ............................................. 100 Figure 13 107 – Total work of breathing and operational lung volumes ............................................. 101 Figure 14 108 – Total work of breathing and operational lung volumes ............................................. 102 Figure 15 109 – Total work of breathing and operational lung volumes ............................................. 103 Figure 16 110 – Total work of breathing and operational lung volumes ............................................. 104 Figure 17 111 – Total work of breathing and operational lung volumes ............................................. 105 Figure 18 112 – Total work of breathing and operational lung volumes ............................................. 106 Figure 19 114 – Total work of breathing and operational lung volumes ............................................. 107 Figure 20 115 – Total work of breathing and operational lung volumes ............................................. 108 Figure 21 201 – Total work of breathing and operational lung volumes ............................................. 109 Figure 22 202 – Total work of breathing and operational lung volumes ............................................. 110 Figure 33 203 – Total work of breathing and operational lung volumes ............................................. 111 Figure 24 204– Total work of breathing and operational lung volumes .............................................. 112 Figure 25 205 – Total work of breathing and operational lung volumes ............................................. 113 Figure 26 206 – Total work of breathing and operational lung volumes ............................................. 114 Figure 27 207 – Total work of breathing and operational lung volumes ............................................. 115 viii  Figure 28 208 – Total work of breathing and operational lung volumes ............................................. 116 Figure 29 210 – Total work of breathing and operational lung volumes ............................................. 117 Figure 30 211 – Total work of breathing and operational lung volumes ............................................. 118 Figure 31 212 – Total work of breathing and operational lung volumes ............................................. 119 Figure 32 104 – Flow volume and pressure volume traces ................................................................. 120 Figure 33 105 – Flow volume and pressure volume traces ................................................................. 121 Figure 34 106 – Flow volume and pressure volume traces ................................................................. 122 Figure 35 107 – Flow volume and pressure volume traces ................................................................. 123 Figure 36 108 – Flow volume and pressure volume traces ................................................................. 124 Figure 37 109 – Flow volume and pressure volume traces ................................................................. 125 Figure 38 110 – Flow volume and pressure volume traces ................................................................. 126 Figure 39 111 – Flow volume and pressure volume traces ................................................................. 127 Figure 40 112 – Flow volume and pressure volume traces ................................................................. 128 Figure 41 114 – Flow volume and pressure volume traces ................................................................. 129 Figure 42 115 – Flow volume and pressure volume traces ................................................................. 130 Figure 43 201 – Flow volume and pressure volume traces ................................................................. 131 Figure 44 202 – Flow volume and pressure volume traces ................................................................. 132 Figure 45 203 – Flow volume and pressure volume traces ................................................................. 133 Figure 46 204 – Flow volume and pressure volume traces ................................................................. 134 Figure 47 205 – Flow volume and pressure volume traces ................................................................. 135 Figure 48 206 – Flow volume and pressure volume traces ................................................................. 136 Figure 49 207 – Flow volume and pressure volume traces ................................................................. 137 Figure 50 208 – Flow volume and pressure volume traces ................................................................. 138 Figure 51 210 – Flow volume and pressure volume traces ................................................................. 139 Figure 52 211 – Flow volume and pressure volume traces ................................................................. 140 Figure 53 212 – Flow volume and pressure volume traces ................................................................. 141   ix  LIST OF ABBREVIATIONS EFL Expiratory Flow Limitation EELV End Expired Lung Volume EILV End Inspiratory Lung Volume ET Endurance Trained Etot  Expiratory Total FAM Familiarization time trial fb  frequency of breathing FEV Forced Expiratory Volume FRC Functional Residual Capacity FVC Forced Vital Capacity He Helium He-O2 Heliox HR Heart Rate Iel Inspiratory elastic Ires Inspiratory resistive IC Inspiratory Capacity M Men MEF Maximum Expiratory Flow  MEFV Maximum Expiratory Flow Volume NEFL Non-Expiratory Flow Limitation NEP Negative Expiratory Pressure N2 Nitrogen PE Esophageal Pressure  PM Mouth Pressure PAV Proportional Assist Ventilator x  PEF Peak Expiratory Flow RA Room Air RER Respiratory Exchange Ratio RPE Rating of Perceived Exertion RPM Revolutions Per Minute TLC Total Lung Capacity TT Time Trial V’E Minute Ventilation V’E CAP Ventilatory Capacity V’O2 Oxygen consumption V’O2MAX Maximal oxygen consumption V’O2RM Maximal oxygen consumption by the respiratory muscles V’O2TOT Total Body maximal oxygen consumption V’CO2 Carbon dioxide production VT Tidal Volume W Women WOB Work of Breathing   xi  ACKNOWLEDGEMENTS I would like to thank Dr. Bill Sheel, Dr. Michael Koehle and Dr. Ben Sporer for serving on my committee and providing insight and advice to enhance my study.  I am especially grateful to my supervisor Dr. Bill Sheel for his guidance.  The knowledge and skills I have acquired as a graduate student will benefit me in my future research and life endeavors. I am grateful to all the past and present members of the Health and Integrative Pulmonary Laboratory for the education and assistance they provided throughout my master’s degree: Jordan Guenette, Paolo Dominelli, Glen Foster, Bill Henderson, Jordan Querido, Josh McKay, Meaghan MacNutt, Jill Kennedy, and Simone Tomczak.  Thank you to Melina Mirzaei and the graduate students in the Environmental Physiology Laboratory and the Genes, RNA, Informatics, and Protein Laboratory for their assistance with this study.   I would like to offer special thanks to the subjects who volunteered their time.  Thank you to Dr. Don McKenzie for the use of the VeloTron cycle ergometer, and to Sid Reeve for helping construct the equipment shelving.   This study and my degree would not have been possible without funding from the National Sciences and Engineering Research Council of Canada and the University of British Columbia. Finally, thank you to my family and friends for supporting my academic pursuits.   1   INTRODUCTION Endurance training causes changes to the cardiovascular and metabolic systems to meet the augmented aerobic energy requirements (26, 42, 72, 73).  Despite high ventilatory rates to enhance oxygen delivery over prolonged periods of time, beneficial effects to the lungs and airways have not been directly demonstrated with endurance training (51, 70).  As such, increased demands from the enhanced cardiovascular (cardiac output and stroke volume) and metabolic systems (skeletal muscles vascularity and oxidative capacity) have been shown to exceed the capabilities of the respiratory system in healthy individuals during progressive exercise. By way of expiratory flow limitation (EFL), an increased work of breathing (WOB), diaphragm fatigue, sensations of breathlessness, and decrements in arterial blood gas status, the respiratory system is able to limit exercise performance (21, 32, 35, 44, 53).  To achieve the high minute ventilation (V’E) required by heavy exercise, both tidal volume (VT) and breathing frequency (fb) must increase.  These increases are met by increasing expiratory and inspiratory flow rates. Unlike inspiratory flow, expiratory flow at mid and low lung volumes is independent of effort and dependent on the intrinsic properties of the lungs.  Healthy individuals exercising near maximal capacity can reach their maximal expiratory flow rates (45).  When maximal expiratory flow rates are reached, expiration becomes flow limited.  For a given lung volume, no further increases in expiratory airflow rate can be achieved despite an increase in pleural pressure.  In order to achieve a further increase in expiratory flow rates and V’E, end expired lung volume (EELV) is increased to take advantage of higher flow rates available at higher operating lung volumes.  As operational lung volumes increase, the shortened inspiratory muscles are at a mechanical disadvantage.  An elevated end inspiratory lung volume (EILV) increases the elastic WOB as the lungs are no longer operating on the most compliant portion of the pressure-volume curve.  The WOB demanded by heavy exercise appears to cause a redistribution of blood flow away from the locomotor muscles, compromising aerobic capacity and exercise performance (35).  If V’E is mechanically constrained by way of EFL, alveolar ventilation could potentially be limited. Consequently the arterial partial pressure of oxygen would decrease, leading to exercise induced arterial hypoxemia and subsequently a reduced exercise capacity.  Concurrent with the onset of EFL and changes in operational lung volumes, there appears to be an accompanying increased sensation of breathlessness (‘exertional’ dyspnea) (37, 54).  The aforementioned findings are predominantly based on data obtained in ET men during heavy or maximal exercise.  There is growing evidence however, that mechanical ventilatory constraints may be more predominant in women as a result of sex-based differences in lung structure and function.  Structurally, for a given height, women have smaller lung volumes and less alveoli with a reduced 2  alveolar surface area (82).  When matched for lung volume, women typically have smaller diameter airways compared to men (56, 77).  Functionally, diffusion capacity is reduced due to the smaller alveolar surface area, while smaller airway diameters increase airflow resistance and reduce maximal expiratory flow rates compared to age and height matched men, even when matched for total lung capacity (TLC) (30, 52, 77).  Due to a lower ventilatory reserve, EFL has shown to be more prevalent in women despite lower maximal V’E, (32).   Lung and airway size appear to play a key role in the susceptibility of EFL within women.  Specifically, reduced vital capacities (based on predictive normative values) and high V’E achieved by ET women appear to increase EFL susceptibility (23, 53).  Women with forced vital capacities (FVC) much larger than predicted values have greater ventilatory reserves allowing the generation of high flow rates less likely to encroach on the maximal expiratory flow-volume (MEFV) curve (32).   The ventilatory reserve can be increased with a helium-oxygen inspirate (heliox, He-O2).  Helium’s (He) lower density and higher viscosity compared to nitrogen (N2) reduces airflow turbulence, reducing the flow-resistive WOB and increasing the MEFV curve compared to room air (RA) (13, 85).  As a result EFL, EELV and the resistive WOB have been shown to decrease in trained male cyclists when breathing He-O2 compared to RA (54).  Elite female runners inspiring He-O2 have also shown reductions in EFL and operational lung volumes with increases in V’E.  However V’E only increased for women that had no longer developed EFL when breathing He-O2 (53) suggesting that limitations to the MEFV curve constrain V’E.  Accordingly, the goal of the present study was to directly compare the effects of unloading the respiratory system using a He-O2 inspirate between men and women.  Specifically, this study aimed at determining: 1) if reducing airflow resistance (by way of He-O2) will reduce EFL, operational lung volumes, and the WOB while increasing V’E  and exercise performance (5 kilometer (km) time trial (TT)) compared to RA 2) if the aforementioned changes will occur to a greater extent in ET women compared to ET men 3) if sensations of breathlessness will be affected by He-O2 and potentially the reduced mechanical ventilatory constraints and 4) if breathing He-O2 in comparison to RA will induce an increase in 5 km TT performance.             3  REVIEW OF LITERATURE It is widely accepted that endurance training causes adaptations to the cardiovascular and metabolic systems, with little direct evidence of change to the pulmonary system (70).  As such, oxygen transport and utilization, by the cardiovascular system (cardiac output and stroke volume) and skeletal muscles (vascularity and oxidative capacity) were the more plausible factors limiting aerobic capacity.  More recently however, young healthy men and women have been shown to reach the limits of their respective pulmonary systems during heavy exercise.  The lungs and airways by way of expiratory flow limitation (EFL), increased operational lung volumes, elevated work of breathing (WOB) and heightened sensations of leg and/or breathing discomfort may be the factors limiting exercise performance.  This is in stark contrast to previous beliefs that the pulmonary system was ‘overbuilt’ and the maximal capacity to generate ventilation would never be reached during rigorous exercise in healthy individuals (65).   Development of EFL and elevated operational lung volumes during maximal exercise have been shown in endurance trained (ET) men (1, 32, 44, 60).   Endurance trained women have been shown to be more susceptible to EFL, with higher relative operational lung volumes and a greater WOB for a given minute ventilation (V’E) compared to their male counterparts (32).  Sex-based differences in pulmonary structure and function are likely the cause of women’s augmented mechanical ventilatory constraints.  Structurally women have smaller lung volumes for a given standing height and comparatively smaller diameter airways when matched for lung volume relative to men (55, 82).  The smaller diameter airways increase airway resistance, reducing expiratory airflow generating a smaller ventilatory capacity.  Despite reaching lower metabolic rates, not only ET but also untrained women develop mechanical ventilatory constraints (23, 53).   To alleviate mechanical ventilatory constraints, researchers have attempted to unload the respiratory system using: mechanical ventilation (proportional assist ventilation (PAV), inspiratory pressure support, and continuous positive airway pressure), bronchodilators and heliox (He-O2). Healthy ET men cycling at a sustained heavy workload under mechanical ventilation (PAV) have shown increased time-to-exhaustion and V’E, with decreased oxygen consumption (V’O2) and sensory perceptions of leg and breathing discomfort for a given workload compared to unassisted breathing (37).  Bronchodiators, short and long-acting B2-agonists, assist in expiration by dilating the conducting airways increasing the forced expiratory volume in 1 sec (FEV1) and V’E in individuals with exercise- induced asthma as well as healthy controls (15).  However, endurance performance was not improved by inhalation of a B2-agonist in studies with strong internal validity using athletes with normal pulmonary function (15, 81).  Bronchodilators have alleviated EFL for chronic obstructive pulmonary disease 4  (COPD) patients, but increases in FEV1.0 and inspiratory capacity (IC) developed irrespective of EFL occurrence (20).  Helium’s (He) lower density relative to nitrogen (N2) decreases airflow resistance.  For a given lung volume airflow rates are higher breathing He-O2 thereby expanding the maximum expiratory flow- volume (MEFV) curve.  Increases in V’E and decreases in EFL and end expired lung volume (EELV) resulting in performance improvements, have been shown in healthy ET individuals and individuals suffering from diseases such as COPD inspiring He-O2 (13, 25, 53, 67).   The current literature is lacking in a direct comparison between men and women matched for aerobic capacity, on the ventilatory effect of mechanically unloading the respiratory muscles.  Potentially a sex-based difference in the susceptibility and magnitude of EFL would cause different V’E and performance responses when mechanically unloaded. The purpose of this review is to examine the existing literature for 1) sex-based differences in pulmonary mechanics, and 2) the effects of He-O2 as an inspirate on lung mechanics, sensory responses and performance.  Mechanical ventilatory constraints effect on blood gases have been thoroughly investigated elsewhere and therefore will not be discussed in the following literature review (22). NORMAL RESPIRATORY RESPONSE TO EXERCISE At rest V’E occurs around functional residual capacity (FRC), where lung compliance is the greatest and a balance occurs between the lungs’ inward elastic recoil and the chest wall’s tendency to spring outward. Inspiration is initiated when the diaphragm contracts bringing the abdominal contents downward, decreasing pressure within the thorax causing air to flow into the lungs.  Expiration is passive as the lung and chest wall return to their equilibrium positions at FRC.  During quiet breathing resistance to airflow is low because flow is laminar with high axial flow rates proportional to pressure development.  Progressive exercise increases the metabolic rate of the exercising muscles.  For which oxygen consumption and removal are met by increasing V’E.  The external intercostals and accessory respiratory muscles (scalene and sternocleidomastoid) assist in inspiration, by further expanding the rib cage generating a greater drop in pressure enhancing the rate of airflow into the lungs.  Expiration becomes active as the abdominals and internal intercostals contract, increasing intra-abdominal pressure pushing the diaphragm upwards while pulling the rib cage down, forcing air out of the lungs.  The work done by the muscles of expiration act to decrease EELV below resting FRC, lengthening the inspiratory muscles to enhance the skeletal muscles length-tension relationship and optimize force output (88).  A reduced EELV allows tidal volume (VT) to increase while keeping end inspired lung volume (EILV) under 90% of 5  total lung capacity (TLC); minimizing the elastic WOB while remaining on the most compliant portion of the lungs pressure-volume curve.    When VT reaches 50-60% of vital capacity, further increases in V’E are met by increasing breathing frequency (fb) which optimizes the elastic WOB by using energy stored and recovered in the lungs and chest wall.  Elevated flow rates come at the expense of a turbulent flow pattern in the larger conducting airways increasing the resistive WOB. Coincidentally, the laryngeal and tracheal diameters increase (bronchodilation), to decrease resistance and increase airflow rate.  Overall the ventilatory pattern and operational lung volumes function at the lowest possible metabolic cost, using less than 10% of total body V’O2 (1).   Exceptions – Endurance-trained Athletes Endurance-trained athletes demand high inspiratory and expiratory flow rates to meet their elevated ventilatory demands during exercise.  Higher flow rates are achieved by generating greater intra- thoracic pressure.  However, unlike inspiration, active expiration is effort independent such that a critical pressure exists at which point maximal expiratory flow is reached.  The critical pressure and maximal expiratory flow rates can be met by ET athletes.  At this point any effort to generate an intra-thoracic pressure exceeding the critical pressure will not increase expiratory flow rate.  Rather, expiratory flow rate can even be reduced as airways downstream from the EFL segment undergo dynamic compression.  At this point, expiratory flow rates can only be increased by increasing EELV to take advantage of higher flow rates available at higher lung volumes.  This action shortens the inspiratory muscles, which are no longer at an optimal length to produce force and have a reduced contractility time due to a higher fb.  Increasing EELV and VT increases EILV which has been shown to exceed 90% of TLC, greatly increasing the elastic WOB.  The resistive WOB is also increased as expiratory flow rates increase and take on a more turbulent pattern in the smaller airways.    Increases in operational lung volumes and/or dynamic compression may cause a reflex inhibition of the hyperventilatory response and alter breathing pattern (69).  An increased WOB will require more oxygen and blood flow, likely taking a larger percentage of total body blood flow away from the exercising muscles (35).  An increased WOB could lead to diaphragm fatigue, increased perceptions of breathing and limb discomfort, and/or blood redistribution, ultimately limiting aerobic exercise capacity.   MECHANICAL VENTILATORY CONSTRAINT IN MEN Expiratory Flow Limitation - Susceptibility Highly trained young men (V’O2MAX > 60 ml∙kg -1∙min-1) with normal pulmonary function have the ability to reach the limits of their pulmonary systems by way of EFL during sustained heavy exercise.  6  Expiratory flow limitation was found in 3 of 8 highly trained male cyclists tested by Guenette et al. (32), all 8 competitive distance runners tested by Johnson et al. (44), and only 1 of 10 competitive cyclist tested by Mota et al. (60).  All men in these studies were of similar age, possessed exceedingly high aerobic capacities (average V’O2MAX: 70, 73, 72 ml∙kg -1∙min-1 respectively), and thus reached similar maximal V’E (average V’E: 161, 186, 147 l∙min -1 respectively) whether EFL or non-EFL (NEFL).  The vast discrepancy in susceptibility of EFL is interesting since subject characteristics were homogenous with the only differences between studies being testing methodologies and exercise modalities.   The forward lean adopted during running facilitates higher flow rates (compared to standing upright) which increase the MEFV curve (33).  The accentuated trunk flexion and arm bracing of cyclists enhances the ability of the accessory muscles of respiration to expand the rib cage, increasing vital capacity (8).  Yet, discrepancies in body position do not account for the differences in EFL susceptibility between the two cycling studies.   Johnson et al. (44) tested EFL by the MEFV curve technique and by athletes meeting or exceeding maximal effective pleural pressure.  Tidal volume impinging on the MEFV curve in addition to attainment of maximal effective pleural pressure appeared to justify a finding of 100% EFL in subjects.  Furthermore, when Johnson et al. (44) gave subjects a chemical stimulus (3% CO2 or hypoxia) to breathe during exercise, sub-maximal exercise V’E increased, but at high work rates where EFL occurred, V’E failed to increase.  Respiratory muscle fatigue was unlikely since peak esophageal pressure increased during the end of exercise and expiratory pressure generation was less than a third of that generated during the maximal voluntary ventilation test performed at rest. The negative expiratory (NEP) technique was used by Guenette et al. (2007) and Mota et al.  (1999), however Guenette et al. (2007) obtained 3 NEP tests during the final workload whereas Mota et al. (1999) obtained only 1 NEP test during the last minute of each stage.  Potentially during the final minute of exercise Mota et al. (1999) subjects altered their EELV and thus removed the EFL.   Overall determination of EFL is highly sensitive to the measurement techniques, and extreme care must be taken to accurately detect EFL.   Expiratory Flow Limitation - Magnitude The magnitude of EFL in male endurance athletes varies from 12-76% (44) to 25-100% (1) VT overlapping the MEFV curve.  The discrepancy in the magnitude of EFL appears to be a result of the V’E the athletes reach during maximal exercise.  For example, the cyclist with 100% VT EFL at maximal exercise was ventilating at 185 l∙min-1 whereas the individuals with 25% VT EFL had maximal V’E of 162 l∙min-1. 7  McClaran et al. (54) tested highly trained male cyclists breathing a hyperoxic mixture (26% O2- N2) and found all 6 subjects developed EFL during heavy and maximal exercise.  When the chemoreceptor drive to breathe was increased via increased VT, by added dead space, the magnitude of EFL was elevated in all subjects.  Overall it appears as V’E increases so does the susceptibility and magnitude of EFL.  In the aforementioned studies athletes were reaching average V’E of 160-170 l∙min -1, far exceeding the V’E of an untrained individual. During heavy exercise, when EFL occurs, VT has been shown to decrease with increases in EELV (32, 53, 54, 60).  This is in contrast to the usual plateau in VT at high V’E, with increases in V’E brought about by increasing fb.  Increases in EELV (potentially in excess of FRC) allow generation of higher expiratory flows at higher lung volumes, however, it comes at the expense of an elevated EILV (90% TLC), thereby increasing the elastic WOB (44).  The increase in operational lung volumes augment inspiratory muscle pressure which can exceed 80% maximal dynamic capacity (1, 44).  Pelligrino et al. (69) showed further evidence for a correlation between changes in operational lung volumes and EFL in which an expiratory threshold load was applied to both EFL and non-EFL subjects.  The expiratory threshold load decreased expiratory flow rates and increased expiratory time for both groups.  However, EELV decreased in EFL subjects because it took longer for EFL subjects to reach flow rates causing EFL, therefore a relative decrease in EELV occurred.  In contrast the NEFL subjects EELV increased, by way of a smaller increase in expiratory time; for the same given V’E less air was expired causing increases in EELV. SEX-BASED DIFFERENCES IN PULMONARY STRUCTURE AND FUNCTION Structural Dysanapsis, or unequal growth between lung parenchyma size and airway (intra-thoracic trachea and large bronchi) size was first introduced by Green et al. (28).  Mead (1980) went on to show that dysanapsis occurs to a greater extent in young boys and women who have airway diameters 17% smaller than men when matched for lung size, with the difference in growth occurring later in life (56).  Acoustic reflectance estimates have shown healthy women’s tracheal cross-sectional areas are 29% less than men matched for TLC (52).  Recently computed tomographic imaging has found the larger conducting airways in women are significantly smaller than those of men matched for lung size, as are the luminal areas (77).  The larger lungs possessed by men for a given height result in larger lung volumes and alveolar surface areas, and therefore a greater number of alveoli (82).  Consequently, at rest, women have a lower diffusing capacity for oxygen and carbon monoxide (66).   8  Functional Structural sex-based differences in the diameter of the large conducting airways and lung volumes translate into differences in pulmonary function.  When airway diameter is reduced, resistance to airflow markedly increases based on Poiseuile’s law.  As airway resistance increases, flow rate decreases; women’s smaller diameter airways reduce maximal expiratory flow rates and maximal expiratory flow at 25% TLC (MEF25%) compared to men when matched for TLC (52) with an overall reduced capacity to generate V’E.  Reduced maximal V’E based on lower achievable metabolic rates by women compared to men led researchers to believe women would not reach their maximal capacity to ventilate.  However, ET women and even untrained women are capable of reaching V’E high enough to impede on their relatively reduced ventilatory reserve (32, 53).   Female Sex Hormones  Evidence of increased resting V’E during the luteal phase due to elevated progesterone (74) led researchers to believe that female steroid hormones could affect ventilatory mechanics.  However, the elevated V’E across cycle phase has only been shown to affected exercise performance in regularly menstruating ‘non-athletes’, not regularly menstruating or amenorrheic ‘athletes’; the discrepancy in exercise tolerance could be due to subjective sensations of dyspnea  (74).  Lebrun et al. (47) found the magnitude of the effect of female sex hormones on indices of performance shows tremendous variability between subjects and appears to be more relevant on an individual basis.  A recent study from our research group (46) found menstrual cycle phase did not have any effect on exercise V’E.  This finding is consistent with several previous studies which failed to find an effect of menstrual cycle phase on the integrated ventilatory response to exercise (9, 10, 18).  Our research group also found vast heterogeneity in the cyclical hormone profiles of a relatively homogeneous subject group.  Menstrual cycles appear to occur along a continuum of the phases; a ‘normal’ cycle with discrete phases is not always apparent.   MECHANICAL VENTILATORY CONSTRAINTS IN WOMEN A reduced ventilatory capacity combined with high V’E would in theory predispose women to mechanical ventilatory constraints – EFL and relative hyperinflation, at a lower V’E and V’O2 compared to men.  The lone female subject studied by Aaron et al. (1) had the greatest magnitude of EFL (60% of VT ), despite a V’E (139 l∙min -1) much lower than the male subjects.  All the ET women with normal pulmonary function tested by Guenette et al. (32) developed EFL during maximal exercise while reaching high V’E (120 l∙min -1).  In contrast to men, EFL is not exclusive to ET women; development of EFL has 9  been shown in healthy women of varying aerobic capacities during maximal and sub-maximal exercise at V’E of only 98 l∙min -1 (23, 53, 84, 86).   The magnitude of EFL in women has been shown to range from 0 (NEFL) to 58% VT overlapping the MEFV curve.  At an equivalent V’E (< 115 l∙min -1) men do not develop EFL, thus making the magnitude of EFL in women much greater.  Overall men develop EFL over a greater % VT (up to 100% VT) compared to women, however these particular men were reaching substantially higher V’E  in excess of 180 l∙min-1 (1, 44).   Walls et al. (84) found, EFL was related to absolute V’E in a group of untrained women.  Despite relatively lower aerobic capacities (V’O2MAX: 47 ml∙kg -1∙min-1), the women with the greatest % VT EFL at maximal exercise were also EFL during sub-maximal exercise (92 and 93% V’O2MAX).  This is in stark contrast to men; whereby only men with large aerobic capacities (V’O2MAX > 55 ml∙kg -1∙min-1) reaching exceedingly high V’E (160 l∙min -1) develop EFL during maximal exercise.  However, McClaran et al. (53) found the magnitude of EFL and changes in operational lung volumes were related to aerobic capacity whereby highly trained female runners (V’O2MAX > 57 ml∙kg -1∙min-1) developed more EFL (32% VT), compared to relatively untrained women (V’O2MAX < 56 ml∙kg -1∙min-1; 10% VT) and had higher EELV (trained: 48 vs. untrained: 53% TLC) and EILV (87 vs. 90% TLC) than their less fit counterparts.  The significantly higher V’E and flow rates the fitter women generated at the elevated work rates would encroach to a greater extent on their MEFV loop compared to women with the same size MEFV loop that reach lower V’E. Size versus Fitness Exceedingly high V’E attained by ET women compiled with smaller diameter airways and lung volumes further exacerbates EFL.  However, women with abnormally large vital capacities (as percent predicted) and high expiratory flow rates do not develop EFL, nor do they show relative hyperinflation despite V’E comparable to other women (1, 32).  These women with enhanced pulmonary structures have unusually large MEFV curves providing a greater ventilatory reserve.  The lone ET women studied by Guenette et al. (32) to not develop EFL possessed an FVC 134% predicted; this women could generate expiratory flow rates demanded by her high work rate without encroaching on her MEFV curve.  Therefore, absolute lung structure, not just sex, appears to have the greatest impact on respiratory mechanics. Recently, our research group showed, EFL was more prevalent in women with smaller lung volumes and diameter airways, and occurred regardless of aerobic capacity (22, 83).  Larger aerobic 10  capacities possessed by ET athletes will necessitate heightened V’E responses that could lead to EFL in both men and women.  However sex-based differences in ventilatory capacity and expiratory flow rates could predispose even untrained women with small aerobic capacities and low V’E to EFL.   Operational Lung volumes        Akin to men, women decrease EELV at the onset of exercise, but when exercise intensities approach maximal, women increase EELV and consequently EILV to a significantly greater extent than men. The additional hyperinflation demonstrated by women may be the result of a reflex response brought about by their increased prevalence of EFL (32) to avoid dynamic airway compression and take advantage of higher flow rates available at higher lung volumes.   The increase in EELV causes women’s VT to be at a higher percent of TLC, where lung compliance is reduced and the elastic WOB increases to a greater extent than men.  In an effort to prevent EFL or possibly because VT is mechanically constrained and cannot be further increased, it appears women alter their breathing pattern, relying more on increases in fb than VT to increase V’E (32, 53). By utilizing the tachypneic breathing pattern, women are able to decrease the elastic WOB using energy stored in the tissues.  WORK OF BREATHING To increase V’E as one transitions from rest to exercise requires an increase in intra-thoracic pressure development.  To develop sufficient pressure, the inspiratory and expiratory muscles of respiration must generate greater muscular contractions, which increase the WOB.  The WOB is comprised of an elastic and a resistive component: the elastic component must overcome the elastic properties of the lungs to recoil inward during inspiration, and the outward recoil of the chest wall during expiration; impediments to airflow through the tracheobronchial tree comprise the resistive component.  When V’E occurs on the compliant portion of the lung’s pressure-volume curve the elastic WOB is minimized.  Increases in the elastic WOB occur when operational lung volumes increase, especially when EELV exceeds resting FRC and EILV is in excess of 80% TLC.  At elevated lung volumes, the shortened inspiratory muscles are at a mechanical disadvantage.  A greater intra-thoracic pressure, and thereby muscular contraction, is required to elicit a given volume change which can reach 89% of maximal dynamic capacity (44).   At rest and during low intensity exercise airflow is laminar, EELV is near resting FRC, and the total WOB for a given V’E is similar in men and women.  During progressive exercise as V’E increases so 11  does the WOB for men and women. For a given V’E, women’s WOB increases to a greater extent and has shown to be twice that of men at V’E above 90 l∙min -1 (32).   To determine what component of the WOB was contributing to the sex-based differences Guenette et al. (30) measured the elastic and resistive components of the WOB during exercise in male and female ET athletes.  An increased resistance was found to account for the total elevated WOB for a given V’E in women.  When both sexes were performing the same relative external muscle work, the total WOB was higher in women due to elevated inspiratory and expiratory resistive WOB components.  The elevated resistive WOB in women was inversely related to lung size, and presumably airway size.   Women’s smaller conducting airway diameters and relatively smaller lung volumes increase resistance to airflow, causing a reduced flow rate for a given driving pressure (ventilatory muscular contraction) (14).  When V’E increases and airflow is predominated by turbulent characteristics, women’s resistive WOB is augmented and requires substantially greater external muscle work.  As a consequence of smaller airway diameters, increased airflow resistance, and likely EFL, women engage in a different breathing pattern than men.  The higher frequency breathing pattern reduces the elastic WOB by taking advantage of energy stored in the tissues.  This is adopted because V’E occurs at a higher percentage of TLC at the expense of reduced lung compliance.  Thus for an absolute VT women’s elastic WOB is higher than men’s but due to the tachypneic breathing pattern, for a given V’E the inspiratory and expiratory elastic WOB is similar to men’s (30).  One could speculate that an increased WOB in women associated with increases in operational lung volumes and EFL would result in a greater oxygen cost of breathing.  CONSEQUENCES OF MECHANICAL VENTILATORY CONSTRAINTS Increased Oxygen Cost of Breathing  There is strong evidence to suggest the oxygen cost of exercise hyperpnea appears to be increased in those susceptible to EFL.  Without mechanical constraint, the respiratory muscle’s oxygen cost of V’E (V’O2RM) during maximal exercise has shown to be ~10% of total body V’O2 (V’O2TOT).  When EFL develops and inspiratory muscle pressure is near capacity, V’O2RM increases to ~13-15% of V’O2TOT (1).  This data was obtained in men, the lone women tested by Aaron et al. (1) developed substantial EFL (60% VT), and had the highest WOB and the highest V’O2RM (15.4% V’O2TOT) despite a lower maximal V’E than men.  Presumably women’s oxygen cost of V’E is greater than men’s. As V’E and the WOB increase, blood flow to the exercising locomotor muscles has been shown to decrease in trained male cyclists possessing a leg V’O2 of 81% V’O2TOT when breathing room air.  When 12  the WOB was artificially increased by imposing a resistive load to the respiratory muscles, leg V’O2 decreased to 71% V’O2TOT and increased (89% V’O2TOT) when respiratory muscles were unloaded with PAV (35).  A correlation between norepinephrine spillover and leg vascular resistance suggests changes in leg blood flow and oxygen delivery are sympathetically mediated and triggered by changes in the WOB, possibly via the respiratory muscle chemoreflex effect.  During maximal exercise in highly trained men, Harms et al. (36) found the respiratory muscles used up to 14-16% of cardiac output.  While EFL was not measured in this study, it is likely those with an elevated WOB due to mechanical constraints would require a larger percentage of cardiac output to meet the increased metabolic demands of their respiratory muscles.  Likely when EFL develops and V’O2RM is further augmented greater amounts of blood flow to the exercising locomotor muscles would be redirected to the respiratory muscles.  A reduction in leg blood flow due to a high WOB occurring during heavy exercise appears to reduce exercise performance in highly trained men.  When respiratory muscles were unloaded (PAV), and the WOB decreased, exercise performance increased by 14%, whereas when respiratory muscles were loaded (resistive) performance decreased by 15% compared to a no load trial (37). If women are predisposed to EFL and thus a greater WOB, it is presumable the proportion of cardiac output directed to the respiratory muscles would be elevated at a cost to leg blood flow.  Consequently women would endure greater decrements in exercise performance relative to men.  If mechanical ventilatory constraints by way of EFL augment the WOB, researchers then speculate if a point exists at which the diaphragm will begin to fatigue. Diaphragm Fatigue A high oxidative capacity and capillary density appeared to make the diaphragm well suited for the high demands imposed by exercise (59).  Recent evidence of diaphragm fatigue is proving the diaphragm may not be ideally designed for prolonged heavy exercise.  Interestingly, sex-based differences with respect to diaphragm fatigue appear to be prevalent (31)  At high exercise intensities (> 85% V’O2MAX) when V’E is in excess of 120 l∙min -1, inspiratory flow rates are increased 8-10 times resting levels, indicating an increase in the velocity of inspiratory muscle shortening, with peak diaphragm pressure reaching 60% maximum capacity.  The increased elastic loads and velocity of muscle shortening cause substantial increases in the work of the diaphragm.  Johnson et al. (43) found evidence of diaphragm fatigue in healthy males, by decreases in trans- diaphragmatic pressure when electrically stimulated (Bilateral Phrenic Nerve Stimulation technique) near 13  end exercise.  At this point the accessory muscles of inspiration were contributing to a greater extent to maintain V’E as evident by a plateau in trans-diaphragmatic pressure with increasing V’E (43).   Compared to men, the female diaphragm appears to be more resilient to fatigue.  When diaphragm fatigue was measured in ET men and women during heavy exercise, women showed smaller decrements in trans-diaphragmatic pressure twitch potentiations 10, 30, and 60 minutes post exercise.  During exercise, the diaphragm’s contribution to total inspiratory force output decreased in male subjects who were more reliant on accessory muscles for inspiration, while the women had little change in diaphragmatic contribution, suggesting women have an increased resistance to fatigue (31).   Despite evidence of diaphragm fatigue, respiratory muscles are still capable of generating high ventilatory rates.  Minute Ventilation increased linearly throughout exhaustive exercise in ET men, while ET women’s V’E plateaued at high rates.  The plateau in V’E was likely due to mechanical ventilatory constraints as women’s diaphragmatic contributions changed little during exercise (31).  Diaphragm fatigue does appear to have an effect on limb blood flow due to its association with a respiratory muscle– limb reflex.   This metaboreflex appears to originate in the diaphragm and occur at its peak during fatiguing diaphragmatic contractions (75), causing ischemia, with increases in limb vascular resistance and decreases in resting limb blood flow.  High levels of central respiratory motor output did not affect leg blood flow or vascular resistance, supporting the argument for a peripheral cause of exercise termination. SENSORY RESPONSES Dyspnea Traditionally, limb discomfort and whole body fatigue have been the primary factors causing cessation of exercise in healthy individuals (63).  The leading source of termination of exercise by individuals suffering from respiratory diseases such as COPD, is dyspnea (63).  Dyspnea is “a subjective experience of breathing discomfort that consists of qualitatively distinct sensations that vary in intensity.  The experience derives from interactions among multiple physiological, psychological, social, and environmental factors, and may induce secondary physiological and behavioral responses” (4).  Dyspnea increases with increasing exercise intensity, and rises steeply during heavy and maximal exercise in healthy individuals.  Although direct evidence relating dyspnea to EFL or hyperinflation in young healthy individuals has yet to be shown in the literature, significant reductions of breathing discomfort during heavy exercise, have been shown when the respiratory muscles were unloaded (37, 71).  When a resistive load was added, ratings of dyspnea significantly increased.  If EFL and hyperinflation 14  increase the work of breathing, based on the aforementioned studies, perceptions of breathing discomfort would likely also be increased.  Considerable evidence relating mechanical ventilatory constraints to heightened dyspnea exists in individuals suffering from COPD and older populations.  Individuals with COPD develop EFL, lung hyperinflation, and an elevated WOB at rest and during exercise.  The best predictor of dyspnea in COPD patients appears to be increases in EELV; Marin et al. (50) found dyspnea increased when IC decreased (indicator of EFL) during exercise.  If similar mechanical ventilatory constraints (increases in operational lung volumes and EFL) are occurring in healthy men and women, dyspnea could potentially cause cessation of exercise via the same mechanism. This mechanism is brought about by lung hyperinflation and airway dynamic compression which is detected by receptors in the airways, lungs, and respiratory muscles and relayed to the somatosensory cortex within the brain.  The somatosensory cortex compares the afferent feedback with the efferent information (copy of the respiratory motor output) from the motor cortex.  If the ventilatory motor output does not match the efferent sensory information (i.e., hyperinflation) neuro-mechanical uncoupling occurs, increasing dyspnea (4, 76).      Sex-based differences in pulmonary structure and function appear to increase dyspnea ratings in older women and women with COPD.  Despite both men and women undergoing the same age-related declines in lung structure and function, for a given V’O2, healthy older women report significantly higher ratings of dyspnea, and a significantly greater number of older women report dypnea as the reason for exercise cessation (64).  Similarly, for a given airway obstruction, women suffering from COPD report higher dyspnea (19).   Evaluating dyspnea provides insight into the interconnection between the psychological and physiological changes occurring during exercise (62).  Potentially, mechanical ventilatory constraints could decrease exercise capacity by way of perceptions of discomfort, which may be higher in women (54). Leg Discomfort  As previously mentioned, diaphragm fatigue appears to trigger a metaboreflex causing vasoconstriction of locomotor muscles, ultimately reducing limb blood flow.  When respiratory muscle work was reduced (PAV) and diaphragm fatigue no longer occurred, sensations of leg discomfort were reduced (37, 71).  When the resistive ventilatory load was increased, further exacerbating diaphragm fatigue, leg fatigue and ratings of leg discomfort were augmented.  15  HELIOX Helium has a density a third that of N2 and a higher viscosity.  When the driving pressure to generate ventilation is low, both He and N2 flow patterns are laminar (streamline with high axial flow rates).  When the driving pressure to breathe is increased, the density and viscosity differences between the gases emerge.  Viscous forces dominate in He due to a low Reynold’s number, so flow remains laminar to a greater extent at high flow rates in the smaller airways.  Nitrogen, however, takes on a more turbulent flow pattern with eddy formations at junctions in the tracheobronchial tree due to the dominance of inertial forces characteristic of a high Reynold’s number.  Breathing heliox (He-O2) instead of room air (RA) will allow higher flow rates directly proportional to the pressure gradient generated by the thoracic cavity. The lower resistance of He-O2 will require smaller increases in trans-pulmonary pressure to generate high expiratory flows; a lower intra-thoracic pressure will decrease dynamic compression of the airways.  Any effect He has on increasing V’E and exercise capacity should be caused by its physical properties (i.e., lower density) as it has no direct positive metabolic action at the cellular level (12).   At low exercise intensities below the ventilatory threshold, He-O2 has not been shown to affect V’E.  Low V’E requires a low driving pressure, so airflow (both RA and He-O2) is laminar.  During heavy exercise when intrapleural pressures increase and V’E exceeds the ventilatory threshold, the density induced differences in airflow characteristics between RA and He-O2 emerge; RA with a more turbulent flow pattern and He-O2 with a predominantly laminar flow pattern.  It is at elevated V’E and flow rates where EFL develops when breathing RA.  For a given lung volume, He-O2 increases airflow rate enabling generation of larger VT, potentially eliminating EFL and the likely ensuing cascade of events – increases in operational lung volumes, WOB, and likely dyspnea.   Above the ventilatory threshold, and above 70-85% V’O2MAX, increases in V’E when inspiring He-O2 have been shown in both healthy young men and women (6, 13, 53, 79, 87).  Although EFL was not measured in all studies, it could be presumed the differences in V’E only occurred during heavy exercise when V’E was potentially mechanically constrained during RA breathing by EFL.    McClaran et al. (53) showed in a group of highly trained female runners, only those that developed EFL during RA breathing increased their V’E and maximal expiratory flow rates when breathing He-O2 while running at maximal capacity.  Heliox, as an inspirate, reduced EFL by increasing the MEFV curve; relatively smaller increases in EELV occurred and subjects were able to increase both VT and fb.  Inspiring He-O2 had no effect on V’E or operational lung volumes in the women that did not develop EFL breathing RA presumably because the NEFL women could achieve the highest V’E they required without mechanical constraint.   16  The chemical drive to breathe can be increased by inspiring 3% CO2.  When a group of untrained young healthy individuals inspired a hypercapnic gas mixture (3% CO2 - 21% O2 - 76% N2) maximal V’E was increased to the same extent as when He-O2 (79% He - 21% O2) was inspired.  However, the magnitude of EFL at maximal exercise was increased during the 3% CO2 trial (16% VT vs. He-O2 5% VT), because 3% CO2 was not capable of enhancing the ventilatory capacity (6).  When the same protocol was used on older men, EFL occurred to a greater extent during 3% CO2 (22% VT) than RA (12% VT) or He-O2 (10% VT).  Above the ventilatory threshold, V’E increased more so when breathing He-O2 compared to RA or 3% CO2, due to age-induced mechanical limitations (7).  It is likely the young subjects were able to increase their V’E to the same level when inspiring 3% CO2 as when inspiring He-O2 because of the lower maximal V’E (100 l∙min -1) their untrained aerobic capabilities demanded.  If the young subject group had been ET as studied by Johnson et al. (44), substantially higher V’E would likely not have been achievable when inspiring 3% CO2 due to mechanical constraint by the relatively reduced ventilatory capacity.  Adding dead space to the breathing apparatus increases the chemoreceptor drive to breathe through increases in VT.  When McClaran et al. (54) had ET male cyclists inspire N2O2, EELV increased and VT decreased at maximal exercise.  When dead space was added to the N2O2, VT was elevated but could not be maintained during maximal exercise due to impedance with the MEFV curve.  A He-O2 inspirate increased the athlete’s MEFV curve, preventing EFL and preserving VT (plateau) during maximal exercise with a lower EELV.  When dead space was added to the He-O2 condition, greater increases in VT were capable with smaller increases in EELV at higher V’E due to removal of EFL.   Performance Increases in time-to-exhaustion, and maximal workloads achieved at a lower V’O2 and V’O2MAX have been shown in healthy individuals when breathing He-O2 (7, 13).  The performance improvement is likely due to the greater V’E and flow rates achievable; a result of the enhanced ventilatory capacity and reduced EFL.  Unloading the respiratory muscles allows a significantly lower ventilatory mass to be moved during He-O2 breathing compared to RA (87).  The reduced oxygen cost of inspiring He-O2 could increase locomotor blood flow (via the metaboreflex) and thus increase exercise performance.   During high-intensity exercise, COPD patients breathing He-O2 were able to increase their endurance capacity via increases in V’E brought about by reduction in lung dynamic hyperinflation, allowing increases in IC (67). The He-O2 induced performance improvements occur only during maximal exercise whereby development of EFL is prevented and V’E is not restricted due to a limited VT (13).     17  Sensory Perceptions Heliox has been shown to reduce breathing discomfort in healthy young ET individuals and healthy older individuals compared to RA breathing by reducing the load on the respiratory muscles, the degree of dynamic hyperinflation and EELV (7, 54).  However, this is not a universal finding, as other studies have failed to find a difference in dyspnea during maximal exercise (6).  Individual dyspnea ratings compared to EFL susceptibility were not provided, so it is unclear whether differences in dyspnea occurred in those that developed EFL compared to those that did not.   Individuals suffering from respiratory diseases have lower ratings of dyspnea when inspiring He- O2.  When the WOB is reduced in individuals with COPD by breathing He-O2, increases in exercise tolerance and reduced rating of dyspnea arise (25, 63, 67).  It should be noted that there are conflicting results with respect to He-O2 alleviating dyspnea and EFL in COPD patients.  However, the discrepancies could be a result of the different mechanisms causing EFL in COPD patients. Heliox has no effect on dynamic hyperinflation if EFL is caused by mucous (viscous) rather than the density independent mechanism occurring in healthy populations (17).   The effect of He-O2 on leg fatigue in COPD patients varies from no effect to reduced ratings (25, 67).  In healthy young individuals leg discomfort was not affected by He-O2 (6) while leg discomfort decreased in older individuals (7).  The current literature is lacking in a measure of leg fatigue for a He-O2 inspirate in healthy individuals.    Work of Breathing, Diaphragm Fatigue, and Oxygen Cost of Inspiring Heliox Due to the reduced airflow resistance, a given V’E with He-O2  will require less muscular effort than that of RA, reducing the WOB (13). Wilson and Welch (87) found a significantly lower ventilatory mass was moved while inspiring He-O2 than 20% O2 - 80% N2 despite significantly higher V’E due to He’s lower density.  The WOB, diaphragm fatigue, and oxygen cost of breathing have yet to be measured during exercise with He-O2 in healthy ET individuals. CONCLUSION A balance between the chemical drive to breathe and mechanical constraints appear to regulate V’E.  Expiratory flow limitation and an increased WOB have been shown to develop in healthy ET men and both ET and untrained women.  Why EFL develops in some individuals and not others, along with its affect on sensory perceptions is not completely understood.  No studies have compared the effect of unloading the respiratory muscles with He-O2 on EFL between ET men and women.  The existing 18  literature indicates that women are more susceptible to developing EFL, as are individuals with extraordinarily high ventilatory requirements.  The differences in mechanical ventilatory constraints appear to be a result of structural and functional sex-based differences with respect to the pulmonary system.  Exercise performance could be at risk due to mechanical ventilatory constraints elevating the WOB leading to diaphragm fatigue and/or a reduction in limb blood flow.                         19  HYPOTHESES 1. During exercise with a He-O2 inspirate EFL (susceptibility and magnitude), operational lung volumes and the WOB will be reduced while expiratory flow rates and V’E will be increased in the men and women that develop EFL when breathing RA. 2. Sensations of breathlessness will be reduced by breathing He-O2 to a greater extent in those experiencing mechanical ventilatory constraints during RA breathing. 3. Increases in TT performance (power) will occur when the load on the respiratory system is reduced with a He-O2 inspirate. 4. It is expected the He-O2 induced changes will occur to a larger extent in women, as they will undergo greater mechanical ventilatory constraints during RA breathing.     20  METHODS SUBJECTS Twenty-seven (15 men and 12 women) competitive cyclists and/or triathletes were recruited to participate in this study.  Subjects were required to be 19-40 years of age (inclusive), free of cardiopulmonary disease, nonsmoking with normal pulmonary function as per % predicted values for age and gender (excluding asthmatics) (3).  In order to be considered ‘competitive’, subjects must have been regularly competing in cycling and/or triathlon races and possess an aerobic capacity greater than 50 or 60 ml∙kg-1∙min-1 (women and men respectively).  Two men and one woman were excluded due to inadequate maximal aerobic fitness.  A third man was excluded as a result of poor pulmonary function (Forced Expiratory Volume in 1 sec (FEV1.0) < 80 % predicted). A fourth man endured an injury preventing him from performing the final test.  In total 11 men and 11 women completed the entire experimental protocol.  Women were tested randomly throughout their menstrual cycle, as female sex hormones do not appear to consistently affect exercise V’E (9, 10, 18, 49) or endurance performance (17, 44).   EXPERIMENTAL PROTOCOL All testing occurred at the Health and Integrative Physiology Laboratory at the University of British Columbia.  Prior to testing, subjects provided written informed consent to participate, completed a Physical Activity Readiness Questionnaire (PAR-Q) (16), and completed a medical, menstrual, and activity history questionnaire (refer to Appendix C).  All procedures were approved by the Clinical Research Ethics Board at the University of British Columbia (H11-02521).  Testing took place over 3 days, from 1 week to slightly over a month apart.  Subjects were either in or out of competition season for both TTs and asked to keep their training regimes consistent prior to each TT (refer to Training Log Appendix C), refraining from caffeine 4 hrs prior to testing.  On Day 1 anthropometric measures were collected and pulmonary function measures were performed prior to an incremental cycle test to exhaustion to determine V’O2MAX.  When subjects deemed themselves sufficiently recovered (5-30 min) a familiarization (FAM) 5 km TT was performed.  A randomized cross-over design was used for the following 2 TTs.  Each subject was instrumented with an esophageal balloon-tipped catheter on Days 2 and 3 before completing a 5 km TT while breathing either humidified compressed RA or He-O2.  Subjects were blinded to the gas mixture they were breathing.   Day 3 was identical to Day 2 with subjects breathing the other gas type.     21  Incremental Exercise Test All exercise was performed on a cycle ergometer (VeloTron Pro, RacerMate Inc, Seattle, WA, USA).  Following a self-selected warm-up (range: 5-30 min), the incremental exercise test started at 260 Watts (W) for men and 160 W for women, with the workload increasing stepwise by 30 W every 3 min (VeloTron Coaching Software, version 1.6.458 RacerMate Inc.) until volitional exhaustion or when pedaling cadence fell below 60 revolutions per min (RPM).  The exercise protocols differed depending on sex, to ensure that both men and women exercised for approximately the same duration.  During the test subjects were verbally encouraged to achieve their maximal capacity.  The amount of recovery time following the V’O2MAX test and prior to the FAM 5 km TT was at each subject’s discretion.  One FAM TT was required based on highly reproducible performance in competitively trained cyclists (80).  Subjects were instructed to give their best effort on the TT, given the condition that they had just performed an exhaustive exercise bout.  The practice 5 km TT was administered in the same manner as the experimental 5 km TTs (see below) with the exception of the esophageal balloon and humidified compressed RA (or He-O2).   Experimental 5 km TTs Environmental conditions were kept as consistent as possible by having subjects perform both experimental TTs at the same time of day (morning or afternoon).  Additionally, on Day 2, subjects completed a food and activity log for that day and 3 prior days.  This log was provided to subjects who were asked to keep their nutrition and activity as consistent as possible for Day 3 (refer to Appendix C).  The esophageal balloon was inserted after which 5 min of resting metabolic data was collected with subjects on the cycle ergometer in a standardized race position.  The experimental 5 km TTs were performed breathing either humidified compressed RA or He-O2 (21% O2 - 79% He).  The percent O2 in the He-O2 was tightly controlled and ranged from 20.87% - 21.04%.  Following a self-selected warm-up similar to Day 1, both TTs began at a still start with subjects either in or out of the saddle.  If subjects chose to start out of the saddle they were required to get in the saddle within a few seconds and remain in the saddle for the duration of the test.  The initial gearing combination chosen by each subject on Day 2 was used again at the start of Day 3, but subjects were allowed to adjust the gears throughout each TT.  Upper body position was also standardized such that subject’s hands were to remain on the brake-hoods at all times during testing.  The straight, flat 5 km TT course was created and operated using commercially available software (VeloTron 3D, version 3, RacerMate Inc.)  During the TT, subjects watched a monitor displaying their distance covered, time elapsed, and cadence.  During the test the experimenter did not 22  verbally encourage subjects.  The exact bike set-up (seat and handle-bar positions) on Day 2 was recorded and subjects were required to ride in the identical position on Day 3 and warm-up for the same duration.   MEASUREMENTS Pulmonary Function Testing On Day 1, forced vital capacity (FVC), FEV1.0 and FEV1.0/FVC were determined using a portable spirometer (Spirolab II, Medical International Research, Vancouver BC, Canada) according to recommended guidelines (3).  Subjects were familiarized with the graded FVC maneuvers to be performed before and after the 5 km TTs to appropriately account for bronchodilation and thoracic gas compression as previously described (29).  Inspiratory capacity (IC) maneuvers were also practiced as they were to be performed at each km during the 5 km TTs.  Subjects were shown their flow-volume traces on a computer monitor and verbally coached on the maneuvers until successful completion was independently attained.  Metabolic Data Inspired and expired gases, pressure and flow values were measured using previously described hardware and software (23, 29, 30, 86).  In brief, ventilatory and mixed expired metabolic parameters were collected using a customized metabolic cart consisting of two calibrated pneumotachographs (model 3813, Hans Rudolph, Kansas City, MO) to measure inspiratory and expiratory flow, and calibrated O2 and CO2 analyzers (Model S-3-A/I and Model CD-3A, respectively, Applied Electrochemistry, Pittsburgh, PA).  Carbon dioxide could not be measured during the He-O2 trials due to He interfering with the infrared signal used by the CO2 analyzer to determine CO2 concentration.  The pneumotachographs were independently calibrated using a 3 l calibration syringe for both RA and He-O2.  Volumes were obtained by numerical integration of the flow signals.  Due to He’s lower heat capacity and higher thermal conductivity relative to N2, a low-resistance spirometry filter (PDS8505, Roxon, Vancouver) was placed before the expired pneumotachograph and the heater was increased to 43°C (RA TT temperature - 37°C).  The filter and elevated temperature were used to prevent moisture build-up on the pneumotachograph causing false measures of flow rates.  The spirometry filter was present in both trials to maintain a consistent set-up and external resistance.  Heliox expired ventilation was temperature corrected off-line during subsequent data analysis to take into account the vapour pressure of water at 43°C.  The humidified gases were inspired via a 2-way breathing valve connected to a continuously filled 200 l meteorological balloon (1197-25, VacuMed, Ventura, CA, USA) via a water-filled basin.  All raw data during the exercise test was recorded continuously at 200 Hz (PowerLab/16SP model ML 796, AD 23  Instruments, Colorado Springs, CO, USA) and stored on a computer for later analysis (Bibo, LabChart v6.1.3, AD Instruments, Colorado Springs, CO, USA).   Heart Rate A heart-rate monitor (S610i, Polar Electro, Kempele, Finland) was worn on the chest, and heart rate was recorded at rest, at every min during the incremental test, and at every 500 meters during the TTs. Sensory Responses Ratings of perceived exertion (RPE) for leg and breathing discomfort were determined using a 10-point category ratio scale (11), with ‘0, representing no breathing (or leg) discomfort’ and ‘10, representing the most severe breathing (or leg) discomfort one has experienced or could imagine experiencing’.  Ratings were recorded at rest and every min during the incremental test and every km during the TTs.  At exercise cessation, subjects were asked to state their main reason for stopping (incremental test) or not cycling faster (TT): leg, respiratory, combination, or other, as well as what relative percentages of leg and breathing discomfort contributed to exercise termination.  The RPEs recorded during the 5 km TTs were repeated back to each subject post exercise to confirm the correct ratings were obtained.  Subjects raised their right hand in the same manner during both TTs to the RPE scale suspended approximately 5 centimeters (cm) directly in front of the right handle bar.  The collection of RPEs on Day 1 during both the V’O2MAX test and FAM 5 km TT served as a familiarization procedure, enabling subjects to become accustomed to reporting how their legs and breathing feel during exercise. Expiratory Flow Limitation Forced Vital Capacities and Graded FVCs were performed pre and post (within 2 min) exercise while ICs were performed at the end of each km.  On Day 1, FVCs and graded FVCs were performed as a familiarization for the forthcoming experimental 5 km TTs.  During the V’O2MAX test, ICs were performed during the last 30 sec of each stage.  If adequate IC maneuvers were not performed during the V’O2MAX test, subjects were given appropriate feedback during the recovery time to correct their ICs for the FAM 5 km TT. The highest flows recorded for a given volume from the FVCs and graded FVCs were compiled to form the outer boundary of the MEFV curve to account for thoracic gas compression and bronchodilation as previously described by Guenette et al. (29).  Expiratory flow limitation was determined by superimposing the expiratory portion of a tidal breath for each km within the MEFV curve.  24  The tidal breath was an ensemble average of approximately 10 tidal breaths preceding the IC maneuver performed at the end of every km during the 5 km TTs.  The magnitude of EFL was calculated as the volume of tidal breath overlapping the MEFV curve divided by the tidal volume during each km. Operational Lung Volumes End expired lung volume (EELV) was measured by subtracting the IC from the resting FVC.  Exercise tidal volume (ensemble average of 10 tidal breaths preceding the IC) was added to EELV to determine end inspired lung volume (EILV).  Inspiratory capacity was considered accurate when peak inspiratory esophageal pressure reached or exceeded that obtained during rest (29, 45). Ventilatory Capacity  Ventilatory capacity (V’E CAP) was estimated for each subject breathing both RA and He-O2.  The V’E CAP is an estimate of the maximal expiratory flows an individual is theoretically capable of attaining for their chosen breathing pattern (49).  Exercise flow-volume loops were placed with the MEFV loop, and the tidal breath was divided into equal 40 ml segments.  For each segment, the change in volume was divided by the highest expiratory flows attained to determine an expiratory duration.  The expiratory durations for the all segments were summed to estimated minimal expiratory duration.  Inspiratory time was calculated based on the ratio of inspiratory-to-total breathing cycle time ratio.  Maximal breathing frequency was calculated based on the minimum tidal breath.  Estimated V’E CAP is the product of maximal breathing frequency and tidal volume.  Ventilatory reserve is the difference between V’E CAP and the subject’s V’E.        Work of Breathing Prior to the insertion of a balloon-tipped esophageal catheter (no. 47-9005-RO, Ackrad, Trumbull, CT), subjects sniffed 1 ml of xylocaine viscous 2% to minimize discomfort.  While the subject sipped water through a straw, the catheter was inserted ~45 cm down the nasal passage.  The catheter was then connected to a 3-way stopcock that connected to a pressure transducer (Validyne, MCI-10, Northridge, CA, USA).  Subjects performed a Valsalva maneuver to expel all air from the balloon. One ml of air, as per manufacturer specifications, was injected into the balloon via the 3-way stopcock.  As the subjects took sharp sniffs, the catheter was slowly pulled out of the nose (thereby out of the stomach and esophagus) until the first negative pressure deflection occurred (indicating the balloon had surpassed the level of the diaphragm).  The catheter was then pulled-up an additional 10 cm, approximately at the level of the heart and sufficiently above the diaphragm. Validity of the balloon placement was determined by having the subject expire against an occluded airway (dynamic occlusion test); if transpulmonary  25  pressure remained constant while airway opening pressure increased, catheter placement was considered correct (58).  Depth markings on the catheter allowed the exact balloon placement to be recorded and replicated for the subsequent test.  Ample surgical tape was used to secure the balloon to the nose in order to prevent movement during exercise.  Mouth pressure was measured at a port in the mouthpiece connected to another pressure transducer.  Transpulmonary pressure was calculated as the difference between esophageal and mouth pressures.  The pressure transducers were calibrated using a mercury manometer; signals were amplified (gain PM: 10, PE: 25), filtered (PM and PE: 200 Hz), and connected to the previously described data acquisition system whereby the signal was converted from volts into cmH2O. The WOB was determined by taking the integral of an ensemble average of several transpulmonary pressure volume loops using a customized software program as previously described (30, 83).  The WOB was multiplied by the frequency of breathing (fb) to determine the work done per min by the respiratory system and converted into joules per min (J∙min-1).     Performance  The VeloTron is a cycle ergometer directly measuring power from which speed is calculated.  As such, improvements in performance were determined from power output over the course of the 5 km and at each km.  Cadence, speed and time were also taken into consideration.  Statistical Analysis A sample size of 16 was selected based on an 80% power to detect a significant difference in dyspnea intensity at a standardized time during the TT via a relevant difference in Borg rating (±1) (64).  However a sample size of 11 was achieved due to the response of adequate subjects willing to volunteer for the study.  As a result the study was likely underpowered to detect a significant difference in sensory responses or performance.   Unpaired t-tests were used to examine descriptive characteristics, pulmonary function and maximal exercise data between men and women.  Repeated measures ANOVA (Statistica 6.1, Stat Soft Inc., Tulsa, OK, USA) were used to compare the effects of RA versus He-O2 between men and women for: metabolic and cycling variables, EFL (magnitude), WOB, RPE and operational lung volumes.  If significant F-ratios were detected, Tukey’s post hoc test was applied to determine where the differences occurred.  Linear regression analysis was used to determine the relationship between EFL, performance and the selected respiratory parameters.  The level of significance was set at P < 0.05 for all statistical comparisons.  26  Performance data from the 2 TTs were analyzed using paired t-tests and the magnitude-based inferences approach (41).  Coefficients of variation (CV) for time and power were determined using previously reported variations for elite cyclists during indoor cycling due to the effects of environmental factors on outdoor cycling performance.  The typical variation in indoor cycling TT performance time in elite cyclists is thought to be approximately 1% (0.7 – 1.1%) (68, 78, 80).  Using the more liberal 0.7% CV the smallest worthwhile change in performance would be 0.21% or a 1.04 sec improvement.  A conservative CV (1.1%) results in the smallest worthwhile change in performance time of 0.33% (1.64 sec improvement) (40).  On an indoor cycle ergometer, the CV for power (W) has shown to be between 1.9 – 2.1% (78, 80).  The smallest worthwhile changes in power would be 0.57% (1.31 W) and 0.63% (1.45 W) for CV of 1.9 and 2.1% respectively (40).    27  RESULTS SUBJECT CHARACTERISTICS AND RESTING PULMONARY FUNCTION Descriptive and anthropometric data for subjects completing the entire experimental protocol are presented in table 1.  Men were on average older than the women, but both groups were under 40 years of age.  Normal pulmonary function was present in all subjects as per the predicted equations set by the American Thoracic Society and European Respiratory Society (3) with FEV1.0/FVC > 80% predicted (table 2).      Table 1 - Descriptive and Anthropometric Data  Men (n = 11) Women (n = 11) P value Age (yr)   30.5 ± 5.3 (22 – 39)   26.3 ± 4.3 (19 – 34)  0.05 Height (cm) 180.4 ± 6.5 (170 – 187) 167.8 ± 6.4 (159 – 179) < 0.001 Weight (kg)   73.7 ± 6.5 (60.1 – 84.8)   59.0 ± 6.1 (50.2 – 70.6) < 0.001   Values are means ± SD (range).        Table 2 - Pulmonary Function Data  Men  (n = 11) Women  (n = 11) P value FVC (l) 5.7 ± 0.7 (4.5 – 6.6)      4.3 ± 0.7 (3.0 – 5.5) < 0.001 FVC (% predicted)        108 ± 8 (96 – 118)     111 ± 11 (85 – 125)  0.48 FEV1.0 (l)         4.5 ± 0.6 (3.6 – 5.6)      3.5 ± 0.6 (2.5 – 4.4) < 0.001 FEV1.0 (% predicted)        102 ± 11 (82 – 118)     105 ± 9 (94 – 122)  0.38 FEV1.0/FVC (%)    79.7 ± 3.6 (74.8 – 85.2)   81.1 ± 4.2 (74.6 – 88.1)  0.22 FEV1.0/FVC (% predicted)          98 ± 4 (92 – 103)       97 ± 5 (89 – 104)  0.90 PEF (l∙sec-1) 11.2 ± 1.3 (9.8 – 13.0)      7.5 ± 1.1 (5.6 – 9.0) < 0.001 PEF (% predicted)        112 ± 11 (99 – 130)     102 ± 15 (78 – 123)  0.08  FVC, forced vital capacity; FEV1.0, forced expired volume in 1 sec; PEF, peak expiratory flow.  Values are means ± SD (range). 28  All subjects met the ‘competitive’ cyclist criteria, and were actively involved in road, mountain, cyclo-cross and/or triathlon, with some athletes competing in more than one discipline (table 3).  Subjects competed at a variety of levels ranging from regional to international competitions.  National or international level competitors did so as ‘age-groupers’ with the exception of 2 women.  One woman was a member of the provincial road cycling team and the other was a professional Ironman triathlete.  Due to the timing and duration of testing, 13 subjects were ‘in’ competition season and 9 subjects were ‘out’ of competition season, but all were actively training (table 3).     Table 3 - Cycling Background Experience   Discipline Competition Level Competition Status  Road Triathlon Mountain Cyclo-cross Regional Provincial National International In-season Off-season Men  (n = 11) 6 3 2 1 5 2 3 1 7 4 Women  (n = 11) 5 6 1 2 5 1 2 3 6 5    INCREMENTAL CYCLE TEST  Maximal oxygen consumption and cycling parameters during the incremental cycle test are presented in table 4.  All women met the required V’O2MAX of 50 ml∙kg∙min -1 (55.9 ± 3.1 ml∙kg∙min-1).  Seven men met the V’O2MAX criteria of 60 ml∙kg∙min -1 (60.8 ± 3.8 ml∙kg∙min-1), and 4 men were within 5 ml∙kg∙min-1 of the standard.  On average men achieved significantly higher V’O2MAX (relative and absolute), V’CO2, V’E and VT than women.  However, women’s V’O2MAX values reached a significantly higher percentage of their predicted maximal aerobic capacities (women: 148 ± 14 vs. men: 134 ± 11 % predicted) (46).  Breathing frequency and HR were comparable between men and women (P > 0.05).  The peak power attained my men was significantly higher than women (men: 361 ± 24 vs. women: 283 ± 34 W, P < 0.001), but this difference was no longer present when expressed relative to body weight (men: 4.9 ± 0.4 vs. women: 4.8 ± 0.4 W∙kg-1, P = 0.50).  The incremental cycle test lasted approximately the same duration for both men and women (women: 835.6 ± 224.1, range: 601.2 – 1217.4 vs. men: 723.9 ± 142.3, range: 607.2 – 1013.4 sec, P = 0.18) with all subjects cycling to volitional exhaustion, as indicated by similar respiratory exchange ratios (RER) (men: 1.11 ± 0.03 vs. women: 1.08 ± 0.04, P = 0.12). At the end of the incremental cycle test men’s RPE for leg discomfort was significantly higher than women’s (men: 9 ± 0.6 and women: 7.5 ± 1.9, P = 0.002). Breathing discomfort was also significantly higher for men (men: 8.5 ± 0.7 vs. women: 7.3 ± 1.7, P = 0.009).  However no sex differences emerged for the 29  relative contribution of leg (men: 56 ± 12 vs. women: 65 ± 9%, P = 0.41) or breathing (men: 44 ± 12 vs. women: 35 ± 9%, P = 0.41) discomfort contributing to exercise termination.  The main reason for exercise termination was leg discomfort (men: n = 7 and women: n = 7) followed by a combination of leg and breathing discomfort (men: n = 3 and women: n = 3) and breathing discomfort (men: n = 1 and women: n = 1).  The FAM 5 km TT was performed in a significantly faster time by the men (477.7 ± 15.6 sec) than it was by the women (534.8 ± 36.9 sec, P = 0.01).  Table 4 - Maximal Values from Incremental Cycle Test to Exhaustion   Men Women P value V’O2 (ml∙kg -1∙min-1) 60.8 ± 3.8 (55.3 – 67.0)          55.9 ± 3.1 (51.8 – 61.3) < 0.05 V’O2 (l∙min -1)  4.47 ± 0.40 (3.80 – 4.98) 3.29 ± 0.40 (2.89 – 3.88) < 0.05 V’O2 (% predicted)            134 ± 11 (118 – 151)           148 ± 14 (131–173)    < 0.05 V’CO2 (l∙min -1)           4.90 ± 0.40 (4.12 – 5.44) 3.55 ± 0.40 (3.12 – 4.21) < 0.001 V’E (l∙min -1)    140.2 ± 11.7 (117.9 – 163.4) 100.7 ± 13.6 (83.7 – 132.9) < 0.001 fb (l∙min -1)              58 ± 14 (34 – 78)             57 ± 9 (46 – 72)  0.75 VT (l)           2.88 ± 0.50 (2.35 – 4.01) 2.10 ± 0.40 (1.44 – 2.75) < 0.001 RER  1.11 ± 0.03 (1.07 – 1.15) 1.08 ± 0.04 (1.03 – 1.14)  0.12 HR (beats∙min-1)            193 ± 16 (178 – 233)           185 ± 11 (168 – 204)  0.22 Peak Power (Watts)            361 ± 24 (320 – 410)           283 ± 34 (250 – 340) < 0.001 Peak Power (Watts∙kg-1)             4.9 ± 0.4 (4.5 – 5.5)            4.8 ± 0.4 (4.3 – 5.6)  0.50 Duration (sec)        723.9 ± 142.3 (525.0 – 1013.4)      835.58 ± 224.1 (601.2 – 1217.4)  0.18  V’O2, oxygen consumption; V’CO2, carbon dioxide production; RER, respiratory exchange ratio; V’E, minute ventilation; VT, tidal volume; fb, frequency of breathing; HR, heart rate.  Values are means ± SD (range).   EXPERIMENTAL 5 KM TIME TRIALS  Performance – Power Heliox was associated with a 2.3% improvement in average power output over the 5 km (~5.3 W, F (1) = 3.98, P = 0.06) compared to the RA trial for men and women combined.  Using the magnitude- based inferences approach with a liberal threshold of performance improvement (1.31 W, refer to Methods) the chances the effect of He-O2 is beneficial/trivial/harmful are 95.5/2.2/2.3%.  Similarly the more conservative performance improvement threshold (1.45 W) finds the chances of the effect beneficial/trivial/harmful to be 95.3/2.5/2.2%.  Based on a 95% CI [-0.2, 10.7] for men and women combined.  The ‘true’ effect of He-O2 on performance could be slightly worse (-0.2 W) or definitely worthwhile (+10.7 W) (figure 1 and table 5).   30  Men’s power output was on average 1.6% higher on the He-O2 TT than the RA TT (~5.0 W, t (10) = 1.29, P = 0.23, d = 0.39).  Using the more liberal threshold of wattage improvement (1.78 W), the chances that the effect of He-O2 is beneficial/trivial/harmful are 31.7/67.7/0.6% using the magnitude- based inferences of performance improvement.  With a more conservative (1.97 W) for performance improvement, the chances are 25.6/74.0/0.4%.  Based on the men’s 95% CI [-2.7, 12.7], the ‘true’ effect of He-O2 on power could be slightly worse (-2.7 W) or definitely worthwhile (+12.7 W).   Women’s power output was on average 2.9% higher on the He-O2 TT than the RA TT (~5.5 W, t (10) = 1.54, P = 0.15, d = 0.47).  Using the more liberal threshold of power improvement (1.08 W), the chances that the effect of He-O2 is beneficial/trivial/harmful are 67.4/31.3/1.3% using the magnitude- based inferences of performance improvement.  With a more conservative (1.19 W) for performance improvement, the chances are 63.5/35.4/1.0%.  Based on the women’s 95% CI [-2.3, 13.2], the ‘true’ effect of He-O2 on wattage could be slightly worse (-2.3 W) or definitely worthwhile (+13.2 W).     Figure 1 - Men and Women TT Performance - Power   RA TT Power (W) 150 200 250 300 350 400 H e- O 2 T T P ow er  (W ) 150 200 250 300 350 400 Men Women Men - Average Women - Average31  Nine men and 8 women had a higher power output on average during the He-O2 TT compared to the RA TT (men: 9.8 ± 7.6; women: 10.6 ± 7.5 W); 2 men and 2 women produced more power breathing RA (men: 16.5 ± 7.8; women: 12.5 ± 9.3 W); 1 women’s power was not affected by He-O2 (table 6).  Men produced significantly more power than women for both RA (men: 312.6 ± 33.8 vs. women: 218.2 ± 39.1 W, P = 0.002) and He-O2 (men: 317.6 ± 36.9 vs. women: 223.6 ± 37.2 W, P = 0.002) TTs.  Performance - Time Heliox was associated with a 0.9% improvement in performance time (~4.5 sec, F (1) = 4.05, P = 0.058) compared to the RA trial for men and women combined.  Using the magnitude-based inferences approach with a liberal threshold of performance improvement (1.04 sec) the chances that the effect of He-O2 is beneficial/trivial/harmful are 96.1/1.6/2.3%.  The conservative performance improvement threshold (1.64 sec) results in 95.2/2.8/2.1% chances that the effect is beneficial/trivial/harmful.  Based on a 95% CI [-0.2, 9.1] for men and women combined.  The ‘true’ effect of He-O2 on performance could be slightly worse (-0.2 sec) or definitely worthwhile (+ 9.1 sec) (table 5). Men completed the He-O2 TT an average of 0.7% faster than the RA TT (~3.2 sec, t (10) = 1.42, P = 0.32, d = 0.43).  With a liberal threshold of performance improvement (0.96 sec), the chances the effect of He-O2 is beneficial/trivial/harmful are 67.4/30.7/1.9% using the magnitude-based inferences of performance improvement.  With a more conservative approach (1.5 sec) for performance improvement, the chances are 46.8/52.4/0.8%.  Based on the men’s 95% CI [-3.4, 9.7], the ‘true’ effect of He-O2 on performance could be slightly worse (-3.4 sec) or definitely worthwhile (+9.7 sec).   Women were on average 1.1% faster on the He-O2 TT than the RA TT (~5.8 sec, t (10) = 1.50, P = 0.16, d = 0.45).  With a liberal threshold of performance improvement (1.1 sec), the chances the effect of He-O2 is beneficial/trivial/harmful are 65.1/33.6/1.3% using the magnitude-based inferences of performance improvement.  With a more conservative (1.7 sec) for performance improvement, the chances are 41.2/58.3/0.5%.  Based on the women’s 95% CI [-0.8, 12.3], the ‘true’ effect of He-O2 on performance could be slightly worse (-0.8 sec) or definitely worthwhile (+12.3 sec).   Eight men and 8 women completed the He-O2 TT faster than the RA TT (men: 6.8 ± 3.7; women: 11.2 ± 9.4 sec); 3 men and 3 women were faster breathing RA (men: 6.4 ± 6.3; women: 8.7 ± 8.6 sec) (table 6).  Men were significantly faster than women for both RA (men: 461.8 ± 19.5 vs. women: 532.0 ± 36.7 sec, P = 0.002) and He-O2 (men: 458.6 ± 20.2 vs. women: 526.2 ± 32.5 sec, P = 0.003) TTs.   32   Table 5 - Summary of 5 km TT Performance Data (Performance Time and Power Output)   Performance Time Power Output Effect of Intervention Subject Group Treatment Intervention Mean (sec) ± SD 95% CI (sec) P Mean (W) ± SD  95% CI (W) P Men & Women RA 496.9 ± 45.9 ± 4.7 [-0.2, 9.1] 0.06 265.4 ± 60.1 ± 5.5 [-0.2,10.7] 0.06 unclear He-O2 492.4 ± 43.5 270.6 ± 60.2 Men RA 461.8 ± 19.5 ± 6.6 [-3.4, 9.7] 0.32 312.6 ± 34.0 ± 7.7 [-2.7,12.7] 0.23 unclear He-O2 458.6 ± 20.2 317.6 ± 36.9 Women RA 532.0 ± 36.7 ± 6.6 [-0.8, 12.3] 0.16 218.2 ± 39.1 ± 7.8 [-2.3, 13.2] 0.15 unclear He-O2 526.2 ± 32.5 223.6 ± 37.2   Table 6 - TT Performance Improvement  Higher Power Output TT He-O2 Higher Power Output TT RA  Subjects  (n) Performance Improvement (W) Test Order (n) Subjects  (n) Performance Improvement (sec) Test Order (n) 1st 2nd 1st 2nd Men 9    9.8 ± 7.6 (1.0 – 23.0) 4 5 2  16.5 ± 7.8 (3.0 – 21.0) 1 1 Women 8  10.6 ± 7.5 (3.0 – 21.0) 4 4 2  12.5 ± 9.3 (6.0 – 9.0) 1 1  Values are means ± SD (range).  The TT with the highest power output was performed 1st for nearly half of the subjects accordingly test order did not appear to have an effect on performance (table 6).  Women had a significantly longer duration between Day 2 and Day 3 tests (men: 7.7 ± 4.1 vs. women: 15.3 ± 10.5 days, P = 0.04).   Average speed, power, and cadence over the RA and He-O2 TTs are presented in table 7.  Men cycled significantly faster (km∙hr-1) on average throughout both 5 km TTs compared to women (P < 0.05) and produced a significantly greater amount of absolute power (P < 0.05).  Power in relation to body weight (W∙kg-1) was not affected by sex or inspirate (P > 0.05).  There were no sex-based differences in RPM during either TT (P > 0.05).   The 5 km TT average speed (km∙hr-1) for men and women combined was significantly greater on He-O2 than on RA (RA: 36.6 ± 3.3 vs. He-O2: 36.9 ± 3.2 km∙hr -1, P = 0.04).  However He-O2 had no effect on men or women’s speed as individual groups (men: P = 0.49, women: P = 0.35).  Combined or separate, men’s and women’s RPM over the 5 km TT’s were not affected by He-O2 (combined: P = 0.35, men: P = 0.94, women: P = 0.86). 33   Table 7 - Average Speed, Power and Cadence over the RA and He-O2 5 km TTs  RA He-O2 P Value Speed (Average km∙hr-1) Combined 36.6 ± 3.2 36.9 ± 3.2  0.04 Men 39.1 ± 1.6 39.4 ± 1.7 0.49 Women 34.1 ± 2.4 34.4 ± 2.2 0.35 Power (Average W) Combined 265.4 ± 60.1 270.6 ± 60.2 0.06 Men 312.6 ± 33.8 317.6 ± 36.9 0.54 Women 218.2 ± 39.0 223.6 ± 37.2 0.47 Power (Average W∙kg-1) Combined 4.0 ± 0.6      4.1 ± 0.6   0.06 Men 4.3 ± 0.5      4.3 ± 0.6   0.68 Women 3.7 ± 0.5      3.8 ± 0.5   0.38 Cadence (Average RPM) Combined      102 ± 7        103 ± 9 0.35 Men      106 ± 8        107 ± 9 0.94 Women 98 ± 5        100 ± 7 0.86   Values are means ± SD.  Performance data for each km is presented in figure 2.  Men cycled at a significantly faster speed (km∙h-1) and produced a significantly greater amount of power than women at each km throughout both the He-O2 and RA 5 km TT.  On He-O2, women cycled at a significantly faster speed (km∙h -1) compared to RA at 3 km, while men displayed no differences between the 2 TTs.  On RA men completed the 1st, 3rd, 4th and 5th km significantly faster than women, while on He-O2 the 1 st, 4th and 5th km were performed significantly faster by men than women.  RPMs were not affected by sex or inspirate throughout the TTs.   Familiarization TT The men’s experimental TTs were completed significantly faster than their respective FAM TTs (P < 0.001).  Women completed the experimental TTs faster but did not reach statistical significance (RA vs. FAM, P = 0.96; He-O2 vs. FAM, P = 0.13).     34   Figure 2 - Time, Cadence, Power and Speed for men and women during the RA and He-O2 TTs.  τ significantly different RA TT men vs. women, * Significantly different He-O2 TT men vs. women, † significantly different RA vs. He-O2 TT for women.  Data are presented as means ± SE.  Statistical significance is set at the level of P < 0.05.     T im e  ( s ec ) 85 90 95 100 105 110 115 120 *   *   *    † Distance (km) 1 2 3 4 5 S p e e d  ( k m . h -1 ) 30 32 34 36 38 40 42 Men RA W RA Men He-O2 Women He-O2 P o w er  ( w a tt s ) 180 200 220 240 260 280 300 320 340 360 *  * * * *    Cad e nce  ( R P M ) 85 90 95 100 105 110 115 * * * *35  Metabolic Data & Breathing Pattern  Metabolic data for each TT is presented in table 8 (RA) and table 9 (He-O2). Throughout the entire RA and He-O2 TTs, men reached significantly higher V’O2 (l∙min -1), V’CO2 (RA only), V’E and V’T than women.  Frequency of breathing, V’O2 (ml∙kg∙min -1), RER (RA only), and HR were not significantly different between men and women at rest or during either TT. The ventilatory response to exercise is presented in figure 3, panel A, B and C.  Women breathed at a significantly higher frequency during the He-O2 TT, while men had a significantly higher fb at 4 km on He-O2 compared to RA.  At 5 km, sex appeared to play a role on VT whereby men’s VT increased on He-O2 and women’s decreased (P = 0.02).  There were no significant differences in V’O2, V’E or HR between the RA and He-O2 TTs for men or women.  Bronchodilation occurred in all subjects as determined by visual inspection.  Post exercise FVC and graded FVC’s were performed with higher expiratory flow rates generating a larger post exercise MEFV curve.  Refer to Appendix B for individual figures.   Heliox significantly increased peak expiratory flow and maximal expiratory flow at 50% of vital capacity for men and women (table 10).  Exercise expiratory flow rates were significantly higher on He- O2 compared to RA for men and women combined (RA: 5.72 ± 1.25 vs. He-O2: 7.05 ± 1.80 l∙sec -1, P < 0.001).  As a group, men’s maximal expiratory flow rates were significantly higher on He-O2 compared to RA (RA: 6.65 ± 0.90 vs. He-O2: 7.25 ± 8.57 l∙sec -1, P < 0.001), as were women’s (RA: 4.78 ± 0.73 vs. He-O2: 5.27 ± 5.52 l∙sec -1, P = 0.002).  Men’s expiratory flow rates increased to a significantly greater extent than women’s (Men: 9% vs. women: 5%, P < 0.001).                36 Table 8 - Room Air TT Metabolic Data RA  Rest 1 km 2 km 3 km 4 km 5 km V’O2 (l∙min-1) Men 0.38* ± 0.08   (0.25 – 0.56) 3.42* ± 0.43   (2.46 – 4.14) 3.82* ± 0.49  (3.10 – 4.78) 4.01* ± 0.50  (3.33 – 4.93) 4.14* ± 0.54   (3.40 – 5.06) 4.21* ± 0.56   (3.54 – 5.17) Women 0.26* ± 0.10  (0.11 – 0.43) 2.66* ± 0.40   (2.11 – 3.13) 2.84* ± 0.44   (2.35 – 3.49) 2.95* ± 0.50  (2.35 – 3.68) 2.98* ± 0.53   (2.33 – 3.70) 3.04* ± 0.55   (2.26 – 3.78) V’O2 (ml∙kg-1∙min-1) Men 5.16 ± 1.12 (3.31 – 6.93)  46.68 ± 6.31 (31.77 – 54.64) 51.91 ± 6.17 (40.00 – 63.16) 54.57 ± 5.98  (42.99 – 65.07) 56.23 ± 6.11 (43.92 – 66.74) 57.19 ± 6.40 (45.70 – 68.23) Women      4.36 ± 1.23     (1.92 – 6.16)  44.92 ± 3.35  (40.10 – 51.52) 48.00 ± 4.03 (42.57 – 55.28) 49.74 ± 5.17 (42.71 – 58.74) 50.35 ± 5.68  (41.61 – 58.70) 51.32 ± 5.84 (41.13 – 58.68) V’CO2 (l∙min-1) Men 0.36* ± 0.09  (0.25 – 0.54) 3.32* ± 0.56  (2.17 – 3.81) 4.47* ± 0.61  (5.42 – 3.47) 4.46* ± 0.47   (3.76 – 5.46) 4.49* ± 0.47   (3.73 – 5.52) 4.57* ± 0.56  (3.79 – 5.65) Women 0.26* ± 0.11  (0.10 – 0.50) 2.51* ± 0.38  (1.93 – 2.98) 3.11* ± 0.53   (2.26 – 3.86) 3.09* ± 0.55 (2.17 – 3.73) 3.08* ± 0.54   (2.20 – 3.80) 3.14* ± 0.53   (2.33 – 3.93) V’E (l∙min-1) Men 11.5 ± 3.4    (8.5 – 19.4) 83.3* ± 18.0    (50.9 – 103.4) 113.6* ± 19.3    (73.3 – 136.8)  121.1* ± 18.7    (86.9 – 151.4) 126.9* ± 15.3    (103.3 – 155.3) 134.4* ± 12.7    (115.8 – 157.3) Women  9.4 ± 5.8   (3.6 – 25.3) 65.2* ± 10.6  (42.9 – 76.0) 83.1* ± 14.0 (55.1 – 93.5) 87.0* ± 15.2    (60.0 – 103.8) 90.3* ± 16.4     (57.5 – 109.5) 94.4* ± 17.8     (56.7 – 117.6) fb (breaths∙min-1) Men          13 ± 3        (11 – 19)   37 ± 10   (23 – 50)   44 ± 11   (28 – 58)   47 ± 12   (31 – 64)   50 ± 12   (35 – 69) 55 ± 12 (39 – 76) Women          13 ± 5          (7 – 25) 39 ± 8   (29 – 52)   48 ± 13   (33 – 76)   51 ± 12   (36 – 76) 52 ± 9   (42 – 66) 54 ± 10 (44 – 72) VT (l) Men  1.0 ± 0.3  (0.7 – 1.6) 2.7* ± 0.5   (2.1 – 3.7) 3.1* ± 0.6   (2.5 – 4.3) 3.1* ± 0.6  (2.5 – 4.4) 3.0* ± 0.6 (2.4 – 4.4)      2.9* ± 0.6       (2.3 – 4.2) Women  0.8 ± 0.2  (0.6 – 1.2) 2.0* ± 0.4 (1.3 – 2.5) 2.2* ± 0.5 (1.0 – 3.0) 2.1* ± 0.5  (1.0 – 3.0) 2.1* ± 0.5   (1.1 – 2.9) 2.1*± 0.4 (1.3 – 2.8) RER Men  0.98 ± 0.14  (0.82 – 1.31) 0.99 ± 0.15 (0.65 – 1.14) 1.18 ± 0.15 (0.87 – 1.34)   1.12 ± 0.11   (0.96 – 1.27)   1.09 ± 0.11   (0.96 – 1.30) 1.09 ± 0.12 (0.96 – 1.38) Women 1.00 ± 0.32 (0.80 – 1.94) 0.96 ± 0.08 (0.88 – 1.11) 1.10 ± 0.10 (0.96 – 1.29)  1.05 ± 0.09 (0.92 – 1.18) 1.03 ± 0.08 (0.94 – 1.18) 1.04 ± 0.08 (0.95 – 1.21) HR (beats∙min-1) Men         61 ± 4      (55 – 69) (n=9) 165 ± 12  (138 – 177)      171 ± 11 (147 – 181)      175 ± 8 (161 – 184)       179 ± 6      (169 – 187)       184 ± 6 (173 – 192) Women         63 ± 7        (56 – 74) 163 ± 11  (147 – 178)      168 ± 12     (150 – 184)    172.4 ± 10 (157 – 186) 175 ± 10   (158 – 188)       181 ± 10      (166 – 195)  V’O2, oxygen consumption; V’CO2, carbon dioxide production; RER, respiratory exchange ratio; V’E, minute ventilation; VT, tidal volume; fb, frequency of breathing; HR, heart rate;  Values are means ± SD (ranges).  *Significantly differences between men and women.           37   Table 9 - Heliox TT Metabolic Data He-O2  Rest 1 km 2 km 3 km 4 km 5 km V’O2 (l∙min-1) Men 0.34 ± 0.09 (0.24 – 0.53) 3.48* ± 0.52  (2.75 – 4.26) 3.72* ± 0.38    (3.10 – 4.31) 3.90* ± 0.42    (3.28 – 4.57) 4.07* ± 0.44   (3.42 – 4.86) 4.15* ± 0.45  (3.47 – 4.93) Women 0.28 ± 0.10 (0.03 – 0.39) 2.54* ± 0.35        (2.15 – 3.11) 2.70* ± 0.41   (2.17 – 3.38) 2.85* ± 0.45    (2.17 – 3.56) 2.84* ± 0.47    (2.22 – 3.69) 2.89* ± 0.49  (2.21 – 3.65) V’O2 (ml∙kg-1∙min-1) Men 4.64 ± 1.11 (3.18 – 7.04)  47.32 ± 6.22 (35.94 – 55.31) 50.63 ± 4.81 (43.42 – 59.18) 52.99 ± 4.86   (45.09 – 61.37) 55.33 ± 4.38 (48.74 – 62.42) 56.40 ± 4.39 (49.36 – 64.11) Women    4.66 ± 1.76   (0.52 – 7.12)  42.99 ± 3.29 (38.93 – 50.64) 45.44 ± 4.37 (39.37 – 51.34) 47.90 ± 5.43   (39.35 – 55.92 ) 48.09 ± 5.73   (40.52 – 57.33) 48.92 ± 6.00 (40.13 – 58.36) V’E (l∙min-1) Men    10.5 ± 3.4    (6.5 – 17.1) 85.3* ± 16.3        (54.1 – 113.5)   116.0* ± 19.2        (83.5 – 144.4)     122.9* ± 17.4     (95.3 – 149.2)     131.0* ± 13.1          (110.0 – 149.8)   141.6* ± 12.6      (123.4 – 160.7) Women 9.2 ± 4.3    (0.9 – 19.4)    66.3* ± 9.5  (46.2 – 78.3) 83.9* ± 14.8        (63.5 – 109.0) 89.2* ± 17.2     (60.8 – 115.8)   92.4* ± 16.5        (64.3 – 117.4) 97.3* ± 18.2     (63.7 – 120.3) fb (breaths∙min-1) Men       13 ± 4    (8 – 18)  41 ± 11   (28 – 58)  49 ± 12   (34 – 65)   53 ± 13    (37 – 74)     57 ± 13      (41 – 78)  62 ± 13  (41 – 82) Women       14 ± 6    (2 – 23) 47 ± 14  (32 – 78) 54 ± 13  (40 – 77)   58 ± 12   (45 – 80)     63 ± 15      (48 – 98) 67 ± 17  ( 52 – 113) VT (l) Men  1.07* ± 0.33       (0.57 – 1.61)   2.70* ± 0.46     (2.12 – 3.59)    3.13* ± 0.46        (2.51 – 3.95) 3.07* ± 0.46   (2.55 – 3.90)   3.03* ± 0.52    (2.41 – 4.09)    3.02* ± 0.59   (2.26 – 4.31) Women  0.83* ± 0.16   (0.64 – 1.09)   1.93* ± 0.46      (1.06 – 2.53)    2.10* ± 0.50        (1.07 – 2.78) 2.05* ± 0.50   (1.05 – 2.67)  1.97* ± 0.50    (1.05 – 2.67)    1.95* ± 0.48 (1.15 – 2.59) HR (beats∙min-1) Men  68 ± 16  (52 – 95)      164 ± 21      (109 – 183)       174 ± 10       (150 – 185)          178 ± 8   (158 – 188)        182* ± 7    (167 – 190)       187 ± 5  (177 – 194) Women 62 ± 7   (50 – 72)      164 ± 8      (152 – 175)        170 ± 9   (158 – 179)          173 ± 9    (162 – 186)        175* ± 8    (166 – 186)       181 ± 10  (170 – 192)  V’O2, oxygen consumption; V’E, minute ventilation; VT, tidal volume; fb, frequency of breathing; HR, heart rate;  Values are means ± SD (ranges).  *Significantly differences between men and women. 38  Distance (km) rest 1 2 3 4 5 V E  ( l . m i n - 1 ) 0 20 40 60 80 100 120 140 160 Men - RA Women - RA Men - HeO 2 Women - HeO 2 * * ** * A Distance (km) rest 1 2 3 4 5 f b  ( b r ea t h s . s e c - 1 ) 0 10 20 30 40 50 60 70 80      C Distance (km) rest 1 2 3 4 5 V T  ( l ) 0.5 1.0 1.5 2.0 2.5 3.0 3.5 **** * B Figure 3 – Ventilatory response for men and women breathing RA and He-O2 (A) V’E (B) VT (C) fb.          * Significant differences between men and women during RA and He-O2 TTs. ω Significant difference between men RA vs. He-O2. τ Significant differences between women RA vs. He-O2. Data are presented as means ± SE.  Statistical significance is set at the level of P < 0.05. 39   Table 10 - Maximal Expiratory Flow Rates and Maximal Expiratory Flow at 50% Vital Capacity  MEF (l∙sec-1) P value MEF-50% (l∙sec-1) P value Men & Women – RA  9.60 ± 2.20 < 0.001 5.71 ± 1.27 < 0.001 Men & Women – He-O2 12.70 ± 3.25 7.76 ± 1.99 Men - RA 11.39 ± 1.08 < 0.001 6.46 ± 0.99 < 0.001 Men – He-O2 15.43 ± 1.73 8.92 ± 1.84 Women - RA  7.63 ± 1.12 < 0.001 4.89 ± 1.03 < 0.001 Women – He-O2  9.70 ± 1.06 6.49 ± 1.27  MEF, Maximal Expiratory Flow; MEF-50%, Maximal Expiratory Flow at 50 % Vital Capacity. Values are means ± SD.  Operational Lung Volumes – Sex Differences When breathing RA men’s absolute EELV and EILV’s were significant greater than women’s at rest and throughout the entire 5 km TT.  With a He-O2 inspirate, men’s EELV was significantly greater than women’s only at rest while men’s EILV was significantly greater than women’s at rest and throughout the 5 km TT.  When EELV and EILV were compared between men and women as percentages of their FVCs no significant differences in operational lung volumes occurred for either condition at any point during the TTs (table 11 and 12, figure 4).  An interaction effect occurred for EELV at 1 and 4 km whereby men had significantly greater EELV breathing RA.  As the TTs progressed no significant differences in operational lung volumes occurred for men and women. Operational Lung Volumes – Effect of Helium Men’s and women’s combined operational lung volumes were significantly reduced with the He- O2 inspirate.  In absolute values EELV (l) was significantly less at rest and at each km (P < 0.05), and EILV (l) was significantly reduced breathing He-O2 at rest, at 1 km, and at 4 km.  In relation to vital capacity (% FVC), EELV for men and women was significantly less at 1 km (RA: 36.8 ± 6.0 vs. He-O2: 30.7 ± 10.0%, P = 0.01), 4 km (RA: 38.9 ± 7.9 vs. He-O2: 35.0 ± 8.5%, P = 0.008) and 5 km (RA: 39.5 ± 8.3 vs. He-O2: 32.8 ± 10.2%, P = 0.02).  End inspired lung volume (% FVC) was significantly reduced breathing He-O2 compared to RA at 4 km (RA: 38.9 ± 7.9 vs. He-O2: 35.0 ± 8.5%, P = 0.008).   Men’s absolute EELV (l) was significantly lower from 3 to 5 km, with the He-O2 inspirate.  As a % FVC, EELV was significantly lower at 1 and 4 km.  Absolute EILV (l) at rest, at 1 km and at 4 km was significantly lower compared to RA.  Expressed as % FVC, EILV was not affected by He-O2.  Women’s operational lung volumes were not different on He-O2 compared to RA (tables 11 and 12, and figure 4). 40  Table 11 - Room Air Operational Lung Volumes   Rest 1 km 2 km 3 km 4 km 5 km EELV (l) Men (n = 11) 2.76* ± 0.60 2.02* ± 0.37 1.91* ± 0.41 2.01*† ± 0.31 2.14*† ± 0.42 2.14*† ± 0.50 Women (n = 10) 1.87* ± 0.44 1.39* ± 0.41 1.47* ± 0.43   1.43* ± 0.56  1.47* ± 0.43  1.53* ± 0.48 EELV (% FVC) Men (n = 11)   46 ± 16 37† ± 7 35 ± 8     33 ± 13       39† ± 8  39 ± 9 Women (n = 10)   45 ± 17  35 ± 6  33 ± 12     32 ± 14 37 ± 8  39 ± 9 EILV (l) Men (n = 11) 3.68*† ± 0.59 (n=10)  4.81*† ± 0.29 4.79* ± 0.50  4.91* ± 0.49 4.97*† ± 0.53  4.84* ± 0.63 Women (n = 10)   2.55* ± 0.46 3.39* ± 0.64 3.61* ± 0.71 3.50* ± 0.80   3.40* ± 0.70  3.46* ± 0.72 EILV (% FVC) Men (n = 11) 61 ± 21 88 ± 7 87 ± 6  80 ± 27        91 ± 5  88 ± 6 Women (n = 10) 61 ± 21 86 ± 4   82 ± 28  79 ± 27        87 ± 5  88 ± 1  EELV, End expired lung volume; EILV; End inspired lung volume.  Values are means ± SD.  * Significantly different lung volumes between sexes, P < 0.05.  † Significantly different lung volumes between men, P < 0.05.   Table 12 - Heliox Operational Lung Volumes   Rest 1 km 2 km 3 km 4 km 5 km EELV (l) Men (n = 11) 2.50* ± 0.68   1.65 ± 0.44  1.64 ± 0.48 (n=10) 1.62† ± 0.52 1.77† ± 0.53 1.83† ± 0.48 (n=10) Women (n = 10) 1.83* ± 0.30    1.36 ± 0.35  1.40 ± 0.42 1.38 ± 0.40   1.48 ± 0.41 1.42 ± 0.41 EELV (% FVC) Men (n = 11)  46 ± 11      27† ± 11  30 ± 7 30 ± 8 33† ± 9 31 ± 13 Women (n = 10)  47 ± 10        34 ± 8  35 ± 10 35 ± 7   37 ± 6      35 ± 6 EILV (l) Men (n = 11)  3.04*† ± 0.55 4.48*† ± 0.52 4.64* ± 0.64 4.59* ± 0.65 4.61*† ± 0.66 4.80* ± 0.67 Women (n = 10)    2.58* ± 0.27   3.35* ± 0.70 3.40* ± 0.82 3.36* ± 0.82   3.37* ± 0.80 3.27* ± 0.85 EILV (% FVC) Men (n = 11)       57* ± 10     75 ± 25 86 ± 5 85 ± 6   85 ± 9  80 ± 27 Women (n = 10)       66* ± 9   84 ± 7   85 ± 10  84 ± 11   84 ± 8  82 ± 11  EELV, End expired lung volume; EILV; End inspired lung volume.  Values are means ± SD.  * Significantly different lung volumes between sexes, P < 0.05.  † Significantly different lung volumes between men, P < 0.05. 41   Figure 4 – Operational lung volumes (A) Men RA vs. He-O2 (B) Women RA vs. He-O2 (C) Men vs. Women RA (D) Men vs. Women He-O2.   ω Significant differences in EELV between men RA vs. He-O2. * Significant differences in EILV between men and women breathing He-O2. Data are presented as means ± SE.  Statistical significance is set at the level of P < 0.05.  Expiratory Flow Limitation - Susceptibility Expiratory flow limitation data is reported as averages of all subjects with attainable flow-volume and IC data. Irregular flow rates made analysis of flow-volume breathing loops unviable at rest for 2 subjects breathing RA (subject numbers: 114 and 208).  Inaccurate IC maneuvers or inconsistent flows during the 5 km TTs resulted in a lack of EFL data for a small number of subjects at a few km points.  Distance (km) Rest 1 2 3 4 5 Lu n g  V o lu m e  ( %  F V C ) 0 20 40 60 80 100 Men - RA Women - RA C A Distance (km) Rest 1 2 3 4 5 Lu n g  V o lu m e  ( %  F V C ) 0 20 40 60 80 100   Distance (km) Rest 1 2 3 4 5 Lu n g  V o lu m e  ( %  F V C ) 0 20 40 60 80 100 B D Distance (km) Rest 1 2 3 4 5 Lu n g  V o lu m e  ( %  F V C ) 0 20 40 60 80 100 Men - H Women - H * VT VT VT VT 42 Subject 201 did not perform correct FVC’s pre and post exercise during the He-O2 TT, therefore she is not included in any of the flow-volume relationship data.   Four of 11 men (36%) and 6 of 10 women (60%) developed EFL during the RA 5 km TT.  Five of 11 men (45%) and 4 of 10 women (40%) developed EFL during the He-O2 TT.  Three of the 4 EFL- RA men also developed EFL during the He-O2 TT.  Two non-EFL-RA (NEFL) men developed EFL breathing He-O2.  Three of the 6 EFL-RA women developed EFL during the He-O2 TT.  Two women NEFL–RA, developed EFL breathing He-O2 (table 13 and Appendix A - tables 35 and 36 for individual data).  During the 1st km of the RA TT, no subjects developed EFL.  Throughout the rest of the TTs, the development of EFL was variable, with some subjects developing EFL early on (1 km – He-O2; 2 km - RA) and maintaining EFL for the duration of the TT, while others developed EFL intermittently.  Table 13 - Expiratory Flow Limitation - Susceptibility EFL susceptibility   (n) Rest 1 km 2 km 3 km 4 km 5 km RA Men (n =11) 0 0 2 3 (n = 10) 2 4 Women (n =10) 0 0 1 (n = 9) 2 (n = 9) 4 4 He-O2 Men ( n =11) 0 2 (n = 10) 2 3 2 3 (n = 10)  Women (n =10) 0 0 2 0 2 2   Values are means of only those subjects having developed EFL.   Expiratory Flow Limitation - Magnitude The magnitude of EFL varied within and between subjects at each km during both TTs (table 14).  Table 15 shows EFL susceptibility and magnitude at 5 km when V’E was the highest.  Four men and 4 women developed EFL breathing RA at 5 km.  Development of EFL at 5 km with a He-O2 inspirate was slightly reduced to 3 men and 2 women.  The magnitude of EFL was not different between men and women breathing RA (Men: 48 ± 24, Women: 30 ± 19%, P = 0.50) or He-O2 (Men: 30 ± 7, Women: 45 ± 3%, P = 0.80) at 5 km.  Heliox did not impact the magnitude of EFL for men, women, or men, and women combined (P > 0.05).  There appeared to be an association between V’E and the magnitude of EFL during the RA TT for men and women combined at 2 km (r = 0.55, P = 0.009), 4 km (r = 0.51, P = 0.02) and 5 km (r = 0.60, P = 0.01).  For men, an association was found at 4 km (r = 0.71, P = 0.01) and 5 km (r = 0.65, P = 0.03) breathing RA.  However no associations between V’E and EFL (%VT) occurred 43  for women breathing RA.   During the He-O2 TT no relationships were found for either sex (separate or combined).  Fitness as determined by V’O2MAX (ml∙kg -1∙min-1) was only related to the magnitude of EFL for men at 5 km breathing RA (r = 0.78, P = 0.004).  Table 14 - Magnitude of EFL for subjects having developed EFL  EFL magnitude  (% VT) Rest 1 km 2 km 3 km 4 km 5 km RA Men 0 0 26 ± 3 35 ± 20 32 ± 1 48 ± 24 Women 0 0 21 ± 0  41 ± 33 36 ± 17 30 ± 19 He-O2 Men  0 19 ± 10 30 ± 23 27 ± 27 32 ± 16 30 ± 7 Women  0 0 16 ± 7 0 42 ± 21 45 ± 3    EFL magnitude; expiratory flow limitation severity (> 5% VT). Values are means ± SD.    Table 15 - Expiratory Flow Limitation susceptibility and magnitude at 5 km  n EFL magnitude at 5 km (% VT)  P value M-RA 4 48 ± 24 0.50 W-RA 4 30 ± 19 M-He-O2 3                      30 ± 7 0.80 W-He-O2 2                      45 ± 3 M & W – RA  8                      39 ± 22 0.39 M & W – He-O2  5                      36 ± 10 M-RA  M-He-O2  4 3 48 ± 24                       30 ± 7 0.55 W-RA W-He-O2 3 2 30 ± 19                      45 ± 3 0.77    Values are means ± SD.  Expiratory Flow Limitation - Performance  Four of the 9 men with improved He-O2 TT power output developed EFL, and 3 of those 4 also developed EFL during the RA TT.  Three of the 8 women who produced more power during the He-O2 TT did so having developed EFL.  Those same 3 women also developed EFL during the RA 5 km TT.  Two additional women developed EFL during the He-O2 5 km TT while NEFL when breathing RA. The 2 men that completed the RA 5 km TT with a higher power output did so having not developed EFL.  One of these men did develop EFL during the He-O2 TT.  One of the 2 women who performed the RA TT with a higher power output developed EFL breathing RA and He-O2, while EFL 44  could not be determined for the other women (201).  The woman with the same power output over the course of the 2 TTs did not develop EFL during either TT.    Expiratory Flow Limitation - Ventilatory Reserve   The ventilatory reserve (V’E as a percentage of V’E CAP) was increased with a He-O2 inspirate in all subjects except 2 men.  Men’s average RA V’E utilized 47.4 ± 9.1% of their average RA V’E CAP and was significantly reduced to 40.7 ± 10.3% during the He-O2 TT (P = 0.002).   Women’s average V’E was 49.0 ± 9.5% of their RA TT V’E CAP, and was significantly reduced to 40.6 ± 9.1% of their He-O2 V’E CAP (P = 0.0004).  No significant differences existed between sexes for RA (P = 0.99) or He-O2 (P = 1.00). Figure 5 shows the ventilatory reserves for both men and women in relation to their respective TT performances.  At 5 km men’s and women’s combined ventilatory reserve was correlated to the magnitude of EFL for both the RA (r = 0.72, P = 0.0003) and He-O2 (r = 0.61, P = 0.004) TT’s.  Men’s RA and He-O2 5 km ventilatory reserves were correlated to their magnitude of EFL (r = 0.72, P = 0.02 and r = 0.79, P = 0.007 respectively).  At 5 km for women the relationship was significant for the RA TT (r = 0.80, P = 0.005), but not the He-O2 TT (r = 0.51, P = 0.13).  Figure 5 – Average ventilatory reserve throughout the TTs for individual subjects in relation to their TT performances.  Group averages are denoted by the larger solid symbols (men) and open symbols (women).  * Significant differences between RA and He-O2 ventilatory reserves for both men and women.  Statistical significance is set at the level of P < 0.05. TT Performance Power (W) 150 200 250 300 350 400 V' E/ V' E CA P ( % ) 20 30 40 50 60 70 Men - RA Men - He-O2 Women - RA Women - He-O2 * *45  Work of Breathing Men and women’s combined total WOB was reduced breathing He-O2 compared to RA from rest to 5 km, with significant reductions at 2 through 5 km (P < 0.05) (table 16).  Table 17 shows men’s and women’s separate total WOB.  Men’s and women’s total WOB were not different at rest or at any km throughout either TT (P > 0.05) (table 17).  However, at each km for an equivalent total WOB to that of men, women had significantly lower V’E (figure 6).    Men’s total WOB was reduced at 3 km (M-RA: 299.1 ± 151.9 vs. M- He-O2: 221.0 ± 74.0 J∙min -1, P = 0.01).  Heliox had no effect on women’s total WOB at any km.    Table 16 - Total Work of Breathing - Men and Women Combined Total Work of Breathing (J∙min-1)   Rest 1 km 2 km 3 km 4 km 5 km M & W RA 3.6 ± 3.3 157 ± 72 214* ± 99 242* ± 127 265* ± 117 299* ± 121 M & W He-O2 3.1 ± 2.4 139 ± 60 181* ± 80    192* ± 80   214* ± 90     264* ± 94 P value 0.42 0.06 0.02 0.003 0.003 0.01  Values are means ± SD.  * Significantly different total WOB men and women RA vs. men and women He-O2 TT    Table 17 - Total Work of Breathing - Men and Women Separate Total Work of Breathing (J∙min-1)   Rest 1 km 2 km 3 km 4 km 5 km M-RA 3.6 ± 3.4 182 ± 92 251 ± 121 299† ± 152 305 ± 141 345 ± 134 W-RA 3.6 ± 3.3 132 ± 31     177 ± 53 191 ± 72   223 ± 67  248 ± 58 P value 1.0    0.53 0.44 0.26 0.49 0.29 M-He-O2 2.5 ± 1.6 157 ± 73 208 ± 82 221† ± 74 250 ± 84 319 ± 79 W-He-O2 3.7 ± 3.0 121 ± 41 153 ± 72   167 ± 79 176 ± 84 204 ± 72 P value  0.88    0.76    0.67    0.78    0.58    0.18 P value M-RA vs. He-O2  0.54   0.22    0.11   0.01    0.07    0.46 P value  W-RA vs. He-O2 1.0   0.81   0.56   0.69   0.18    0.13  Values are means ± SD.  † Significantly different total WOB in men RA vs. He-O2 TT   46   Figure 6 – Total WOB for men and women breathing RA and He-O2. * Significant differences in V’E between men and women during RA and He-O2 TTs. ω Significant difference between men RA vs. He-O2. Data are presented as means ± SE.  Statistical significance is set at the level of P < 0.05.   V ' E  ( l. m in -1 ) 0 60 80 100 120 140 Distance (km) rest 1 2 3 4 5  T o tal W or k  o f B rea thin g  ( J . m in -1 ) 0 100 200 300 400 500 Men RA Women RA Men He-O2 Women He-O2 Men RA V'E Women RA V'E Men He-O2 V'E Women He-O2 V'E * * * * * 47  The Ires (inspiratory resistive) WOB was significantly reduced breathing He-O2 compared to RA for men and women combined throughout the 5 km TT (P < 0.05).  Figure 7 (Panel A and B) shows the Ires WOB for men and women separately.  The Ires WOB was not different between the sexes for either inspirate (P > 0.05).  Men’s Ires WOB was significantly reduced breathing He-O2 compared to RA at 1 through 5 km (figure 7, Panel B).  Women’s Ires WOB was significantly reduced breathing He-O2 compared to RA at 5 km (figure 7, Panel A).   Figure 7 – Ires WOB breathing RA and He-O2 for women (A) and men (B).  τ Significant differences between women RA vs. He-O2. * Significant differences between men RA vs. He-O2. Data are presented as means ± SE.  Statistical significance is set at the level of P < 0.05. Distance (km) rest 1 2 3 4 5 Ir es  W OB  ( J. m in -1 ) 0 20 40 60 80 100 120 140 Women RA Women He-O 2  A Distance (km) rest 1 2 3 4 5 Ir es  W OB  ( J. m in -1 ) 0 20 40 60 80 100 120 140 Men RA Men He-O 2 * * * * * B48  Men’s and women’s combined Iel (inspiratory elastic) WOB during the He-O2 TT was not statistically different from the RA TT (table 18).  Sex had an effect on the Iel WOB only at 5 km breathing He-O2 (men: 227.2 vs. women: 130.1 J∙min -1, P = 0.02).  Separately both women and men’s Iel WOB was not affected by the He-O2 inspirate (table 19).  The Etot (expiratory total) WOB for men and women combined was reduced during the He-O2 TT compared to the RA TT, reaching statistical significance at 2 and 4 km (RA: 16.2 ± 30.1 vs. He-O2: 2.0 ± 2.8 J∙min-1, P = 0.03; RA: 24.5 ± 41.4 vs.He-O2: 4.8 ± 6.7 J∙min -1, P = 0.04, respectively) (table 20).  Sex did not affect the Etot WOB nor did inspirate for men and women as separate groups (table 21).    Table 18 - Inspiratory Elastic Work of Breathing - Men and Women Combined Iel Work of Breathing (J∙min-1) M & W Rest 1 km 2 km 3 km 4 km 5 km RA 2.4 ± 2.2 104 ± 46 135 ± 58 147 ± 62 157 ± 58 176 ± 60 He-O2 2.4 ± 1.9 105 ± 45 134 ± 59  139 ± 57   152 ± 62 183 ± 67 P value 0.98 0.91 0.97 0.13 0.40 0.27  Values are means ± SD.       Table 19 - Inspiratory Elastic Work of Breathing - Men and Women Separate Iel Work of Breathing (J∙min-1)   Rest 1 km 2 km 3 km 4 km 5 km M-RA 2.3 ± 1.5 122 ± 57 160 ± 70 181 ± 69 186 ± 61 208 ± 62 W-RA 2.6 ± 2.8 87 ± 21 109 ± 29 115 ± 32 125 ± 33 140 ± 30 P value   0.99   0.46   0.35   0.18   0.22   0.12 M-HeO2 2.0 ± 1.2 123 ± 54 163 ± 60 166 ± 55 184 ± 59 227* ± 61 W-HeO2 2.8 ± 2.2   87 ± 26 105 ± 43 113 ± 43 113 ± 43 130* ± 33 P value   0.90  0.45    0.25    0.34    0.14      0.02 M-RA vs. He-O2 P value   0.94  1.00   0.99   0.26   0.99   0.16 W-RA vs. He-O2 P value   0.93  1.00   0.99   0.99   0.75   0.95  Values are means ± SD.  *Significantly different Ires WOB between men and women on He-O2.       49  Table 20 - Expiratory Total Work of Breathing - Men and Women Combined Etot Work of Breathing (J∙min-1)  M & W Rest 1 km 2 km 3 km 4 km 5 km RA 0.08 ± 0.14 8.6 ± 18.1 16.2* ± 30.1 20.2 ± 42.5 24.5* ± 41.4 23.6 ± 40.5 He-O2 0.03 ± 0.07   1.4 ± 2.2 2.0* ± 2.8  3.0 ± 3.44 4.8* ± 6.7 5.9 ± 7.8 P value 0.59       0.22    0.03  0.31    0.04  0.49  Values are means ± SD.  *Significantly different Etot WOB between men and women combined on He-O2 vs. RA.  Table 21 - Expiratory Total Work of Breathing - Men and Women Separate Etot Work of Breathing (J∙min-1)   Rest 1 km 2 km 3 km 4 km 5 km M-RA 0.1 ± 0.2 14.0 ± 24.6 25.8 ± 40.7 30.2 ± 57.1 32.8 ± 54.8 32.6 ± 53.8 W-RA 0.1 ± 0.1 3.1 ± 4.1 6.7 ± 7.4 8.4 ± 11.3 14.1 ± 17.0 12.4 ± 14.8 P value 0.95 0.24 0.20 0.43 0.59 0.50 M-HeO2 0.0 ± 0.1 2.4 ± 2.8 3.2 ± 3.4 4.1 ± 3.8 6.3 ± 7.5 9.2 ± 9.0 W-HeO2 0.0 ± 0.1 0.4 ± 0.6 0.7 ± 1.3 1.7 ± 2.7 2.9 ± 5.5 1.9 ± 3.9 P value 1.00 0.99 0.99 1.00 1.00 0.95 P value  M-RA vs. He-O2 0.46 0.13 0.06 0.18 0.16 0.23 P value  W-RA vs. He-O2 0.89 0.95 0.98 0.94 0.76 0.79  Values are means ± SD.  SENSORY RESPONSES Neither sex nor inspirate affected dyspnea or leg discomfort at rest or at any km during the 5 km TT except at 2 km where men’s and women’s combined dyspnea ratings were significantly lower when breathing He-O2 (figure 8).  Additionally, the relative contributions of leg and breathing discomfort preventing faster cycling were not affected by sex or gas type (table 22).  The main reason for men not cycling faster breathing RA was leg discomfort (n = 6), followed by a combination of leg and respiratory discomfort (n = 3), and lastly respiratory discomfort (n = 2).  With a He-O2 inspirate, 7 men reported their performance was limited by their legs and 4 by a combination of legs and breathing.  Women’s reasons for not cycling faster during the RA TT were equally distributed between leg discomfort and a combination of leg and breathing discomfort, with one woman rating ‘other’ inhibiting her performance.  Women’s ratings were similar during the He-O2 TT with 6 women claiming leg discomfort and 5 reporting a combination of leg and breathing discomfort (table 22).  50    Figure 8 – Breathing (A) and Leg (B) discomfort for men and women breathing RA and He-O2. 51  Table 22 - Ratings of Perceived Exertion at TT Completion RA Men (n = 11) Women (n = 11) P value Reason for not going faster:          Respiratory 2 0        Leg 6 5        Combination 3 5        Other 0 1  Relative Contributions preventing faster TT:          % respiratory discomfort 44 ± 17 (30 – 85) 36 ± 21 (0 – 70) 0.14       % leg discomfort 56 ± 17 (15 – 70) 64 ± 21 (30 – 100) 0.14 He-O2    Reason for not going faster:          Respiratory 0 0        Leg 7 6        Combination 4 5        Other 0 0  Relative Contributions preventing faster TT:          % respiratory discomfort 37 ± 8.8 33 ± 13.1 0.40       % leg discomfort 63 ± 8.8 67 ± 13.1 0.40  Values are means ± SD (ranges).                52  DISCUSSION The main findings of this investigation were: 1) the exercise performance improvements when breathing He-O2 were modest, variable between subjects and equally variable between men and women; 2) women were more susceptible to EFL than men breathing RA, and the effects of He-O2 on EFL development were equally variable for both men and women; 3) for a significantly lower V’E, women had the same total WOB and operational lung volumes as men; 4) sensory responses were similar for men and women regardless of inspirate or EFL.  The collective findings from this study suggest that the reduced density of He relative to N2 may not necessarily unload the respiratory system of sufficient magnitude to remove EFL and reduce the total WOB, to enable large and consistent gains in exercise performance.  It appears EFL (susceptibility and magnitude) is not an all-or-none phenomenon and can occur to varying extents in both sexes during rigorous exercise.  Sex-based differences in pulmonary structure and function predispose women to mechanical ventilatory constraints breathing RA.  Ventilatory capacity in conjunction with changes in EELV and expiratory flow rates are likely the main contributors to avoiding and/or removing EFL.  Sensory responses are not affected by sex-based differences in pulmonary structure or function, nor are they affected by He-O2 or the development of EFL.   PERFORMANCE EFFECTS OF HELIOX Endurance trained cyclists/triathletes were tested because their elevated metabolic demands require greater V’E despite possessing resting pulmonary function values (lung size and flow rates) that are similar to untrained individuals.  As such, this makes ET athletes more likely to develop EFL (70).  To date there is no evidence that cycling training regimes and/or fitness level positively affect pulmonary function (44, 51, 57, 61). Men and women in this study are comparable to ET cyclists/triathletes studied by others (31, 32, 44, 53), and previous racing experience meant the athletes could perform reproducible TTs.  Both men and women in this study had pulmonary function values that met or exceeded predicted values (3).  Men’s lung volumes and peak expiratory flow rates were significantly higher than women’s suggesting the men had larger diffusion surfaces (82) and airway diameters (55).       The He-O2 TT was completed faster and at a higher power output than the RA TT although neither variable reached statistical significance (P = 0.06).  Despite this the observed performance improvements are scientifically meaningful although mechanistically unclear as the likely range of the true values (95% CI) results in both performance enhancement and decrement.  A greater performance improvement would likely be observed with a larger sample size as similar (non-significant) 53  improvements in time-to-exhaustion have been reported for men with a 20% O2 – 80% He inspirate compared to RA (87).  The performance improvement can be attributed to the effects of He’s reduced density on ventilatory mechanics (refer to Lung Mechanics).  This is because He has no known metabolic affects for individuals with healthy pulmonary systems (12).  Helium’s relatively high thermal conductivity does not appear to have an effect on body temperature when used as an inspirate or on bronchodilation in individuals without asthma (87).    Over the course of each TT, men and women cycled at a consistent cadence and speed.  Men on average completed the RA and He-O2 TTs faster than women, however not all men outperformed women on either trial (refer to Methodological Considerations).  Cycling improvements were attributed to He-O2 because almost half of the TTs with a higher power output were performed 1st eliminating a potential ‘learning effect’, and the duration between tests had no bearing on performance.  The ‘training log’ (Appendix C) assured training (volume and intensity), nutrition, and sleep were consistent between trials so as to minimize any confounding effects.   The FAM TT was expectedly slower than the experimental TTs since it was performed shortly after the incremental cycle test, but subjects pushed themselves to volitional exhaustion.  By providing subjects an opportunity to become accustomed to the ergometers gearing, and their desired pacing strategy, the FAM TT limited any ‘learning effect’ that could have potentially confounded any observed performance related changes. EXPIRATORY FLOW LIMITATION Susceptibility & Magnitude Consistent with previous findings, women in the present study were more susceptible to developing EFL compared to men during RA exercise despite having significantly lower V’E and expiratory flow rates (23, 32, 44, 53, 86).  Sex-based differences in pulmonary structure (lung and airway size) (55) and function (MEFV curve) (51) are likely the cause for the differences.  As such, women have relatively less ventilatory reserve within their MEFV curve to accommodate exercise-induced increases in V’E.  Previous research has revealed women that possess FVC (32) and dysanapsis ratios similar in size to that predicted for men (23) are less susceptible to developing EFL.  The enhanced lung volumes and airflow rates possessed by these women greatly expand their MEFV curves and thus increase their ventilatory capacities decreasing their propensity to develop mechanical ventilatory constraints. Accordingly the subjects in this study utilizing a greater percentage of their ventilatory capacity developed EFL of a greater magnitude. 54  Helium was used in place of N2 in an attempt to increase airflow rate thereby lessening or eliminating EFL due to He’s substantial affects on both the inspiratory and expiratory portions of the maximal flow-volume curve.  Expiratory flow limitation was not substantially affected in either sex compared to RA, because for a similar lung volume subjects utilized the greater ventilatory reserve by increasing exercise expiratory flow rates until the MEFV curve was intersected.  Men increased their expiratory flow rates by a significantly greater amount compared to women (men: 22% vs. women: 13%) and in doing so a greater number of men developed EFL during the He-O2 TT compared to women (45% men vs. 40% women).        Changes in EELV and expiratory flow rates had the greatest impact on the magnitude of EFL for each subject breathing RA or He-O2, regardless of an increased MEFV curve.  A strong relationship existed between the magnitude of EFL and ventilatory capacity at 5 km for both RA and He-O2.  Heliox slightly increased V’E however the magnitude of EFL was slightly decreased at 5 km for men and increased at 5 km for women.  This is in contrast to McClaran et al. (53) who found the He-O2 induced increases of the MEFV curve reduced EFL in women.  However a He-O2 inspirate has not always demonstrated a reduction in the development of EFL (6).  In support of previous research in our laboratory, fitness was not related to the magnitude of EFL in women.  Presumably women’s lung and airway size play a bigger role in the susceptibility of EFL than fitness and V’E alone (23).     Impending EFL  There is growing evidence supporting the concept of EFL as a continuum rather than an all-or- none phenomenon.  Impending EFL occurs when the exercise flow-volume loop follows (but does not intersect) the MEFV curve, and EELV increases towards resting (54).  Nearly all NEFL subjects in this study exhibited the characteristics of impending EFL.  Given that the presence or absence of EFL did not directly affect operational lung volumes, presumably impending EFL regulates EELV.  Changes in EELV were variable between subjects, as each subject attempted to maximize expiratory flow rates at the lowest EELV (i.e., the diaphragm’s optimal length-tension relationship) without developing EFL.  It has been suggested that EFL (full or impending) causes a reflex inhibition of expiration, causing premature inspiration and increases in EELV (54, 69).  This phenomenon has been shown in a group of healthy moderately active men studied by Younes and Kivinen (88) that did not development EFL (due to relatively low V’E) but showed relative lung hyperinflation as maximal exercise capacity was approached.  In the present study, EFL had variable effects on performance for both sexes, with subjects performing better on the RA or He-O2 TTs despite EFL development.  Potentially, alterations in lung volumes 55  brought about by impending EFL have a profound effect on performance in addition to the presence or absence of full EFL.   RESPIRATORY MECHANICS Metabolic Data and Breathing Pattern  The larger stature and greater metabolic requirements of men in the present study resulted in a higher V’E compared to women.  Men were able to increase their V’E through increases in VT made possible through their relatively larger vital capacities.  Consistent with previous findings in ET women (30), the women in this study adopted a different breathing pattern relying to a greater extent on fb to elevate V’E.  This ‘tachypneic’ breathing pattern reduces the Iel WOB by recovering energy used during expiration.  Previous studies have shown women to have significantly higher operational lung volumes compared to men and thus explaining the tachypneic breathing pattern.    Although sex-based differences in operational lung volumes were not shown in this study it is likely the women were trying to reduce their total WOB by reducing their Iel WOB.  Over the last 2 km’s during both TTs, men’s VT decreased as EILV approached 90% of FVC.  At this point men utilized the tachypneic pattern to decrease the metabolic cost of breathing (Iel WOB) as lung volumes encroached on the non-compliant portion of the lungs’ pressure-volume curve.  It is also believed the lungs’ stretch receptors inhibit inspiration, constraining the ventilatory response when EILV approaches 90% FVC (54).  A reduced contribution of VT near maximal exercise is consistent with the finding of other highly trained cyclists (48, 54).   Heliox caused a small (non-significant) increase in V’E regardless of EFL development or attenuation. This is in contrast to previous reports whereby in healthy young men and women V’E increased only for those that underwent reductions (susceptibility or magnitude) in EFL from RA to He- O2 (53, 54).    Older individuals with mild chronic airflow limitation have shown increases in V’E at ventilatory threshold and maximal exercise despite no changes in EFL susceptibility or magnitude (5).  It appears the He-O2 induced resistive unloading of the pulmonary system allowed for increases in V’E.  However, women’s flow rates were likely not high enough for He-O2 to greatly affect the resistive unloading of the airways enabling women to increase V’E through increases in VT (increasing alveolar V’E).  Thus women’s fb was significantly higher during the He-O2 TT. Operational Lung Volumes Operational lung volumes were similar between sexes when breathing RA.  This is in contrast to Guenette et al. (30) who found that EELV and EILV (expressed as % FVC) were significantly higher in women.  Nevertheless, the general operational lung volume strategy was consistent with that previously 56  reported in the literature (23, 32, 69, 86, 88).  All subjects reduced their EELV at the beginning of both TTs from resting levels via active expiration to facilitate inspiration by optimizing diaphragmatic length. By doing so expiration is performed primarily by elastic work from chest wall recoil, of which some energy is recovered for the preceding inspiration.  Breathing at lower operational lung volumes retains lung compliance.  During the RA TT, men and women continued to reduce their EELV from 1 – 3 km for the aforementioned reasons.  At 4 km both sexes increased their EELV (men: 6%, women: 5%); and at 5 km women increased (2%), while men maintained, their EELV taking advantage of higher flow rates available at higher operational lung volumes, preventing dynamic airway compression, and potentially reducing, removing or avoiding EFL (figure 9).  Figure 9 – Representative subject demonstrating increasing EELV as EFL developed throughout the TT.  Both men and women underwent non-significant similar changes for operational lung volumes breathing He-O2 compared to RA (except men’s EELV at 1 and 4 km); however, the general trend is worth noting.  Men and women slightly increased their EELV from 2 – 4 km.  At 5 km both men and women reduced their EELV because of the extra expiratory flow reserve brought from the increased MEFV curve.  This allowed the preservation of expiratory flow rates at a lower EELV and thus reduced metabolic cost (i.e., optimal diaphragmatic position for force generation and most favorable lung compliance).  Men’s EELV was slightly lower throughout the He-O2 TT compared to RA.  This was likely because men’s significantly higher flow rates benefited to a greater extent from the reduced Volume (l) 3 2 1 0 Flo w  (l . s ec -1 ) -6 -4 -2 0 2 4 6 857  resistance of He-O2.  At a lower lung volume, men accordingly have more ventilatory reserve than women.   Changes in EILV followed that of EELV and were not different between sexes or influenced by inspirate.  Throughout both TTs, EILV reached or exceeded 80% FVC increasing the elastic WOB by way of shifting VT to the less compliant portion of the pressure-volume curve.  However, EILV remained for the most part below 90% FVC to avoid excessively elevating the elastic WOB.  A constant EILV from RA to He-O2 is supported by others (5).  Resting operational lung volumes were not significantly different between RA and He-O2 for men and women.  At rest subjects are overly conscious of their breathing pattern and performing the IC maneuver so resting V’E is highly susceptible to irregular breathing through uncharacteristic alterations in fb, VT, and flow rates.  During timed exercise, performance motivation, physical exertion and mental exhaustion act to distract subjects from overanalyzing their respective breathing patterns. Due to the variability in the susceptibility and magnitude of EFL over the course of the TT, EFL had no consistent effect on operational lung volumes.  The maintenance of EELV occurred regardless of EFL development and is in contrast to McClaran et al. (53) who found that EELV was lower in women only when He-O2 significantly reduced EFL.  Work of Breathing  Helium caused a lower WOB at every km despite a higher V’E.  However, the WOB reductions with He administration were similar between men and women.  Women’s V’E was significantly lower than men’s breathing RA or He-O2 despite a similar WOB. Thus, for a given V’E women had a greater WOB.  A higher physiological cost of breathing for women has previously been reported in our laboratory (32), with the sex-based differences rising exponentially at V’E above 90 l∙min -1.   Over the second half of the TTs in this study, V’E exceeded 90 l∙min -1.  The greater sex-based disparity in the total WOB as V’E increases appears to be a result of differences in the work to overcome airflow resistance.  Guenette et al. (30) found the Ires WOB was the main cause for women’s relatively higher total WOB. Women’s significantly smaller conducting airways (52, 77) exponentially increase airflow resistance based on Poiseuille’s law.  As such, the women in this study had a similar Ires WOB despite significantly lower expiratory flow rates compared to their male counterparts.  Tidal volume was also significantly lower for women despite a similar Iel WOB.  Although the Iel WOB has not shown sex-based differences (30), women in this and other studies (23, 30, 53) utilized a tachypneic ventilatory pattern to minimize the Iel WOB since previously discussed anatomical differences limit women’s ability to reduce their resistive 58  WOB.  As such, women’s expiratory resistive WOB would have been the major cause of their relatively higher Etot WOB.      Heliox reduced the Ires WOB for men throughout the TT and women at 5 km in spite of both sexes obtaining significantly higher expiratory flow rates.  Men’s V’E was high enough for He-O2 to have a significant effect on the airflow characteristics (turbulent vs. laminar).  Women’s V’E was likely not high enough for the density and viscosity differences between He and N2 to emerge until 5 km, at which point V’E exceeded 90 l∙min -1 and the Ires WOB was significantly reduced. Tidal volumes and operational lung volumes were not affected by He-O2 for either men or women, and thus the Iel WOB was unchanged with He-O2.  The Etot WOB was reduced breathing He-O2 for men and women combined at 2 and 4 km, likely due to the decreased expiratory airflow resistance.  For each sex however, the Etot WOB was similar between He-O2 and RA despite significantly higher He-O2 expiratory flow rates, presumably because of the reduced airflow resistance.   Expiratory flow limitation increases the WOB for a given V’E.  When EFL develops, the rate of expiratory airflow is constrained, and attempts to increase expiratory airflow (and V’E) by generating greater trans-pulmonary pressures are ineffective.  Generation of trans-pulmonary pressures in excess of the maximal effective pressures (critical pressure at iso-lung volume resulting in maximal expiratory flow) can occur and due to airway compression potentially decrease expiratory airflow (60).  Due to the variability in the susceptibility and magnitude of EFL, and the V’E at which EFL occurred over the course of the 2 TTs, discerning the effects of mechanical ventilatory constraints on the WOB in this study is problematic. Proportional-assist ventilation unloads the inspiratory muscles, and in doing so improves time-to- exhaustion and attenuate the respiratory muscle metaboreflex decreasing sensory perceptions of respiratory and leg discomfort in healthy male athletes (37).  Obese individuals and those suffering from disease such as COPD have shown improvements in exercise performance and attenuations in dyspnea with PAV (24, 39)  Both He-O2 and PAV reduce the expiratory WOB to a similar extent, however PAV unloads inspiration by a substantially greater amount compared to He-O2 (2).  The present study aimed to disrupt inspiration as little as possible thereby facilitating the analysis of EFL’s affect on V’E.  The V’E of a cyclist during a TT involving non-uniform gearing ratios and power output can cause PAV to disrupt the athlete’s preferred breathing pattern (35, 37).  It is tremendously difficult to blind subjects to PAV and minimize confounding errors with negligible disruption to subject’s normal breathing and cycling responses thus making PAV a poor methodological choice (Refer to Methodological Considerations).    59  Body Position  Body position was identical during both TTs to avoid confounding lung mechanics and sensory responses.  However, respiratory changes induced by cycling position are worth noting especially when comparing lung mechanics of a cyclist to those of upright exercise disciplines.  Trunk flexion causes abdominal compression which has been shown to increase V’E through fb as the diaphragm is restricted in its ability to descend and expand lung volume (27).  Diaphragmatic restrictions rather than EFL would potentially cause EELV to increase.  However, EELV in this study was not different from that of runners (44, 53) so presumably abdominal compression was not the cause.  Furthermore, EELV was regulated by proximity of expiratory flows to the MEFV curve and subjects were not positioned in the more aggressive ‘drops’ or ‘aerobars’, which further increase abdominal compression.  Rather the hands were placed on the ‘brake-hoods’ allowing for arm bracing which improves the function of the accessory muscles to expand the rib cage and increase vital capacity (8).   SENSORY EFFECTS This study supports previous findings that leg discomfort is the main symptom limiting exercise in most healthy men and women (34).  Leg discomfort was rated higher as the limiting factor to exercise performance both as an absolute cause and as a relative contribution in the present study.  There is belief dyspnea may be higher in young women compared to young men due to anatomical differences (smaller airway diameters) which increases airway resistance (76).  This is based on significantly different dyspnea ratings between older healthy men and women (64) and those suffering from clinical illness such as chronic obstructive pulmonary disease (19). However there were no sex-based differences in dyspnea during either TT in this study.  Similar non-significant findings have been reported by others comparing ET men and women during sustained heavy exercise (31).  Expiratory flow limitation did not affect sensory responses for either sex in this study and is consistent with previous findings in our laboratory (23, 86).  Dyspnea is not likely the symptom limiter of exercise in healthy individuals (34).  Heliox did not affect sensory responses for either sex.  Within the literature, He-O2 has not made a significant impact on dyspnea rating during rigorous exercise in men and women of average fitness (6) or highly trained men (54).  Babb (5) also failed to find a difference in dyspnea rating in a group of older individuals with a He-O2 inspirate.  Men and women’s sensory responses post RA and He-O2 TTs were significantly lower than after the V’O2MAX test.  Significant sex-based differences in RPE at the end of the incremental exercise test with no differences during constant load exercise have been shown before (31).  Possibly, the ability of 60  subjects to control the intensity, and thereby their effort during the TTs, caused the reduced RPEs relative to the computer controlled incremental cycle test.   METHODOLOGICAL CONSIDERATIONS The IC and MEFV curve method of detecting EFL, when done correctly, can be accurate despite its caveats.  Using an IC to measure EELV could be problematic because the mere action of performing an IC could alter EELV either before or after the IC is performed (60).  By having subjects practice the maneuver and observing a few tidal breaths before the IC, normal breathing can be ensured.  The IC maneuver does require subject motivation; if subjects do not give their best effort they may not fully inspire to TLC.  A continuous measure of esophageal pressure confirmed that maximal inspiratory pressure (same as at rest) was achieved to perform the IC (32, 45).  Measurement of EFL is limited in that it cannot be measured continuously during exercise, only at the end of a specified time period (each km).  Due to changes in operational lung volumes throughout the TT, the susceptibility and magnitude of EFL may have been underestimated.  The negative expiratory pressure technique (NEP) allows for a continuous measure of EFL susceptibility throughout exercise but it does not provide an indication of impending EFL an important variable in this study.  In addition NEP may cause collapse of the upper airways potentially causing a reflexive increase in EELV confounding comparisons to RA trials.   Using esophageal balloons to measure the WOB does not take into account the flow-resistive work done on the tissues of the thorax and abdomen.  The amount of work is small at low V’E and increases at higher V’E, which would increase the total WOB.  Unlike PAV where the degree of inspiratory unloading can be adjusted, the precise amount of respiratory unloading that He-O2 provides is unknown.  Heliox unloads both the inspiratory and expiratory side of V’E.  Therefore consideration needs to be taken if changes to the inspiratory WOB were a direct result of He-O2 or the secondary effects of alleviated expiratory mechanical ventilatory constraints.   Cycling does recruit less muscle mass than running or cross-country skiing, therefore theoretically requiring a lower V’E to sustain exercise.  However, studies using ET cyclists (32) have found V’E comparable to those achieved by elite runners (44).  Healthy young men have been shown to develop EFL during heavy exercise at V’E in excess of 120 l∙min -1 (44).  The men in this study reached V’E in excess of 120 l∙min -1 from 3 to 5 km.  Furthermore both sex’s V’E at 5 km during the TTs were similar to their respective V’E at V’O2MAX, assuring subjects were reaching their full ventilatory capacities.  The controlled setting provided by the cycle ergometer allowed for the collection of data with fewer 61  artifacts (compared to tread-mill) and also provided insight into ventilatory constraints affecting cyclists with a high degree of trunk flexion.   The maximal power output achieved on the incremental test is likely an underrepresentation of the athlete’s true capabilities due to the abrupt wattage increments characteristic of the step-wise protocol. Women were at a higher percentage of their predicted V’O2MAX compared to men.  This was  likely the result of 4 men slightly below the V’O2MAX criteria, and possibly the prediction equation (46) (created 25 years ago) underestimating the women’s predicted V’O2MAX.  However men and women were similar based upon power-to-weight ratios.  Three women produced more power than 1 man breathing RA, and 2 of those women again produced more power than 2 men breathing He-O2.  The 2 ‘less powerful’ men both exceeded the V’O2MAX criteria and were experienced in road and mountain cycling respectively.  The 3 ‘more powerful’ women competed at the highest level of all subjects and reached a power output on the V’O2MAX comparable with most men.  Recruitment strived to attain the fittest cyclists/triathletes with ample race experience.  However, women were on average more aerobically fit (as determined by V’O2MAX as percent predicted) and subjects were not TT specialists, which could have been why some women outperformed men.  Also, the CVs for indoor cycling were based on elite cyclists and thus may have been slightly misrepresentative.  A few FAM TTs to determine a CV for each individual subject would have given more precise insight into each individual subject’s performance improvement.  However there was no difference in performance between the 1st and 2nd TT so it appears that the learning or knowledge of time (as displayed on the monitor) did not affect performance. Subject 108’s (man) exercise inspiratory flow-volume loops revealed a saw tooth pattern during the RA TT that was no longer present breathing He-O2 (Refer to Appendix C, Figure 35).  The saw tooth pattern, determined by visual inspection of  fluctuations in inspiratiory flow, is characteristic of vocal cord dysfunction (38).  However, the degree of irregular inspiratory flow exhibited by subject 108 was less than half of that shown in previous reports (38).  Furthermore, inspiratory and expiratory flow rates were not affected. This subject did not have severe dyspnea ratings or rate dyspnea as his exercise symptom limiting factor.  Breathing He-O2 appeared to remove the saw tooth pattern however no changes in dyspnea resulted.      FUTURE CONSIDERATIONS A larger sample size of elite men and women TT specialists would help clarify whether He-O2 can induce a true performance improvement, as the current study was underpowered.    Development of a method with the ability to unload only expiration (undetectable by subjects) would isolate and clarify how the effects of EFL, operational lung volumes, the WOB, and potentially sex affect endurance 62  performance.  Potentially TTs of a longer duration involving short sprints would generate V’E high enough for EFL to develop while determining the effects of endurance exercise (an hour or more) on the WOB, sensory responses and diaphragm fatigue.   A 3rd TT could be performed to determine if the ventilatory drive could be increased without manipulating the MEFV curve and the subsequent effects on performance.  This could be done by increasing the chemical drive to breath via CO2 loading (44). Structural and functional sex-based differences with respect to the pulmonary system could be further analyzed by comparing a group of men and women matched for height and a group of men and women matched for lung size.                     63  CONCLUSION Based on the results from this study, the effects of He-O2 on cycling performance appear small and are variable between subjects.  Further testing of a larger sample size is required to say with certainty whether the effects of He-O2 do or do not improve performance.  The susceptibility of EFL was found to be higher in women breathing RA, however the magnitude was comparable between the sexes and not affected by He-O2.  This was because throughout both TTs men and women took full advantage of their MEFV curve.  As such, nearly all subjects demonstrated impending EFL.  By regulating their EELV subjects strived to achieve the highest expiratory flows possible, free of mechanical ventilatory constraint.  It was also observed that He-O2 does not appear to reduce airflow resistance enough to substantially reduce the total WOB compared to RA in men or women.  Women demonstrated a significantly greater WOB compared to men for a similar V’E, which is likely due to women’s inherently smaller diameter airways and lower maximal flow rates.  Despite the greater absolute cost of breathing, men and women have similar sensory responses regardless of inspirate, potentially attributed to differences in psychosocial factors or stoicism.  Further research with the ability to unloading expiration and isolate the effects of expiratory mechanical ventilatory constraints on endurance performance is necessary to understand how EFL, operational lung volumes, the WOB, and potentially sex affect endurance performance.    64  REFERENCES 1. Aaron EA, Seow KC, Johnson BD, and Dempsey JA. Oxygen cost of exercise hyperpnea: implications for performance. J Appl Physiol 72: 1818-1825, 1992.  2. 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J Appl Physiol 57: 1773-1782, 1984.    70  APPENDIX A - INDIVIDUAL DATA – TABLES    Table 23 - Individual descriptive and anthropometric data  Age (yr) Height (cm) Mass (kg) Men 104 27 187.2 84.8 105 38 186.0 77.9 106 29 186.0 77.3 107 30 187.0 77.4 108 36 171.5 67.5 109 32 175.0 69.0 110 39 178.0 71.1 111 22 181.0 75.2 112 28 170.0 60.1 114 30 186.0 75.8 115 25 177.0 74.9 Women 201 26 171.0 54.7 202 19 160.0 55.2 203 22 171.5 58.6 204 30 166.0 60.2 205 28 163.0 50.2 206 34 159.0 55.0 207 24 166.0 58.1 208 24 170.0 58.9 210 31 176.0 70.6 211 24 179.0 69.6 212 27 164.0 58.2    71  Table 24 - Individual pulmonary function data. FVC, forced vital capacity; FEV1.0, forced expired volume in 1 sec; PEF, peak expiratory flow.    FVC (l) FVC            (% predicted) FEV1.0 (l) FEV1.0  (% predicted) FEV1.0/FVC  (%) FEV1.0/FVC  (%  predicted) PEF  (l∙sec-1) PEF  (% predicted) Men       104 6.61 115 5.63 118 85.2 103 11.6 111  105 5.50 102 4.54 103 82.5 103 13.0 130  106 6.45 115 5.28 113 81.9 100 10.8 104  107 6.37 113 5.08 109 79.7 97 12.6 122  108 4.46 96 3.64 82 81.6 101  9.8 107  109 5.77 118 4.32 105 74.9 92 10.2 108  110 5.32 109 3.98 99 74.8 93 12.0 127  111 5.32 97 4.13 89 77.6 93 10.6 102  112 4.67 99 3.72 93 79.7 97  9.8 104  114 6.46 116 4.87 105 75.4 92 12.9 121  115 5.34 102 4.45 101 83.3 101  9.9 99  Women       201 4.34 108 3.48 99 80.2 95 8.0 106  202 4.31 116 3.52 109 81.7 96 7.1 100  203 5.03 122 3.79 105 75.3 89 7.6 100  204 4.16 113 3.53 110 84.9 102 8.5 119  205 3.05 85 2.45 96 80.3 96 5.6 79  206 3.58 109 3.06 107 85.5 103 8.2 123  207 3.76 98 3.14 94 83.5 99 6.5 88  208 4.87 121 4.29 122 88.1 104 9.0 120  210 4.48 109 3.34 94 74.6 90 6.0 78  211 5.52 125 4.44 115 80.4 95 8.3 103  212 4.02 110 3.43 107 85.3 102 7.4 104        72  Table 25 - Individual cycling experience   Discipline Highest Level of Competition Training Status Road Triathlon Mountain Cyclo-cross Regional Provincial National International In-season Off-season Men           104 X    X     X 105 X    X     X 106 X    X    X  107  X     X   X 108  X     X  X  109 X      X  X  110  X      X X  111   X   X   X  112 X   X X    X  114 X    X    X  115   X   X    X Women 201  X    X    X 202  X   X     X 203 X  X X   X   X 204  X   X     X 205 X   X X     X 206  X      X X  207 X    X    X  208 X       X X  210  X      X X  211 X    X    X  212  X     X  X        73  Table 26 - Individual Day 1 maximal exercise data.  V’O2, oxygen consumption; V’CO2, carbon dioxide production; RER, respiratory exchange ratio; V’E, minute ventilation; VT, tidal volume; fb, frequency of breathing; HR, heart rate.      V’O2 (ml∙kg-1∙min-1) V’O2           (l∙min-1) V’O2 (% predicted) V’CO2 (l∙min-1) RER V’E (l∙min-1) fb (breaths∙min-1) VT (l) HR (beats∙min-1) Duration (sec) Power (Watts) Power (Watts∙kg-1) Men          104 58.7 5.0 133 5.4 1.08 138 43 3.4 192 853.2 380 4.5 105 61.8 4.8 140   144 57 2.9 190 607.2 350 4.5 106 55.3 4.3 118 4.7 1.10 132 46 3.3 233 640.8 350 4.5 107 56.0 4.3 118 4.8 1.12 143 63 2.7 178 704.4 350 4.5 108 60.7 4.1 145 4.7 1.15 148 65 2.6 190 637.8 350 5.2 109 67.0 4.6 151 5.0 1.07 138 57 2.8 196 868.2 380 5.5 110 63.7 4.5 148 4.9 1.09 163 77 2.4 180 786.0 380 5.3 111 60.1 4.5 127 5.2 1.14 148 78 2.3 n/a 631.2 350 4.7 112 63.2 3.8 130 4.1 1.09 130 64 2.3 189 525.0 320 5.3 114 65.6 5.0 137 5.4 1.10 118 34 4.0 180 1013.4 410 5.4 115 57.1 4.3 129 4.8 1.13 140 56 2.9 197 695.4 350 4.7 Women          201 57.5 3.1 131 3.6 1.14 98 48 2.4 189 795.6 280 5.1 202 54.8 3.0 149 3.2 1.07 89 72 1.4 177 610.2 250 4.5 203 56.0 3.3 131 3.4 1.03 95 52 2.1 190 841.2 280 4.8 204 58.3 3.5 169 4.0 1.13 106 62 2.0 168 786.6 280 4.7 205 59.5 3.0 151 3.3 1.11 84 52 1.9 185 789.6 280 5.6 206 52.6 2.9 173 3.2 1.11 94 61 1.8 186 601.2 250 4.5 207 51.8 3.0 137 3.1 1.04 107 64 1.9 196 652.8 250 4.3 208 61.3 3.6 151 4.0 1.10 109 46 2.7 194 1096.2 310 5.3 210 54.6 3.9 153 4.0 1.03 105 51 2.4 168 1217.4 340 4.8 211 56.3 3.9 139 4.2 1.09 133 66 2.3 204 1159.8 340 4.9 212 52.5 3.1 149 3.2 1.06 89 50 2.1 178 640.8 250 4.3      74   Table 27 - Individual overall TT performance data  Performance Time (sec) Amount Faster (sec) Faster TT order (first or second)   Time between tests (days)  RA  He-O2 RA He-O2 Men      104 452.1 442.3  9.8 1 1 1 2 2 2 2 2 1 2 2 6  105 470.2 483.2 13.0  7  106 458.7 447.7  11.0 7  107 481.0 475.2  5.7 7  108 466.1 471.9 5.8  7  109 439.7 435.4  4.2 2  110 453.3 453.7 0.5  7  111 497.1 485.0  12.1 9  112 481.6 476.4  5.3 7  114 433.5 429.0  4.5 19  115 446.9 445.2  1.7 7  Women      201 519.7 536.96 17.3  1 2 1 2 2 2 1 1 1 1 2 35  202 591.0 564.1  26.9 3  203 523.8 513.69  10.1 7  204 531.2 527.01  4.2 14  205 533.1 523.48  9.6 24  206 565.7 574.46 8.7  7  207 573.2 548.77  24.4 21  208 492.7 485.95  6.7 25  210 482.0 480.6  1.4 4  211 483.9 484.0 0.1  21  212 555.7 549.4  6.3 7      75   Table 28 - Individual RA TT performance data  1 km 2 km 3 km 4 km 5 km  Speed (km∙h-1) Power (Watts) Cadence (RPM) time (sec) Speed (km∙h-1) Power (Watts) Cadence (RPM) time (sec) Speed (km∙h-1) Power (Watts) Cadence (RPM) time (sec) Speed (km∙h-1) Power (Watts) Cadence (RPM) time (sec) Speed (km∙h-1) Power (Watts) Cadence (RPM) time (sec) Men                  104 35.9 262 93 101.1 39.5 316 97 90.6 40.7 337 98 88.2 40.7 337 96 88.2 42.7 393 101 84.0 105 40.4 368 111 89.6 37.6 268 109 95.6 37.8 279 110 95.2 38.2 281 110 94.8 38.0 279 110 95.2 106 38.2 306 104 95.0 39.2 304 110 91.6 39.3 311 110 92.0 39.7 315 108 90.3 40.6 329 113 89.8 107 33.0 218 104 109.3 36.2 248 114 100.0 37.9 284 115 94.2 39.3 302 111 91.6 41.1 358 111 85.8 108 39.0 342 103 92.7 39.2 302 103 92.6 38.8 295 100 92.7 38.2 289 102 94.3 38.3 292 107 93.9 109 40.3 361 107 90.2 41.3 353 109 86.6 41.4 348 108 88.1 41.0 342 108 87.4 41.5 356 108 87.4 110 39.9 349 96 91.0 40.1 325 94 89.2 39.7 316 95 91.3 39.5 310 91 90.9 39.8 315 94 90.9 111 37.0 287 121 98.3 36.2 245 119 99.7 35.7 242 120 100.1 36.3 246 120 100.1 36.3 250 120 98.9 112 37.7 308 105 95.7 37.1 262 105 97.5 37.4 282 93 96.2 37.0 260 93 97.9 38.3 293 94 94.3 114 40.5 366 104 89.8 41.9 368 108 86.2 42.1 373 112 85.3 42.3 373 112 84.9 41.2 360 114 87.4 115 41.0 383 102 88.5 40.6 335 104 88.4 40.2 329 106 89.6 40.2 317 100 90.4 40.0 326 103 90.0 Women                  201 35.0 249 101 103.7 35.4 235 105 101.9 33.4 200 106 107.1 34.2 212 108 106.1 35.5 239 105 100.9 202 29.3 159 99 123.9 29.7 151 101 121.3 30.4 161 103 118.0 30.6 161 101 118.5 32.5 188 96 109.3 203 32.6 205 93 111.3 34.4 215 99 105.1 34.7 219 102 103.6 34.7 225 102 102.7 36.1 241 104 101.2 204 33.7 234 98 107.6 33.9 212 106 106.2 34.1 211 108 105.7 33.9 203 108 106.6 34.4 215 110 105.2 205 31.4 187 92 115.7 33.8 207 96 106.5 34.1 215 97 104.9 34.7 223 99 105.0 35.5 233 96 101.1 206 32.3 202 92 112.4 32.3 182 94 111.4 31.7 177 93 113.0 31.7 171 89 115.0 31.5 173 92 114.0 207 30.0 171 86 120.2 32.0 179 92 112.3 31.6 175 92 113.9 31.6 171 90 114.0 32.3 184 95 112.8 208 36.9 286 100 97.9 36.9 266 100 98.3 35.7 237 103 101.1 36.1 247 105 99.3 37.4 279 107 96.1 210 34.5 239 99 105.1 37.7 277 103 95.8 38.2 285 101 93.6 38.0 283 101 94.5 39.1 296 101 93.1 211 35.3 254 89 102.9 37.1 262 95 97.0 37.4 273 98 96.1 38.2 279 98 95.2 38.5 297 100 92.6 212 31.8 198 91 114.0 31.8 176 93 113.5 32.4 184 92 111.5 32.8 190 96 110.0 33.7 207 93 106.8         76  Table 29 - Individual He-O2 TT performance data  1 km 2 km 3 km 4 km 5 km  Speed (km∙h-1) Power           (Watts) Cadence (RPM) time (sec) Speed (km∙h-1) Power (Watts) Cadence (RPM) time (sec) Speed (km∙h-1) Power (Watts) Cadence (RPM) time (sec) Speed (km∙h-1) Power (Watts) Cadence (RPM) time (sec) Speed (km∙h-1) Power (Watts) Cadence (RPM) time (sec) Men                  104 38.6 317 98 94.1 40.0 323 104 89.9 41.4 353 101 87.5 41.6 359 97 86.7 42.4 378 105 84.2 105 37.5 297 110 96.9 36.3 249 116 98.7 37.5 267 119 96.9 37.5 275 119 96.0 38.2 277 121 94.7 106 40.3 364 101 89.4 39.5 308 103 91.4 40.2 330 108 89.8 40.8 334 104 88.9 40.7 344 109 88.2 107 33.5 224 108 108.5 37.5 270 112 95.7 38.2 286 113 94.0 39.2 308 111 90.9 41.6 357 106 86.1 108 39.0 336 104 92.5 39.0 302 108 92.9 37.8 277 109 95.1 37.8 269 111 96.4 37.9 281 108 95.0 109 42.3 407 110 85.8 41.5 353 108 86.9 41.3 350 109 87.8 40.9 342 109 87.7 41.5 353 109 87.4 110 40.6 373 94 89.0 39.8 315 94 91.0 39.3 308 91 91.9 39.5 308 93 91.0 39.8 316 93 91.0 111 38.5 322 122 94.2 37.3 266 124 96.4 37.0 258 123 97.7 36.4 250 119 99.5 36.8 259 122 97.2 112 37.5 299 98 96.5 38.3 285 90 94.7 37.9 280 88 95.1 37.9 276 88 95.1 37.9 285 96 95.1 114 40.7 367 108 88.9 41.7 361 110 86.8 42.1 373 109 85.6 42.7 379 113 84.5 43.3 400 115 83.3 115 41.2 380 102 87.7 40.4 328 104 89.3 40.2 324 103 90.5 39.4 316 103 90.9 41.3 352 108 86.8 Women                  201 32.7 211 108 110.1 34.1 209 108 106.8 33.4 204 108 107.6 33.4 196 108 108.2 34.4 220 113 104.2 202 31.6 196 145 114.7 31.2 168 35 175.7 31.7 176 90 53.7 32.3 184 94 112.1 33.2 201 91 107.9 203 33.9 227 90 106.8 34.9 225 92 103.5 35.9 238 94 100.2 34.9 226 92 103.5 35.9 244 92 99.7 204 34.4 240 106 105.7 34.8 222 110 103.3 34.0 210 108 106.2 33.6 204 108 107.2 34.7 214 108 104.7 205 32.2 199 95 111.8 34.4 217 99 105.0 35.1 229 100 102.5 35.1 227 98 103.1 35.7 243 98 101.1 206 32.0 196 96 113.1 31.6 174 102 114.2 31.2 167 99 115.7 30.8 163 99 116.8 31.4 175 94 114.7 207 31.6 189 90 114.1 33.2 197 96 109.5 33.0 193 96 129.1 32.6 193 94 90.1 34.1 213 99 106.1 208 36.6 294 98 98.8 38.2 284 100 94.8 37.7 274 99 95.2 36.3 256 103 99.8 36.7 272 105 97.4 210 34.7 243 99 104.4 37.9 281 111 94.5 38.4 286 111 94.6 38.2 290 111 93.3 38.8 290 113 93.7 211 34.5 238 94 104.7 37.9 282 98 94.8 38.0 278 99 95.3 36.8 258 101 97.9 39.3 309 103 91.3 212 31.7 193 92 113.7 32.7 189 96 110.7 33.1 194 94 109.2 33.3 196 98 108.7 33.7 203 95 107.2          77  Table 30 - Individual RA TT metabolic data.  V’O2, oxygen consumption; V’CO2, carbon dioxide production; RER, respiratory exchange ratio; V’E, minute ventilation; VT, tidal volume; fb, frequency of breathing; HR, heart rate.  Rest            V’O2            (l∙min-1) V’CO2 (l∙min-1) RER V’E (l∙min-1) fb (breaths∙min-1) VT (l) HR (beats∙min-1)  Men       104  0.4 0.3 0.82 9 13 0.8   105  0.6 0.5 0.98 15 11 1.6   106  0.4 0.4 0.96 13 13 1.2 65  107  0.3 0.3 0.84 10 16 0.7 55  108  0.3 0.3 1.00 10 16 0.7 57  109  0.3 0.3 0.91 9 11 1.0 61  110  0.4 0.3 0.88 11 12 1.1 60  111  0.2 0.3 1.01 9 16 0.7 57  112  0.4 0.5 1.31 19 14 1.6 63  114  0.4 0.3 0.92 9 11 0.9 63  115  0.4 0.3 0.86 9 11 1.0 69  Women       201  0.3 0.5 1.82 22 22 1.1   202  0.1 0.1 0.93 4 7 0.6   203  0.3 0.3 0.86 9 16 0.7 74  204  0.3 0.3 1.06 12 14 1.0 58  205  0.2 0.2 0.89 6 12 0.6 56  206  0.2 0.2 1.09 8 10 0.9 60  207  0.2 0.2 0.91 8 15 0.6 71  208  0.2 0.2 0.91 5 8 0.9 65  210  0.4 0.3 0.80 9 13 0.8 56  211  0.4 0.4 0.82 11 16 0.8 69  212  0.3 0.2 0.86 6 12 0.6 61  1 km            V’O2            (l∙min-1) V’CO2 (l∙min-1) RER V’E (l∙min-1) fb (breaths∙min-1) VT (l) HR (beats∙min-1)  Men       104  3.4 2.2 0.65 50.9 24 2.5 148  105  3.7 3.8 1.06 92.0 31 3.4 176  106  3.8 3.3 0.87 81.1 28 3.3 172  107  2.5 2.3 0.94 52.2 29 2.1 138  108  3.3 3.6 1.14 96.3 50 2.2 173  109  3.4 3.6 1.07 95.8 40 2.8 177  110  3.3 3.7 1.14 100.1 45 2.6 162  111  3.4 3.6 1.08 90.5 50 2.1 161  112  3.2 3.5 1.11 103.4 48 2.5 166  114  4.1 3.5 0.87 74.6 23 3.7 165  115  3.6 3.4 0.97 79.2 34 2.7 174  Women       201  2.5 2.6 1.03 74.1 37 2.3 177  202  2.3 2.0 0.89 51.0 47 1.3 151  203  2.6 2.3 0.89 63.2 33 2.3 161  204  2.8 2.6 0.95 63.0 41 1.8 154  205  2.1 1.9 0.92 42.9 29 1.7 156  206  2.2 2.5 1.11 74.8 52 1.7 169  207  2.3 2.0 0.88 64.3 49 1.5 170  208  3.0 2.9 1.02 76.0 35 2.5 174  210  3.2 2.9 0.92 73.6 35 2.4 147  211  3.3 3.0 0.92 72.1 34 2.4 178  212  2.7 2.7 1.05 62.7 34 2.1 157   78  Table 30 - Individual RA TT metabolic data, continued… 2 km            V’O2            (l∙min-1) V’CO2 (l∙min-1) RER V’E (l∙min-1) fb (breaths∙min-1) VT (l) HR (beats∙min-1)  Men       104  4.0 3.5 0.87 73.3 28 3.1 157  105  4.2 4.8 1.15 124.2 41 3.6 180  106  4.4 4.3 0.99 104.5 34 3.6 181  107  3.1 3.7 1.20 85.3 36 2.7 147  108  3.5 4.7 1.34 130.2 58 2.6 177  109  3.8 5.0 1.30 136.8 52 3.0 178  110  3.6 4.6 1.28 128.4 52 2.9 168  111  3.5 4.3 1.21 115.5 52 2.6 166  112  3.4 3.8 1.13 115.4 54 2.5 174  114  4.8 5.4 1.14 113.8 30 4.3 170  115  3.7 4.9 1.33 121.9 46 3.1 178  Women       201  2.7 3.3 1.22 93.5 44 2.5 184  202  2.3 2.3 0.96 62.0 75 1.0 150  203  3.0 3.1 1.02 88.5 44 2.3 171  204  3.3 3.7 1.11 91.4 48 2.2 161  205  2.4 2.6 1.10 55.1 33 2.0 170  206  2.4 2.8 1.20 89.8 59 1.8 171  207  2.6 2.6 1.03 88.1 62 1.7 173  208  3.0 3.9 1.29 92.8 36 3.0 176  210  3.5 3.5 1.01 90.6 42 2.5 151  211  3.4 3.6 1.06 93.5 43 2.5 182  212  2.6 2.8 1.06 69.1 37 2.1 158      3 km            V’O2            (l∙min-1) V’CO2 (l∙min-1) RER V’E (l∙min-1) fb (breaths∙min-1) VT (l) HR (beats∙min-1)  Men       104  4.5 4.3 0.96 86.9 31 3.3 168  105  4.3 4.4 1.03 123.6 42 3.4 183  106  4.6 4.5 0.97 106.8 34 3.6 179  107  3.3 4.2 1.26 101.2 42 2.8 161  108  3.7 4.4 1.16 131.9 60 2.6 178  109  4.0 4.9 1.22 139.9 54 3.0 184  110  3.7 4.6 1.22 151.4 64 2.7 169  111  3.7 3.9 1.06 111.0 52 2.5 167  112  3.6 3.8 1.05 118.6 56 2.5 177  114  4.9 5.5 1.11 124.8 33 4.4 174  115  3.8 4.8 1.27 136.3 54 2.9 182  Women       201  2.7 3.1 1.14 92.7 44 2.4 186  202  2.4 2.2 0.92 60.0 76 1.0 159  203  3.2 3.2 0.99 92.3 48 2.3 177  204  3.5 3.7 1.04 103.8 56 2.2 167  205  2.5 2.9 1.16 63.0 36 2.0 176  206  2.3 2.7 1.13 92.5 62 1.7 171  207  2.6 2.5 0.97 85.4 62 1.6 177  208  3.2 3.7 1.18 97.3 38 3.0 177  210  3.7 3.6 0.98 96.9 47 2.4 157  211  3.6 3.7 1.04 101.0 46 2.5 186  212  2.7 2.7 0.99 71.6 41 2.0 163   79  Table 30 - Individual RA TT metabolic data, continued… 4 km            V’O2            (l∙min-1) V’CO2 (l∙min-1) RER V’E (l∙min-1) fb (breaths∙min-1) VT (l) HR (beats∙min-1)  Men       104  4.9 4.8 1.00 103.3 35 3.5 175  105  4.4 4.4 0.99 129.7 45 3.4 183  106  4.7 4.5 0.96 112.0 36 3.6 183  107  3.4 4.4 1.30 116.6 47 2.9 169  108  3.9 4.2 1.08 133.7 62 2.5 180  109  4.0 4.8 1.19 140.9 58 2.8 187  110  3.8 4.5 1.17 155.3 69 2.6 170  111  3.9 4.0 1.01 113.1 54 2.4 172  112  3.7 3.7 1.01 121.2 58 2.4 184  114  5.1 5.5 1.09 130.4 35 4.4 179  115  3.8 4.6 1.21 139.9 56 2.9 183  Women       201  2.8 3.0 1.08 92.4 46 2.3 188  202  2.3 2.2 0.94 57.5 62 1.1 161  203  3.4 3.3 0.97 95.2 49 2.2 182  204  3.5 3.5 1.00 107.8 62 2.1 170  205  2.5 3.0 1.18 70.8 42 1.9 180  206  2.3 2.6 1.12 93.7 66 1.7 174  207  2.6 2.5 0.95 85.0 61 1.6 177  208  3.2 3.6 1.13 104.8 43 2.9 182  210  3.7 3.7 0.98 100.0 49 2.3 158  211  3.7 3.8 1.04 109.5 50 2.5 186  212  2.8 2.8 0.99 76.2 44 2.0 166        5 km            V’O2            (l∙min-1) V’CO2 (l∙min-1) RER V’E (l∙min-1) fb (breaths∙min-1) VT (l) HR (beats∙min-1)  Men       104  5.0 5.3 1.06 127.8 47 3.2 187  105  4.4 4.3 0.97 132.0 45 3.4 189  106  4.8 4.6 0.96 116.9 39 3.6 187  107  3.5 4.9 1.38 137.9 54 3.0 178  108  4.0 4.2 1.06 137.0 64 2.5 185  109  4.1 4.8 1.17 142.5 64 2.6 192  110  3.9 4.5 1.14 157.3 76 2.4 173  111  3.9 3.9 1.00 115.8 57 2.4 173  112  3.8 3.8 1.01 123.8 62 2.3 189  114  5.2 5.7 1.09 144.7 39 4.3 182  115  3.7 4.4 1.18 143.2 60 2.8 185  Women       201  2.9 3.1 1.10 98.8 50 2.3 194  202  2.4 2.3 0.97 56.7 50 1.3 174  203  3.4 3.4 0.98 99.7 51 2.3 188  204  3.6 3.5 0.99 116.4 72 1.9 174  205  2.5 3.0 1.21 74.8 45 1.9 183  206  2.3 2.5 1.12 95.8 69 1.6 176  207  2.7 2.5 0.95 90.3 65 1.6 183  208  3.3 3.6 1.10 102.4 44 2.8 189  210  3.8 3.7 0.98 103.3 52 2.3 166  211  3.7 3.9 1.05 117.6 55 2.5 195  212  2.9 2.9 1.00 82.7 48 2.0 173   80  Table 31 - Individual He-O2 TT metabolic data.  V’O2, oxygen consumption; V’CO2, carbon dioxide production; RER, respiratory exchange ratio; V’E, minute ventilation; VT, tidal volume; fb, frequency of breathing; HR, heart rate.   Rest            V’O2            (l∙min-1) V’CO2 (l∙min-1) RER V’E (l∙min-1) fb (breaths∙min-1) VT (l) HR (beats∙min-1)  Men       104  0.5   12 14 1.0 84  105  0.4   13 13 1.3   106  0.4   13 11 1.6 60  107  0.4   11 17 0.9   108  0.3   8 18 0.6 55  109  0.2   6 9 1.0 77  110  0.3   7 8 1.0 56  111  0.2   8 16 0.6 52  112  0.3   13 15 1.1 95  114  0.5   17 14 1.6 63  115  0.3   7 9 1.1 84  Women       201  0.4   19 23 1.1 66  202  0.0   1 2 0.7   203  0.4   10 15 0.9 72  204  0.3   9 11 1.1 50  205  0.3   8 13 0.7 58  206  0.2   8 10 1.0 63  207  0.3   10 20 0.7 71  208  0.3   10 15 0.8 65  210  0.3   9 15 0.8 54  211  0.3   10 15 0.8 54  212  0.2   8 15 0.6 67       1 km            V’O2            (l∙min-1) V’CO2 (l∙min-1) RER V’E (l∙min-1) fb (breaths∙min-1) VT (l) HR (beats∙min-1)  Men       104  4.3   84.6 34 2.9 161  105  3.0   71.3 31 2.9 166  106  3.3   81.8 34 3.1 179  107  2.8   54.1 33 2.1 142  108  3.2   90.5 50 2.2 174  109  3.8   113.5 49 3.0 183  110  3.6   100.0 53 2.5 109  111  3.6   101.0 58 2.3 177  112  2.8   88.9 50 2.3 167  114  4.2   78.8 28 3.6 170  115  3.8   73.8 33 2.8 171  Women       201  2.3   66.9 42 2.0 163  202  2.3   64.1 78 1.1 157  203  2.5   64.5 34 2.4 170  204  2.6   65.3 64 1.4 152  205  2.3   46.2 32 1.8 166  206  2.2   74.2 52 1.8 168  207  2.3   68.0 53 1.6 175  208  3.0   76.6 44 2.3 174  210  3.1   78.3 39 2.5 153  211  3.1   70.7 38 2.4 166  212  2.3   54.1 38 1.8 159   81   Table 31 - Individual He-O2 TT metabolic data, continued… 2 km            V’O2            (l∙min-1) V’CO2 (l∙min-1) RER V’E (l∙min-1) fb (breaths∙min-1) VT (l) HR (beats∙min-1)  Men       104  4.2   97.4 37 3.1 172  105  3.4   105.0 40 3.5 170  106  3.7   107.2 38 3.7 183  107  3.4   83.5 38 2.9 150  108  3.3   136.3 64 2.7 179  109  4.1   144.4 55 3.4 184  110  3.8   141.5 63 2.9 173  111  3.8   126.1 65 2.5 185  112  3.1   115.4 56 2.6 172  114  4.3   106.6 35 4.0 170  115  3.8   112.3 45 3.2 177  Women       201  2.5   84.7 48 2.3 168  202  2.2   63.7 77 1.1 159  203  2.7   87.7 46 2.5 178  204  2.8   96.1 71 1.8 158  205  2.6   63.5 41 2.0 174  206  11.3   89.3 59 1.9 167  207  2.3   85.7 70 1.6 179  208  3.0   109.0 50 2.8 179  210  3.4   89.8 44 2.6 161  211  3.2   89.8 46 2.5 181  212  2.4   63.8 41 2.0 161         3 km            V’O2            (l∙min-1) V’CO2 (l∙min-1) RER V’E (l∙min-1) fb (breaths∙min-1) VT (l) HR (beats∙min-1)  Men       104  4.5   111.8 41 3.2 177  105  3.5   106.4 42 3.3 174  106  3.9   112.1 41 3.5 184  107  3.7   95.3 42 2.9 158  108  3.4   143.1 68 2.6 179  109  4.2   144.7 54 3.4 187  110  3.9   149.2 74 2.6 172  111  3.9   131.5 67 2.6 188  112  3.3   121.4 61 2.5 176  114  4.6   112.4 37 3.9 179  115  4.0   123.6 50 3.2 180  Women       201  2.6   86.5 50 2.2 172  202  2.2   60.8 73 1.1 162  203  2.9   98.5 52 2.4 186  204  2.9   103.4 80 1.7 163  205  2.8   70.2 45 2.0 182  206  8.9   89.9 64 1.8 168  207  2.4   85.6 70 1.6 180  208  3.2   115.8 55 2.7 180  210  3.6   99.8 50 2.6 165  211  3.4   103.0 51 2.6 184  212  2.5   67.5 45 1.9 165   82   Table 31 - Individual He-O2 TT metabolic data, continued… 4 km            V’O2            (l∙min-1) V’CO2 (l∙min-1) RER V’E (l∙min-1) fb (breaths∙min-1) VT (l) HR (beats∙min-1)  Men       104  4.9   131.3 46 3.3 183  105  3.8   118.0 47 3.2 189  106  4.1   121.2 45 3.5 185  107  3.9   110.0 48 3.0 167  108  3.5   147.5 73 2.6 181  109  4.3   149.8 62 3.1 189  110  4.0   145.6 78 2.4 175  111  4.0   130.0 69 2.4 190  112  3.4   120.8 62 2.5 181  114  4.7   129.0 41 4.1 181  115  4.1   137.4 58 3.1 183  Women       201  2.7   86.0 52 2.1 175  202  2.3   64.3 79 1.1 168  203  2.9   100.2 55 2.4 186  204  2.9   109.3 98 1.5 166  205  2.9   79.2 52 2.0 183  206  2.2   86.8 67 1.7 168  207  2.4   88.3 76 1.5 181  208  3.3   117.4 56 2.7 182  210  3.7   108.1 57 2.4 167  211  3.4   102.8 54 2.4 183  212  2.6   73.6 48 2.0 167          5 km            V’O2            (l∙min-1) V’CO2 (l∙min-1) RER V’E (l∙min-1) fb (breaths∙min-1) VT (l) HR (beats∙min-1)  Men       104  4.9   143.8 50 3.4 188  105  3.8   128.6 52 3.2 188  106  4.2   135.4 51 3.5 188  107  4.1   134.2 55 3.2 177  108  3.6   153.6 75 2.6 186  109  4.3   160.7 74 2.8 194  110  4.2   156.6 82 2.5 179  111  4.0   131.4 75 2.3 194  112  3.5   123.4 64 2.5 186  114  4.9   137.4 41 4.3 188  115  4.2   152.8 65 3.0 188  Women       201  2.8   93.6 58 2.1 180  202  2.3   63.7 71 1.1 173  203  3.0   103.4 59 2.3 192  204  2.9   120.3 113 1.4 170  205  2.9   84.1 54 2.0 187  206  2.2   90.8 77 1.5 173  207  2.5   92.0 74 1.6 190  208  3.3   119.7 59 2.6 187  210  3.6   108.3 60 2.3 170  211  3.6   116.2 59 2.5 196  212  2.6   78.0 52 1.9 169   83   Table 32 – Individual expiratory flow rates.  MEF, Maximal Expiratory Flow; MEF-50%, Maximal Expiratory Flow at 50 % Vital Capacity; MEF-exercise, maximal expiratory flow achieved during the time trial.  Subject MEF (l∙sec-1) MEF-50 % (l∙sec-1) MEF-exercise (l∙sec-1) RA He-O2 RA He-O2 RA He-O2 Men       104 11.76 16.40 7.21 10.00 6.58 9.01 105 12.99 17.71 7.52 10.91 7.44 8.60 106 11.86 14.41 7.94 10.63 5.28 7.40 107 12.19 17.13 6.69 7.75 6.42 7.98 108 10.74 13.73 5.50 6.46 6.54 8.52 109 10.02 13.33 5.38 7.02 7.27 9.74 110 13.19 16.82 6.69 8.67 7.21 8.74 111 10.56 14.47 6.12 9.34 5.29 7.44 112 10.38 12.72 4.59 6.06 5.97 7.12 114 10.50 16.75 6.52 11.05 8.17 9.64 115 11.11 16.22 6.89 10.27 7.00 10.12 Women       202 6.81 10.10 4.74 7.25 3.12 4.63 203 7.58 10.18 4.17 5.43 5.42 6.35 204 9.38 11.78 6.68 8.26 5.37 6.64 205 5.77 8.59 4.04 5.00 4.03 5.10 206 7.65 9.69 4.73 6.40 4.67 4.63 207 6.84 8.74 4.17 6.11 4.80 5.28 208 9.35 10.81 6.46 8.26 5.51 5.98 210 7.26 8.64 3.85 5.10 5.15 6.55 211 8.22 9.75 5.73 7.56 5.43 6.09 212 7.45 8.74 4.37 5.48 4.53 4.49         84  Table 33 - Individual RA TT operational lung volumes.  EELV, End expired lung volume; EILV; End inspired lung volume.   Rest  EELV (l) EELV (% FVC) EILV (l) EILV (% FVC) Men  104 2.7 44.0 3.9 62.2 105 2.5 43.7 3.7 64.7 106 3.6 57.2 4.6 73.6 107 3.8 59.7 4.6 71.6 108 2.7 54.5 3.3 67.8 109 3.0 54.6 3.7 67.3 110 2.8 55.2 3.6 69.6 111 1.9 40.5 2.6 54.8 112 2.0 44.0 3.4 75.4 114     115 2.6 50.1 3.5 67.8 Women 201 1.5 41.2 2.6 74.4 202 1.9 57.9 2.4 74.8 203 2.4 54.5 3.1 70.8 204 1.4 36.6 2.2 58.1 205 1.8 59.9 2.3 76.8 206 1.5 45.0 2.1 63.8 207 1.5 45.0 2.1 62.1 208     210 2.2 51.6 2.9 68.1 211 2.7 54.6 3.5 70.0 212 1.9 45.6 2.4 57.2       1 km  EELV (l) EELV           (% FVC) EILV (l) EILV           (% FVC) Men  104 2.4 38.3 4.9 78.1 105 1.5 25.5 4.9 85.5 106 2.0 31.7 5.1 81.7 107 2.8 43.7 5.2 80.9 108 2.2 44.5 4.6 93.7 109 1.8 32.7 4.8 88.0 110 2.2 42.3 4.8 93.8 111 2.1 45.8 4.4 95.1 112 2.0 44.5 4.5 98.5 114 1.7 27.1 5.3 86.5 115 1.7 33.0 4.6 87.7 Women 201 0.8 22.4 3.2 89.5 202 1.4 43.3 2.7 83.5 203 1.6 36.7 3.8 87.0 204 1.2 30.5 3.0 79.3 205 0.9 31.6 2.7 92.3 206 1.1 32.8 2.8 85.1 207 1.2 34.3 2.8 83.1 208 2.2 42.2 4.4 85.2 210 1.7 38.4 4.0 93.5 211 1.7 34.7 4.2 84.1 212 1.6 38.6 3.7 87.3  2 km  EELV (l) EELV           (% FVC) EILV (l) EILV           (% FVC) Men  104 2.3 36.6 5.0 80.5 105 1.6 27.1 4.8 84.4 106 2.0 31.8 5.4 86.0 107 2.7 41.7 5.3 82.4 108 2.1 42.9 4.6 92.9 109 2.1 38.0 5.0 90.3 110 1.5 29.8 4.2 82.7 111 1.4 30.6 3.9 82.4 112 2.2 49.6 4.5 100.2 114 1.4 23.0 5.6 90.5 115 1.7 32.8 4.6 88.1 Women 201 1.1 31.3 3.3 93.5 202  0.0  0.0 203 1.5 35.5 3.8 88.6 204 1.1 28.6 3.2 85.4 205 1.0 34.7 3.0 99.3 206 1.0 31.6 2.7 82.1 207 1.2 36.7 2.9 86.4 208 2.2 42.2 4.9 93.8 210 1.8 40.5 4.1 95.6 211 2.0 39.5 4.4 87.7 212 1.8 42.8 3.8 90.4  85  Table 33 - Individual RA TT operational lung volumes, continued… 3km  EELV (l) EELV           (% FVC) EILV (l) EILV           (% FVC) Men  104 2.2 34.6 5.0 79.9 105 1.6 27.8 4.9 84.8 106 2.1 33.9 5.5 88.1 107 2.6 40.4 5.3 82.6 108 2.0 40.8 4.4 89.0 109 2.1 38.9 5.0 90.3 110 1.6 31.2 4.2 81.3 111  0.0  0.0 112 2.2 48.9 4.5 100.4 114 1.7 27.2 5.7 93.5 115 2.1 39.5 4.8 92.5 Women 201 0.8 21.3 3.0 84.9 202  0.0  0.0 203 1.5 35.5 3.6 84.5 204 0.8 22.3 2.8 73.5 205 0.9 30.6 2.9 97.0 206 1.2 35.9 2.8 86.0 207 1.1 31.1 2.7 78.7 208 2.0 39.1 4.8 93.1 210 1.6 38.0 3.9 89.4 211 2.3 45.4 4.6 92.9 212 2.1 49.6 4.0 93.4      4 km  EELV (l) EELV           (% FVC) EILV (l) EILV           (% FVC) Men  104 2.1 34.1 5.1 82.8 105 1.8 31.1 5.0 87.8 106 1.9 30.9 5.3 85.4 107 3.1 48.3 5.9 91.7 108 2.5 51.0 4.9 99.0 109 2.4 43.6 5.0 90.5 110 2.1 40.5 4.5 88.3 111 1.8 37.5 4.1 87.6 112 2.2 48.2 4.3 95.8 114 1.6 25.3 5.6 92.0 115 2.2 43.0 5.0 95.6 Women 201 1.0 28.1 3.1 88.1 202 1.6 49.5 2.8 86.9 203 1.4 32.5 3.6 82.6 204 0.9 24.4 2.8 72.9 205 0.9 29.3 2.7 89.6 206 1.3 39.5 2.9 87.2 207 1.4 41.7 2.9 84.3 208 1.8 35.1 4.4 85.4 210 1.8 42.1 4.0 93.5 211 2.1 41.9 4.5 90.1 212 2.0 46.6 3.9 91.1  5km  EELV (l) EELV           (% FVC) EILV (l) EILV           (% FVC) Men  104 2.2 35.7 5.3 85.7 105 1.8 31.8 5.1 88.6 106 2.0 32.3 5.0 80.2 107 3.1 48.0 5.9 92.0 108 2.6 53.3 5.0 101.0 109 2.7 48.9 5.1 93.1 110 2.1 40.9 4.3 84.6 111 1.7 36.4 3.9 83.9 112 1.6 34.7 3.7 81.9 114 1.5 24.0 5.1 83.7 115 2.3 43.8 4.9 93.1 Women 201 1.0 28.1 3.1 89.2 202 1.6 49.5 3.0 92.5 203 1.6 36.7 3.7 86.8 204 0.8 21.2 2.6 67.6 205 1.0 33.0 2.8 94.9 206 1.4 43.5 2.9 87.5 207 1.4 39.9 2.9 85.8 208 2.2 42.8 4.7 90.2 210 1.9 43.3 4.0 93.5 211 2.0 39.7 4.3 86.5 212 2.1 49.4 4.0 94.8  86  Table 34 - Individual He-O2 TT operational lung volumes.  EELV, End expired lung volume; EILV; End inspired lung volume.   Rest  EELV (l) EELV           (% FVC) EILV (l) EILV           (% FVC) Men  104 2.2 36.8 3.0 49.0 105 2.1 39.0 2.9 53.6 106 3.9 67.6 2.2 38.5 107 3.5 55.8 4.3 67.9 108 2.4 50.6 2.9 60.8 109 2.7 49.3 3.4 62.2 110 2.8 55.1 3.4 66.7 111 1.7 36.0 2.4 50.5 112 2.1 46.3 3.0 68.1 114 1.8 29.3 2.7 43.2 115 2.3 43.6 3.2 62.0 Women 201 1.6 49.2 2.6 82.6 202 2.2 70.9 2.6 84.6 203 1.9 43.9 2.9 66.3 204 1.5 41.1 2.4 65.9 205 1.7 56.3 2.3 76.3 206 1.3 36.7 2.3 67.3 207 1.7 49.4 2.3 65.7 208 2.1 41.1 2.9 57.3 210 1.9 43.6 2.7 61.6 211 2.2 43.9 3.0 59.3 212 1.9 44.0 2.5 57.6      1km  EELV (l) EELV           (% FVC) EILV (l) EILV           (% FVC) Men  104 2.0 33.1 5.0 82.1 105 1.2 21.7 4.2 77.5 106 1.2 21.3 4.3 74.0 107 2.6 41.8 5.2 82.6 108 1.9 38.8 4.3 89.8 109 1.5 28.4 4.7 86.9 110       111 1.3 28.2 3.7 78.5 112 1.3 28.8 3.7 83.1 114 1.7 26.8 5.0 79.7 115 1.8 33.7 4.7 90.6 Women 201 0.6 17.4 2.6 80.8 202 1.5 50.0 2.7 86.6 203 1.3 30.0 3.8 87.5 204 0.9 24.3 2.5 66.8 205 0.8 27.7 2.8 93.0 206 1.0 28.3 2.8 81.2 207 1.4 41.0 3.0 86.9 208 1.7 33.5 4.3 84.8 210 1.4 32.9 3.9 88.1 211 1.9 37.9 4.3 85.4 212 1.6 36.8 3.5 82.4  2km  EELV (l) EELV           (% FVC) EILV (l) EILV           (% FVC) Men  104 1.9 31.8 5.0 82.0 105 1.2 21.4 4.0 73.5 106 1.2 21.3 5.1 88.5 107 2.8 45.1 5.6 89.3 108 1.8 37.5 4.4 91.5 109 1.5 28.4 4.7 86.9 110 1.7 33.7 4.4 86.5 111 1.5 32.4 4.0 84.4 112 1.1 24.7 3.6 80.9 114 1.7 26.5 5.6 89.3 115 1.5 29.1 4.7 89.3 Women 201 0.7 20.5 2.9 90.5 202 1.6 52.9 2.7 87.3 203 1.6 36.0 4.0 92.8 204 0.8 20.7 2.3 62.4 205 1.0 33.0 2.9 98.0 206 0.8 22.0 2.6 74.9 207 1.4 40.4 2.9 82.8 208 1.7 33.5 4.5 88.6 210 1.5 33.1 4.0 90.9 211 1.9 38.5 4.4 87.8 212 1.8 42.9 3.7 87.6  87  Table 34 - Individual He-O2 TT operational lung volumes, continued… 3km  EELV (l) EELV           (% FVC) EILV (l) EILV           (% FVC) Men  104 1.8 30.0 5.1 84.9 105 1.1 19.5 4.0 73.3 106 1.3 22.5 4.7 81.5 107 2.9 46.1 5.7 90.6 108 1.8 36.7 4.2 87.9 109 1.7 31.0 5.0 93.0 110 1.9 37.1 4.3 85.1 111 1.4 29.7 3.9 81.5 112 1.0 22.7 3.5 79.6 114 1.2 19.8 5.2 82.5 115 1.8 33.5 4.8 91.6 Women 201 0.7 20.8 2.9 89.9 202 1.5 49.7 2.5 82.4 203 1.6 36.0 4.0 92.8 204 0.8 20.7 2.3 63.8 205 1.0 34.7 3.0 101.0 206 1.1 30.6 2.8 79.5 207 1.0 29.9 2.6 75.3 208 1.9 37.4 4.5 88.4 210 1.6 36.8 4.1 92.7 211 1.9 38.5 4.4 87.4 212 1.5 34.7 3.4 80.6      4km  EELV (l) EELV           (% FVC) EILV (l) EILV           (% FVC) Men  104 1.8 29.3 5.1 83.8 105 1.2 21.9 3.7 67.4 106 1.2 20.2 4.3 75.6 107 2.8 45.3 5.7 90.7 108 2.4 49.2 4.8 100.4 109 2.1 37.8 4.9 90.8 110 1.8 35.7 4.2 81.4 111 1.9 40.6 4.2 88.0 112 1.2 26.5 3.7 83.1 114 1.4 22.0 5.4 86.6 115 1.7 33.3 4.8 91.4 Women 201 0.6 19.6 2.6 83.3 202 1.4 46.4 2.5 82.7 203 1.3 29.6 3.5 81.8 204 1.0 27.8 2.5 67.6 205 1.1 35.7 2.9 96.3 206 1.1 30.6 2.6 74.6 207 1.4 41.3 2.9 85.2 208 2.0 39.2 4.6 91.1 210 1.6 36.8 3.8 87.7 211 2.2 43.9 4.5 89.6 212 1.8 41.9 3.8 87.8  5km  EELV (l) EELV           (% FVC) EILV (l) EILV           (% FVC) Men  104 1.9 31.8 5.5 91.4 105 1.3 24.7 4.4 81.2 106 1.6 27.9 4.9 85.0 107 2.7 43.2 5.9 94.3 108       109 2.4 44.5 5.1 93.7 110 2.0 39.4 4.4 87.1 111 2.1 43.8 4.2 89.3 112 1.3 29.9 3.8 85.8 114 1.4 22.2 5.4 86.4 115 1.5 28.9 4.3 81.6 Women 201 0.7 22.4 2.8 87.1 202 1.3 42.5 2.5 81.0 203 1.6 36.0 3.7 86.4 204 0.9 24.3 2.2 59.9 205 0.9 30.7 2.9 96.0 206 1.2 33.2 2.5 73.1 207 1.0 29.7 2.5 72.1 208 2.0 39.8 4.4 87.2 210 1.7 38.8 4.0 91.3 211 1.8 36.7 4.4 87.0 212 1.8 41.2 3.6 85.2  88  Table 35 - RA TT individual EFL susceptibility and magnitude  Rest (%VT) 1km (%VT) 2km (%VT) 3km (%VT) 4km (%VT) 5km (%VT) Men 104 0 0 0 0 0 0 105 0 0 0 0 0 0 106 0 0 0 0 0 0 107 0 0 0 0 0 0 108 0 0 0 0 0 0 109 0 0 28 51 31 60 110 0 0 0 41 0 12 111 0 0 0  0 0 112 0 0 0 0 1 60 114  0 24 13 33 60 115 0 0 0 0 0 0 Women 201 0 33 27 44 35 37 202 0 0   0 0 203 0 0 0 0 37 24 204 0 0 0 4 25 44 205 0 0 0 0 21 3 206 0 0 21 0 0 0 207 0 0 0 18 0 5 208  0 0 0 0 0 210 0 0 1 65 60 45 211 0 0 0 0 0 0 212 0 0 0 0 0 0        89  Table 36 – He-O2 TT individual EFL susceptibility and magnitude  Rest (%VT) 1km (%VT) 2km (%VT) 3km (%VT) 4km (%VT) 5km (%VT) Men 104 0 0 0 0 0 0 105 0 0 0 0 0 0 106 0 0 0 0 0 0 107 0 0 0 0 0 0 108 0 0 0 12 0  109 0 26 14 10 21 0 110 0  0 0 0 0 111 0 0 0 0 0 0 112 0 12 46 57 43 35 114 0 0 0 0 1 22 115 0 0 0 0 0 32 Women 201 0 0 0 0 0 0 202 0 0 0 0 0 0 203 0 0 0 0 28 42 204 0 0 0 0  47 205 0 0 0 0 0 0 206 0 0 21 0 0 0 207 0 0 0 0 0 0 208 0 0 0 0 0 0 210 0 0 10 0 60 0 211 0 0 0 0 0 0 212 0 0 0 0 0 0        90  Table 37 - Individual RA TT work of breathing data.  Iel, inspiratory elastic work of breathing; Ires, inspiratory resistive work of breathing; Exp total, total expiratory work of breathing; WOB, work of breathing (inspiratory and expiratory); Fb, frequency of breathing; WOB, work of breathing (inspiratory and expiratory); V’E, minute ventilation.   Rest – RA  Iel (cmH2O) Ires (cmH2O) Exp total (cmH2O) WOB (cmH2O) Fb (breaths∙min-1) VT (l) WOB (J∙min-1) V’E (l∙min-1)  Iel (cmH2O) Ires (cmH2O) Exp total (cmH2O) WOB (cmH2O) Fb (breaths∙min-1) VT (l) WOB (J∙min-1) V’E (l∙min-1) Men   Women   104 1.8 0.0 0.0 1.6 11 0.8 1.7 11 201 4.1 0.9 0.0 5.0 24 1.1 11.9 25 105 2.7 0.6 0.0 3.3 13 1.6 4.1 15 202 1.5 0.6 0.1 2.1 23 0.6 4.7 10 106 2.2 1.1 0.0 3.3 13 1.2 4.1 13 203 0.6 0.0 0.0 0.6 15 0.7 1.0 10 107 1.1 0.6 0.0 1.7 19 0.7 3.3 14 204      1.0   108 0.7 0.2 0.0 0.9 15 0.7 1.3 18 205 0.9 0.7 0.2 1.8 19 0.6 3.2 8 109 0.5 0.3 0.3 1.0 13 1.0 1.3 9 206 1.7 0.3 0.0 2.0 12 0.9 2.4 7 110 1.1 0.2 0.0 1.3 11 1.1 1.4 7 207 1.3 0.2 0.0 1.6 21 0.6 3.1 11 111 1.2 0.9 0.0 2.1 24 0.7 4.7 15 208      0.9   112 4.2 1.8 0.4 6.4 14 1.6 8.9 17 210 1.0 0.7 0.0 1.8 14 0.8 2.5 9 114      0.9   211 1.2 0.5 0.0 1.8 16 0.8 2.8 11 115 1.8 -0.1 0.0 1.6 10 1.0 1.7 11 212 0.0 0.3 0.2 0.6 13 0.6 0.7 7  1 km – RA  Iel (cmH2O) Ires (cmH2O) Exp total (cmH2O) WOB (cmH2O) Fb (breaths∙min-1) VT (l) WOB (J∙min-1) V’E (l∙min-1)  Iel (cmH2O) Ires (cmH2O) Exp total (cmH2O) WOB (cmH2O) Fb (breaths∙min-1) VT (l) WOB (J∙min-1) V’E (l∙min-1) Men   Women   104 12.3 3.5 0.1 15.9 29 2.5 44.5 63 201 20.4 6.2 0.0 26.7 37 2.3 97.8 79 105 33.3 16.9 0.5 50.7 35 3.4 174.0 111 202 16.1 9.9 0.6 26.5 53 1.3 137.4 63 106 32.2 10.6 1.6 44.5 31 3.3 134.1 87 203 17.5 14.4 3.4 35.2 38 2.3 132.3 75 107 14.7 10.1 0.0 24.8 29 2.1 70.1 62 204 14.2 10.7 1.6 26.5 45 1.8 117.3 80 108 43.5 9.7 0.3 53.5 53 2.2 278.7 119 205 19.6 6.1 0.1 25.7 31 1.7 77.1 49 109 43.0 19.1 19.1 81.3 44 2.8 354.0 122 206 20.5 8.2 0.1 28.8 55 1.7 153.9 84 110 29.0 9.4 0.3 38.7 45 2.6 171.4 108 207 18.3 10.5 0.6 29.4 49 1.5 140.8 74 111 20.8 8.4 1.6 30.8 47 2.1 142.2 98 208 24.3 12.5 0.0 36.8 35 2.5 125.9 82 112 30.4 19.4 4.6 54.4 53 2.5 280.3 118 210 32.7 17.0 1.8 51.5 39 2.4 195.2 83 114 52.2 15.7 2.5 70.3 27 3.7 184.3 91 211 25.5 9.7 0.2 35.4 35 2.4 122.9 79 115 31.8 8.2 6.4 46.4 38 2.7 171.6 98 212 30.1 11.0 0.1 41.2 38 2.1 154.8 74  91  Table 37 - Individual RA TT work of breathing data, continued…  2 km – RA  Iel (cmH2O) Ires (cmH2O) Exp total (cmH2O) WOB (cmH2O) Fb (breaths∙min-1) VT (l) WOB (J∙min-1) V’E (l∙min-1)  Iel (cmH2O) Ires (cmH2O) Exp total (cmH2O) WOB (cmH2O) Fb (breaths∙min-1) VT (l) WOB (J∙min-1) V’E (l∙min-1) Men   Women   104 10.9 5.2 0.1 16.1 27 3.1 42.3 74 201 19.7 9.2 0.0 28.9 45 2.5 128.7 96 105 35.0 20.6 1.0 56.5 43 3.6 237.4 125 202 7.8 5.5 0.7 14.0 101 1.0 138.7 69 106 40.2 12.2 1.7 54.1 34 3.6 180.6 106 203 21.3 18.0 5.8 45.1 42 2.3 187.3 89 107 20.9 13.0 0.5 34.4 37 2.7 126.5 88 204 21.0 13.3 2.7 36.9 50 2.2 182.8 96 108 49.1 11.1 0.7 60.9 59 2.6 349.3 131 205 23.1 7.1 0.7 30.9 33 2.0 100.1 57 109 43.0 25.1 25.1 93.2 55 3.0 500.4 144 206 20.3 9.5 0.4 30.2 62 1.8 183.2 91 110 38.1 11.1 0.6 49.8 52 2.9 253.1 128 207 24.3 12.7 0.6 37.7 59 1.7 216.5 91 111 26.4 8.0 2.4 36.9 53 2.6 190.3 117 208 46.8 31.3 2.6 80.7 35 3.0 275.4 93 112 27.0 17.1 4.6 48.8 56 2.5 270.0 117 210 33.8 20.5 2.6 56.8 43 2.5 239.6 91 114 68.5 16.8 9.4 94.8 31 4.3 284.9 118 211 26.5 13.6 0.1 40.2 44 2.5 172.1 97 115 37.8 18.2 13.6 69.6 47 3.1 323.3 123 212 24.0 8.0 0.1 32.2 38 2.1 118.5 67  3 km – RA  Iel (cmH2O) Ires (cmH2O) Exp total (cmH2O) WOB (cmH2O) Fb (breaths∙min-1) VT (l) WOB (J∙min-1) V’E (l∙min-1)  Iel (cmH2O) Ires (cmH2O) Exp total (cmH2O) WOB (cmH2O) Fb (breaths∙min-1) VT (l) WOB (J∙min-1) V’E (l∙min-1) Men   Women   104 19.2 5.3 1.0 25.5 36 3.3 89.5 93 201 19.7 8.1 0.0 27.8 45 2.4 122.0 91 105 31.9 18.3 0.3 50.5 42 3.4 209.1 126 202 7.9 5.2 0.5 13.6 102 1.0 135.6 71 106 42.9 13.8 2.3 58.9 35 3.6 201.5 107 203 25.8 25.0 7.2 58.0 51 2.3 287.8 99 107 25.2 14.2 1.7 41.1 43 2.8 173.5 105 204 21.1 14.4 1.9 37.3 63 2.2 231.1 111 108 44.3 15.3 1.0 60.5 61 2.6 362.3 133 205 26.6 8.1 0.6 35.2 35 2.0 122.0 62 109 46.8 35.5 35.5 117.9 55 3.0 630.4 141 206 18.6 8.0 0.4 27.0 59 1.7 157.6 88 110 39.6 11.5 0.2 51.3 65 2.7 327.4 156 207 21.1 12.8 0.8 34.7 58 1.6 196.3 84 111      2.5   208 40.9 24.5 1.8 67.2 41 3.0 267.3 105 112 27.0 18.5 4.0 49.6 56 2.5 274.1 122 210 33.5 21.3 4.8 59.6 50 2.4 293.1 101 114 68.1 17.3 5.8 91.2 34 4.4 300.6 128 211 26.2 15.7 0.1 42.0 48 2.5 198.2 104 115 40.2 24.1 13.8 78.2 55 2.9 422.6 139 212 16.4 3.3 0.0 19.8 44 2.0 85.1 75  92  Table 37 - Individual RA TT work of breathing data, continued…  4 km – RA  Iel (cmH2O) Ires (cmH2O) Exp total (cmH2O) WOB (cmH2O) Fb (breaths∙min-1) VT (l) WOB (J∙min-1) V’E (l∙min-1)  Iel (cmH2O) Ires (cmH2O) Exp total (cmH2O) WOB (cmH2O) Fb (breaths∙min-1) VT (l) WOB (J∙min-1) V’E (l∙min-1) Men   Women   104 22.6 9.1 0.4 32.2 37 3.5 117.3 112 201 18.4 9.0 9.0 36.5 49 2.3 175.2 97 105 31.7 18.4 2.4 52.5 44 3.4 227.2 126 202 15.4 9.5 0.2 25.1 58 1.1 143.8 71 106 44.9 15.6 1.9 62.4 36 3.6 221.5 112 203 25.4 25.2 9.7 60.4 50 2.2 293.8 96 107 33.5 14.3 1.3 49.1 47 2.9 226.8 121 204 22.5 15.8 1.9 40.3 69 2.1 272.4 115 108 44.1 14.6 0.8 59.6 63 2.5 365.4 133 205 23.4 9.5 2.4 35.3 46 1.9 158.6 74 109 43.2 31.1 31.1 105.4 61 2.8 634.1 144 206 18.9 8.8 0.1 27.8 65 1.7 176.6 97 110 37.0 10.3 0.5 47.8 68 2.6 318.7 154 207 15.5 10.8 1.1 27.4 61 1.6 163.2 80 111 25.9 8.4 1.1 35.4 54 2.4 185.9 115 208 37.8 27.3 1.8 66.9 43 2.9 284.0 108 112 24.6 17.5 4.7 46.8 63 2.4 291.1 125 210 35.7 22.7 4.6 63.0 52 2.3 323.8 104 114 66.4 17.1 12.7 96.2 35 4.4 325.6 132 211 27.3 17.9 0.2 45.4 51 2.5 227.3 113 115 40.4 27.4 11.3 79.1 56 2.9 435.7 141 212      2.0    5 km – RA  Iel (cmH2O) Ires (cmH2O) Exp total (cmH2O) WOB (cmH2O) Fb (breaths∙min-1) VT (l) WOB (J∙min-1) V’E (l∙min-1)  Iel (cmH2O) Ires (cmH2O) Exp total (cmH2O) WOB (cmH2O) Fb (breaths∙min-1) VT (l) WOB (J∙min-1) V’E (l∙min-1) Men   Women   104 32.6 17.4 2.8 52.7 48 3.2 246.8 136 201 18.1 15.2 0.1 33.4 52 2.3 170.6 105 105 33.0 14.9 1.7 49.6 46 3.4 223.3 136 202 18.3 11.7 1.9 31.9 52 1.3 162.6 66 106 40.3 14.3 2.5 57.0 41 3.6 226.8 118 203 24.1 23.0 10.1 57.1 52 2.3 291.7 103 107 41.6 21.6 1.8 65.0 57 3.0 365.2 148 204 22.8 14.7 1.5 38.9 77 1.9 293.5 125 108 45.7 15.9 1.9 63.5 64 2.5 397.0 136 205 26.8 12.7 2.0 41.5 48 1.9 194.1 80 109 41.7 29.2 29.2 100.2 65 2.6 640.2 147 206 19.1 9.6 0.1 28.8 78 1.6 219.7 103 110 34.3 10.9 0.5 45.7 75 2.4 335.8 159 207 22.3 12.8 2.2 37.3 67 1.6 246.6 101 111 23.9 7.8 1.1 32.7 56 2.4 179.6 115 208 37.9 28.2 3.4 69.5 46 2.8 311.7 104 112 22.8 20.2 5.5 48.5 62 2.3 294.6 123 210 32.6 23.2 4.1 59.9 53 2.3 314.1 104 114 62.6 27.2 3.5 93.3 45 4.3 415.0 147 211 28.0 20.2 0.4 48.6 57 2.5 270.9 122 115 41.6 29.0 10.5 81.1 60 2.8 474.2 142 212      2.0    93  Table 38 - Individual He-O2 TT work of breathing data.  Iel, inspiratory elastic work of breathing; Ires, inspiratory resistive work of breathing; Exp total, total expiratory work of breathing; WOB, work of breathing (inspiratory and expiratory); Fb, frequency of breathing; WOB, work of breathing (inspiratory and expiratory); V’E, minute ventilation.  Rest – He-O2  Iel (cmH2O) Ires (cmH2O) Exp total (cmH2O) WOB (cmH2O) Fb (breaths∙min-1) VT (l) WOB (J∙min-1) V’E (l∙min-1)  Iel (cmH2O) Ires (cmH2O) Exp total (cmH2O) WOB (cmH2O) Fb (breaths∙min-1) VT (l) WOB (J∙min-1) V’E (l∙min-1) Men   Women   104 0.8 0.1 0.0 1.0 18 1.0 1.7 12 201 3.9 1.0 0.0 4.9 23 1.1 11.2 20 105 1.5 0.2 0.0 1.7 16 1.3 2.7 12 202 0.7 0.0 0.0 0.7 2 0.7 1.5 1 106 4.9 1.0 0.0 5.9 10 1.6 6.0 14 203 3.1 1.1 0.0 4.2 12 0.9 4.9 9 107 0.7 0.0 0.0 0.7 20 0.9 1.4 13 204 2.0 0.8 0.0 2.8 12 1.1 3.2 9 108 0.4 0.0 0.0 0.3 25 0.6 0.8 10 205 1.0 0.5 0.0 1.5 15 0.7 2.2 7 109 1.3 0.5 0.0 1.8 11 1.0 1.9 8 206 3.1 0.6 0.3 4.0 9 1.0 3.7 8 110 0.8 0.2 0.0 1.0 13 1.0 1.3 8 207 1.1 0.2 0.0 1.3 22 0.7 2.8 9 111 1.2 0.6 0.0 1.8 23 0.6 4.1 13 208 1.5 0.4 0.0 1.9 16 0.8 2.9 10 112 1.6 0.5 0.1 2.2 15 1.1 3.2 12 210 1.5 0.6 0.0 2.0 14 0.8 2.8 9 114      1.6   211 1.2 0.4 0.0 1.6 17 0.8 2.7 12 115 2.1 0.3 0.0 2.4 9 1.1 2.0 7 212 0.9 0.3 0.0 1.2 15 0.6 1.7 7  1 km – He-O2  Iel (cmH2O) Ires           (cmH2O) Exp total (cmH2O) WOB           (cmH2O) Fb (breaths∙min-1) VT (l) WOB (J∙min-1) V’E (l∙min-1)  Iel (cmH2O) Ires           (cmH2O) Exp total (cmH2O) WOB           (cmH2O) Fb (breaths∙min-1) VT (l) WOB (J∙min-1) V’E (l∙min-1) Men   Women   104 22.4 4.9 0.0 27.3 33 2.9 88.4 79 201 14.2 3.4 0.0 17.6 44 2.0 76.5 73 105 23.7 3.9 0.0 27.6 36 2.9 98.2 86 202 7.6 1.8 0.0 9.4 88 1.1 81.2 78 106 29.3 6.9 0.2 36.4 38 3.1 134.8 88 203 28.7 16.7 0.2 45.5 38 2.4 168.7 77 107 16.8 6.5 0.0 23.3 32 2.1 74.0 66 204 10.6 5.4 0.0 16.0 62 1.4 96.9 69 108 30.5 6.9 0.0 37.5 59 2.2 218.6 119 205 21.7 3.2 0.0 24.9 37 1.8 89.4 56 109 44.9 15.8 0.9 61.6 54 3.0 325.5 133 206 19.7 6.2 0.0 25.9 56 1.8 143.0 82 110 33.3 5.2 0.0 38.5 55 2.5 206.2 123 207 12.5 6.7 0.0 19.2 63 1.6 118.4 80 111 21.6 3.5 1.4 26.4 59 2.3 153.0 112 208 29.1 10.1 0.2 39.4 47 2.3 183.4 97 112 20.1 9.6 0.6 30.3 57 2.3 170.1 110 210 29.5 14.6 0.5 44.6 41 2.5 179.7 85 114 35.8 14.6 2.0 52.3 29 3.6 149.3 86 211 16.2 8.6 0.0 24.8 41 2.4 100.4 80 115 27.8 0.4 0.9 29.1 36 2.8 103.1 81 212 19.4 4.7 0.2 24.3 39 1.8 92.3 60  94  Table 38 - Individual He-O2 TT work of breathing data, continued…  2 km – He-O2  Iel (cmH2O) Ires           (cmH2O) Exp total (cmH2O) WOB           (cmH2O) Fb (breaths∙min-1) VT (l) WOB (J∙min-1) V’E (l∙min-1)  Iel (cmH2O) Ires           (cmH2O) Exp total (cmH2O) WOB           (cmH2O) Fb (breaths∙min-1) VT (l) WOB (J∙min-1) V’E (l∙min-1) Men   Women   104 24.4 5.5 0.1 30.1 39 3.1 114.7 96 201 16.7 4.0 0.1 20.8 49 2.3 99.5 86 105 23.9 5.0 0.0 28.8 42 3.5 117.8 108 202 6.8 1.9 0.1 8.8 89 1.1 76.4 74 106 48.1 9.0 0.7 57.9 35 3.7 197.3 109 203 28.8 21.2 0.3 50.3 49 2.5 242.7 93 107 20.6 8.1 0.3 28.9 40 2.9 113.0 90 204 11.8 4.4 0.0 16.2 87 1.8 138.6 104 108 33.6 9.2 0.0 42.9 66 2.7 277.5 144 205 22.3 5.0 0.1 27.3 43 2.0 114.8 65 109 49.6 19.1 0.8 69.5 55 3.4 371.6 145 206 19.7 5.5 0.0 25.2 63 1.9 156.8 94 110 34.2 7.0 0.0 41.2 70 2.9 284.0 151 207 12.0 6.1 0.0 18.1 76 1.6 135.5 89 111 24.2 3.1 0.7 28.0 67 2.5 183.1 135 208 39.1 18.9 0.1 58.0 51 2.8 289.9 111 112 23.9 11.4 1.5 36.8 59 2.6 213.4 118 210 32.6 18.2 1.0 51.8 47 2.6 239.2 97 114 57.8 14.4 1.3 73.6 34 4.0 248.2 110 211 11.6 7.9 0.0 19.4 49 2.5 93.8 100 115 33.6 3.2 2.1 39.0 45 3.2 172.0 112 212 17.4 5.6 0.0 23.0 43 2.0 97.4 67  3 km – He-O2  Iel (cmH2O) Ires           (cmH2O) Exp total (cmH2O) WOB           (cmH2O) Fb (breaths∙min-1) VT (l) WOB (J∙min-1) V’E (l∙min-1)  Iel (cmH2O) Ires           (cmH2O) Exp total (cmH2O) WOB           (cmH2O) Fb (breaths∙min-1) VT (l) WOB (J∙min-1) V’E (l∙min-1) Men   Women   104 27.4 9.5 0.5 37.4 37 3.2 136.5 102 201 16.8 3.8 0.0 20.6 49 2.2 100.1 85 105 24.4 6.8 0.0 31.2 42 3.3 129.1 107 202 5.9 1.6 0.1 7.5 85 1.1 62.4 70 106 38.3 10.4 0.7 49.3 41 3.5 196.9 109 203 31.9 23.4 1.0 56.3 53 2.4 292.7 103 107 22.8 10.0 0.2 33.0 44 2.9 143.3 104 204 12.9 5.6 0.1 18.5 88 1.7 160.6 111 108 32.0 10.3 0.2 42.6 71 2.6 298.3 147 205 23.6 3.8 0.6 28.0 47 2.0 130.1 74 109 46.8 17.7 1.4 65.9 54 3.4 351.0 145 206 16.9 4.7 0.0 21.6 66 1.8 139.8 90 110 29.4 5.3 0.0 34.7 76 2.6 260.1 153 207 12.7 6.8 0.0 19.6 71 1.6 136.7 88 111 23.2 5.1 1.0 29.3 67 2.6 192.7 129 208 35.4 18.2 0.0 53.6 57 2.7 296.9 120 112 22.3 10.7 1.9 34.9 61 2.5 208.6 124 210 31.3 17.7 1.6 50.6 51 2.6 253.0 100 114 57.2 14.0 1.6 72.7 38 3.9 270.6 116 211 18.2 12.3 0.0 30.5 54 2.6 160.4 108 115 34.0 6.8 1.2 42.0 52 3.2 215.9 128 212 18.3 5.2 0.1 23.6 44 1.9 101.7 68  95  Table 38 - Individual He-O2 TT work of breathing data, continued…  4 km – He-O2  Iel (cmH2O) Ires           (cmH2O) Exp total (cmH2O) WOB           (cmH2O) Fb (breaths∙min-1) VT (l) WOB (J∙min-1) V’E (l∙min-1)  Iel (cmH2O) Ires           (cmH2O) Exp total (cmH2O) WOB           (cmH2O) Fb (breaths∙min-1) VT (l) WOB (J∙min-1) V’E (l∙min-1) Men   Women   104 31.3 9.4 0.3 41.1 46 3.3 186.5 121 201 14.6 3.7 0.0 18.3 55 2.1 99.0 90 105 19.1 4.2 0.0 23.3 48 3.2 110.5 119 202 7.9 2.2 0.1 10.2 93 1.1 92.8 85 106 38.1 10.7 1.0 49.8 52 3.5 252.9 128 203 27.8 19.6 2.6 50.0 57 2.4 278.5 103 107 27.6 10.0 0.0 37.6 50 3.0 185.8 114 204 11.5 4.6 0.2 16.3 95 1.5 152.9 112 108 33.6 11.2 0.3 45.0 76 2.6 334.7 154 205 21.9 4.1 0.0 26.0 53 2.0 135.6 83 109 40.9 19.2 0.9 61.0 68 3.1 407.0 154 206 14.0 4.2 0.0 18.2 73 1.7 129.9 89 110 27.6 6.2 0.0 33.8 81 2.4 268.0 152 207 11.4 6.6 0.0 18.0 72 1.5 127.5 86 111 18.9 4.8 0.7 24.5 71 2.4 170.9 126 208 32.6 18.5 0.2 51.3 57 2.7 285.2 120 112 23.9 14.2 3.8 41.9 60 2.5 248.6 122 210 30.3 18.5 2.2 51.0 64 2.4 319.1 116 114 60.6 17.5 2.2 80.3 40 4.1 318.2 132 211 14.8 10.6 0.0 25.4 55 2.4 136.5 102 115 37.0 6.2 3.1 46.3 58 3.1 262.0 138 212 17.7 4.8 0.0 22.5 48 2.0 106.5 75  5 km – He-O2  Iel (cmH2O) Ires           (cmH2O) Exp total (cmH2O) WOB           (cmH2O) Fb (breaths∙min-1) VT (l) WOB (J∙min-1) V’E (l∙min-1)  Iel (cmH2O) Ires           (cmH2O) Exp total (cmH2O) WOB           (cmH2O) Fb (breaths∙min-1) VT (l) WOB (J∙min-1) V’E (l∙min-1) Men   Women   104 37.5 16.0 4.6 58.1 46 3.4 262.3 134 201 18.6 4.5 0.0 23.2 59 2.1 134.9 98 105 29.5 11.2 0.0 40.8 55 3.2 219.2 133 202 9.7 2.0 0.0 11.7 90 1.1 104.1 87 106 45.3 12.3 0.4 58.1 55 3.5 310.4 142 203 28.0 21.9 2.2 52.1 62 2.3 314.8 109 107 37.2 11.4 0.4 49.0 59 3.2 283.5 152 204 12.1 4.1 0.0 16.2 121 1.4 191.0 123 108 36.9 11.5 0.5 48.9 79 2.6 378.6 157 205 24.9 5.7 0.6 31.2 57 2.0 174.9 88 109 38.7 18.6 1.5 58.8 75 2.8 431.8 163 206 13.7 4.0 0.0 17.7 88 1.5 152.4 98 110 32.3 8.8 0.0 41.1 84 2.5 338.6 164 207 13.3 7.8 0.0 21.2 87 1.6 179.9 102 111 18.6 5.2 1.1 24.9 79 2.3 192.5 135 208 30.1 20.2 0.1 50.3 63 2.6 309.2 122 112 25.1 16.8 4.6 46.5 62 2.5 283.1 127 210 28.0 17.9 0.7 46.6 59 2.3 270.4 112 114 61.9 23.8 2.9 88.6 45 4.3 389.1 145 211 20.6 14.7 0.0 35.3 61 2.5 211.5 128 115 41.0 12.8 1.6 55.4 77 3.0 416.2 169 212 16.1 4.0 0.0 20.1 53 1.9 104.0 77  96  Table 39 - Individual RA TT Ratings of Perceived Exertion   Rest 1 km 2 km 3 km 4 km 5 km Reason for not cycling faster Relative Contribution Dyspnea Leg Dyspnea Leg Dyspnea Leg Dyspnea Leg Dyspnea Leg Dyspnea Leg Breathing Leg Combination Other Breathing (%) Leg (%) Men 104 0 0 2 2 3 3 3 3 3 3 4 4  X   40 60 105 0 0 3 3 4 4 5 5 5 5 7 7   X  40 60 106 1 1 3 3 4 4 4 4 5 5 7 6 X    70 30 107 0 0 1 3 2 4 3 5 5 7 9 10  X   30 70 108 0 0.5 2 2 4 4 4 5 6 6 7 9   X  30 70 109 0.5 0 4 4 6 5 7 5 9 6 9 6 X    85 15 110 0 0 5 5 6 6 8 8 8 8 9 9   X  45 55 111 0 0 1 1 1 1 4 4 6 6 7 8  X   40 60 112 0 0 2 2 3 3 3 3 4 6 8 9  X   40 60 114 0 0 3 3 5 5 5 5 7 8 8 10  X   30 70 115 0 0 3 3 4 4 5 5 8 8 9 10  X   40 60 Women 201 0 0 0.5 0.5 1 1 1 1 2 2 2 2  X   30 70 202 0.5 0.5 3 3 5 6 6 6 6 6 7 7    X 40 60 203 0 0 4 3 4 4 4 5 6 6 8 9  X   40 60 204 0 0 4 5 5 5 6 6 7 7 9 9   X  30 70 205 0 0.5 3 4 5 5 7 7 7 7 7 8   X  35 65 206 0 0 1 1 3 2 3 3 3 3 4 4  X   0 100 207 0 0 4 4 6 6 8 8 8 8 8 8   X  50 50 208 0 0 5 5 8 6 8 6 8 6 9 10  X   50 50 210 0 0 2 2 4 4 4 4 5 5 8 8   X  45 55 211 0.5 0.5 3 3 3 3 3 3 3 4 5 5   X  70 30 212 0.5 0 0.5 0.5 1 1 1 2 1 2 1 3  X   2 98       97  Table 40 - Individual He-O2 TT Ratings of Perceived Exertion   Rest 1 km 2 km 3 km 4 km 5 km Reason for not cycling faster Relative Contribution Dyspnea Leg Dyspnea Leg Dyspnea Leg Dyspnea Leg Dyspnea Leg Dyspnea Leg Breathing Leg Combination Other Breathing (%) Leg (%) Men 104 0 0 0.5 0.5 2 2 4 4 5 5 5 5  X   30 70 105 1 1 3 3 4 4 4 4 4 5 6 7  X   40 60 106 0 0 2 2 3 3 5 5 5 5 8 7  X   30 70 107 0.5 0.5 2 2 3 4 4 5 5 7 9 10  X   30 70 108 0 0.5 3 3 3 3 4 4 6 6 8 8   X  50 50 109 0.5 0 4 4 5 6 5 6 7 8 8 8   X  50 50 110 0 0 5 5 6 7 7 8 7 8 8 9   X  35 65 111 0 0 2 2 4 4 6 6 6 9 6 9  X   35 65 112 0 0 2 3 2 3 4 5 5 6 7 9  X   30 70 114 0 0 3 4 5 5 6 7 7 8 10 10   X  50 50 115 0.5 0.5 2 2 3 3 3 3 4 4 8 10  X   30 70 Women 201 0 0 1 1 2 3 2 3 2 3 2 3  X   30 70 202 0.5 0.5 4 4 4 4 5 5 7 7 8 8  X   30 70 203 0 0 4 3 3 2 4 4 5 5 9 9  X   40 60 204 0 0 4 4 4 5 5 6 6 7 8 9   X  40 60 205 0 0 4 4 4 4 7 7 7 7 10 10   X  30 70 206 0 0 0.5 0.5 2 2 2 2 4 4 4 4  X   0 100 207 0 0 4 4 4 5 5 6 6 7 8 9  X   40 60 208 0 0 6 6 7 7 9 9 8 9 9 9   X  40 60 210 0 0 1 1 3 3 4 4 5 5 7 7   X  50 50 211 0 0 2 2 3 4 3 3 3 3 5 5   X  40 60 212 0 0 0.5 2 0.5 2 0.5 3 2 3 2 4  X   25 75       98  APPENDIX B - INDIVIDUAL DATA – FIGURES  Figure 10 – Subject 104 total WOB vs. V’E, and operational lung volumes throughout the TTs. 104 V' E  (l.min-1) 0 20 40 60 80 100 120 140 160 T o tal  W O B  ( J . m in -1 ) 0 50 100 150 200 250 300 RA He-O2 Distance (km) 0 1 2 3 4 5 V olu m e  ( % F V C ) 20 30 40 50 60 70 80 90 100 RA - EILV RA - EELV He-O2 - EILV He-O2 - EELV 99   Figure 11 – Subject 105 total WOB vs. V’E, and operational lung volumes throughout the TTs Distane (km) 0 1 2 3 4 5 V olu m e  ( % F V C ) 0 20 40 60 80 100 EILV - RA EELV - RA EILV - He-O2 EELV - He-O2 105 V' E  (l.min-1) 0 20 40 60 80 100 120 140 160 T o tal  W O B  ( J . m in -1 ) 0 50 100 150 200 250 RA He-O2 100   Figure 12 – Subject 106 total WOB vs. V’E, and operational lung volumes throughout the TTs Distance (km) 0 1 2 3 4 5 V olu m e  ( % F V C ) 0 20 40 60 80 100 EILV - RA EELV - RA EILV - He-O2 EELV - He-O2 106 V' E  (l.min-1) 0 20 40 60 80 100 120 140 160 T o tal  W O B  ( J . m in -1 ) 0 50 100 150 200 250 300 350 RA He-O2 101   Figure 13 – Subject 107 total WOB vs. V’E, and operational lung volumes throughout the TTs Distance (km) 0 1 2 3 4 5 V olu m e  ( %  FVC ) 0 20 40 60 80 100 EILV - RA EELV - RA EILV - He-O2 EELV - He-O2 107 V' E  (l.min-1) 0 20 40 60 80 100 120 140 160 T o tal W OB  ( J . m in -1 ) 0 100 200 300 400 RA He-O2 102   Figure 14 – Subject 108 total WOB vs. V’E, and operational lung volumes throughout the TTs 108 V' E  (l.min-1) 0 20 40 60 80 100 120 140 160 180 T o tal  W O B  ( J . m in -1 ) 0 100 200 300 400 500 RA He-O2 Distance (km) 0 1 2 3 4 5 V olu m e  ( % F V C ) 0 20 40 60 80 100 EILV - RA EELV - RA EILV - He-O2 EELV - He-O2 103    Figure 15 – Subject 109 total WOB vs. V’E, and operational lung volumes throughout the TTs  109 V' E  (l.min-1) 0 20 40 60 80 100 120 140 160 180 T o tal  W O B  ( J . m in -1 ) 0 100 200 300 400 500 600 700 RA He-O2 Distance (km) 0 1 2 3 4 5 V olu m e  ( % F V C ) 0 20 40 60 80 100 EILV - RA EELV - RA EILV - He-O2 EILV - He-O2 104   Figure 16 – Subject 110 total WOB vs. V’E, and operational lung volumes throughout the TTs  110 V' E  (l.min-1) 0 20 40 60 80 100 120 140 160 180 T o tal  W O B  ( J . m in -1 ) 0 100 200 300 400 RA He-O2 Distance (km) 0 1 2 3 4 5 V olu m e  ( % F V C ) 0 20 40 60 80 100 EILV - RA EELV - RA EILV - He-O2 EELV - He-O2 105    Figure 17 – Subject 111 total WOB vs. V’E, and operational lung volumes throughout the TTs  Distance (km) 0 1 2 3 4 5 V olu m e  ( % F V C ) 0 20 40 60 80 100 EILV - RA EELV - RA EILV - He-O2 EELV - He-O2 111 V' E  (l.min-1) 0 20 40 60 80 100 120 140 160 T o tal W OB  ( J . m in -1 ) 0 50 100 150 200 250 RA He-O2 106   Figure 18 – Subject 112 total WOB vs. V’E, and operational lung volumes throughout the TTs 112 V' E  (l.min-1) 0 20 40 60 80 100 120 140 T o tal  W O B  ( J . m in -1 ) 0 50 100 150 200 250 300 350 RA He-O2 Distance (km) 0 1 2 3 4 5 V olu m e  (% F V C ) 0 20 40 60 80 100 EILV - RA EELV - RA EILV - He-O2 EELV - He-O2 107   Figure 19 – Subject 114 total WOB vs. V’E, and operational lung volumes throughout the TTs  Distance (km) 0 1 2 3 4 5 V olu m e  ( %  FVC ) 0 20 40 60 80 100 EILV - RA EELV - RA EILV - He-O2 EELV- He-O2 114 V' E  (l.min-1) 80 90 100 110 120 130 140 150 160 T o tal W OB  ( J . m in -1 ) 100 150 200 250 300 350 400 450 RA He-O2 108  Figure 20 – Subject 115 total WOB vs. V’E, and operational lung volumes throughout the TTs  115 V' E  (l.min-1) 0 20 40 60 80 100 120 140 160 180 T o tal  W O B  ( J . m in -1 ) 0 100 200 300 400 500 RA He-O2 Distance (km) 0 1 2 3 4 5 V ol u m e  (% F V C ) 0 20 40 60 80 100 EILV - RA EELV - RA EILV - He-O2 EELV - He-O2 109  Figure 21 – Subject 210 total WOB vs. V’E, and operational lung volumes throughout the TTs  201 V' E  (l.min-1) 0 20 40 60 80 100 120 T o tal  W O B  ( J . m in -1 ) 0 20 40 60 80 100 120 140 160 180 200 RA He-O2 Distance (km) 0 1 2 3 4 5 V olu m e  ( % F V C ) 0 20 40 60 80 100 EILV - RA EELV - RA EILV - He-O2 EELV - He-O2 110   Figure 22 – Subject 202 total WOB vs. V’E, and operational lung volumes throughout the TTs  202 V' E  (l.min-1) 0 20 40 60 80 100 T otal W OB  ( J . m in -1 ) 0 20 40 60 80 100 120 140 160 180 RA He-O2 Distance (km) 0 1 2 3 4 5 V ol u m e (%  FV C ) 0 20 40 60 80 100 EILV - RA EELV - RA EILV - He-O2 EELV - He-O2 111   Figure 23 – Subject 203 total WOB vs. V’E, and operational lung volumes throughout the TTs  203 V' E  (l.min-1) 0 20 40 60 80 100 120 T o tal  W O B  ( J . m in -1 ) 0 50 100 150 200 250 300 350 RA He-O2 Distance (km) 0 1 2 3 4 5 V olu m e  (% F V C ) 0 20 40 60 80 100 EILV - RA EELV - RA EILV - He-O2 EELV - He-O2 112  Figure 24 – Subject 204 total WOB vs. V’E, and operational lung volumes throughout the TTs  Distance (km) 0 1 2 3 4 5 V olu m e  ( % F V C ) 0 20 40 60 80 100 EILV - RA EELV - RA EILV - He-O2 EELV - He-O2 204 V' E  (l.min-1) 0 20 40 60 80 100 120 140 T o tal W O B  ( J . m in -1 ) 0 50 100 150 200 250 300 350 RA He-O2 113   Figure 25 – Subject 205 total WOB vs. V’E, and operational lung volumes throughout the TTs  Distance (km) 0 1 2 3 4 5 V olu m e  (% F V C ) 0 20 40 60 80 100 EILV - RA EELV - RA EILV - He-O2 EELV - He-O2 205 V' E  (l.min-1) 0 20 40 60 80 100 T o tal  W O B  ( J . m in -1 ) 0 50 100 150 200 250 RA He-O2 114   Figure 26 – Subject 206 total WOB vs. V’E, and operational lung volumes throughout the TTs  Distance (km) 0 1 2 3 4 5 V olu m e  (% F V C ) 0 20 40 60 80 100 EILV - RA EELV - RA EILV - He-O2 EELV - He-O2 206 V' E  (l.min-1) 0 20 40 60 80 100 120 T o tal  W O B  ( J . m in -1 ) 0 50 100 150 200 250 RA He-O2 115   Figure 27 – Subject 207 total WOB vs. V’E, and operational lung volumes throughout the TTs  Distance (km) 0 1 2 3 4 5 V olu m e  (% F V C ) 0 20 40 60 80 100 EILV - RA EELV - RA EILV - He-O2 EELV - He-O2 207 V' E  (l.min-1) 0 20 40 60 80 100 120 T o tal  W O B  ( J . m in -1 ) 0 50 100 150 200 250 300 RA He-O2 116  Figure 28 – Subject 208 total WOB vs. V’E, and operational lung volumes throughout the TTs  Distance (km) 0 1 2 3 4 5 V olu m e  ( %  FV C ) 0 20 40 60 80 100 EILV - RA EELV - RA EILV - He-O2 EELV - He-O2 208 V' E  (l.min-1) 0 20 40 60 80 100 120 140 T o tal W OB  ( J . m in -1 ) 0 50 100 150 200 250 300 350 RA He-O2 117   Figure 29 – Subject 210 total WOB vs. V’E, and operational lung volumes throughout the TTs  210 V' E  (l.min-1) 0 20 40 60 80 100 120 140 T o tal W OB  ( J . m in -1 ) 0 50 100 150 200 250 300 350 RA He-O2 Distance (km) 0 1 2 3 4 5 V olu m e  ( % F V C ) 0 20 40 60 80 100 120 EILV - RA EELV - RA EILV - He-O2 EELV - He-O2 118   Figure 30 – Subject 211 total WOB vs. V’E, and operational lung volumes throughout the TTs  Distance (km) 0 1 2 3 4 5 V olu m e  (% F V C ) 0 20 40 60 80 100 EILV - RA EELV - RA EILV - He-O2 EELV - He-O2 211 V' E  (l.min-1) 0 20 40 60 80 100 120 140 T o tal  W O B  ( J . m in -1 ) 0 50 100 150 200 250 300 RA He-O2 119   Figure 31 – Subject 211 total WOB vs. V’E, and operational lung volumes throughout the TTs  212 V' E  (l.min-1) 0 10 20 30 40 50 60 70 80 T o tal  W O B  ( J . m in -1 ) 0 20 40 60 80 100 120 140 160 180 RA He-O2 Distance (km) 0 1 2 3 4 5 V olu m e  (% F V C ) 0 20 40 60 80 100 EILV - RA EELV - RA EILV - He-O2 EELV - He-O2 120   FIGURE 32 – Subject 104 flow-volume RA (Panel A) and He-O2 (Panel B), and transpulmonary pressure-volume RA (Panel C) and He-O2 (Panel D) traces. Volume (l) 7 6 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -15 -10 -5 0 5 10 15 20 Pre FVC Post FVC Rest 1 km 2 km 3 km 4 km 5 km Volume (l) 7 6 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -15 -10 -5 0 5 10 15 20 Volume (l) 6 5 4 3 2 1 0 T ran s pu lm ona ry  P re s s u re (c m H 2 O ) -20 -10 0 10 Volume (l) 6 5 4 3 2 1 0 T ran s pu lm ona ry  P re s s u re (c m H 2 O ) -20 -10 0 10 B C D A 121    FIGURE 33 – Subject 105 flow-volume RA (Panel A) and He-O2 (Panel B), and transpulmonary pressure-volume RA (Panel C) and He-O2 (Panel D) traces.  Volume (l) 6 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -10 -5 0 5 10 15 20 Pre FVC Post FVC Rest 1 km 2 km 3 km 4 km 5 km Volume (l) 6 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -10 -5 0 5 10 15 20 Volume (l) 6 5 4 3 2 1 0 T ran s pu lm ona ry  P re s s u re (c m H 2 O ) -20 -15 -10 -5 0 5 10 15 Volume (l) 6 5 4 3 2 1 0 T ran s ppu lm ona ry  P re s s u re (c m H 2 O ) -20 -15 -10 -5 0 5 10 15 rv vs r-P 1v vs 1k-p 2v vs 2-p 3v vs 3-p 4v vs 4-p 5v vs 5-p A B C D 122    FIGURE 34 – Subject 106 flow-volume RA (Panel A) and He-O2 (Panel B), and transpulmonary pressure-volume RA (Panel C) and He-O2 (Panel D) traces.  Volume (l) 7 6 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -10 -5 0 5 10 15 20 Volume (l) 7 6 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -10 -5 0 5 10 15 20 Pre FVC Post FVC Rest 1 km 2 km 3 km 4 km 5 km Volume (l) 7 6 5 4 3 2 1 0 Tr a n s p u lm o n a ry  Pr e ss u re  (c m H 2 O ) -30 -25 -20 -15 -10 -5 0 5 10 Volume (l) 7 6 5 4 3 2 1 Tr a n s p u lm o n a ry  Pr e ss u re  (c m H 2 O ) -30 -25 -20 -15 -10 -5 0 5 10 A B C D 123     FIGURE 35 – Subject 107 flow-volume RA (Panel A) and He-O2 (Panel B), and transpulmonary pressure-volume RA (Panel C) and He-O2 (Panel D) traces.  Volume (l) 7 6 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -10 -5 0 5 10 15 Volume (l) 7 6 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -10 -5 0 5 10 15 Pre FVC Post FVC Rest 1 km 2 km 3 km 4 km 5 km Volume (l) 7 6 5 4 3 2 1 0 T ra n s p u lm o n a ry  P re s s u re  ( c m H 2 O ) -30 -20 -10 0 10 Volume (l) 7 6 5 4 3 2 1 0 T ra n s p u lm o n a ry  P re s s u re  ( c m H 2 O ) -30 -25 -20 -15 -10 -5 0 5 10 A B C D 124   FIGURE 36 – Subject 108 flow-volume RA (Panel A) and He-O2 (Panel B), and transpulmonary pressure-volume RA (Panel C) and He-O2 (Panel D) traces.   Volume (l) 6 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -10 -5 0 5 10 15 Pre FVC Post FVC Rest 1 km 2 km 3 km 4 km 5 km Volume (l) 6 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -10 -5 0 5 10 15 Volume (l) 6 5 4 3 2 1 0 T ra n s p u lm o n a ry  P re s s u re  ( c m H 2 O ) -25 -20 -15 -10 -5 0 5 10 Volume (l) 6 5 4 3 2 1 0 T ra n s p u lm o n a ry  P re s s u re  ( c m H 2 O ) -40 -30 -20 -10 0 10 20 A B C D 125    FIGURE 37 – Subject 109 flow-volume RA (Panel A) and He-O2 (Panel B), and transpulmonary pressure-volume RA (Panel C) and He-O2 (Panel D) traces.  Volume (l) 6 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -15 -10 -5 0 5 10 15 Pre FVC Post FVC Rest 1 km 2 km 3 km 4 km 5 km Volume (l) 6 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -15 -10 -5 0 5 10 15 Volume (l) 8 6 4 2 0 T ra n s p u lm o n a ry  P res s u re  ( c m H 2 O ) -30 -20 -10 0 10 20 30 Volume (l) 8 6 4 2 0 T ra n s p u lm o n a ry  P res s u re  ( c m H 2 O ) -30 -20 -10 0 10 20 30 A B C D 126    FIGURE 38 – Subject 110 flow-volume RA (Panel A) and He-O2 (Panel B), and transpulmonary pressure-volume RA (Panel C) and He-O2 (Panel D) traces.  Volume (l) 6 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -10 -5 0 5 10 15 20 Pre FVC Post FVC Rest 1 km 2 km 3 km 4 km 5 km Volume (l) 6 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -10 -5 0 5 10 15 20 Volume (l) 6 5 4 3 2 1 0 T ran s pu lm ona ry  P re s s u re  ( c m H 2 O ) -30 -20 -10 0 10 20 Volume (l) 6 5 4 3 2 1 0 T ran s pu lm ona ry  P re s s u re  ( c m H 2 O ) -30 -20 -10 0 10 20 A B C D 127   FIGURE 39 – Subject 111 flow-volume RA (Panel A) and He-O2 (Panel B), and transpulmonary pressure-volume RA (Panel C) and He-O2 (Panel D) traces.  Volume (l) 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -10 -5 0 5 10 15 20 Volume (l) 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -10 -5 0 5 10 15 20 Pre FVC Post FVC Rest 1 km 2 km 3 km 4 km 5 km Volume (l) 5 4 3 2 1 0 T ranspu lm on a ry  P res s u re  ( c m H 2 O ) -25 -20 -15 -10 -5 0 5 Volume (l) 5 4 3 2 1 0 T ranspu lm on a ry  P res s u re  ( c m H 2 O ) -25 -20 -15 -10 -5 0 5 A B C D 128    FIGURE 40 – Subject 112 flow-volume RA (Panel A) and He-O2 (Panel B), and transpulmonary pressure-volume RA (Panel C) and He-O2 (Panel D) traces.  Volume (l) 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -10 -5 0 5 10 15 Volume (l) 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -10 -5 0 5 10 15 Pre FVC Post FVC Rest 1 km 2 km 3 km 4 km 5 km Volume (l) 5 4 3 2 1 0 T ranspu lm on a ry  P res s u re  ( c m H 2 O ) -20 -15 -10 -5 0 5 10 15 20 Volume (l) 5 4 3 2 1 0 T ranspu lm on a ry  P res s u re  ( c m H 2 O ) -20 -15 -10 -5 0 5 10 15 20 A B C D 129    FIGURE 41 – Subject 114 flow-volume RA (Panel A) and He-O2 (Panel B), and transpulmonary pressure-volume RA (Panel C) and He-O2 (Panel D) traces. Volume (l) 7 6 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -10 -5 0 5 10 15 20 Pre FVC Post FVC 1 km 2 km 3 km 4 km 5 km Volume (l) 7 6 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -10 -5 0 5 10 15 20 Volume (l) 7 6 5 4 3 2 1 0 T ra n s p u lm o n a ry  P res s u re  ( c m H 2 O ) -40 -30 -20 -10 0 10 20 Volume (l) 7 6 5 4 3 2 1 0 T ra n s p u lm o n a ry  P res s u re  ( c m H 2 O ) -40 -30 -20 -10 0 10 20 A B C D 130    FIGURE 42 – Subject 115 flow-volume RA (Panel A) and He-O2 (Panel B), and transpulmonary pressure-volume RA (Panel C) and He-O2 (Panel D) traces. Volume (l) 6 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -10 -5 0 5 10 15 20 Pre FVC Post FVC Rest 1 km 2 km 3 km 4 km 5 km Volume (l) 6 5 4 3 2 1 0 F lo w  ( l. s ec -1 ) -10 -5 0 5 10 15 20 Volume (l) 6 5 4 3 2 1 0 T ranspu lm on a ry  P res s u re  ( c m H 2 O ) -30 -20 -10 0 10 20 30 Volume (l) 6 5 4 3 2 1 0 T ranspu lm on a ry  P res s u re  ( c m H 2 O ) -30 -20 -10 0 10 20 30 A B C D 131    FIGURE 43 – Subject 201 flow-volume RA (Panel A) and He-O2 (Panel B), and transpulmonary pressure-volume RA (Panel C) and He-O2 (Panel D) traces.  Volume (l) 4 3 2 1 0 Flo w (l. se c- 1 ) -6 -4 -2 0 2 4 6 8 10 Pre FVC Post FVC Rest 1 km 2 km 3 km 4 km 5 km Volume (l) 4 3 2 1 0 Tr an spu m on ar y P ressu re  (c m H 2 O) -20 -15 -10 -5 0 5 10 15 Rest 1 km 2 km 3 km 5 km A B 132   FIGURE 44 – Subject 202 flow-volume RA (Panel A) and He-O2 (Panel B), and transpulmonary pressure-volume RA (Panel C) and He-O2 (Panel D) traces.   Volume (l) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 F lo w  ( l. s e c -1 ) -8 -6 -4 -2 0 2 4 6 8 10 12 Pre FVC Post FVC Rest 1 km 2 km 3 km 4 km 5 km Volume (l) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 F lo w  ( l. s e c -1 ) -8 -6 -4 -2 0 2 4 6 8 10 12 Volume (l) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 Tr a n s p u lm o n ar y  P re s s ur e  ( c m H 2 O ) -30 -25 -20 -15 -10 -5 0 5 10 Volume (l) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 T ra n s p u lm o n a ry  P re s s u re  ( c m H 2 O ) -30 -25 -20 -15 -10 -5 0 5 10 A B C D 133    FIGURE 45 – Subject 203 flow-volume RA (Panel A) and He-O2 (Panel B), and transpulmonary pressure-volume RA (Panel C) and He-O2 (Panel D) traces. Volume (l) 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -8 -6 -4 -2 0 2 4 6 8 10 12 Volume (l) 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -8 -6 -4 -2 0 2 4 6 8 10 12 Pre FVC Post FVC Rest 1 km 2 km 3 km 4 km 5 km Volume (l) 5 4 3 2 1 0 T ra n s p u lm o n a ry  P res s u re  ( c m H 2 O ) -25 -20 -15 -10 -5 0 5 10 15 20 25 Volume (l) 5 4 3 2 1 0 T ra n s p u lm o n a ry  P res s u re  ( c m H 2 O ) -25 -20 -15 -10 -5 0 5 10 15 20 25 A B C D 134     FIGURE 46 – Subject 204 flow-volume RA (Panel A) and He-O2 (Panel B), and transpulmonary pressure-volume RA (Panel C) and He-O2 (Panel D) traces. Volume (l) 4 3 2 1 0 F lo w  ( l. s e c -1 ) -10 -5 0 5 10 15 Volume (l) 4 3 2 1 0 F lo w  ( l. s e c -1 ) -10 -5 0 5 10 15 Pre FVC Post FVC Rest 1 km 2 km 3 km 4 km 5 km Volume (l) 4 3 2 1 0 T ranspu lm on a ry  P res s u re  ( c m H 2 O ) -25 -20 -15 -10 -5 0 5 10 Volume (l) 4 3 2 1 0 T ranspu lm on a ry  P res s u re  ( c m H 2 O ) -25 -20 -15 -10 -5 0 5 10 A B C D 135     FIGURE 47 – Subject 205 flow-volume RA (Panel A) and He-O2 (Panel B), and transpulmonary pressure-volume RA (Panel C) and He-O2 (Panel D) traces. Volume (l) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 F lo w  ( l. s e c -1 ) -8 -6 -4 -2 0 2 4 6 8 10 Volume (l) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 F lo w  ( l. s e c -1 ) -8 -6 -4 -2 0 2 4 6 8 10 Pre FVC Post FVC Rest 1 km 2 km 3 km 4 km 5 km Volume (l) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 T ra n s p u lm o n a ry  P re s s u re  ( c m H 2 O ) -30 -25 -20 -15 -10 -5 0 5 10 Voume (l) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 T ra n s p u lm o n a ry  P re s s u re  ( c m H 2 O ) -30 -25 -20 -15 -10 -5 0 5 10 A B C D 136   FIGURE 48 – Subject 206 flow-volume RA (Panel A) and He-O2 (Panel B), and transpulmonary pressure-volume RA (Panel C) and He-O2 (Panel D) traces.  Volume (l) 3 2 1 0 F lo w  ( l. s e c -1 ) -6 -4 -2 0 2 4 6 8 10 12 Volume (l) 3 2 1 0 F lo w  ( l. s e c -1 ) -6 -4 -2 0 2 4 6 8 10 12 Pre FVC Post FVC Rest 1 km 2 km 3 km 4 km 5 km Volume (l) 3 2 1 0 T ra n s p u lm o n a ry  P re s s u re  ( c m H 2 O ) -25 -20 -15 -10 -5 0 5 10 Volume (l) 3 2 1 0 T ra n s p u lm o n a ry  P re s s u re  ( c m H 2 O ) -25 -20 -15 -10 -5 0 5 10 A B C D 137   FIGURE 49 – Subject 207 flow-volume RA (Panel A) and He-O2 (Panel B), and transpulmonary pressure-volume RA (Panel C) and He-O2 (Panel D) traces. Volume (l) 4 3 2 1 0 F lo w  ( l. s ec -1 ) -6 -4 -2 0 2 4 6 8 10 Volume (l) 4 3 2 1 0 F lo w  ( l. s e c -1 ) -6 -4 -2 0 2 4 6 8 10 Pre FVC Post FVC Rest 1 km 2 km 3 km 4 km 5 km Volume (l) 4 3 2 1 0 T ra n s p u lm o n a ry  P res s u re  ( c m H 2 O ) -30 -25 -20 -15 -10 -5 0 5 10 Volume (l) 4 3 2 1 0 T ra n s p u lm o n a ry  P res s u re  ( c m H 2 O ) -30 -25 -20 -15 -10 -5 0 5 10 C D A B 138    FIGURE 50 – Subject 208 flow-volume RA (Panel A) and He-O2 (Panel B), and transpulmonary pressure-volume RA (Panel C) and He-O2 (Panel D) traces.  Volume (l) 6 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -8 -6 -4 -2 0 2 4 6 8 10 12 Volume (l) 6 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -8 -6 -4 -2 0 2 4 6 8 10 12 Pre FVC Post FVC Rest 1 km 2 km 3 km 4 km 5 km Volume (l) 6 5 4 3 2 1 0 T ra n s p u lm o n a ry  P res s u re  ( c m H 2 O ) -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 1 km 2 km 3 km 4 km 5 km Volume (l) 6 5 4 3 2 1 0 T ra n s p u lm o n a ry  P res s u re  ( c m H 2 O ) -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 C D A B 139   FIGURE 51 – Subject 210 flow-volume RA (Panel A) and He-O2 (Panel B), and transpulmonary pressure-volume RA (Panel C) and He-O2 (Panel D) traces.  Volume (l) 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -8 -6 -4 -2 0 2 4 6 8 10 Volume (l) 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -8 -6 -4 -2 0 2 4 6 8 10 Pre FVC Post FVC Rest 1 km 2 km 3 km 4 km 5 km Volume (l) 5 4 3 2 1 0 T ra n s p u lm o n a ry  P re s s u re  ( c m H 2 O ) -30 -20 -10 0 10 20 Volume (l) 5 4 3 2 1 0 T ra n s p u lm o n a ry  P re s s u re  ( c m H 2 O ) -30 -20 -10 0 10 20 A B C D 140   FIGURE 52 – Subject 211 flow-volume RA (Panel A) and He-O2 (Panel B), and transpulmonary pressure-volume RA (Panel C) and He-O2 (Panel D) traces.  Volume (l) 6 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -10 -8 -6 -4 -2 0 2 4 6 8 10 12 Volume (l) 6 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -10 -8 -6 -4 -2 0 2 4 6 8 10 12 Pre FVC Post FVC Rest 1 km 2 km 3 km 4 km 5 km Volume (l) 6 5 4 3 2 1 0 T ranspu lm on a ry  P res s u re  ( c m H 2 O ) -25 -20 -15 -10 -5 0 5 10 Volume (l) 6 5 4 3 2 1 0 T ranspu lm on a ry  P res s u re  ( c m H 2 O ) -25 -20 -15 -10 -5 0 5 10 C D A B 141   FIGURE 53 – Subject 212 flow-volume RA (Panel A) and He-O2 (Panel B), and transpulmonary pressure-volume RA (Panel C) and He-O2 (Panel D) traces.   Volume (l) 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -6 -4 -2 0 2 4 6 8 10 Pre FVC Post FVC Rest 1 km 2 km 3 km 4 km 5 km Volume (l) 5 4 3 2 1 0 F lo w  ( l. s e c -1 ) -6 -4 -2 0 2 4 6 8 10 Volume (l) 5 4 3 2 1 0 T ra n s p u lm o n a ry  P re s s u re  ( c m H 2 O ) -25 -20 -15 -10 -5 0 5 10 Volume (l) 5 4 3 2 1 0 T ra n s p u lm o n a ry  P re s s u re  ( c m H 2 O ) -25 -20 -15 -10 -5 0 5 10 C D A B 142  APPENDIX C – QUESTIONNAIRES   Effect of Heliox on Respiratory Mechanics, Sensory Responses, and Performance during Exercise in Endurance-Trained Men and Women                                                                                         Subject Identifier:    Medical History  1.  Are you currently taking any medications (excluding oral contraceptives)?   Please List:  ____________________________________________________  2.  Do you currently smoke?  YES/NO  3.  Are you a past smoker?  YES/NO  4.  When was the last time you had a cold?  ___________________  5. Do you have asthma, other lung problems or significant illness?  Please List:  _____________________________________________________________________   6. Have you had recent nasopharyngeal surgery?  YES/NO  7.  Do you have an ulcer or tumour in your esophagus?  YES/NO  8. Are you sensitive to local anaesthetics or do you have allergies to latex?  YES/NO  9. Are you pregnant or is there any chance you could be pregnant?  YES/NO  Menstrual History Questionnaire:  1. Are you having regular periods?      YES/NO  2. How long is your cycle length?                              (days)  3. How many days long is your flow?                              (days)  4. Can you usually tell, by the way you feel, that your period is coming?    YES/NO  5. Do you usually experience the following symptoms?  Breast tenderness    YES/NO Appetite changes    YES/NO Mood changes     YES/NO Fluid retention     YES/NO  6. How many times did you menstruate in the past year?  7. How many periods have you missed in the last five years?  143                     8. Are you currently taking oral contraceptives?   YES/NO If yes, for how long? What is the name of the oral contraceptive pill which you are taking?   9. When was the last start date of your period (DAY 1; i.e., when you began to menstruate)?    Physical Activity History  Type of Physical Activity:  _______________________________________________  Volume per week:  _____________________________________________________  Are you: in-season or off-season?  ___________________________________________________  Highest level of competition: ___________________________________________________  V’O2MAX (if known):  _____________date: _______________exercise modality:________________  Last cycling race: _____________ distance: _________time: ___________date: _______________  Cycling Category (if applicable):   144      145      146      147      148    Today’s Date: Food Consumption: What:  Time: Activity: Type:  Duration:  Intensity:  Caffeine:  YES /  NO      If yes, when: Hours of Sleep:  1 Day Prior: Food Consumption: What:  Time: Activity: Type:  Duration:  Intensity:   2 Days Prior: Activity: Type:  Duration:  Intensity:   3 Days Prior: Activity: Type:  Duration:  Intensity:   Day 2 – 5 km TT       Training Log Subject Identifier   149  Today’s Date: Food Consumption: What:  Time: Activity: Type:  Duration:  Intensity:  Caffeine:  YES /  NO      If yes, when: Hours of Sleep:  1 Day Prior: Food Consumption: What:  Time: Activity: Type:  Duration:  Intensity:   2 Days Prior: Activity: Type:  Duration:  Intensity:   3 Days Prior: Activity: Type:  Duration:  Intensity:   Day 3 – 5 km TT       Training Log Subject Identifier  

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