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Comparison of cardiorespiratory parameters during treadmill and immersion running Welsh, Donald Gordon 1988

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COMPARISON OF CARDIORESPIRATORY PARAMETERS DURING TREADMILL AND IMMERSION RUNNING by DONALD GORDON WELSH B.P.E., The University o£ Calgary, 1986 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTERS in PHYSICAL EDUCATION , We a c c e p t t h i s t h e s i s as co n f o r m i n g t o the r e q u i r e d s t a n d a r d The University of British Sept, 1988 ©Donald Gordon Welsh, Columbia 1988 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 DE-6(3/81) i i ABSTRACT The purpose of t h i s s t u d y was t o compare the r e l a t i o n s h i p between immersion r u n n i n g and t r e a d m i l l r u n n i n g t h r o u g h the measurement of c a r d i o r e s p i r a t o r y p a r a m e t e r s . S i x t e e n s u b j e c t s completed two e x e r c i s e p r o t o c o l s t o e x h a u s t i o n . The t r e a d m i l l r u n n i n g p r o t o c o l was i n i t i a t e d a t 3.08 m*s-l and i n c r e a s e d a 0.22 m*s-l e v e r y s i x t y seconds. The immersion r u n n i n g p r o t o c o l u t i l i z e d an immersion r u n n i n g Ergometer ( I R E ) . The IRE i s s i m i l a r t o a t e t h e r e d swim machine. The i n i t i a l w eight was s e t a t 1 kg and I n c r e a s e d a 1/2 kg e v e r y s i x t y seconds. Heart r a t e ( H R ) , oxygen consumption ( V 0 2 ) , v e n t i l a t o r y e q u i v a l e n t ( V E / V 0 2 ) , and minute v e n t i l a t i o n (VE) were de t e r m i n e d a t v e n t i l a t o r y t h r e s h o l d and a t maximal e f f o r t , HR, V 0 2 , VE/V02 and VE were a n a l y z e d by MANOVA (RM). T i d a l volume and fr e q u e n c y of b r e a t h i n g were c o l l e c t e d f o r f o u r s u b j e c t s a t v e n t i l a t o r y t h r e s h o l d and a t maximal e f f o r t (no s t a t i s t i c a l a n a l y s i s ) . Two s u b j e c t s who had completed the i n i t i a l e x e r c i s e p r o t o c o l s v o l u n t e e r e d f o r a f o l l o w up s t u d y of bl o o d f l o w d i s t r i b u t i o n t e s t i n g (no s t a t i s t i c a l a n a l y s i s ) . These s u b j e c t s were i n j e c t e d w i t h Tc-99 2-methyloxy i s o b u t y l i s o n i t r l l e a t v e n t i l a t o r y t h r e s h o l d d u r i n g immersion and t r e a d m i l l r u n n i n g . Imaging was performed w i t h a Selmans Gamma Camera a t the UBC Dept. of N u c l e a r M e d i c i n e . V 0 2 and HR a t v e n t i l a t o r y t h r e s h o l d and maximal e f f o r t were s i g n i f i c a n t l y lower (P < .05) d u r i n g immersion r u n n i n g . VE/V02 I l l was s i g n i f i c a n t l y greater at maximal e f f o r t during immersion. Minute v e n t i l a t i o n was unaffected by immersion, however, there was a trend towards a smaller t i d a l volume and greater frequency of breathing. The blood flow d i s t r i b u t i o n data varied considerably p a r t i a l l y between subjects. The s i g n i f i c a n t drop in V02 at maximum e f f o r t and at v e n t i l a t i o n threshold during immersion running may be accounted for by changes in muscle mass recruitment, muscle f i b r e type recruitment, recruitment pattern and state of peripheral adaptation (muscular). A lower heart rate during immersion may be due to increases in intrathoracic blood volume. The trend towards a higher breathing frequency and lower t i d a l volume during immersion running may be due to the increased e f f o r t to breath caused by hydrostatic chest compression. The s i g n i f i c a n t increase in VE/V02 at maximal e f f o r t during immersion running was due to the s i g n i f i c a n t drop in V02. It may be concluded that immersion running causes s i g n i f i c a n t changes in cardiorespiratory parameters at ven t i l a t o r y threshold and at maximal e f f o r t . Research is needed to investigate the significance of the changes. i v TABLE OF CONTENTS Page Abstract i i L i s t of Tables v i 1. Introduction: The Problem 1 Hypothesis 6 Delimitations 9 Limitations 9 Definitions 10 2. Methods and Procedures 11 Subjects 11 Testing Protocols 12 3. Literature Review 19 The Cardiovascular System During Body Immersion 20 The Respiratory System During Body Immersion 27 Task S p e c i f i c i t y and Its Relationship to Cardiorespiratory Parameters 32 4. Results and Discussion 40 Results 40 Discussion 47 5. Summary 63 References 66 Appendix 76 Appendix A 76 Appendix B Appendix C Appendix D Appendix E Appendix F Appendix G Appendix H Appendix I Appendix J Appendix K Appendix L v i LIST OF TABLES Page Table I D e s c r i p t i v e d a t a of 16 t r a i n e d m i d d l e d i s t a n c e r u n n e r s . 41 Table II C a r d i o r e s p i r a t o r y parameters c o l l e c t e d a t v e n t i l a t o r y t h r e s h o l d d u r i n g immersion t r e a d m i l l r u n n i n g . 41 Table III C a r d i o r e s p i r a t o r y parameters c o l l e c t e d a t maximal e f f o r t d u r i n g immersion and t r e a d m i l l r u n n i n g . 42 Table IV Mean v a l u e s f o r f o u r s u b j e c t s a t v e n t i l a t i o n t h r e s h o l d d u r i n g Immersion and t r e a d m i l l r u n n i n g . 43 Table V Mean v a l u e s f o r f o u r s u b j e c t s a t maximal e f f o r t d u r i n g immersion and t r e a d m i l l r u n n i n g . 44 1 CHAPTER 1 THE PROBLEM INTRODUCTION Immersion r u n n i n g (IR) i n v o l v e s t he s i m u l a t i o n of r u n n i n g motion w h i l e immersed t o the neck i n an aqueous environment. IR has been u t i l i z e d f o r two s p e c i f i c f u n c t i o n s . They i n c l u d e : 1. R e h a b i l i t a t i o n of r u n n e r s s u f f e r i n g from lower l e g I n j u r i e s (Johnson e t a l . , 1977; K o s z u t a , 1986); and 2. I n i t i a t i n g p h y s i o l o g i c a l a d a p t a t i o n s s p e c i f i c t o l a n d based r u n n i n g ( K o s z u t a , 1986). K o s z u t a (1986), documented the use of immersion r u n n i n g as a form of r e h a b i l i t a t i o n f o r r u n n e r s w i t h s t r e s s r e l a t e d i n j u r i e s ( i . e . s t r e s s f r a c t u r e s and a c h i l l e s t e n d o n i t i s ) . I n j u r e d r u n n e r s upon r e s u m p t i o n of l a n d t r a i n i n g , s u b j e c t i v e l y f e l t t h a t t h e y were a b l e t o m a i n t a i n or improve c a r d i o r e s p i r a t o r y f i t n e s s as i t r e l a t e d t o l a n d based r u n n i n g performance because of immersion r u n n i n g . The s u b j e c t i v e measures from i n j u r e d r u n n e r s has p r o v i d e d the f o u n d a t i o n upon which coaches and a t h l e t e s have u t i l i z e d immersion r u n n i n g as an a l t e r n a t i v e form of a t h l e t i c t r a i n i n g . To d a t e , t h e r e i s a l a c k of r e s e a r c h s u b s t a n t i a t i n g the s u b j e c t i v e measures. For immersion r u n n i n g t o be u t i l i z e d as a mode of a t h l e t i c t r a i n i n g f o r the c o m p e t i t i v e r u n n e r , i t s h o u l d Induce a d a p t a t i o n s s p e c i f i c t o l a n d based r u n n i n g performance. Land 2 based performance I s a f u n c t i o n of two p r o p e r t i e s . Those p r o p e r t i e s a r e : 1. A h i g h l y d e v e l o p e d c e n t r a l c a r d i o r e s p i r a t o r y system w i t h the a b i l i t y t o s u s t a i n p r o l o n g e d endurance a c t i v i t i e s ( A s t r a n d , 1977); and 2. A h i g h l y d eveloped p e r i p h e r a l m u s c u l a t u r e w i t h the a b i l i t y t o s u s t a i n a r u n n i n g performance f o r a g i v e n p e r i o d of time ( A s t r a n d , 1977). The a r e a s documented i n the p r e v i o u s paragraph ( c a r d i o r e s p i r a t o r y and p e r i p h e r a l a d a p t a t i o n s ) can be measured by a number of v a r y i n g methods. A l t h o u g h both a r e a s a r e worthy o£ i n v e s t i g a t i o n , i t i s the purpose of t h i s s t u d y t o c o n c e n t r a t e on comparing c a r d i o r e s p i r a t o r y parameters between an immersion and t r e a d m i l l r u n n i n g c o n d i t i o n . T r a d i t i o n a l l y , the measurement of maximum oxygen consumption (V02max) has been used t o a s s e s s the degree of c a r d i o r e s p i r a t o r y f i t n e s s ( A s t r a n d , 1977). C h a r a c t e r i s t i c a l l y , h i g h l y t r a i n e d m i d d l e d i s t a n c e r u n n e r s e l i c i t V02max v a l u e s g r e a t e r than 65 m l * k g - l * m i n - l . More r e c e n t l y , a number of a u t h o r s have u t i l i z e d v e n t i l a t o r y t h r e s h o l d as a measure of c a r d i o r e s p i r a t o r y f i t n e s s because of i t s c o r r e l a t i o n w i t h endurance performance (Rhodes e t a l . , 1984; W i t h e r s e t a l . , 1981). W e l l t r a i n e d m i d d l e d i s t a n c e r u n n e r s t r a d i t i o n a l l y a c q u i r e a v e n t i l a t o r y t h r e s h o l d g r e a t e r than 80% of V02max (Da v i s e t a l . , 1984; W i t h e r s e t a l . , 1981). In o r d e r f o r immersion r u n n i n g t o be u t i l i z e d e f f e c t i v e l y by 3 a t h l e t e s , I t must be a b l e t o e l i c i t oxygen consumption v a l u e s ( a t maximal e f f o r t and a t v e n t i l a t o r y t h r e s h o l d ) e q u i v a l e n t or g r e a t e r t o t h o s e measured d u r i n g a t r e a d m i l l r u n n i n g p r o t o c o l . I f immersion r u n n i n g can e l i c i t a V02 a t maximum e f f o r t and a t v e n t i l a t o r y t h r e s h o l d e q u i v a l e n t t o t r e a d m i l l r u n n i n g , an i n d i v i d u a l may be a b l e t o m a i n t a i n or improve t h e i r l e v e l of c a r d i o r e s p i r a t o r y a d a p t a t i o n , u l t i m a t e l y , any change i n oxygen consumption t h a t may occur between an immersion r u n n i n g and t r e a d m i l l c o n d i t i o n w i l l be due t o : 1. The i n t r o d u c t i o n of a water environment which i n c r e a s e s t h o r a c i c b l o o d volume and h y d r o s t a t i c c h e s t compression ( E p s t e i n , 1976; B e g i n e t a l . , 1976); and 2. Changes i n t a s k s p e c i f i c i t y ( A s t r a n d , 1977; secher e t a l . , 1977; W i t h e r s e t a l . , 1981). W i t h i n the a r e a of t a s k s p e c i f i c i t y , t h e r e a r e a number of s u b f a c t o r s t h a t may a f f e c t V02 a t maximal e f f o r t and a t v e n t i l a t o r y t h r e s h o l d . It'was hoped t h a t some of t h e s e f a c t o r s c o u l d be I s o l a t e d and measured u t i l i z i n g an e x p e r i m e n t a l r a d i o n u c l i d e p r o c e d u r e . The p r i m a r y f a c t o r i n c a r d i o r e s p i r a t o r y f i t n e s s i s oxygen consumption. However, s e c o n d a r y t o t h i s f a c t o r , a number of o t h e r parameters i n c l u d i n g h e a r t r a t e , minute v e n t i l a t i o n , t i d a l volume, b r e a t h i n g f r e q u e n c y and VE/V02 may h e l p i n o v e r a l l c a r d i o r e s p i r a t o r y f u n c t i o n . The measurement of t h e s e parameters w i l l be i n c l u d e d i n t h i s s t u d y . S i m i l a r l y , any changes t h a t may 4 occur i n the c i t e d parameters between an immersion and t r e a d m i l l r u n n i n g c o n d i t i o n w i l l be due t o e i t h e r the I n t r o d u c t i o n of the water environment and/or changes i n t a s k s p e c i f i c i t y ( A s t r a n d , 1977; E p s t e i n , 1976; W i t h e r s e t a l . , 1988). U l t i m a t e l y , u n d e r s t a n d i n g the n a t u r e of immersion r u n n i n g i s im p o r t a n t t o the coach, the a t h l e t e , and the p h y s i o t h e r a p i s t . The use o£ IR may: 1. Decrease the r a t e of i n c i d e n c e and p r e v e n t lower e x t r e m i t y i n j u r i e s (and t h e r e f o r e i n c r e a s e the e f f e c t i v e t r a i n i n g t i m e ) ; and 2. I n c r e a s e the performance l e v e l of the a t h l e t e due t o i t s p o t e n t i a l a b i l i t y t o induce c a r d i o r e s p i r a t o r y and p e r i p h e r a l a d a p t a t i o n s s p e c i f i c t o l a n d based r u n n i n g . STATEMENT OF THE PROBLEM The purpose of t h i s s t u d y was t o compare the r e l a t i o n s h i p s between immersion r u n n i n g and t r e a d m i l l r u n n i n g through the measurements of c a r d i o r e s p i r a t o r y p arameters. I t has been h y p o t h e s i z e d t h a t oxygen consumption w i l l be s i m i l a r under both c o n d i t i o n s and t h a t the VE/V02 r a t i o s h o u l d be lower d u r i n g immersion r u n n i n g . I t has a l s o been h y p o t h e s i z e d t h a t h e a r t r a t e , v e n t i l a t i o n and t i d a l volume w i l l be g r e a t e r d u r i n g t r e a d m i l l r u n n i n g t h a n immersion r u n n i n g . 5 H Y P O T H E S I S 1. Maximal oxygen consumption (V02max) during an IR protocol (W) w i l l be equal to maximal oxygen consumption during a treadmill running protocol (T). Equality s h a l l be defined as a P >.50. V02maxW = V02maxT 2. Oxygen consumption at v e n t i l a t i o n threshold (V02vt) w i l l be equal during an IR protocol and during a treadmill protocol. Equality s h a l l be defined as P >.50. V02vtW =V02vtT 3. Heart rate at V02max (HRmax) w i l l be greater during a treadmill protocol than an IR protocol. HRmaxT > HRmaxW 4. Heart rate at v e n t i l a t i o n threshold (HRvt) w i l l be greater during a treadmill protocol than an IR protocol. HRvtT > HRvtW 5. V e n t i l a t i o n at V02max (VEmax) w i l l be greater during a treadmill protocol than an IR protocol. VEmaxT > VEmaxW 6. Ve n t i l a t i o n at v e n t i l a t i o n threshold (VEvt) w i l l be greater during a treadmill protocol than an IR protocol. VEvtT > VEvtW 7. Ti d a l volume at V02max (TVmax) w i l l be greater during a treadmill protocol than an IR protocol. TVmaxT > TVmaxW 8. Tid a l volume at v e n t i l a t i o n threshold (TVvt) w i l l be greater during a treadmill protocol than an IR protocol. TVvtT >TVvtW 6 9. Ventilatory equivalent at V02max (VE/V02max) w i l l be smaller during an IR protocol than a treadmill protocol. VE/V02maxW < VE/V02maxT 10. Ventilatory equivalent at v e n t i l a t i o n threshold (VE/V02vt) w i l l be smaller during an IR protocol than a treadmill protocol. VE/V02vtW < VE/V02vtT 11. Frequency of breathing at V02max (Fmax) w i l l be greater during an IR protocol than a treadmill protocol. FmaxW > FmaxT 12. Frequency of breathing at v e n t i l a t i o n threshold (Fvt) w i l l be greater during an IR protocol than a treadmill protocol. Fvtw > FvtT RATIONALE 1. It has been hypothesized that there w i l l be a non-s i g n i f i c a n t change in oxygen consumption at maximum e f f o r t and at v e n t i l a t o r y threshold during immersion and treadmill running. These hypothesis are based upon two assumptions. Those assumptions are: A. That the water environment w i l l not a f f e c t normal cardiorespiratory function as i t relates to oxygen consumption. Dressendorfer et a l . , 1976 and Denison et a l . , 1972 noted that there were non-significant changes in V02 at maximal and submaximal i n t e n s i t i e s 7 comparatively between a land and immersion cycling protocol; and B. That any changes (or lack of changes) in task s p e c i f i c factors w i l l not cause s i g n i f i c a n t changes in the rate of oxygen consumption. 2. It has been hypothesized that there w i l l be a s i g n i f i c a n t l y lower heart rate (at maximal e f f o r t and v e n t i l a t o r y threshold) during immersion running. These hypothesis are based upon two assumptions. Those assumptions are: A. That the increase in Intrathoracic blood volume due to the introduction of a water environment w i l l Increase stroke volume and lower heart rate at any given cardiac output or exercise i n t e n s i t y . A lower heart rate due to water immersion during exercise has been reported by investigators (Sheldahl et a l . , 1976; Sheldahl et a l . , 1984; Dressendorfer et a l . , 1976); B. That task s p e c i f i c factors ( i . e . the t r a i n i n g state of recruited musculature and the type of recruited musculature) which may increase heart rate at v e n t i l a t o r y threshold during immersion running w i l l be i n s i g n i f i c a n t comparatively to the e f f e c t s of the water environment (Clausen et a l . , 1973; withers et a l . , 1981). 3. It has been hypothesized that v e n t i l a t i o n at maximal e f f o r t and at v e n t i l a t o r y threshold w i l l be s i g n i f i c a n t l y lower 8 d u r i n g immersion r u n n i n g . These h y p o t h e s i s a r e based upon two a s s u m p t i o n s . Those assumptions a r e : A. That the i n c r e a s e In h y d r o s t a t i c c h e s t c o m p r e s s i o n and i n t r a t h o r a c i c b l o o d volume (the water e n v i r o n m e n t ) , w i l l r e s u l t i n an I n c r e a s e d e f f o r t t o b r e a t h e . An i n c r e a s e d e f f o r t t o b r e a t h e may be c h a r a c t e r i z e d by . changes In l u n g mechanics (Dahlback e t a l . , 1975, 1978a and 1978b); B. That t a s k s p e c i f i c f a c t o r s ( i . e . the i n v o l v e m e n t of l a r g e q u a n t i t i e s of upper body m u s c u l a t u r e ) may c o n t r i b u t e i n l o w e r i n g minute v e n t i l a t i o n d u r i n g Immersion r u n n i n g (Secher e t a l . , 1977; Toner e t a l . , 1984). 4. I t has been h y p o t h e s i z e d t h a t t i d a l volume w i l l be s i g n i f i c a n t l y h i g h e r and b r e a t h i n g frequency s i g n i f i c a n t l y lower d u r i n g Immersion r u n n i n g . These h y p o t h e s i s are based upon two a s s u m p t i o n s . Those assumptions a r e : A. That the i n c r e a s e i n i n t r a t h o r a c i c b lood volume and h y d r o s t a t i c c h e s t c o m p r e s s i o n (the water environment) w i l l i n h i b i t normal r e s p i r a t o r y mechanics (Dahlback e t a l . , 1975, 1978a and 1978b); B. That t a s k s p e c i f i c f a c t o r s ( i . e . the u t i l i z a t i o n of upper body m u s c u l a t u r e ) may c o n t r i b u t e t o the changes i n t i d a l volume and b r e a t h i n g f r e q u e n c y i n i t i a t e d by 9 the water environment (Secher e t a l . , 1977; Toner e t a l . , 1984). 5. I t has been h y p o t h e s i z e d t h a t the VE/V02 r a t i o w i l l be s i g n i f i c a n t l y lower d u r i n g immersion r u n n i n g a t maximum e f f o r t and a t v e n t i l a t o r y t h r e s h o l d . These h y p o t h e s i s a r e based upon two a s s u m p t i o n s . Those assumptions a r e : A. Oxygen consumption w i l l be e q u i v a l e n t between the two e x e r c i s e c o n d i t i o n s ; and B. Minute v e n t i l a t i o n w i l l be lower d u r i n g immersion r u n n i n g c o m p a r a t i v e l y t o l a n d r u n n i n g . DELIMITATIONS 1. The sample type ( male m i d d l e aged r u n n e r s t r a i n e d i n both l a n d and Immersion r u n n i n g ) . 2. The sample s i z e (22 male s u b j e c t s ) . 3. The I n i t i a l l y h i g h l e v e l of a e r o b i c f i t n e s s of the s u b j e c t s (a maximal oxygen consumption of 6 0 m l * k g * - l m l n - l or g r e a t e r i s needed i n o r d e r t o p a r t i c i p a t e i n the s t u d y ) . T h i s c r i t e r i a has been u t i l i z e d i n o r d e r t o ensure t h a t the s u b j e c t s a r e a d e q u a t e l y t r a i n e d i n r e l a t i o n t o c a r d i o r e s p i r a t o r y f i t n e s s . LIMITATIONS 1. The a b i l i t y of the s u b j e c t s t o s i m u l a t e the immersion r u n n i n g motion c o r r e c t l y . 10 2. The a b i l i t y of the researcher to ensure that the subject w i l l be able to perform maximally on both tests during the time required. 3. The a b i l i t y of the immersion running ergometer (IRE) to apply resistance to the subject allowing expression of v e n t i l a t i o n threshold and maximal oxygen consumption. 4. The a b i l i t y of the investigator to accurately extrapolate v e n t i l a t i o n threshold from excess C02, v e n t i l a t i o n , and VE/V02. DEFINITIONS 1. Maximal oxygen consumption - the highest oxygen uptake attained during physical work while breathing at sea l e v e l . 2. Ventilation threshold - V e n t i l a t i o n threshold is the point at which a nonlinear increase in excess C02 is detected. Because of potential v a r i a b i l i t y in excess C02, VE and VE/V02 were u t i l i z e d secondarily to increase the accuracy of the excess C02 parameter. Ventilatory threshold was determined Independently by three separate Investigators. Excess C02 = VC02 - Resting RQ * V02 11 CHAPTER 2 METHODS AND PROCEDURES SUBJECTS Twenty-two male s u b j e c t s between the ages of e i g h t e e n and t h i r t y - o n e were u t i l i z e d i n t h i s s t u d y . A l l s u b j e c t s were t r a i n e d m i d d l e d i s t a n c e , r u n n e r s (members of the UBC middle d i s t a n c e h i g h performance u n i t ) f a m i l i a r w i t h immersion r u n n i n g . These s u b j e c t s were u t i l i z e d because immersion r u n n i n g was a r e g u l a r p a r t of t h e r e t r a i n i n g program. S u b j e c t s were r e q u i r e d t o have a V02max of 60 m l * k g * - l m i n * - l ( t r e a d m i l l ) or h i g h e r t o p a r t i c i p a t e i n the s t u d y . A l l s u b j e c t s completed a consent form d e s c r i b i n g the l a b o r a t o r y p r o c e d u r e s . Four of the twenty-two s u b j e c t s v o l u n t e e r e d f o r a f o l l o w - u p procedure which i n v o l v e d n u c l e a r imaging t e c h n i q u e s t o a s s e s s changes . I n b l o o d f l o w d i s t r i b u t i o n . The f o u r s u b j e c t s completed a d d i t i o n a l consent forms d e s c r i b i n g t h e s e p r o c e d u r e s . TESTING PROCEDURES 1. L a b o r a t o r y Measures a) H e i g h t and weight d e t e r m i n a t i o n s 2. IR Measures a) Maximal 02 consumption t e s t b) ECG m o n i t o r i n g t o dete r m i n e h e a r t r a t e c) Beckman M e t a b o l i c C a r t t o measure V02, v e n t i l a t i o n , t i d a l volume and f r e q u e n c y of b r e a t h i n g 12 d) Extrapolation o£ v e n t i l a t i o n threshold from excess C02, v e n t i l a t i o n and VE/V02 3. Treadmill Measures a) Maximal 02 consumption test b) ECG monitoring to determine heart rate c) Beckman Metabolic Cart to measure V02, v e n t i l a t i o n , t i d a l volume and frequency of breathing d) Extrapolation of v e n t i l a t i o n threshold from excess C02, v e n t i l a t i o n and VE/V02 4. Blood Flow D i s t r i b u t i o n Measures (Nuclear Imaging) a) Two submaximal exercise protocols (immersion vs land) b) ECG monitoring to determine heart rate c) Beckman Metabolic Cart to assess V02 d) I.V. catheterization of the cephalic vein e) Injection of TC-99 2 methyloxy isobutyl i s o n i t r i l e during the exercise protocol. The subjects were asked to r e f r a i n from t r a i n i n g on the day of the testing session. TESTING PROTOCOLS C a r d i o r e s p i r a t o r y T e s t i n g A. IR and maximal 02 consumption t e s t An immersion running ergometer (IRE) was developed to test maximal 02 consumption in an aqueous environment. The IRE is box shaped, measuring 2.5 metres high and one metre long and wide. A 13 metal bar was a t t a c h e d l e n g t h w i s e a c r o s s the bottom of the IRE. A t t a c h e d t o the t o p of the IRE and the m e t a l bar was a p u l l e y system c r e a t i n g a one t o one advantage. One-half c e n t i m e t r e n y l o n rope was used, th r o u g h o u t the p u l l e y system. A f i v e c e n t i m e t r e f l a t webbing w a i s t harness a t t a c h e d the s u b j e c t t o the IRE. S u b j e c t s were immersed t o the neck In wa t e r . The IRE was p l a c e d by the s i d e of a p o o l and 1.5 metres of rope was p a s s i v e l y p u l l e d t h r o u g h the p u l l e y system. The s u b j e c t s were r e q u i r e d by c o r r e c t r u n n i n g motion t o p u l l out an a d d i t i o n a l 1.5 metres. T h i s a c t i o n moved the weight a t t a c h e d t o the end of the p u l l e y system 1.5 metres. A marker was used t o i n d i c a t e the t h r e e metre p o i n t . S u b j e c t s were asked t o m a i n t a i n the t h r e e metre p o s i t i o n t h r o u g h o u t the t e s t . The IR p r o t o c o l used t o t e s t maximal oxygen consumption was a c o n t i n u o u s model w i t h a p r o g r e s s i v e l o a d i n c r e a s e e v e r y s i x t y seconds. The i n i t i a l weight v a l u e was s e t a t one k i l o g r a m w i t h a l o a d i n c r e a s e of 500 grams e v e r y s i x t y seconds. The t e s t was performed t o e x h a u s t i o n . E x h a u s t i o n was d e t e r m i n e d when the s u b j e c t c o u l d not m a i n t a i n a p o s i t i o n between the 1.5 and 3.0 metre mark. The t e s t p r o t o c o l was a p p r o x i m a t e l y 12 t o 14 minutes i n l e n g t h . Immersion r u n n i n g p o s t u r e was measured s u b j e c t i v e l y . R e s e a r c h e r s were l o o k i n g s p e c i f i c a l l y f o r h i p f l e x i o n f o l l o w e d by h i p and l e g e x t e n s i o n . Arm a c t i o n f o l l o w e d a normal r u n n i n g m o t i o n . The s u b j e c t s were asked not t o cup t h e i r hands. 14 B. Treadmill running and maximal oxygen consumption test The treadmill protocol to test maximal 02 consumption was a continuous model with a progressive load increase every s i x t y seconds. The treadmill run was i n i t i a t e d at 3.08 m*s-l and increased 0.22 m*s-l every s i x t y seconds u n t i l exhaustion. Exhaustion was determined when the subject could no longer maintain treadmill v e l o c i t y . The test protocol was approximately 12 to 14 minutes in length. C. Gas analysis and anaerobic threshold Gas analysis was conducted using a second generation Beckman Metabolic Measurement Cart. Minute v e n t i l a t i o n , VC02, V02, t i d a l volume and breathing frequency were measured and tabulated every f i f t e e n seconds during treadmill running and every 30 seconds during water immersion running. V e n t i l a t i o n threshold was determined by the break or non-linear increase in excess C02. VE and VE/V02 were used secondarily to confirm the threshold break in excess C02. Three examiners determined v e n t i l a t i o n threshold independently. Discrepancies that may occur in v e n t i l a t o r y threshold determination were reviewed by the examiners c o l l e c t i v e l y . The use of "excess C02" has been studied and validated against other metabolic gas parameters used In the prediction of v e n t i l a t i o n threshold (Rhodes et a l . , 1984). 15 D. Heart r a t e d e t e r m i n a t i o n A s t a n d a r d ECG machine and e l e c t r o d e s were used t o d e t e r m i n e h e a r t r a t e . Three e l e c t r o d e s were used. One e l e c t r o d e was p l a c e d on the sternum, the o t h e r two e l e c t r o d e s were p l a c e d on the l e f t and r i g h t s i d e s on the l a t e r a l a s p e c t s of the f i f t h i n t e r c o s t a l space. The e l e c t r o d e s d u r i n g the Immersion c o n d i t i o n were c o v e r e d w i t h w a t e r p r o o f tape t o p r e v e n t i n t e r f e r e n c e from the water environment. The Immersion r u n n i n g p r o t o c o l was performed p r i o r t o the t r e a d m i l l p r o t o c o l . One t o t h r e e weeks s e p a r a t e d the two e x e r c i s e p r o t o c o l s . S t a t i s t i c a l a n a l y s i s was performed on h e a r t r a t e , oxygen consumption, minute v e n t i l a t i o n and VE/V02 u t i l i z i n g a MANOVA model w i t h a r e p e a t e d measure on the e x e r c i s e c o n d i t i o n (immersion vs t r e a d m i l l r u n n i n g ) . V a l u e s a t v e n t i l a t o r y t h r e s h o l d and a t maximal e f f o r t were a n a l y z e d i n s e p a r a t e MANOVAs. Bl o o d Flow D i s t r i b u t i o n T e s t i n g Tc-99 2 methyloxy i s o b u t y l i s o n i t r i l e was u t i l i z e d i n t h i s p a r t of the s t u d y t o demonstrate changes i n b l o o d f l o w d i s t r i b u t i o n . I s o n i t r i l e i s a l i p o p h i l i c compound t h a t b i n d s t o the i n n e r and o u t e r membrane of muscle c e l l s . I s o n i t r i l e i s most commonly used i n h e a r t t i s s u e t o image i s c h e m i a . R e c e n t l y , i n v e s t i g a t o r s have u t i l i z e d i s o n i t r i l e t o image s k e l e t a l muscle t i s s u e (Dhekne e t a l . , 1988). S c i e n t i f i c e v i d e n c e seems t o show 16 that there i s a linear r e l a t i o n s h i p between i s o n i t r i l e uptake and muscle blood flow (Mousa et a l . , 1987b; Liu et a l . , 1987). A. IR protocol The subject performed the IR protocol at the University of B r i t i s h Columbia Aquatic Center. An I.V. catheter was inserted into the cephalic vein of the right arm. The catheter was secured to the arm with waterproof tape. The catheter l i n e was washed with a d i l u t e Heparin solution. Heart rate and V02 were monitored by the procedures described above. The subject was secured to the immersion running ergometer as described previously. Once immersed to the neck, the subject performed IR as previously described. The subject warmed up at a workload of 1.5 kgs for five minutes. At the end of the warmup period, the load was increased to e l i c i t a heart rate (plus or minus 5 bpm) and a V02 (plus or minus 3 ml*kg*-lmin-l) that corresponded with ve n t i l a t o r y threshold (previously determined). The subject maintained t h i s i n t e n s i t y for five minutes. At the end of the five minute period approximately 740 MBq of TC-99 2-methyloxy lsobutyl i s o n i t r i l e was Injected and washed into the I.V. catheter with saline solution. Approximately 90 seconds was required for injec t i o n of the radiopharmaceutical and 30 ml of sa l i n e . The subject continued to exercise at ven t i l a t o r y threshold for two minutes to allow optimum uptake. At the end of 17 the e x e r c i s e p r o t o c o l , the c a t h e t e r was removed. The s u b j e c t was then e s c o r t e d t o the Dept. of N u c l e a r M e d i c i n e f o r imagery. The immersion r u n n i n g p r o t o c o l was performed a p p r o x i m a t e l y one week p r i o r t o the t r e a d m i l l p r o t o c o l . B. Treadmill Protocol An I.V. c a t h e t e r was i n s e r t e d i n t o the c e p h a l i c v e i n of the s u b j e c t . The c a t h e t e r was s e c u r e d w i t h w a t e r p r o o f t a p e . The l i n e was washed w i t h a d i l u t e Heparin s o l u t i o n . Heart r a t e and V02 were m o n i t o r e d as p r e v i o u s l y d e s c r i b e d . The s u b j e c t warmed up a t a t r e a d m i l l v e l o c i t y of 3.08 m*s-l f o r 5 m i n u t e s . At the end of the warmup p e r i o d , the v e l o c i t y of the t r e a d m i l l was i n c r e a s e d t o e l i c i t a h e a r t r a t e ( p l u s or minus 5 bpm) and a V02 ( p l u s or minus 3 m l * k g * - l m i n - l ) t h a t c o r r e s p o n d e d w i t h v e n t i l a t o r y t h r e s h o l d ( p r e v i o u s l y d e t e r m i n e d ) . The s u b j e c t m a i n t a i n e d t h i s i n t e n s i t y f o r 5 minut e s . At the end of the f i v e minute p e r i o d , 740 MBq of Tc-99 2 methyloxy i s o b u t y l I s o n i t r i l e was I n j e c t e d I n t o the c a t h e t e r and washed w i t h a s a l i n e s o l u t i o n . The s u b j e c t , c o n t i n u e d t o e x e r c i s e a t v e n t i l a t o r y t h r e s h o l d f o r 2 minutes p o s t - I n j e c t i o n t o a l l o w optimum upt a k e . At the end of e x e r c i s e p r o t o c o l , the c a t h e t e r was removed and the s u b j e c t was e s c o r t e d t o the Dept. of N u c l e a r M e d i c i n e f o r body imagery. 18 C. Imaging Techniques Imaging was performed u t i l i z i n g a Seiman Gamma Camera. A signature I.D. of 500 counts per square cm was used. Fifteen views were obtained. They included: 1. Anterior Right and Left Oblique; 2. Posterior Thorax; 3. A n t e r i o r and P o s t e r i o r Abdominal; 4. Anterior Right and Left Thigh; 5. Posterior Right and Left Thigh; 6. Lateral Right Thigh; 7. A n t e r i o r R i g h t and L e f t Leg; 8. Posterior Right and Left Leg; and 9. Lateral Cranium From the planar images, regions of interest were drawn and analyzed using ex i s t i n g nuclear medicine software. Data obtained from the regions of interest included area ( p i x e l s ) , radiation count, and radiation count per p i x e l . In order to "semi" quantify the data, two 'ratios were generated. The f i r s t r a t i o was radiation count (muscle group) divided by radiation count (central brain area). The central brain case was u t i l i z e d because of consistently low i s o n i t r i l e uptake. The second r a t i o was the radiation count (muscle group) divided by t o t a l radiation count (whole body) and multiplied by 100%. An example of the t o t a l r a d i a t i o n c a l c u l a t i o n i s supplied in Appendix J. 19 CHAPTER 3 LITERATURE REVIEW The l i t e r a t u r e r e v i e w w i l l be d i v i d e d i n t o t h r e e a r e a s . Those a r e a s a r e : 1. The c a r d i o v a s c u l a r system d u r i n g body immersion; 2. The r e s p i r a t o r y system d u r i n g body immersion; 3. Task s p e c i f i c i t y and i t s r e l a t i o n s h i p to c a r d i o r e s p i r a t o r y parameters d u r i n g dynamic e x e r c i s e . I n t r o d u c t i o n E a r l y i n v e s t i g a t i o n s u t i l i z e d immersion as a medium t o c o u n t e r a c t g r a v i t a t i o n a l f o r c e s (Howard e t a l . , 1967; G r a v e l i n e e t a l . 1962; G r a y b l e l e t a l . , 1961; Torphy e t a l , 1966). The c o u n t e r a c t i o n was u s e f u l i n the s i m u l a t i o n of s p a c e f l i g h t (Howard e t a l . , 1967; Torphy e t a l . , 1966). These r e p o r t s p r o v i d e d the f o u n d a t i o n f o r f u t u r e immersion r e s e a r c h . C a r d i o v a s c u l a r and r e s p i r a t o r y changes d u r i n g immersion are due t o two b a s i c p h y s i o l o g i c a l phenomena ( E p s t e i n , 1976; G r e e n l e a f , 1984). They a r e : 1. The h y d r o s t a t i c c o m p r e s s i o n of the lower l i m b s c a u s i n g a r e d i s t r i b u t i o n of b l o o d from the l e g v a s c u l a r beds t o the t h o r a c i c c a v i t y ( E p s t e i n , 1976); 2. The h y d r o s t a t i c c o m p r e s s i o n of the abdominal and t h o r a c i c r e g i o n c a u s i n g diaphragm l i f t and r e l o c a t i o n 20 o£ b l o o d from the abdominal t o the t h o r a c i c r e g i o n ( E p s t e i n , 1976). The C a r d i o v a s c u l a r System D u r i n g Body Immersion A. C a r d i a c Output: D u r i n g r e s t i n g immersion, c a r d i a c o utput ( C O . ) i n c r e a s e s ( A r b o r e l i u s e t a l . , 1972; B e g i n e t a l . , 1976; F a r h i e t a l . , 1977). A r b o r e l i u s e t a l . (1972), u s i n g a d i l u t i o n dye t e c h n i q u e , demonstrated t h a t r e s t i n g C O . r o s e from 6.0 1/min t o 7.7 1/min d u r i n g immersion. The 32% r i s e c o r r e s p o n d s w e l l w i t h i n v e s t i g a t i o n s r e p o r t i n g o v e r a l l i n c r e a s e s r a n g i n g from 20 t o 60 p e r c e n t ( B e g i n e t a l . , 1976; F a r h i e t a l . , 1977). F a r h i e t a l . (1977) c o n c l u d e d t h a t C O . i n c r e a s e d l i n e a r l y w i t h the depth of immersion. Two f a c t o r s t h a t may s u p p r e s s C O . i n c r e a s e s a t r e s t d u r i n g immersion a r e water temperature and measurement r e l i a b i l i t y . A r b o r e l i u s e t a l . (1972), q u e s t i o n e d the r e l i a b i l i t y of the C02 r e b r e a t h i n g t e c h n i q u e d u r i n g r e s t i n g c o n d i t i o n s . C o r r e s p o n d i n g l y , McArdle e t a l . (1976), r e p o r t e d t h a t water temperature below the body's t h e r m o n e u t r a l p o i n t ( a p p r o x i m a t e l y 35C) can d e p r e s s h e a r t r a t e , v e n t i l a t i o n , and V02 a t r e s t (McArdle e t a l . , 1976). B. Heart Rate A l t h o u g h c o n t r o v e r s i a l , h e a r t r a t e d u r i n g r e s t i n g immersion i s lower than e r e c t p o s t u r e on l a n d (Lange e t a l . , 1974; F a r h i e t 21 a l . , 1977). T h i s i s an a r e a w i d e l y debated because of c o n f l i c t i n g r e s u l t s ( A r b o r e l i u s e t a l . , 1972; B e g i n e t a l . , 1976). D i s c r e p a n c i e s i n h e a r t r a t e may be accounted f o r by d i f f e r e n c e s i n water t e m p e r a t u r e , m e t h o d o l o g i c a l p r o c e d u r e s and r e f l e x mechanisms ( A r b o r e l i u s e t a l . , 1972; B e g i n e t a l . , 1976; F a r h i e t a l . , 1977). As r e p o r t e d e a r l i e r , a drop i n water temperature may lower h e a r t r a t e d u r i n g immersion w h i l e i n v a s i v e p h y s i o l o g i c a l t e c h n i q u e s may i n c r e a s e h e a r t r a t e under both an immersion and l a n d c o n d i t i o n ( A r b o r e l i u s e t a l . , 1972,; B e g i n e t a l . , 1976). The i n f l u e n c e of r e f l e x mechanisms on h e a r t r a t e has been d i s c u s s e d by L i n (1988). D u r i n g Immersion, t h e r e i s an i n c r e a s e i n c e n t r a l b l o o d volume and p r e s s u r e . An i n c r e a s e i n t h e s e parameters may induce a g e n e r a l t a c h y c a r d i a ( L i n , 1988). The induced t a c h y c a r d i a may be c o u n t e r e d by a b r a d y c a r d i a response e l i c i t e d by an i n c r e a s e i n s t r o k e volume ( L i n , 1988). Changes i n the magnitude of e i t h e r response c o u l d a l s o i n f l u e n c e h e a r t r a t e d u r i n g r e s t ( L i n , 1988). C. S t r o k e Volume A r i s e i n c a r d i a c output d u r i n g r e s t i n g immersion may be e x p l a i n e d t h r o u g h i n c r e a s e s i n s t r o k e volume ( A r b o r e l i u s e t a l . , 1972; L o l l g e n e t a l . , 1981). Recent l i t e r a t u r e has c o n c e n t r a t e d on the e x t e n t of the r i s e i n s t r o k e volume (S.V.) and how i t i s 22 a f f e c t e d by a dynamic e x e r c i s e c o n d i t i o n ( G r e e n l e a f , 1984; L i n , 1988). The g e n e r a l i n c r e a s e i n s.v. and r e d u c t i o n i n h e a r t r a t e d u r i n g immersion i s i n i t i a t e d by h y d r o s t a t i c l i m b compression ( E p s t e i n , 1976; G r e e n l e a f , 1984). H y d r o s t a t i c l i m b c o m p r e s s i o n d u r i n g immersion c o u n t e r a c t s the e f f e c t of g r a v i t y w i t h i n the columns ( a r t e r i e s and v e i n s ) of b l o o d . As the depth o£ immersion I n c r e a s e s , the e x t e n t of the h y d r o s t a t i c c o m p r e s s i o n r i s e s ( L o l l g e n e t a l . 1981). A r b o r e l i u s e t a l . (1972), c o n c l u d e d t h a t d u r i n g neck immersion the i n c r e a s e i n c e n t r a l b l o o d volume was a p p r o x i m a t e l y 0.7 1. Lange e t a l . (1974) e s t i m a t e d the r i s e i n h e a r t volume t o be a p p r o x i m a t e l y 180ml or 26% of the i n c r e a s e i n i n t r a t h o r a c i c b l o o d volume. A r i s e i n h e a r t volume s h o u l d I n c r e a s e end d i a s t o l i c volume and, t h e r e f o r e , cause an I n c r e a s e In s t r o k e volume (Echt e t a l . , 1974; P o l i n e r e t a l . , 1980). S t r o k e volume i s a f u n c t i o n of f o u r major d e t e r m i n a n t s . Those d e t e r m i n a n t s a r e : 1. P r e l o a d ; 2. A f t e r l o a d ; 3. Heart Rate; 4. I n o t r o p i c S t a t e . The measurement of t h e s e d e t e r m i n a t e s and how t h e y may a f f e c t s t r o k e volume d u r i n g immersion w i l l be d i s c u s s e d i n the f o l l o w i n g p a r a g r a p h s . 1. Preload Preload can be described as the tension in the ventricular wall at the end of diastole (West, 1 9 8 4 ) . The tension within the wall w i l l determine the rest i n g , fiber length (West, 1984). Preload is most commonly determined through ventricular end d i a s t o l i c volume, ventricular end d i a s t o l i c pressure and other hemodynamic parameters. Measurement of preload can be categorized into three areas. These are : 1. Indirect hemodynamic measurements; 2. Echocardlographic studies; and 3. Radiopharmaceutical studies. Hemodynamic measurements have been u t i l i z e d to make indirect inferences on changes in preload and stroke volume during immersion (Farhi et a l . , 1977; Lollgen et a l . , 1981; Risch et a l . , 1978a; Risch et a l . , 1 9 7 8 b ) . The most commonly measured hemodynamic parameters are central venous pressure, pulmonary artery pressure, pulmonary wedge pressure, e f f e c t i v e compliance, a t r i a l transmural pressure and right a t r i a l pressure (Arborelius et a l . , 1972; Lollgen et a l . , 1981; Lange et a l . , 1974). During immersion, there are increases in central venous pressure (12-17mm Hg) and central blood volume (Arborelius et a l . , 1972; Echt et a l . , 1974; Koubenec, 1978; Risch et a l . , 1978a). Investigators have also reported greater pulmonary artery pressure, pulmonary wedge pressure, and right a t r i a l pressure 24 ( A r b o r e l i u s e t a l . , 1972; Koubenec, 1978; L o l l g e n e t a l . , 1981). The measurement of hemodynamic parameters s u g g e s t s t h a t p r e l o a d (and p o t e n t i a l l y s t r o k e volume) i s enhanced d u r i n g immersion ( L o l l g e n e t a l . , 1981). S h e l d a h l e t a l . (1984), u s i n g e c h o c a r d i o g r a p h y measurements noted i n c r e a s e s i n end d i a s t o l i c d i m e n s i o n a t r e s t and a t two submaximal e x e r c i s e c o n d i t i o n s d u r i n g immersion. D u r i n g u p r i g h t r e s t , the average l e f t v e n t r i c l e d i m e n s i o n was 4.54 cm on l a n d v s . 4.92 cm d u r i n g neck immersion. At the h i g h e s t of the two e x e r c i s e c o n d i t i o n s , the u p r i g h t l e f t -v e n t r i c l e d i m e n s i o n on l a n d was 4.76 cm v s . 5.27 cm d u r i n g neck immersion ( S h e l d a h l e t a l . , 1984). The r i s e i n l e f t v e n t r i c u l a r d i m e n s i o n a l o n g w i t h i n c r e a s e s i n hemodynamic parameters s u p p o r t s the h y p o t h e s i s of augmented p r e l o a d and s t r o k e volume d u r i n g r e s t i n g immersion ( L o l l g e n e t a l . , 1981; E p s t e i n e t a l . , 1975). F u r t h e r s t u d i e s have been conducted u s i n g t e c h n e t i u m l a b e l l e d r e d b l o o d c e l l s t o m o n i t o r changes i n l e f t v e n t r i c u l a r f u n c t i o n d u r i n g v a r i e d p o s t u r a l p o s i t i o n s and e x e r c i s e l e v e l s . L e f t v e n t r i c u l a r end d i a s t o l i c p r e s s u r e (LVedp) and volume (LVedv) r i s e s above normal d u r i n g s u p i n e r e s t and e x e r c i s e compared t o e r e c t p o s t u r e (Crawford e t a l . , 1978; P o l i n e r e t a l . , 1980; Thadani e t a l . , 1978). R e s u l t s from P o l i n e r e t a l . (1980), s u ggest t h a t the d i f f e r e n c e between LVedv a t r e s t ( s u p i n e v s . u p r i g h t ) t o be a p p r o x i m a t e l y 22 ml (107 ml v s . 85 m l ) . P o l i n e r e t a l . (1980), a l s o r e p o r t e d t h a t LVedv r o s e p r o g r e s s i v e l y d u r i n g 25 p r o g r e s s i v e e x e r c i s e i n t e n s i t i e s , however, the d i f f e r e n c e between the s u p i n e and u p r i g h t e x e r c i s e remained r e l a t i v e l y c o n s t a n t (22 m l ) . L e f t v e n t r i c u l a r end s y s t o l i c volume ( s u p i n e ) remained c o n s t a n t a t 32 ml d u r i n g low and moderate w o r k l o a d s . L e f t v e n t r i c u l a r end s y s t o l i c volume ( u p r i g h t ) was lower d u r i n g low and moderate e x e r c i s e (Crawford e t a l . , 1979; P o l i n e r e t a l . , 1980). The u t i l i z a t i o n of r a d i o g r a p h i c t e c h n i q u e s a l l o w s d i r e c t measurement of S.V. and l e f t v e n t r i c u l a r e j e c t i o n f r a c t i o n ( L V e f ) . Under s p e c i f i c r e s t i n g and e x e r c i s e c o n d i t i o n s , S.V. i n the s u p i n e p o s i t i o n i s g r e a t e r r e l a t i v e t o S.V. In the u p r i g h t p o s i t i o n (Bevegard e t a l . , 1960; C r a w f o r d e t a l . 1979; Weiss et a l . 1979). T h i s i s i n agreement w i t h the measurement of LVedv and LVesv c i t e d above ( P o l i n e r e t a l . 1980). Thadanl et a l . (1978) and Crawford e t a l . (1979) c o n c l u d e d t h a t the i n c r e a s e i n measured s t r o k e volume a t r e s t and e x e r c i s e ( s u p i n e v s . u p r i g h t ) was due t o the r i s e i n LVedv. P o l i n e r e t a l . (1980), r e p o r t e d s m a l l e r changes i n LVef from r e s t t o h i g h e r e x e r c i s e i n t e n s i t i e s d u r i n g a s u p i n e p o s i t i o n . P o l i n e r e t a l . (1980), c o n c l u d e d t h a t l e f t v e n t r i c u l a r response t o e x e r c i s e , i r r e s p e c t i v e of the p o s i t i o n , i n c l u d e s a c o m b i n a t i o n of a F r a n k - S t a r l i n g mechanism and an i n c r e a s e i n c o n t r a c t i l e s t a t e , however, changes i n c o n t r a c t i l e s t a t e are of g r e a t e r r e l a t i v e Importance i n the u p r i g h t r a t h e r t h a n i n the s u p i n e p o s i t i o n . 26 2. Afterload Afterload can be described as the tension developed by the fi b r e s of the ventricular wall (West, 1984). Two measures of afterload are s y s t o l i c a o r t i c pressure and s y s t o l i c l e f t v entricular pressure (West, 1984). Under experimental conditions, i f preload is constant and a o r t i c pressure is gradually I n c r e a s e d , a steady decrease in stroke volume and peak ejection v e l o c i t y should occur (West, 1984). There is a lack of investigation evaluating s y s t o l i c a o r t i c p r e s s u r e and s y s t o l i c l e f t v e n t r i c u l a r p r e s s u r e d u r i n g immersion. However, some indire c t evidence may warrant attention. Sheldahl et a l . (1984), reported increases in end d i a s t o l i c and s y s t o l i c dimension during immersion under resting and exercise conditions. From these results Sheldahl et a l . (1984), calculated ventricular shortening. It was concluded that during immersion, ventricular shortening was lower at rest and during exercise and that changes may be accounted for by an increase in afterload or a decrease in myocardial c o n t r a c t i l i t y (Sheldahl et a l . , 1984). Investigations reporting decreases in the s y s t o l i c blood pressure to end s y s t o l i c dimension r a t i o , s y s t o l i c pressure, and systemic vascular resistance suggests that afterload i s not increased during immersion (Epstein et a l . , 1975; Greenleaf, 1984). Further investigations are needed. 27 3. Inotrophic State The I n o t r o p h i c s t a t e r e f e r s t o the c o n t r a c t i l i t y of the h e a r t (West, 1984). Under e x p e r i m e n t a l c o n d i t i o n s , a p o s i t i v e i n o t r o p h i c s t a t e w i l l induce a r i s e In s t r o k e volume and peak e j e c t i o n v e l o c i t y (West, 1984). The r e l a t i o n s h i p between neck immersion and the i n o t r o p h i c s t a t e remains u n c l e a r . More i n v e s t i g a t i o n s are needed. 4. Heart Rate A l t h o u g h c o n t r o v e r s i a l , i t may be s t a t e d t h a t d u r i n g immersion, e x e r c i s e and r e s t i n g h e a r t r a t e remains d e p r e s s e d ( D r e s s e n d o r f e r e t a l . , 1976; S h e l d a h l e t a l . , 1984) T h i s d e p r e s s i o n i n f l u e n c e s s t r o k e volume i n a two f o l d e d manner ( p a r t i c u l a r l y d u r i n g e x e r c i s e ) . At h i g h e x e r c i s e i n t e n s i t i e s a d e p r e s s e d h e a r t r a t e may enhance s t r o k e volume by a l l o w i n g a g r e a t e r v e n t r i c u l a r f i l l i n g t i m e . However, the h e a r t r a t e d e p r e s s i o n may a l s o i n h i b i t the i n c r e a s e In s t r o k e volume t h r o u g h a f o r c e f r e q u e n c y r e l a t i o n s h i p (West, 1984). Hemodynamic, e c h o c a r d i o g r a p h i c , and r a d i o p h a r m a c e u t i c a l s t u d i e s suggest t h a t the l a t t e r p l a y s a minor r o l e i n s t r o k e volume r e g u l a t i o n ( A r b o r e l i u s e t a l . , 1972; P o l i n e r e t a l . , 1980). The Respiratory System During Immersion E v a l u a t i n g the e f f e c t s of s t a t i c and dynamic immersion on the r e s p i r a t o r y system can be d i v i d e d i n t o two c a t e g o r i e s : 28 A. Lung volumes and the factors influencing those volumes; and B. Pulmonary gas exchange in respect to v e n t i l a t i o n , d i f f u s i o n and perfusion. A. Lung Volumes 1. V i t a l c a p a c i t y V i t a l Capacity (VC) decreases between 1.9% and 8% during neck immersion (Hong et a l . , 1969; Agonstoni et a l . , 1966; Dahlback et a l . , 1975; Dahlback et a l . , 1979a). The decrease in VC is due to increased central thoracic blood volume (Dahlback et a l . , 1978a; Dahlback et a l . , 1978b). Using radiographic techniques, Risch et a l . (1978a & 1978b) correlated the r i s e in lung blood volume with decreases in VC. 2. T o t a l Lung C a p a c i t y and R e s i d u a l Volume During thorax immersion (which e n t a i l s the Immersion o£ th£ chest and abdominal region without the upper and lower limbs), t o t a l lung volume (TLC) s i g n i f i c a n t l y decreases (Bondi et a l 1976; Dahlback et a l . , 1975; Dahlback et a l . , 1978a). The decrease in TLC correlates with a lower residual volume ( decrease in TLC = .31 L, decrease in RV = .25 L ) . Dahlback et a l . (1978a), concluded that thorax immersion inhibited i n s p i r a t i o n as much as i t enhanced expiration (Dahlback et a l . , 1978a and 1978b). Changes in TLC and RV during thorax immersion 29 a r e due t o h y d r o s t a t i c c h e s t c o m p r e s s i o n . D u r i n g neck immersion (immersion i n c l u d i n g the upper and lower l i m b s ) , TLC dropped .44 L (Dahlback e t a l . , 1978a and 1978b). The d e c r e a s e was not c o u n t e r e d by a c o r r e s p o n d i n g d e c r e a s e i n RV (RV r o s e .06 L ) . I n v e s t i g a t o r s c o n c l u d e d t h a t the d e c r e a s e i n TLC was due t o the space c o m p e t i t i o n between a l v e o l a r gas and r e d i s t r i b u t e d b l o o d (Dahlback e t a l . , 1978a; and 1978b). ' 3. Functional Residual Capacity Dahlback e t a l . (1978b), r e p o r t e d d e c r e a s e s i n f u n c t i o n a l r e s i d u a l c a p a c i t y (FRC) d u r i n g t h o r a x Immersion. The i n v e s t i g a t o r s were, however, unable t o demonstrate d e c r e a s e s i n FRC d u r i n g neck immersion. I n c r e a s e s i n t h o r a c i c b l o o d volume may e n l a r g e pulmonary c a p i l l a r i e s c o n t r i b u t i n g t o l u n g s t i f f e n i n g . Decreases i n l u n g c o m p l i a n c e and l u n g r e c o i l d u r i n g immersion c o n f i r m the h y p o t h e s i s of l u n g s t i f f e n i n g ( A g o n s t o n i e t a l . , 1966; B l o m q u i s t e t a l . , 1983; Hong e t a l . , 1969). 4. Lung Recoil Lung r e c o i l p r e s s u r e a t TLC d e c r e a s e s from -42 cm of H20 d u r i n g nonimmersion t o -25 cm of H20 d u r i n g neck immersion (Dahlback e t a l . , 1978a and 1978b). High l u n g r e c o i l p r e s s u r e s c o r r e l a t e p o s i t i v e l y w i t h h i g h i n s p i r a t o r y and t o t a l l u n g c a p a c i t i e s (West, 1984). 30 5. Lung Compliance Lung compliance expresses the rela t i o n s h i p between lung volume and lung pressure (West, 1984). During immersion, the pressure volume relationship w i l l change (Agonstoni et a l . , 1966; Hong et a l . , 1969). Lung compliance during immersion decreases from .39 cm of H20 (land) to .27 cm of H20 (Dahlback et a l . , 1978b). Lung compliance is reduced because of hydrostatic thoracic compression and blood r e d i s t r i b u t i o n (Dahlback et a l . , 1978b). 5. Trapped Air and Closing Lung Volume Under experimental conditions (c o n t r o l l i n g end expiratory and t i d a l volume), the volume of trapped a i r (Vtr) during immersion Increased 2.5 L (Dahlback et a l . , 1975). Dahlback et a l . (1975) concluded that decreases in Vtr were due to a r i s e in hydrostatic chest compression and intrathoracic blood volume (Dahlback et a l . 1975). The increase in Vtr could be the result of either premature airway closure or lung s t i f f e n i n g . A further investigation has demonstrated that premature airway closure does occur during Immersion (Bondi et a l . , 1976). B. Pulmonary Gas Exchange: V e n t i l a t i o n , Perfusion and Diffusion Pulmonary gas exchange is a coordinated rel a t i o n s h i p between lung v e n t i l a t i o n , lung perfusion, and pulmonary d i f f u s i o n . Risen et a l . (1978a & 1978b) documented increases in thoracic blood 31 volume d u r i n g immersion. R i s c h e t a l . (1978a & 1978b) c o n c l u d e d t h a t the change i n t h o r a c i c b l o o d volume r e s u l t e d i n an i n c r e a s e i n h e i g h t , w i d t h and a r e a of b l o o d p e r f u s i o n . S i m i l a r changes have been documented by o t h e r r e s e a r c h e r s ( P r e f a u t e t a l . , 1978). Changes i n b l o o d p e r f u s i o n l e d t o a g r e a t e r l u n g p e r f u s i o n homogeneity ( R i s c h e t a l . , 1978a; R i s c h e t a l . , 1978b; P r e f a u t e t a l . , 1978). R i s c h e t a l ( 1 9 7 8 b ) , h y p o t h e s i z e d t h a t i t was the opening of a p i c a l c h a n n e l s t h a t l e a d t o the p e r f u s i o n homogeneity d u r i n g Immersion. The opening of a p i c a l l u n g c h a n n e l s a l s o o c c u r s d u r i n g e x e r c i s e ( R i s c h e t a l . , 1978a and 1978b). R i s e s i n p e r f u s i o n homogeneity was accompanied by an I n c r e a s e i n r i g h t a t r i a l p r e s s u r e , pulmonary a r t e r i a l - p r e s s u r e , pulmonary wedge p r e s s u r e and "cardiac output ( R i s c h e t a l . , 1978a and 1978b). P r e f a u t et a l . , (1980) r e p o r t e d an I n v e r s i o n of b l o o d p e r f u s i o n i n some s u b j e c t s d u r i n g immersion. P r e f a u t e t a l . (1980) h y p o t h e s i z e d t h a t an i n v e r s i o n of b l o o d p e r f u s i o n may occur i f t h e r e was an i n c r e a s e i n pulmonary v a s c u l a r r e s i s t a n c e a t the base of the l u n g . I t was suggested t h a t an i n c r e a s e i n pulmonary v a s c u l a r r e s i s t a n c e was f e a s i b l e because of the I n t e r a c t i o n of t h r e e mechanisms. Those mechanisms were: 1. A d e c r e a s e i n l u n g volumes; 2. Hypoxic v a s o c o n s t r i c t i o n ; and 3. I n c r e a s e s In a l v e o l a r p r e s s u r e . Changes i n Pa02 and PaC02 occur d u r i n g immersion ( L o l l g e n e t a l . , 1976; Cohen et a l . , 1971). A drop i n the Pa02 (9mm Hg), an 32 i n c r e a s e i n (A-a)D02 d i f f e r e n c e (16mm Hg) and i n PaC02 (2 mm Hg) were r e p o r t e d d u r i n g r e s t i n g immersion (Cohen e t a l . , 1971; L o l l g e n e t a l . , 1976). These changes may occ u r because of a l t e r a t i o n s i n v e n t i l a t i o n and d i f f u s i o n . More s p e c i f i c a l l y , t h e s e changes were a t t r i b u t e d t o : 1. A de c r e a s e i n the pulmonary d i f f u s i o n c o n s t a n t . G uyatt e t a l . (1965) and Hyde e t a l . ( 1 9 7 1 ) , demonstrated d e c r e a s e s i n carbon monoxide d i f f u s i o n c a p a c i t y d u r i n g immersion; 2. A s m a l l e r d i f f u s i o n a r e a . L o l l g e n e t a l . (1976) h y p o t h e s i z e d t h a t d u r i n g immersion, d i f f u s i o n a r e a may dec r e a s e due t o a r i s e i n i n t r a t h o r a c i c b l o o d volume and h y d r o s t a t i c c o m p r e s s i o n of the c h e s t . Lower l u n g volumes d u r i n g Immersion s u b s t a n t i a t e t h i s argument (Dahlback e t a l . , 1 9 7 8 a ; Dahlback e t a l . , 1978b); and 3. Changes i n lu n g v e n t i l a t i o n . Cohen e t a l . (1971) s u g g e s t e d t h a t changes i n l u n g v e n t i l a t i o n d u r i n g r e s t i n g immersion were m i n i m a l and t h a t t h i s f a c t o r p l a y s a minor r o l e i n b l o o d gas changes. Task S p e c i f i c i t y and i t s R e l a t i o n s h i p t o C a r d i o r e s p i r a t o r y Parameters A. Oxygen consumption 1. Task S p e c i f i c i t y Oxygen consumption and i t s r e l a t i o n s h i p t o e x e r c i s e 33 s p e c i f i c i t y has been s t u d i e d i n t e n s e l y ( G e r g l e y e t a l . , 1984; M a t s u l e t a l . , 1978; McArdle e t a l . , 1972; Secher e t a l . , 1977; W i t h e r s e t a l . , 1981). E a r l y s t u d i e s compared the r e l a t i o n s h i p between t r e a d m i l l and b i c y c l e oxygen consumption (McArdle e t a l . , 1972; R o b e r t s e t a l . , 1972; W i t h e r s e t a l . , 1981). I t was co n c l u d e d t h a t : 1. The p h y s i o l o g i c a l r e sponses t o e x e r c i s e a r e s i g n i f i c a n t l y i n f l u e n c e d by the q u a n t i t y of a c t i v e m u s c u l a t u r e ( G e r g l e y e t a l . , 1984); 2. The t r a i n i n g s t a t e of a muscle group has a r e l a t i v e l y h i g h degree of s p e c i f i c i t y i n r e l a t i o n t o oxygen consumption ( G e r g l e y e t a l . , 1984). S u b j e c t s e l i c i t h i g h e r oxygen consumption r a t e s on work m o d a l i t i e s t h a t u t i l i z e d t r a i n e d m u s c u l a t u r e ( W i t h e r s e t a l . , 1981); 3. Muscle r e c r u i t m e n t p a t t e r n s . T r a i n e d s u b j e c t s w i l l r e g i s t e r h i g h e r V02max v a l u e s on work m o d a l i t i e s t h a t g e n e r a t e d f a m i l i a r r e c r u i t m e n t p a t t e r n s ( W i t h e r s e t a l . , 1981; McArdle e t a l . , 1971); and 4. D i f f e r e n c e s i n the type of muscle c o n t r a c t i o n s between the two a c t i v i t i e s may s i g n i f i c a n t l y a f f e c t o v e r a l l b l o o d f l o w and oxygen consumption (Davies e t a l . , 1972; E i k e n e t a l . , 1987; G e r g l e y e t a l . , 1984; M a t s u i e t a l . , 1978). Running i s a b a l l i s t i c movement w i t h s h o r t c o n t r a c t i o n phases i n v o l v i n g c o n c e n t r i c and e c c e n t r i c motions ( G e r g l e y e t a l . , 1984; M a t s u l e t a l . , 1978). 34 Cycling is a slower movement comprised on concentric motions (Gergley et a l . , 1984; Matsui et a l . , 1978). A number of investigators have suggested that at equivalent workloads concentric work require a larger recruitment of muscle fibres comparatively to eccentric work (Abbott et a l . , 1952; Davies et a l . , 1972). As the amount of recruited muscle fibres is increased, r i s e s in s y s t o l i c a r t e r i a l and tissue pressure w i l l occur r e s u l t i n g in lower blood flow to active musculature (Eiken et a l . , 1987). Therefore, maximal oxygen consumption during cycl i n g a c t i v i t y (concentric work) may be lower comparatively to treadmill running (concentric and eccentric work) because of a decrease in muscle blood flow e l i c i t e d by changes in the type of muscle contraction (Gergley et a l . , 1984; Matsui et a l . , 1978). The central and peripheral responses to combined exercise have been investigated (Secher et a l . , 1977; Secher et a l . , 1974; Toner et a l . , 1983). V02max (arm and leg exercise) can vary considerably, r e l a t i v e to normal leg exercise (Secher et a l . , 1977; Secher et a l . , 1974; Toner et a l . , 1983). Secher et a l . (1977) concluded that the fluctuations may be accounted for by the percentage of work performed by the upper body. Secher et a l . (1977), noticed that a decrease in V02max (compared to leg exercise alone) was most pronounced when the upper body performed more than 40% of the t o t a l exercise load (as measured by V02) . Secher et a l . (1977), Toner et a l . (1983), and Clausen et a l . (1976) have attributed the decrease In V02max to: 1. A decrease in blood flow to slow twitch (ST) musculature; 2. An increase in blood flow to fast twitch (FT) musculature; and 3. Changes in vascular resistance; A number of investigations have compared oxygen consumption during upper and lower body exercise (Dixon et a l . , 1971;Gergley et a l . , 1984; McArdle et a l . , 1978; McArdle et a l . , 1971; secher et a l . , 1974). It has been concluded that V02max was s i g n i f i c a n t l y lower during upper body exercise (Dixon et a l . , 1971; Gergley et a l . , 1984; McArdle et a l . , 1971). This reduction was due to the following: 1. A s i g n i f i c a n t decrease in the quantity of active musculature (Gergley et a l . , 1984); and 2. Inadequate blood flow to upper body musculature (Clausen et a l . , 1976; McArdle et a l . , 1971). The combination of inadequate blood flow and a smaller a t r l o - v e n t r i c u l a r (a-v) 02 difference leads to lower V02max and an increase in anaerobic metabolism (Clausen et a l . , 1976; Klausen et a l . , 1974). 36 2. Immersion Exercise There have been a number of studies investigating cardiovascular changes during immersion exercise ( A v e l l i n i et a l . , 1983; Dressendorfer et a l . , 1976; Denison et a l . , 1972; Sheldahl et a l . , 1984; Sheldahl et a l . , 1986). It may be concluded from these studies that: 1. V02max was not compromised by a water environment (Denison et a l . , 1972; Dressendorfer et a l . 1976; Moore et a l . , 1970; Sheldahl et a l . , 1983). Similar V02max values were obtained during immersion despite a drop in maximal heart rate (approximately 10 bpm) (Denison et a l . , 1972; Dressendorfer et a l . , 1976); 2. At a given submaximal V02, heart rate was s i g n i f i c a n t l y less during Immersion (Denison et a l . , 1972; Sheldahl et a l . , 1983). A lower heart rate is accompanied by a r i s e in stroke volume (Sheldahl et a l . , 1983) 3. The cephalad s h i f t in blood volume with water immersion does not a l t e r normal cardiovascular adaptation to exercise t r a i n i n g ( A v e l l i n i et a l . , 1983; Sheldahl et a l . , 1986); 4. Water temperature below the thermoneutral point (33 degrees celsius) may cause Increases in submaximal V02 (McArdle et a l . , 1976). McArdle et a l . (1976), recorded a 9.0% increase in submaximal V02 when water temperature was dropped from 33 to 27 degrees c e l s i u s . 37 B. V e n t i l a t i o n , Breathing Frequency and Ti d a l Volume 1. V e n t i l a t i o n Changes in v e n t i l a t i o n , frequency and t i d a l volume may be attributed to a number of factors. They Include: 1. Changes in the surrounding environment (Dressendorfer et a l . , 1976). Hydrostatic chest compression, thoracic blood volume and water temperature may contribute to a decrease in v e n t i l a t i o n . A number of investigators, however, have reported no s i g n i f i c a n t changes in v e n t i l a t i o n at submaximal and maximal immersion exercise (Denison et a l . , 1972; Moore et a l . , 1970; McArdle et a l . , 1976); 2. The t r a i n i n g state of a s p e c i f i c muscle (Gergley et a l . , 1984; Withers et a l . , 1981). Reductions in v e n t i l a t i o n are greatest when a task uses previously trained muscles. Withers et a l . , (1981), consistently found that trained runners and c y c l i s t s ventilated higher on the modalities that they were unfamiliar with; and 3. The involvement of upper body musculature in exercise. Dixon et a l . (1971) noted" s i g n i f i c a n t decreases in v e n t i l a t i o n during swimming. The decrease in v e n t i l a t i o n was attributed to arm and i n t e r c o s t a l a c t i v i t y . McArdle et a l . (1978) drew similar conclusions. A decrease in minute v e n t i l a t i o n has also 38 been r e p o r t e d d u r i n g maximal arm c r a n k i n g (Secher et a l . , 1977; Secher e t a l . , 1974; Toner e t a l . , 1984). 2. T i d a l Volume and Breathing Frequency Changes i n t i d a l volume and b r e a t h i n g f r e q u e n c y have been r e p o r t e d by a number of i n v e s t i g a t o r s (Denison e t a l . , 1972; Holmer e t a l . , 1 9 7 4 ; Hermansen e t a l . , 1969; McArdle e t a l . , 1970; McArdle e t a l . , 1971). These changes have been a t t r i b u t e d t o : 1. The s u r r o u n d i n g environment ( D r e s s e n d o r f e r e t a l . , 1976; Holmer e t a l . , 1974; McArdle e t a l . , 1971). D u r i n g immersion, t i d a l volume may decrease and b r e a t h i n g f r e q u e n c y i n c r e a s e because of h y d r o s t a t i c c h e s t compression and an i n c r e a s e In i n t r a t h o r a c i c b l o o d volume; and 2. The e x e r c i s e m o d a l i t y (McArdle e t a l . , 1971; Secher et a l . , 1977; Toner e t a l . , 1984). E x e r c i s e m o d a l i t i e s w hich r e q u i r e c o n s i d e r a b l e r e c r u i t m e n t of upper body m u s c u l a t u r e may i n h i b i t normal r e s p i r a t i o n mechanics (Secher e t a l . , 1977; Toner e t a l . , 1984). C. Heart Rate 1. Immersion Exercise Heart r a t e a t submaximal and maximal e x e r c i s e remains s i g n i f i c a n t l y lower d u r i n g immersion (Krasney e t a l . , 1984; Moore et a l . , 1970; S h e l d a h l e t a l . , 1983). The r e d u c t i o n i n submaximal h e a r t r a t e has been a t t r i b u t e d t o : 1. The r i s e i n i n t r a t h o r a c i c b l o o d volume which, as e x p l a i n e d e a r l i e r i n the c a r d i o v a s c u l a r s e c t i o n , causes an I n c r e a s e i n p r e l o a d and m y o c a r d i a l c o n t r a c t i l i t y . T h i s i n t u r n i n c r e a s e s s t r o k e volume ( A r b o r e l i u s e t a l . , 1972). 2. Task S p e c i f i c i t y Submaximal h e a r t r a t e i s s i g n i f i c a n t l y a f f e c t e d by a number of t a s k s p e c i f i c f a c t o r s ( C l a u s e n e t a l . , 1973; Homer e t a l . , 1974; McArdle e t a l . , 1976; McArdle e t a l . , 1977; Toner e t a l . , 1974 ) . They I n c l u d e : 1. The t r a i n i n g s t a t e of the muscle group ( C l a u s e n e t a l . , 1973; W i t h e r s e t a l . , 1981). C l a u s e n e t a l . (1973) r e p o r t e d t h a t submaximal h e a r t r a t e dropped s i g n i f i c a n t l y a f t e r t r a i n i n g a s p e c i f i c muscle group; and 2. The q u a n t i t y and type of m u s c u l a t u r e r e c r u i t e d ( G e r g l e y e t a l . , 1984). Submaximal h e a r t r a t e was s i g n i f i c a n t l y h i g h e r ( a t a g i v e n V02) d u r i n g arm e x e r c i s e as compared t o l e g e x e r c i s e ( C l a u s e n e t a l . 1973; G e r g l e y e t a l . , 1984). Maximal h e a r t r a t e seems t o be r o b u s t t o changes In e x e r c i s e m o d a l i t y and t a s k s p e c i f i c i t y ( C l a u s e n e t a l . , 1973; Toner e t a l . , 1984). 40 CHAPTER 4 RESULTS Twenty-two male middle d i s t a n c e r u n n e r s completed the two t e s t i n g p r o t o c o l s . Four s u b j e c t s d i d not meet the minimum c r i t e r i a of 60 m l * k g * - l m i n - l ( t r e a d m i l l ) and were s u b s e q u e n t l y removed from the s t u d y . Two a d d i t i o n a l s u b j e c t s were removed because of poor immersion r u n n i n g t e c h n i q u e . The mean age, h e i g h t and weight of the r e m a i n i n g 16 s u b j e c t s was 22.5 y r s + 4.2, 180.1 cms + 6.0, and 69.8 kgs + 5.5 r e s p e c t i v e l y . H e i g h t Weight Age (cm) (kg) ( y r s ) mean 180.1 69.8 22.5 S t . Dev. 6.0 5 . 5 4 . 2 T a b l e 1: D e s c r i p t i v e d a t a f o r 16 male m i d d l e d i s t a n c e r u n n e r s . 41 The c a r d i o r e s p i r a t o r y parameters measured a t v e n t i l a t o r y t h r e s h o l d a r e o u t l i n e d In Table 2. The m u l t i v a r i a t e P r e c o r d e d f o r a l l f a c t o r s w i t h i n the e x e r c i s e c o n d i t i o n was l e s s than 0.01. C o n s e q u e n t l y , t h i s was s i g n i f i c a n t a t the p r e s e t P l e v e l of l e s s t han .05. U n i v a r i a t e s i g n i f i c a n c e was demonstrated (P < .05) between e x e r c i s e c o n d i t i o n s (immersion v s . t r e a d m i l l ) f o r h e a r t r a t e and oxygen consumption. Heart r a t e s (HR) d u r i n g Immersion and l a n d c o n d i t i o n s were 165.9 and 177.5 bpm. Oxygen consumption (V02) was 51.8 and 56.8 m l * k g * - l m i n - l f o r the immersion and l a n d p r o t o c o l s . Mean St.Dev. P HRvt (immersion) 165.9 bpm 10.1 < 0.01 HRvt ( t r e a d m i l l ) 177.5 bpm 7.4 VEvt (immersion) 83.9 l * m l n - l 8.5 < 0.07 VEvt ( t r e a d m i l l ) 88.7 l * m i n - l 9.4 VE/V02vt (Immersion) 1.61 0.18 < 0.07 VE/V02vt ( t r e a d m i l l ) 1.55 0.15 V02vt (immersion) 51.8 m l * k g * - l m i n - l 4.5 < 0.01 V02vt ( t r e a d m i l l ) 56.8 m l * k g * - l m i n - l 3.6 Table 2: C a r d i o r e s p i r a t o r y parameters c o l l e c t e d a t v e n t i l a t o r y t h r e s h o l d ( v t ) d u r i n g immersion r u n n i n g and t r e a d m i l l r u n n i n g . V a l u e s a r e n o r m a l i z e d a t STPD. N=16 42 The cardiorespiratory parameters measured at maximal e f f o r t are outlined in Table 3. The multivariate P recorded for a l l factors within the exercise condition was less than .01. Correspondingly, the multivariate P was s i g n i f i c a n t at a preset l e v e l of .05. Univariate significance (P < .05) was demonstrated for heart rate, oxygen consumption and VE/V02. Heart rates (HR) during immersion and land conditions were 182.4 and 194.1 bpm respectively. Oxygen consumption (V02) was 62.6 and 66.3 ml*kg*-lmin-1 for the immersion and land protocols. Mean St.Dev. P HRmax(immersion) 182.4 bpm 8. ,2 < 0. .01 HRmax(treadmill) 194.1 bpm 11. ,0 VEmax(immersion) 124.1 l*min- -1 11. .3 < 0. .42 VEmax(treadmill) 122.0 l*min- -1 8. .8 VE/V02max(immersion) 2.01 0. ,19 < 0. .01 VE/V02max(treadmill) 1.88 0. .15 V02max(Immersion) 62.6 ml*kg*--lmln-1 3, .9 < 0, .01 V02max(treadmill) 66.3 ml*kg*--lmin-1 4. .0 Table 3: cardiorespiratory parameters col l e c t e d at maximal effort(max) during immersion running and treadmill running. Values were normalized to STPD. N=16 43 V e n t i l a t i o n and f r e q u e n c y of b r e a t h i n g measurements were measured f o r f o u r s u b j e c t s under both an immersion and l a n d c o n d i t i o n s . The c a r d i o r e s p i r a t o r y parameters measured f o r the f o u r s u b j e c t s were a l s o used as p a r t of the d a t a i n T a b l e s Two and Three. M e t h o d o l o g i c a l problems ( i . e . the computer I n t e g r a t i o n w i t h the d a t a a c q u i s i t i o n system) p r e v e n t e d the c o l l e c t i o n of f r e q u e n c y measurements f o r the r e m a i n i n g 12 s u b j e c t s . T i d a l volume was c a l c u l a t e d , d i v i d i n g v e n t i l a t i o n by b r e a t h i n g f r e q u e n c y . Table 4 c o n t a i n s t h e s e parameters as measured a t v e n t i l a t o r y t h r e s h o l d . T able 5 c o n t a i n s s i m i l a r parameters measured a t maximal e f f o r t . The mean v e n t i l a t i o n a t v e n t i l a t o r y t h r e s h o l d d u r i n g immersion and l a n d c o n d i t i o n s was 81.8 and 84.5 l * m i n - l r e s p e c t i v e l y . The b r e a t h i n g f r e q u e n c y a t v e n t i l a t o r y t h r e s h o l d was 37.9 and 37.1 b r * m i n - l d u r i n g immersion and l a n d r u n n i n g r e s p e c t i v e l y . The c a l c u l a t e d t i d a l volumes were 2.17 l i t r e s and 2.28 l i t r e s were f o r Immersion and l a n d r u n n i n g a t v e n t i l a t o r y t h r e s h o l d . V e n t i l a t i o n ( v t ) F r e q u e n c y ( v t ) T i d a l Volume(vt) IR T r e a d m i l l IR T r e a d m i l l IR T r e a d m i l l ( l * m i n - l ) ( b r * m i n - l ) (1) Mean 81.8 87.4 37.9 37.1 2.17 2.28 S.D. 7.4 11.2 5.3 5.6 0.17 0.23 Tab l e 4: Mean v a l u e s f o r f o u r s u b j e c t s a t v e n t i l a t i o n t h r e s h o l d ( v t ) d u r i n g immersion r u n n i n g ( I R ) and t r e a d m i l l r u n n i n g . V a l u e s were n o r m a l i z e d t o STPD. 44 The mean v e n t i l a t i o n a t maximal e f f o r t d u r i n g immersion and l a n d c o n d i t i o n s were 126.6 and 123.5 l * m l n - l r e s p e c t i v e l y . The-f r e q u e n c y of b r e a t h i n g a t maximal e f f o r t was 54.6 and 48.7 b r * m l n - l d u r i n g immersion and l a n d r u n n i n g r e s p e c t i v e l y . The c a l c u l a t e d t i d a l volumes f o r immersion and t r e a d m i l l r u n n i n g a t maximal e f f o r t were 2.32 l i t r e s and 2.56 l i t r e s . V e n t i l a t i o n ( m a x ) IR T r e a d m i l l Frequency(max) IR T r e a d m i l l ( b r * m l n - l ) 54.6 48.7 T i d a l Volume(max) IR T r e a d m i l l Mean ( l * m i n - l ) 126.6 123.5 (1) 2.32 2.56 St.Dev. 6.0 5.0 3.1 1.3 0.08 0.15 Tab l e 5: Mean v a l u e s f o r f o u r s u b j e c t s a t maximal e f f o r t ( m a x ) d u r i n g immersion r u n n i n g and t r e a d m i l l r u n n i n g . V a l u e s were n o r m a l i z e d t o STPD. 45 An e x p e r i m e n t a l t e c h n i q u e u t i l i z i n g Tc-99 2-methyloxy i s o b u t y l i s o n i t r i l e was i n c o r p o r a t e d t o a t t empt t o monitor changes i n b l o o d f l o w d i s t r i b u t i o n d u r i n g immersion and t r e a d m i l l r u n n i n g a t v e n t i l a t i o n t h r e s h o l d . Appendices E, F, G, H, and I c o n t a i n d a t a r e f e r r i n g t o the r e g i o n a l uptake of i s o n i t r i l e . Because of problems w i t h the m e t h o d o l o g i c a l p r o c e d u r e s d a t a c o u l d o n l y be c o l l e c t e d f o r two s u b j e c t s . In s u b j e c t one t h e r e was a lower uptake of I s o n i t r i l e i n the a n t e r i o r t h i g h , p o s t e r i o r t h i g h , a n t e r i o r c a l f and p o s t e r i o r c a l f d u r i n g immersion r u n n i n g a t v e n t i l a t o r y t h r e s h o l d . I n s u b j e c t two, an i n c r e a s e d uptake of i s o n i t r i l e was measured i n the a n t e r i o r and p o s t e r i o r t h i g h d u r i n g Immersion r u n n i n g . A lower uptake of i s o n i t r i l e was measured i n the p o s t e r i o r g l u t e a l r e g i o n , a n t e r i o r c a l f and p o s t e r i o r c a l f . I t can be p o s t u l a t e d from the d a t a , t h a t uptake (and p o t e n t i a l l y b l o o d f l o w ) changed from r e g i o n t o r e g i o n depending on the e x e r c i s e c o n d i t i o n . Because t h i s was an e x p e r i m e n t a l p r o c e d u r e w i t h a s m a l l number of s u b j e c t s , d i r e c t i n f e r e n c e s from the I s o n i t r i l e d a t a t o e x p l a i n changes i n c a r d i o r e s p i r a t o r y parameters w i l l not be p o s s i b l e . 46 H y p o t h e s i s V e r i f i c a t i o n H y p o t h e s i s A c c e p t or R e j e c t 1. V02maxW = V02maxT Reject 2. V02vtW = V02vtT Reject 3. HRmaxW < HRmaxT Accept 4. HRvtW < HRvtT Accept 5. VEmaxw < VEmaxT Reject 6. VEvtW < VEvtT Reject 7. VE/V02maxW < VE/V02maxT Reject 8. VE/V02vtW < VE/V02vtT Reject 47 DISCUSSION A. Oxygen Consumption: V02max and V02vt were s i g n i f i c a n t l y lower during immersion running comparatively to treadmill running. This study appears to be the f i r s t to attempt to measure oxygen consumption during immersion running and, therefore, comparative data from other Investigations is not ava i l a b l e . It was i n i t i a l l y hypothesized that oxygen consumption at maximal e f f o r t and at v e n t i l a t o r y threshold would be equivalent under an immersion and treadmill running condition. The results of t h i s study are contrary to the i n i t i a l hypothesis. The lower oxygen consumption values recorded during IR may be explained by the influence of a water environment and/or changes in task s p e c i f i c i t y . Because the i n i t i a l purpose of th i s study was to record basic physiological data comparing the two exercise conditions, the s c i e n t i f i c measurement of water environmental and task s p e c i f i c factors was not pursued. The V02 values measured in this study did, however, allow researchers to develop a theoret i c a l model whereby water environmental and task s p e c i f i c factors may be discussed in rela t i o n s h i p to oxygen consumption. The section to follow w i l l express t h i s t h e o r e t i c a l model. At the conclusion of the model, the ef f e c t s of water temperature on oxygen consumption w i l l be discussed. 48 1. The Water Environment I t c o u l d be t h e o r e t i c a l l y h y p o t h e s i z e d t h a t the s i g n i f i c a n t l y lower oxygen consumption v a l u e s r e c o r d e d d u r i n g immersion r u n n i n g may be t h e r e s u l t of a water environment i m p a i r i n g the normal r e l a t i o n s h i p between a l v e o l a r v e n t i l a t i o n and p e r f u s i o n . Such a h y p o t h e s i s can be based on r e s e a r c h s u g g e s t i n g a l t e r e d r e s p i r a t o r y and p e r f u s i o n parameters a t r e s t (Cohen e t a l . , 1971; R i s c h e t a l . , 1978a + 1978b). I n response t o t h i s h y p o t h e s i s , however, i n v e s t i g a t i o n s s t u d y i n g the s p e c i f i c r e l a t i o n s h i p between oxygen consumption and a water environment d u r i n g c y c l i n g have c o n c l u d e d t h a t oxygen consumption was not s i g n i f i c a n t l y a f f e c t e d even though t h e r e were changes i n s t a t i c r e s p i r a t o r y parameters ( D r e s s e n d o r f e r e t a l . , 1976; Denison e t a l . , 1972; S h e l d a h l e t a l . , 1984). Because the immersion c o n d i t i o n i n t h i s s t u d y was i d e n t i c a l t o those r e p o r t e d i n the c y c l i n g s t u d i e s , i t seems u n l i k e l y t h a t the t h e o r e t i c a l model proposed i n i t i a l l y i s r e s p o n s i b l e f o r the r e d u c t i o n i n oxygen consumption d u r i n g immersion r u n n i n g . 2. Task S p e c i f i c i t y H y p o t h e t i c a l l y , i f the r e d u c t i o n i n oxygen consumption can not be a t t r i b u t e d t o the water environment, I t s h o u l d be a t t r i b u t e d t o changes i n t a s k s p e c i f i c i t y . Task s p e c i f i c i t y i s a f u n c t i o n of f i v e f a c t o r s . Those f a c t o r s a r e : a. T o t a l muscle mass r e c r u i t m e n t ( G e r g l e y e t a l . , 1984); 49 b. Type of muscle mass recruited (Secher et a l . , 1974); c. The f a m i l i a r i t y with recruitment pattern (Secher et a l . , 1974); d. The type of muscular contractions (Gergley et a l . , 1984); and d. The state of the muscular adaptation (Withers et a l . , 1981). Theoretically, any one or a combination of these factors may have contributed in lowering oxygen consumption during immersion running. a) Muscle Mass R e c r u i t m e n t Maximal oxygen consumption is a function of muscle mass (Astrand, 1977; Gergley et a l . 1984.; McArdle et a l . , 1971). As the amount of recruited muscle mass i s elevated, an increase in V02max w i l l usually occur (Astrand, 1977; McArdle et a l . , 1971). Correspondingly, any decrease in oxygen consumption may be the re s u l t of a smaller recruited muscle mass (Astrand, 1977; McArdle et a l . , 1971). It may be hypothesized that the reduction in oxygen consumption during immersion running may be due to a decrease in the recruited muscle mass. It was hoped that the I s o n i t r i l e data collected In th i s study would help to measure the amount of recruited muscle mass. Unfortunately, because of the small number of subjects and the c o n f l i c t i n g r e s u l t s , i t is not 50 possible to make accurate inferences in r e l a t i o n to the quantity of recruited muscle mass. b) Muscle F i b r e Type Muscle f i b r e type can a f f e c t V02 at submaximal and maximal exercise (Dixon et a l . , 1971; McArdle et a l . , 1971; Secher et a l . , 1974). This was i l l u s t r a t e d by Secher et a l . (1977), who u t i l i z e d an exercise protocol that varied the contribution of upper and lower body musculature to overall V02max. Secher et a l . (1977), concluded that V02max was s i g n i f i c a n t l y lower when an exercise protocol required 40% of the t o t a l power output to be generated by the upper body. It was suggested that the lower V02max was due to blood shunting from slow to fast twitch fibres (Secher et a l . , 1977). It may be theorized from the information cited in the previous paragraph, that a decrease in V02max during immersion running may be due to the shunting of blood from the 02 e f f i c i e n t lower extremities to the 02 i n e f f i c i e n t upper extremities. It was hoped that the data from subjects injected with i s o n i t r i l e would c l a r i f y t h i s factor in r e l a t i o n to oxygen consumption. c) The F a m i l i a r i t y W i th Motor R e c r u i t m e n t P a t t e r n Exercise recruitment patterns may s i g n i f i c a n t l y a f f e c t oxygen consumption at submaximal and maximal i n t e n s i t i e s (Gergley et a l . , 1984; Dixon et a l . , 1971; A v e l l i n i et a l . , 51 1983). McArdle e t a l . (1978) r e p o r t e d t h a t V02max i n t r a i n e d swimmers was comparable between a t r e a d m i l l run and a t e t h e r e d swim. I t was suggested t h a t a l t h o u g h l e s s muscle mass was r e c r u i t e d d u r i n g swimming (which s h o u l d promote a d e c r e a s e i n V02max as p r e v i o u s l y c i t e d ) , t h a t l o c a l muscular a d a p t a t i o n and the f a m i l i a r i t y w i t h motor r e c r u i t m e n t p a t t e r n s (of the swimmers) may c o u n t e r a c t any d e c r e a s e r e s u l t i n g i n a n o n - s i g n i f i c a n t change. I t may be t h e o r i z e d from the c i t e d l i t e r a t u r e , t h a t a d e c r e a s e i n V02max and V02vt d u r i n g immersion r u n n i n g may be due t o u n f a m i l i a r motor r e c r u i t m e n t p a t t e r n s . A l t h o u g h the s u b j e c t s were a c q u a i n t e d w i t h immersion r u n n i n g In t h i s s t u d y , I t may be h y p o t h e s i z e d t h a t t h e i r degree of f a m i l i a r i t y was lower c o m p a r a t i v e l y t o t r e a d m i l l r u n n i n g . d) The Type of Muscular Contraction As s t a t e d i n the l i t e r a t u r e r e v i e w , a c t i v i t i e s such as c y c l i n g may e l i c i t a lower oxygen consumption ( c o m p a r a t i v e l y t o t r e a d m i l l r u n n i n g ) a t maximal e f f o r t because of a r t e r i a l o c c l u s i o n ( G e r g l e y e t a l . , 1984; M a t s u i e t a l . , 1978). M a t s u l e t a l . ( 1978), suggested t h a t a r t e r i a l o c c l u s i o n was more l i k e l y t o occur d u r i n g c y c l i n g ( c o m p a r a t i v e l y t o t r e a d m i l l r u n n i n g ) because I t was p r e d o m i n a t e l y c o n c e n t r i c i n n a t u r e . I t may be suggested t h a t immersion r u n n i n g i s s i m i l a r t o c y c l i n g i n t h a t i t i s p r e d o m i n a t e l y c o n c e n t r i c . C o r r e s p o n d i n g l y , i t may be 52 h y p o t h e s i z e d t h a t a decrease In oxygen consumption a t maximal e f f o r t and a t v e n t i l a t o r y t h r e s h o l d d u r i n g immersion r u n n i n g may be due t o b l o o d f l o w r e s t r i c t i o n e l i c i t e d by s t r o n g c o n c e n t r i c c o n t r a c t i o n s . C o n c e n t r i c c o n t r a c t i o n s a r e more l i k e l y t o r e s t r i c t b l o o d f l o w because a g r e a t e r r e c r u i t m e n t of muscle f i b r e s ( i . e . f o r c e g e n e r a t i o n ) a r e r e q u i r e d f o r a g i v e n work out p u t c o m p a r a t i v e l y t o e c c e n t r i c c o n t r a c t i o n s (Abbott e t a l . , 1952; E i k e n e t a l . , 1987) . e) The s t a t e of M u s c u l a r A d a p t a t i o n T r a i n e d m u s c u l a t u r e may e l i c i t h i g h e r oxygen consumption v a l u e s t h a n u n t r a i n e d m u s c u l a t u r e ( K l a u s e n e t a l . , 1974; W i t h e r s e t a l . , 1981; D a v i s e t a l . , 1984). W i t h e r s e t a l . (1981), demonstrated a p o s i t i v e r e l a t i o n s h i p between oxygen consumption and muscular a d a p t a t i o n . They c o n c l u d e d t h a t c y c l i s t s and ru n n e r s e l i c i t e d a g r e a t e r oxygen consumption v a l u e on e x e r c i s e m o d a l i t i e s which u t i l i z e d t r a i n e d m u s c u l a t u r e ( W i t h e r s e t a l . , 1981). I t may be t h e o r i z e d from the c i t e d l i t e r a t u r e t h a t a de c r e a s e i n V02max and V02vt d u r i n g immersion r u n n i n g may be due t o d i f f e r e n c e s i n muscular a d a p t a t i o n ( i . e . lower a d a p t a t i o n w i t h i n immersion r u n n i n g m u s c u l a t u r e ) . 3. Water Temperature A drop i n water temperature below the t h e r m o n e u t r a l p o i n t can I n c r e a s e oxygen consumption a t a g i v e n e x e r c i s e i n t e n s i t y . McArdle et a l . (1976), observed a 9.0% Increase in submaximal V02 when water temperature was dropped from 33 degree to 27 degrees c e l s i u s . The average water temperature during t h i s study was between 29 and 30 degrees. This is below the thermoneutral point and t h e o r e t i c a l l y may resu l t in a s l i g h t elevation of oxygen consumption at maximal e f f o r t and at v e n t i l a t o r y threshold. If such a mechanism did occur during t h i s study, i t may be hypothesized that the effects of the water temperature were minimal in comparison to the changes in task s p e c i f i c i t y B. V e n t i l a t i o n , Breathing Frequency, T i d a l Volume, and VE/V02. Ven t i l a t i o n Minute v e n t i l a t i o n at maximal e f f o r t and at the ve n t i l a t o r y threshold did not s i g n i f i c a n t l y change between the two exercise conditions. As stated e a r l i e r , t h i s study seems to be the f i r s t to attempt to measure cardiorespiratory parameters during immersion running and, therefore, comparative data i s unavailable. The non-significant changes in VEmax and VEvt during immersion running suggests that neither the water environment nor changes in task s p e c i f i c i t y s i g n i f i c a n t l y affected minute v e n t i l a t i o n . The results reported in thi s study are contrary to the i n i t i a l hypothesis. 54 1. Water Environment It was i n i t i a l l y hypothesized that minute v e n t i l a t i o n would be lower during immersion running. This hypothesis was based p a r t i a l l y upon the assumption that the water environment would increase intrathoracic blood volume and hydrostatic chest compression, r e s u l t i n g in r e s t r i c t e d respiratory mechanics. A number of investigations have reported inhibited respiratory mechanics during resting immersion (Dahlback et a l . , 1975; 1978a and 1978b). Contrary to resting immersion studies, exercise studies have concluded that although resting respiratory mechanics were affected by water Immersion, minute v e n t i l a t i o n did not s i g n i f i c a n t l y change. (Dressendorfer et a l . , 1976; Denison et a l . , 1972; Sheldahl et a l . , 1976). Therefore, i t maybe theorized (after the fact) that the non-significant change in minute v e n t i l a t i o n during immersion running (at maximal e f f o r t and at v e n t i l a t o r y threshold) is in agreement with exercise Immersion studies (Dressendorfer et a l . , 1976; Denison et a l . , 1972). 2. Task S p e c i f i c i t y It was i n i t i a l l y hypothesized that task s p e c i f i c factors ( i . e . u t i l i z a t i o n of upper body musculature) during Immersion running would contribute to a lower minute v e n t i l a t i o n . This hypothesis is contrary to the reported results in t h i s study. Minute v e n t i l a t i o n is a function of two task s p e c i f i c factors. Those factors are: a. The involvement of large quantities of upper body musculature; and b. The t r a i n i n g state of recruited musculature. a) The Involvement of Large Quantities of Upper Body Musculature The involvement of large quantities of upper body musculature during exercise may s i g n i f i c a n t l y lower submaximal and maximal v e n t i l a t i o n . These decreases are most noticeable in a c t i v i t i e s including swimming and arm cranking (Dixon et a l . , 1971; Toner et a l . , 1984; Secher et a l . , 1977). Toner et a l . (1984) suggested lower v e n t i l a t i o n during exercise was due to the i n h i b i t i o n of normal respiratory mechanics. It may be theorized from the c i t e d l i t e r a t u r e that the non-significant change in minute v e n t i l a t i o n during treadmill and Immersion running r e f l e c t s the minor role of upper body muscle recruitment (immersion running) on th i s parameter. b) The Training State of Recruited Musculature Investigators have concluded that s i g n i f i c a n t changes in minute v e n t i l a t i o n may occur on exercise modalities that u t i l i z e musculature with varying degrees of peripheral adaptation. This was i l l u s t r a t e d by Withers et a l . (1981) who consistently found 56 that trained runners and c y c l i s t s ventilated higher on modalities not s p e c i f i c to their muscular adaptation. It was theorized e a r l i e r in the discussion (in r e l a t i o n to oxygen consumption), that the l e v e l of adaptation within recruited immersion running musculature was lower comparatively to treadmill musculature. Taking into consideration t h i s statement, It may be hypothesized that discrepancies in muscular adaptation could promote a r i s e in minute v e n t i l a t i o n during immersion running. These Increases are contrary to the recorded results of t h i s study and, therefore, i t may be hypo.thetically concluded within this section that ei t h e r : 1. The water environment, the recruitment of upper body musculature ( s p e c i f i c to immersion running) and the t r a i n i n g state of recruited musculature had no e f f e c t on minute v e n t i l a t i o n ; or 2. The potential decrease in minute v e n t i l a t i o n attributed to the water environment and to upper body muscle recruitment are counteracted by the potential increases in minute v e n t i l a t i o n due to the t r a i n i n g state of recruited musculature. T i d a l Volume and B r e a t h i n g Frequency V e n t i l a t i o n is a function of t i d a l volume and breathing frequency. There was a trend towards a smaller t i d a l volume and higher breathing frequency at V02vt and V02max during IR. This is in agreement with the i n i t i a l hypothesis that stated that 57 changes In t i d a l volume and breathing frequency would be due to a water environment and to task s p e c i f i c factors. The section to follow w i l l develop a t h e o r e t i c a l model to explain the lower t i d a l volumes and higher breathing frequencies reported during immersion running. 1. The Water Environment It may be suggested that the lower t i d a l volumes and higher breathing frequencies during immersion running were due to water immersion. It could be hypothesized that the Increase in intrathoracic blood volume and hydrostatic chest compression may Increase a subject's e f f o r t to breathe at normal lung volumes (Dahlback et a l . , 1978a and 1978b). This hypothesis is supported by Dressendorfer et a l . (1976), who reported greater breathing frequencies and lower t i d a l volumes during submaximal and maximal immersion c y c l i n g . 2. Task S p e c i f i c i t y Exercise a c t i v i t i e s which involve a large proportion of upper body musculature may l i m i t t i d a l volume (McArdle et a l . , 1971; Toner et a l . , 1984; Secher et a l . , 1977). Toner et a l . (1984), concluded that arm cranking at submaximal workloads reduced t i d a l volume because upper body recruitment interfered with normal respiratory mechanics. It may be hypothesized that a higher breathing frequency and a lower t i d a l volume during 58 immersion running may be p a r t i a l l y due to an increased u t i l i z a t i o n of upper body musculature. When considering t h i s hypothetical model, i t should be noted that minute v e n t i l a t i o n l i k e t i d a l volume can be altered by u t i l i z a t i o n of upper body musculature. However, as reported e a r l i e r , the non-significant change in minute v e n t i l a t i o n may suggest that the recruitment of upper body musculature may be a minor factor in the determination of v e n t i l a t i o n l e v e l s . Therefore, a similar r e l a t i o n s h i p may exist for t i d a l volume regulation. VE/V02 A s i g n i f i c a n t increase in the VE/V02 r a t i o was reported at maximal e f f o r t during Immersion running. A small increase in the VE/V02 r a t i o was reported at v e n t i l a t i o n threshold, however, th i s increase was non-significant. The increase in VE/V02 at maximal e f f o r t was primarily the r e s u l t of a lower V02 at maximal e f f o r t . This seems to be the f i r s t exercise immersion study reporting the VE/V02 r a t i o . C. Heart Rate A s i g n i f i c a n t l y lower heart rate at v e n t i l a t i o n threshold and at maximal e f f o r t occurred during immersion running. This is in agreement with the i n i t i a l hypothesis stating that the water environment would increases intrathoracic blood volume. The discussion to follow w i l l be used to develop a t h e o r e t i c a l model 59 around which a lower immersion heart rate can be f u l l y explained. At the conclusion of t h i s section, the effects of water temperature on heart rate w i l l be considered. 1. The Water Environment c A number of investigators have reported lower submaximal and maximal heart rates during exercise immersion (Krasney et a l . , 1984; Dressendorfer et a l . , 1976; Sheldahl et a l . , 1983). Krasney et a l . (1984) attributed the changes to a greater intrathoracic blood volume, which may in turn enhance preload and stroke volume. It may be theorized that the reduction in heart rate during immersion running at maximal e f f o r t and at ventilatory threshold is due to a greater intrathoracic blood volume. 2. Task S p e c i f i c i t y Theoretically, two task s p e c i f i c factors can a f f e c t submaximal heart rate. They Included: a. The t r a i n i n g state of the recruited musculature; and b. The quantity and type of musculature recruited. a) The Training State of the Recruited Musculature Heart rate at submaximal i n t e n s i t i e s are s i g n i f i c a n t l y lower when exercise modalities u t i l i z e trained musculature (Clausen et a l . , 1973; Withers et a l . , 1981). This is best I l l u s t r a t e d by Withers et a l . (1981), who concluded that heart rate at the 60 v e n t i l a t o r y t h r e s h o l d was lower on m o d a l i t i e s which u t i l i z e d p r e v i o u s l y t r a i n e d m u s c u l a t u r e . T h e o r e t i c a l l y , i f such a model d i d e x i s t d u r i n g Immersion r u n n i n g , one may ex p e c t a s l i g h t I n c r e a s e In submaximal h e a r t r a t e . T h i s model i s based on the assumption t h a t the t r a i n i n g s t a t e of r e c r u i t e d immersion m u s c u l a t u r e i s lower c o m p a r a t i v e l y t o t r e a d m i l l m u s c u l a t u r e . Such a mechanism would be c o n t r a r y t o r e s u l t s o b t a i n e d i n t h i s s t u d y . b) The Q u a n t i t y and Type of M u s c u l a t u r e R e c r u i t e d The u t i l i z a t i o n of l a r g e q u a n t i t i e s of upper body m u s c u l a t u r e a t submaximal workloads ( i . e . swimming and arm ergometer) can e l i c i t a h i g h e r h e a r t r a t e t h a n lower body m u s c u l a t u r e ( C l a u s e n e t a l . , 1973; McArdle e t a l . , 1971). Secher et a l . (1977), c o n c l u d e d t h a t i n u n t r a i n e d males, i n c r e a s e s i n submaximal h e a r t were s i g n i f i c a n t when 40% or more of the t o t a l power o u t p u t was g e n e r a t e d by the upper body ( c o m p a r a t i v e l y t o 100% l e g e x e r c i s e ) . I t may be h y p o t h e s i z e d from the c i t e d l i t e r a t u r e t h a t t h i s f a c t o r may i n c r e a s e submaximal h e a r t r a t e (at v e n t i l a t o r y t h r e s h o l d ) d u r i n g immersion r u n n i n g . T h i s h y p o t h e s i s i s based upon the assumption t h a t the q u a n t i t y of upper body m u s c u l a t u r e r e c r u i t e d d u r i n g Immersion r u n n i n g Is l a r g e enough t o e l i c i t the d e s c r i b e d r e s p o n s e . Such a model i s c o n t r a r y t o the r e s u l t s r e c o r d e d i n t h i s s t u d y . 61 I t s h o u l d be noted t h a t maximal h e a r t r a t e i s r o b u s t t o t a s k s p e c i f i c f a c t o r s ( C l a u s e n e t a l . , 1973; Toner e t a l . , 1984). I t may be s u g g e s t e d , t h e r e f o r e , t h a t any d e c r e a s e i n maximal h e a r t r a t e d u r i n g immersion r u n n i n g Is the r e s u l t of an i n c r e a s e i n i n t r a t h o r a c i c b l o o d volume. 3 . Water Temperature Water te m p e r a t u r e below the t h e r m o n e u t r a l p o i n t may cause r e d u c t i o n s i n h e a r t r a t e d u r i n g immersion e x e r c i s e (McArdle e t a l . , 1976). McArdle e t a l . , (1976), r e p o r t e d t h a t a drop i n water temperature from 33 degrees t o 27 degrees c e l s i u s was r e s p o n s i b l e f o r . a s i g n i f i c a n t r e d u c t i o n i n submaximal e x e r c i s e h e a r t r a t e . The average water temperature d u r i n g t h i s s t u d y was between 29 and 30 degrees c e l s i u s . I t may be t h e o r e t i c a l l y h y p o t h e s i z e d t h a t water temperature d u r i n g t h i s s t u d y may have c o n t r i b u t e d s l i g h t l y t o the r e d u c t i o n i n h e a r t r a t e a t v e n t i l a t o r y t h r e s h o l d . D. I s o n i t r i l e Data Technetium-99 l a b e l e d i s o n i t r i l e was u t i l i z e d t o measure b l o o d f l o w d i s t r i b u t i o n d u r i n g immersion and l a n d r u n n i n g . T h i s was an e x p e r i m e n t a l t e c h n i q u e used on a l i m i t e d number of s u b j e c t s . Because of m e t h o d o l o g i c a l problems ( i . e . c a t h e t e r p r o b l e m s ) , o n l y two s u b j e c t s completed the f u l l p r o c e d u r e . 62 C o n f l i c t i n g r e s u l t s i n r e l a t i o n t o the i s o n i t r i l e d a t a were o b t a i n e d . I t was hoped t h a t d a t a from t h i s s e c t i o n would h e l p t o f u r t h e r e x p l a i n changes i n c a r d i o r e s p i r a t o r y parameters ( i n r e l a t i o n t o the t a s k s p e c i f i c f a c t o r s ) . S u b j e c t one demonstrated a g e n e r a l r e d u c t i o n i n l e g i s o n i t r i l e uptake d u r i n g immersion. T h i s s u g g e s t s t h a t a d e c r e a s e i n l e g b l o o d f l o w may have o c c u r r e d d u r i n g immersion r u n n i n g . However, c o n t r a r y t o s u b j e c t one, l e g uptake of I s o n i t r i l e i n s u b j e c t two was i n c r e a s e d above t r e a d m i l l v a l u e s . With the e x c e p t i o n of the a n t e r i o r and p o s t e r i o r c a l f r e g i o n s , b l o o d f l o w t o the l e g d u r i n g immersion r u n n i n g may have i n c r e a s e d ( s u b j e c t t w o ) . A l t h o u g h more i n v e s t i g a t i o n Is needed, one may s p e c u l a t e t h a t the i n t e r s u b j e c t d i f f e r e n c e s i n b l o o d f l o w d i s t r i b u t i o n were due t o immersion r u n n i n g s t y l e s . A l t h o u g h c o n c l u s i v e i n f o r m a t i o n cannot be drawn from the d a t a , i t may be s uggested t h a t i s o n i t r i l e c o u l d be u s e f u l i n human e x e r c i s e b l o o d f l o w s t u d i e s i n the f u t u r e . 63 CHAPTER 5 SUMMARY Five cardiorespiratory parameters (at maximal e f f o r t and at ven t i l a t o r y threshold) were compared between an immersion and treadmill running condition. Those cardiorespiratory parameters were oxygen consumption, minute v e n t i l a t i o n , t i d a l volume, breathing frequency and heart rate. Secondarily, an experimental technique u t i l i z i n g Tc-99 2-methyloxy isobutyl i s o n i t r i l e was u t i l i z e d to measured changes in blood flow d i s t r i b u t i o n . From the data collected in this study, i t may be concluded that: 1. V02 at maximal e f f o r t and at v e n t i l a t o r y threshold was s i g n i f i c a n t l y reduced during an immersion running condition. It was theorized that the reduction in oxygen consumption was . due to changes in task s p e c i f i c i t y . 2. There was no s i g n i f i c a n t change in minute v e n t i l a t i o n comparatively between and an immersion and treadmill running protocol. It was further hypothesized that either task s p e c i f i c and water environmental factors had l i t t l e e f f e c t on minute v e n t i l a t i o n or that any increases in v e n t i l a t i o n were e f f e c t i v e l y countered by factors that lowered minute v e n t i l a t i o n . 3. There was a trend towards a higher breathing frequency and lower t i d a l volume during immersion running (at maximal e f f o r t and at v e n t i l a t o r y threshold). It was further hypothesized that the changes In t i d a l volume 64 and breathing frequency may be due to the introduction of the water environment. 4. There was a s i g n i f i c a n t l y lower heart rate at maximal e f f o r t and at v e n t i l a t o r y threshold during immersion running. It was hypothesized that the lower heart rate at v e n t i l a t o r y threshold may be due to an Increase in intrathoracic blood volume and p a r t i a l l y to the low water temperature. It was further hypothesized that the lower maximal heart rate was due s o l e l y to the increase in Intrathoracic blood volume. 5. That i s o n i t r i l e may be u t i l i z e d to measure changes in blood flow d i s t r i b u t i o n between exercise conditions. It was the purpose of t h i s study to compare the r e l a t i o n s h i p of s p e c i f i c cardiorespiratory parameters during immersion and treadmill running. It was also the- objective of t h i s study to hypothetically discuss reasons for changes in these parameters. The hypothetical discussions may help future research in t h i s area. It may be recommended that future research be guided into six main areas. These areas are: 1. To study the long term cardiovascular adaptations of untrained subjects to immersion and treadmill running. 2. To study the long term peripheral adaptations of untrained subjects to immersion and treadmill running. 3. To examine factors leading to decreased oxygen consumption rates during Immersion running. 65 To examine the re l a t i o n s h i p between blood gas parameters during immersion exercise. To study the c o r r e l a t i o n between i s o n i t r i l e uptake and blood flow rate in ske l e t a l muscle during exercise. 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S a l t i n , B., Mazar, K., C o s t l l l , D., Stein, E., Jansson, E., Essen, B., Gollnick, P. The nature of the tr a i n i n g response; peripheral and central adaptations to one-legged exercise. Acta Physiol. Scand., 96:289-305, 1976. 82. Secher, N., Clausen, J., Klausen, K., Noer, I., Trap-Jenson, J. Central and regional c i r c u l a t o r y e f f e c t s of adding arm exercise to leg exercise. Acta Physiol. Scand., 100:288-297. 83. Secher, N., Roberg-Larsen, N., Blnkhorst, R., Bonde-Petersen, F. Maximal oxygen uptake during arm cranking and combined arm plus leg exercise. J. Appl. Physiol., 36:5:515-518, 1974. 84. Shedldahl, L., Trist a n ! , F., C l i f f o r d , P., K a l b f l e i s c h , J., Smits, G., Hughes, C. Effe c t of head-out water immersion of response to exercise t r a i n i n g . J. Appl.  Physiol., 60:6: 1878-1881, 1976. 85. Shedldahl, L., Wann, L., C l i f f o r d , P., T r i s t a n i , F., Wolf, L., K a l b f l e i s c h , J. Effects of central hypervolemia on cardiac performance during exercise. J. Appl. Physiol., 57:1662-1667, 1984. 86. Sporn, V., Perez- Balino, N., Holman, B.L., Jones, A.G., Davison, A., Camin, L., Liprandi, A.S., Masoli, O., Kronauge, J.F., Lister-James, J ., Mitta, A.E.A., Sia, B.S.T., Campbell, S. Myocardial imaging with Tc-99m CPI: I n i t i a l experience in the human. J. Nuc. Med., 27:6:878, 1986. 87. Stenberg, J., Astrand, P.O., Ekblom, B., Royce, J., S a l t i n , B. Hemodynamic response to work with d i f f e r e n t muscle groups, s i t t i n g and supine. J. Appl. Physiol., 22:1:61-70, 1967. 74 88. Sybrecht, G., Garrett, L., Anthonison, N. Ef f e c t s of chest strapping on regional lung function. J. Appl. Physiol., 39:707-713, 1975. 89. T a i l l e f e r , R., Laflamme, L., Dupras, G., Picard, M., Phaneuf, D., L e v e i l l e , J. Myocardial perfusion imaging with Tc-99m Methoxy-Isobutyl I s o n i t r i l e (MIBI). Nuc. Med.. 28:4:662, 1987. 90. Thandani, U., Parker, J.O. Hemodynamics at rest and during supine and s i t t i n g bicycle exercise in normal subjects. Am. J. Cardiol, 41:52, 1978. 91. Toner, M., sawka, M., Levine, L., Pandolf, K. Cardiorespiratory responses to exercise d i s t r i b u t e d between the upper and lower body. J. Appl. Physiol., 54:5:1403-1407, 1983. 92. Toner, M., Sawka, M., Pandolf, K. Thermal responses during arm and leg and combined arm-leg exercise in water. J.  Appl. Physiol.: Respirat. Environ. Exercise  Physiol., 56:5:1355-1360, 1984. 93. Torphy, D. Effects of immersion, recumbency and a c t i v i t y on orthostatic tolerance. Aerospace Med., 37;2;119-124, 1966. 94. Wassernam, K., Van Kessel, A.L., Burton, G.G. Interaction of physiological mechanisms during exercise. J. Appl.  Physiol.. 22:1:71-85, 1967. 95. Watson, D.D., Smith, W.H., Teates, CD., Be l l e r , G.A. Quantitaive myocardial imaging with Tc-99m MIBI: Comparlsion with TL-201. J. Nuc. Med., 28:4:653, 1987. 96. Weiss J.L., Weisfeldt M.L., Mason, S.L., Garrison, J.B., Rainbow, R.G., Taylor S.H. Evidence of Frank-Starling e f f e c t in man during severe semisuplne exercise. C i r c u l a t i o n 59: 651-658, 1979. 97. West, J.B. Physiological Basis of Medical Practice. Williams and Wilkins, Baltimore, 1984. 98. Withers, R.T., Sherman, W.M., M i l l e r , J.M., C o s t i l l , D.L. S p e c i f i c i t y of the anaerobic threshold in endurance trained c y c l i s t s and runners. Eur. J. Physiol., 47:93-104, 1981. 75 99. Williams, S.J, Mousa, S.A., Morgan, R.A., C a r o l l , T.R., Maheu, L.J. Pharmacology of Tc-99m I s o n i t r l l e s : Agents with favorable c h a r a c t e r i s t i c s for heart imaging. J.  Nuc. Med., 27:6:877-888, 1986. 100. Young, I.H., Woolcock, J. Changes in a r t e r i a l blood gas tensions during unsteady state exercise. J. Appl.  Physiol., 44:1:93-96, 1978. 76 Appendix A E M 80 60 40 -20 M V02(vtW V02(vt)T V02maxW Exercise Condition V02maxT Figure 1: V02 at v e n t i l a t i o n threshold (vt) and maximal e f f o r t during immersion (W) and treadmill (T) running. 77 Appendix B 200 HR(vt)W HR(vt)T HRrnaxW HRmaxT F i g u r e 2: Heart r a t e a t v e n t i l a t i o n ( v t ) t h r e s h o l d and maximal e f f o r t (max) d u r i n g immersion (W) and t r e a d m i l l (T) r u n n i n g . 78 Appendix C VE(vtJW VE(vt)T VEmaxW VEmaxT Exercise Condition Figure 3: V e n t i l a t i o n at v e n t i l a t i o n (vt) threshold and maximal e f f o r t (max) during immersion (W) and treadmill (T) running. Values are normalized to STPD. S i u > 150 100-50 79 Appendix D: Raw Data: Cardiorespiratory Parameters Subject HR VE(STPD) V02 VE/V02 (vt) max ( V t ) max ( V t ) max ( V t ) max Treadmill 1 174 185 94.6 107.9 54.6 61.2 1.74 1.78 2 168 182 83.4 129.0 56.3 67.9 1.48 1.90 3 179 194 102.2 131.4 62.1 74.7 1.65 1.77 4 164 187 86.5 129.5 56.2 66.3 1. 42 1.72 5 188 204 95.9 126.0 58.5 69.0 1.64 2.23 6 179 193 95.5 120.8 61.3 68.5 1.55 1.74 7 180 191 99.7 132.7 53.8 63.0 1.85 2.09 8 179 195 99.5 134.4 57.9 66.7 1.72 2.02 9 177 194 79.6 128.3 54.3 70.3 1.47 1.83 10 177 194 82.0 109.2 55.7 64.8 1.47 1.73 11 190 205 94.5 126.7 56.8 62.9 1.61 2.04 12 174 187 81.9 110.0 54.7 62.3 1. 50 1.8 3 13 204 228 86.4 116.6 52.7 60.8 1.63 1.99 14 170 191 67.9 113.9 50.1 63.9 1.36 1. 82 15 165 185 78.7 117.6 62.9 71.9 1.25 1.72 16 172 191 90.5 118.4 60.8 66.7 1.49 1.86 mean 177.5 194.1 88.6 122.0 56.7 66.3 1.55 1.88 Immersion 17 154 176 93.0 121.4 46.8 57.9 2.00 2.16 18 162 168 89.2 129.9 52.3 61.1 1.71 2.12 19 163 187 89.7 135.8 54.1 70.3 1.66 1.93 20 167 183 89 .9 123.1 56.7 63.4 1. 59 1.99 21 175 189 94.8 137.9 50.9 63.1 1.87 2.19 22 166 175 96.0 124.0 54.6 59.6 1.76 2.10 23 167 187 84.2 135.6 47.3 62.3 1.78 2.23 24 174 189 85.6 119.2 50.8 60.1 1.69 2.05 25 164 179 81.9 112.7 54.8 64.9 1.49 1.75 26 177 194 87.3 112.6 57.2 64.8 1.47 1.74 27 158 186 81.9 142.8 52.3 64.9 1.54 2.29 28 162 177 79.4 101.9 47.6 55.7. 1.49 1. 85 29 181 204 64.5 125.4 41.8 57.6 1.55 2.22 30 164 175 79 .3 114.9 54.3 61.6 1.46 1.88 31 160 180 74.7 114.7 58.6 69.1 1.27 1.67 32 160 180 72.3 133.7 49 .3 65.6 1.45 2.04 mean 165.9 182.4 83.9 124.1 51.8 62.6 1.61 2.01 80 Appendix E Subject 1: I s o n i t r i l e Uptake Data (T=treadmill, W=immersion) Count/pixel(muscle) Difference View Condition Count/pixel(Brain) (T-W) Ventricles T 11.6 1.7 W 9.9 Ventr i c l e s T 12.7 2.1 (horseshoe) W 10.6 Deltoid Region T 5.5 2.6 W 2.9 Anterior Thigh T 7.1 1.6 (Full) W 5.5 Anterior Medial T 7.4 1.4 Thigh W 6.0 Anterior Lateral T 7.2 2.3 Thigh W 4.9 Posterior Gluteal T 7.2 1.1 W 6.1 Posterior Thigh T 6.3 0.9 ( f u l l ) W 5.6 Posterior Medial T 7.1 1.0 Thigh W 6.1 Posterior Lateral T 6.1 0.9 Thigh W 5.2 Posterior Calf T 4.7 3.3 ( f u l l ) W 1.4 Posterior Medial T 4.8 3.8 Calf W 1.0 Posterior Lateral T 5.2 3.3 Calf W 1.9 Anterior Calf T 4.0 0.4 ( f u l l ) W 3.6 Anterior Medial T 3.8 3.1 Calf W 0.7 Anterior Lateral T 5.2 2.5 W 2.7 Lateral Thigh T ( f u l l ) W Lateral Superior T Thigh W Lateral Inferior T Thigh w 81 Appendix F. Subject 1: I s o n i t r i l e Uptake Data (T=treadmill, W=immersion) Counts(muscle) * 100% Difference View Condition Counts (whole body) (T-W) v e n t r i c l e s T 1.2 0.4 W 0.8 Ventricles T 0.8 0.2 (horseshoe) W 0.6 Deltoid Region T 0.3 0.0 W 0.3 Anterior Thigh T 5.9 1.7 (Full) W 4.2 Anterior Medial T 3.3 0.7 Thigh W 2.6 Anterior Lateral T 1.9 0.6 Thigh w 1.3 Posterior Gluteal T 2.4 0.0 w 2.4 Posterior Thigh T 5.4 0.7 ( f u l l ) W 3.7 Poster lor Medial T 2.6 0.4 Thigh W 2.2 Poster lor Lateral T 2.0 0.7 Thigh W 1.3 Poster lor Calf T 2.7, 1.9 ( f u l l ) W 0.8 Posterior Medial T 1.3 1.0 Calf W 0.3 Posterior Lateral T 1.3 0.8 Calf W 0.5 Anterior Calf T 2.3 1.6 ( f u l l ) W 0.7 Anterior Medial T 1.2 1.0 Calf W 0.2 Anterior Lateral T 0.9 0.4 W 0.5 Lateral Thigh T ( f u l l ) W Lateral Superior T Thigh W Lateral Inferior T Thigh W 82 Appendix G Subject 2: I s o n i t r i l e Uptake Data (T=treadmill, W=immersion) Counts/pixel(muscle) Difference View Condition Counts/pixel(brain) (T-W) ve n t r i c l e s T 15.3 0.5 W 14.8 Ventricles T 17.0 1.2 (horseshoe) w 15.8 Deltoid Region T 6.0 1.4 W 4.8 Anterior Thigh T 8.0 -0.2 (Full) W 8.2 Anterior Medial T 7.9 -0.7 Thigh W 8.6 Anterior Lateral T 8.6 -0.1 Thigh W 8.7 Posterior Gluteal T 9.1 3.5 W 6.6 Posterior Thigh T 7.9 -1.8 ( f u l l ) W 8.7 Posterior Medial T 8. 4 -0.3 Thigh W 8.7 Posterior Lateral T 7.9 -0.1 Thigh W 8.0 Posterior Calf T 6.3 3.9 ( f u l l ) W 2.4 Posterior Medial T Calf W 2.3 Posterior Lateral T Calf W 2.8 Anterior Calf T 5.1 2.7 ( f u l l ) W 2.4 Anterior Medial T 5.1 1.0 Calf W 4.1 Anterior Lateral T 5.7 1.2 W 4.5 Lateral Thigh T 7.6 -1.7 ( f u l l ) W 9.3 Lateral Superior T 8.2 -1.9 Thigh W 10.1 Lateral Inferior T 7.8 -1.1 Thigh W 9.9 83 Appendix H Subject 2 : I s o n i t r i l e Uptake Data (T=treadmill / W=immersion) Counts(muscle) * 100% Difference View Condition Counts (whole body) (T-W) Ventricles T 1.2 0.2 w 1.0 Ventricles T 0.9 0.2 (horseshoe) W 0.7 Deltoid Region T 0.3 0.0 W 0.3 Anterior Thigh T 4.5 -1.2 (Full) W 5.7 Anterior Medial T 2.5 -1.0 Thigh W 3.5 Anterior Lateral T 1.6 0.0 Thigh W 1.6 Posterior Gluteal T 2.3 0.6 W 1.6 Posterior Thigh T 3.3 -1.5 ( f u l l ) W 4.8 Posterior Medial T 1.7 -1.1 Thigh W 2.8 Posterior Lateral T 1.1 -0.6 Thigh W 1.7 Posterior Calf T 1.9 0.9 ( f u l l ) W 1.0 Posterior Medial T Calf W Posterior Lateral T Calf W Anterior Calf T 1.8 0.7 ( f u l l ) W 1.1 Anterior Medial T 0.8 0.3 Calf W 0.5 Anterior Lateral T 0.7 0.1 W 0.6 Lateral Thigh T 4.6 -3.0 ( f u l l ) W 7.6 Lateral Superior T 1.9 -0.7 Thigh W 2.6 Lateral Inferior T 1.6 -0.9 Thigh W 2.5 ' ( 84 Appendix I I s o n i t r i l e Data f o r C e n t r a l B r a i n Area S u b j e c t C o n d i t i o n View C o u n t s / p i x e l 1 T r e a d m i l l B r a i n 9.1 1 Immersion B r a i n 8.0 2 T r e a d m i l l B r a i n 6.7 2 Immersion B r a i n 5.4 85 Appendix J Whole Body Photon Calculation This i s an example c a l c u l a t i o n of whole body photon count. The whole body photon count represents the number of photons released during the sp e c i f i e d camera picture time. 95348 photon counts in syringe 193551 photon counts in t o t a l (includes syringe and a l l other material in contact with i s o n i t r i l e ) (The counts are collected by the Seiman's Gamma Camera. This represents the residual counts and must be subtracted from the o r i g i n a l dose.) 15.2 MBq dose in syringe after Injection (This i s read through a dosemeter) Therefore Ideal Dose: 15.2 MBq = 95348 counts x 98203 counts ( t o t a l - syringe) x = 15.8 MBq (dose in the contact materials) 769.7 MBq in syringe (preinjection) - 19.1 MBq in syringe (post injection) ( 15.2 divided by .794 (decay factor)) - 19.9 MBq in contact materials (post injection) ( 15.8 divided divided .794 (decay factor)) = 730.7 MBq injected into subject at time zero Dose at time of data c o l l e c t i o n 730.7 MBq * .865 (decay factor) = 632.1 MBq Whole Body Photon Count 95348 = 632.1 x 15.2 x = 3965096 photons counts (This number represents the number of photons released during a s p e c i f i c time i n t e r v a l (signature I.D. = 500 counts)). 87 You w i l l go d i r e c t l y to the Dept. of Nuclear Medicine where you s h a l l undergo scanning procedures. The scanning procedures w i l l take approximately one hour. The exercise testing procedures w i l l take approximately 20 minutes. Twenty minutes w i l l be required for arm catheterization. One hour w i l l be required for tissue imaging at the Dept. of Nuclear Medicine (University of B r i t i s h Columbia Hospital). The t o t a l time required by you to perform the f u l l t e sting protocol w i l l be a minimum of 1.5 hours to a maximum of two hours. Consent; At any time before or during the testing you may withdraw from t h i s study within jepordizing your standing within the university structure. Every e f f o r t w i l l be made to ensure that you do not experience any unnecessary discomfort. If you wish to ask any questions of the researcher and of thi s study f e e l free to do so. In signing t h i s consent form you w i l l have stated that you have read and understood the description of the test and the potential complications. You enter t h i s test w i l l i n g l y and may withdraw at any time. I have read the above comments and understand the explanation, and I wish to proceed with the tes t s . Date: S u b j e c t ( s i g n a t u r e ) : W i t n e s s : 89 You w i l l go d i r e c t l y to the Dept. of Nuclear Medicine where you s h a l l undergo scanning procedures. The scanning procedures w i l l take approximately one hour. The exercise testing procedures w i l l take approximately 20 minutes. Twenty minutes w i l l be required for arm catheterization. One hour w i l l be required for tissue imaging at the Dept. of Nuclear Medicine (University of B r i t i s h Columbia Hospital). The t o t a l time required by you to perform the f u l l testing protocol w i l l be a minimum of 1.5 hours to a maximum of two hours. Consent: At any time before or during the test i n g you may withdraw from .this study within jepordizlng your standing within the university structure. Every e f f o r t w i l l be made to ensure that you do not experience any unnecessary discomfort. If you wish to ask any questions of the researcher and of thi s study f e e l free to do so. In signing t h i s consent form you w i l l have stated that you have read and understood the description of the test and the potential complications. You enter t h i s test w i l l i n g l y and may withdraw at any time. I have read the above comments and understand the explanation, and I wish to proceed with the tes t s . Date: Subject (signature): Witness: 

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