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The relationship between anaerobic threshold, excess CO² and blood lactate in elite marathon runners 1982

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THE RELATIONSHIP BETWEEN ANAEROBIC THRESHOLD, EXCESS C0 2 AND BLOOD LACTATE IN ELITE MARATHON RUNNERS by WILLIAM EDWARD HEARST B.P.H.E., Lakehead U n i v e r s i t y , Thunderbay, 19 77 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTERS OF PHYSICAL EDUCATION i n THE FACULTY OF GRADUATE STUDIES School o f P h y s i c a l Education and R e c r e a t i o n We accept t h i s t h e s i s as conforming t o the r e q u i r e d standards. THE UNIVERSITY OF BRITISH COLUMBIA October, 19 82 (c) W i l l i a m Edward Hearst, 19 82 . I n p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r an advanced degree a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , I agree t h a t t h e L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y purposes may be g r a n t e d by t h e head o f my department o r by h i s o r h e r r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Department o f The U n i v e r s i t y o f B r i t i s h Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date DE-6 (3/81) ABSTRACT The purpose of t h i s s t u d y was t o i n v e s t i g a t e the use o f e x c e s s CC>2 (ExC0 2) as a d e t e r m i n a n t o f t h e a n a e r o b i c t h r e s h o l d (AT) and t h e subsequent r e l a t i o n s h i p t o b l o o d l a c t a t e ( L a ) . Four h i g h l y t r a i n e d marathon r u n n e r s (x v a l u e s , age=30.6 y e a r s ; % body f a t = 8.2; V0 2max = 6 8 ml-kg "*"'min "*") v o l u n t e e r e d t o p a r t i c i p a t e i n t h i s s t u d y . M e t a b o l i c and r e s p i r a t o r y exchange v a r i a b l e s were a s s e s s e d by an open c i r c u i t method u t i l i z i n g a Beckman m e t a b o l i c measurement c a r t i n t e r f a c e d o n - l i n e w i t h a H e w l i t t Packard..3052A d a t a a c q u i s i t i o n system. V0 2max and the t r e a d m i l l v e l o c i t y a t t h e t h r e s h o l d o f a n a e r o b i c m e t a b o l i s m (V ) were o b t a i n e d from a p r o g r e s s i v e , t r e a d m i l l r u n (.81 kph. ^ min.) u n t i l v o l i t i o n a l f a t i g u e . v t a m ( K i l o m e t e r s per hour, Kph) was c a l c u l a t e d from t h e p o i n t o f .a n o n - l i n e a r i n c r e a s e i n E x C 0 2 . S u b j e c t s p e r formed s e t t r e a d m i l l runs o f 10 minutes on a l t e r n a t e d ays. V a r i a t i o n s ( l a t i n square) i n c l u d e d r u n s a t V / V n , t cim t cirri i x ^tam+2' a n < ^ V t a m - 1 " A n a l y s i s o f v a r i a n c e w i t h p r e p l a n n e d o r t h o g o n a l comparisons and S c h e f f e p o s t hoc c o n t r a s t s were used t o determine t h e e f f e c t s o f the t r e a d m i l l v a r i a t i o n s on La and ExC0„. There was no s i g n i f i c a n c e found between V. and 2 y tam Vj_ . f o r La o r E x C 0 o . S i g n i f i c a n c e ( p ^ .05) was e v i d e n t w i t h tam-1 2 ^ ^ - V. -CV. . i r f o r La and V. i V. f o r ExCO„. tam tam+1 tam tam+2 tam tam+2 2 An o v e r a l l c o r r e l a t i o n o f .; 89 ( p ^ . 0 0 5 ) demonstrated a h i g h p o s i t i v e , . r e l a t i o n s h i p between ExCC>2 and L a . F i n d i n g s i n d i c a t e t o be a c r i t i c a l p o i n t i n d e t e r m i n i n g t h e a n a e r o b i c tam ^ 3 i i i t h r e s h o l d i n marathoners, and performance above t h i s d e m a r c a t i o n r e s u l t s i n a s t a t e o f a n a e r o b i o s i s . i v ACKNOWLEDGMENT The a u t h o r would l i k e t o thank those, i n d i v i d u a l s who a s s i s t e d him i n c o m p l e t i n g t h i s t h e s i s : Committee chairman Dr. E. Rhodes, committee members Dr.D.McKenzie, Dr. J . Taunton and Dr. K. C o u t t s . f o r t h e i r v a l u a b l e guidance and p a t i e n c e ; and t o a l l my s u b j e c t s my g r e a t a d m i r a t i o n . The a u t h o r would a l s o l i k e t o e x p r e s s a d d i t i o n a l thanks t o Mr. D. Dunwoody, Mr. W. Parkhouse, Dr. D. Montgomery, Dr. R. S c h u t z , my p a r e n t s L i l l i a n and Roy H e a r s t , and my w i f e T o n i a E. H e a r s t , f o r t h e i r s u p p o r t t h r o u g h o u t t h i s p r o j e c t . V ' TABLE OF CONTENTS Page ABSTRACT • • i i ACKNOWLEDGMENT— i v LIST OF FIGURES ; • v i i LIST OF TABLES • v i i i C h a p ter 1. INTRODUCTION '• 1 STATEMENT OF THE. PROBLEM — — 7 HYPOTHESIS 7 RATIONALE 8 DELIMITATIONS 9 LIMITATIONS • 9 DEFINITION OF TERMS — • . 10 2. REVIEW OF SELECTED LITERATURE 12 INTRODUCTION : 12 LACTIC ACID • 12 FORMS OF LACTIC ACID • 14 LACTIC ACID ASSAY- 15 LACTATE CONCENTRATION 16 C 0 2 — — — — 21 ANAEROBIC THRESHOLD 23 THE MARATHONER •- 29 EFFECTS OF TRAINING ON AT : v- 30 REPRODUCIBILITY OF AT 31 v i 3. METHODS AND PROCEDURES : 32 SUBJECTS 32 TESTING PROCEDURES 32 TESTING PROTOCOLS 33 EXPERIMENTAL DESIGN AND DATA ANALYSIS 34 4. RESULTS AND DISCUSSION 35 RESULTS 35 DISCUSSION : 45 5. SUMMARY AND CONCLUSIONS 56 SUMMARY 56 CONCLUSIONS 58 RECOMMENDATIONS 59 BIBLIOGRAPHY 6 0 APPENDIX : : 69 y i i LIST OF FIGURES FIGURE PAGE I Common V a r i a b l e s Used f o r AT D e t e r m i n a t i o n 4 I I H y p o t h e t i c a l Model Of Three Phase, Double Breakaway Model 6 I I I Means + S.D. F o r Four S u b j e c t s Over Four C o n d i t i o n s - La • 41 IV Means ± S.D. F o r Four S u b j e c t s Over Four C o n d i t i o n s - ExCO_, 42 V C o r r e l a t i o n Between ExCO„ and La 43 y i i i LIST OF TABLES TABLE PAGE I P h y s i c a l C h a r a c t e r i s t i c s o f S u b j e c t s 36 I I R e l e v a n t Data • 37 I I I A n a l y s i s o f V a r i a n c e W i t h P r e p l a n n e d O r t h o g a n a l Comparisons and S c h e f f e ' P o s t Hoc C o n t r a s t s 38 IV C o r r e l a t i o n C o e f f i c i e n t s : La and EXCO2 39 V Summary o f H y p o t h e s i s T e s t i n g 40 CHAPTER I INTRODUCTION TO THE PROBLEM The " a n a e r o b i c t h r e s h o l d " as d e f i n e d by Wasserman e t a l (196 4) i s synonymous w i t h t h e o n s e t o f m e t a b o l i c a c i d o s i s . A n a e r o b i c t h r e s h o l d has been measured v i a gas exchange v a r i a b l e s and d i r e c t b l o o d l a c t a t e s a m p l i n g w i t h c o n s i d e r a b l e s u c c e s s (Wasserman e t a l , 1973; Wasserman and Whipp, 1975; D a v i s e t • al f-'19 76;'. K a t c h , 19 79; F a r r e l l e t a l , 19 7 9 ) . R e s p i r a t o r y exchange va r i a b l e s . : measured d u r i n g a c o n s t a n t i n c r e a s e in.work r e v e a l t h e f o l l o w i n g : 1. V„ (minute v e n t i l a t i o n ) and VCO„ (Volume o f C0_ hj A Z. produced) i n i t i a l l y i n c r e a s e s w i t h VO2/* 2. A t t h e a n a e r o b i c t h r e s h o l d t h e V 0 2 remains l i n e a r * • w i t h work r a t e , b u t V C 0 2 i n c r e a s e s f a s t e r t h a n V 0 2 p r i m a r i l y due t o the b u f f e r i n g o f l a c t a t e by t h e b i c a r b o n a t e system; * • 3. V„ i n c r e a s e s i n p r o p o r t i o n t o VCO„; 4. End t i d a l P C 0 2 does n o t change, b u t e n d - t i d a l P 0 2 i n c r e a s e s ; 5. Because V C 0 2 i n c r e a s e s above V 0 2 , R i n c r e a s e s ; As work r a t e s become h i g h e r ( a p p r o x i m a t e l y 80% o f • * maximum), t h e i n c r e a s e d V„ i n c r e a s e s VCO„ w i t h a consequent r e d u c t i o n o f e n d - t i d a l P C 0 o (Wasserman and Whipp, 19 7 5 ) . 2 The measurement o f the a e r o b i c - a n a e r o b i c t r a n s i t i o n v i a t h e appearance o f l a c t a t e i n the b l o o d i n . e x c e s s o f r e s t i n g l e v e l s r e v e a l t h e f o l l o w i n g p a t t e r n : 1. A t v e r y low work r a t e s : no i n c r e a s e i n b l o o d l a c t a t e ; 2. A t moderate work r a t e s : l a c t a t e peaks e a r l y i n work and t h e n r e t u r n s t o r e s t i n g v a l u e s as V 0 2 r e a c h e s a s t e a d y s t a t e ( l a c t a t e i s o x i d i z e d t o CC>2 and H^O i n t h e t i s s u e ) ; 3. A t heavy i n t e n s i t i e s : L a c t a t e i n c r e a s e s and t h e n may d e c r e a s e s l i g h t l y , b u t i s m a i n t a i n e d a t h i g h e r t h a n r e s t i n g v a l u e s by a b a l a n c e between s u s t a i n e d p r o d u c t i o n and r e m o v a l ; 4. A t s e v e r e i n t e n s i t i e s : l a c t a t e c o n t i n u e s t o i n c r e a s e t h r o u g h o u t t h e work (Diamant e t a l , .19 68) . L a c t a t e a c c u m u l a t i o n l e a d s t o a d e c r e a s e i n b i c a r b o n a t e ( b u f f e r i n g o f l a c t i c a c i d ) , t o t h e appearance o f e x c e s s i v e ( r e l a t i v e t o the r e s t i n g m e t a b o l i c l e v e l ) amounts o f CO^ (ExC0 2) and t o t h e p r o d u c t i o n o f hydrogen i o n s (which s t i m u l a t e t h e chemoreceptors t o i n c r e a s e t h e v e n t i l a t i o n r a t e ) . V o l k o v e t a l (19 74) s t a t e s t h a t i t i s p o s s i b l e t o d e t e r m i n e t h e l e v e l o f a n a e r o b i c m e t a b o l i s m from t h e e x c e s s o f r e l e a s e d CO ' t h r o u g h t h e f o l l o w i n g c a l c u l a t i o n : 3 ExC0 2 = AIR • VC>2 = VG0 2 - (R)rest«V0 2, -1 - i • where E x C 0 2 i s e x c e s s C 0 2 (ml-kg/; :-.min ) , VC>2 i s the l e v e l o f oxygen consumption d u r i n g work (ml-kg "'"•min "*") * -1 -1 VC0 2 i s t h e l e v e l o f CO^ r e l e a s e d (ml-kg •min ).. T h e r e f o r e , a t work r a t e s a t o r above t h e a n a e r o b i c t h r e s h o l d , a d d i t i o n a l CC>2 i s added t o t h e e x p i r a t e p r i m a r i l y t h r o u g h t h e / f o l l o w i n g r e a c t i o n , w h i c h i n v o l v e s t h e b u f f e r i n g o f l a c t i c a c i d produced t h r o u g h t h e g l y c o l y t i c pathways: Na HC0 3~ + H + l a c t a t e —> N a + l a c t a t e + H 2 C 0 3 —> C 0 2 t + H 20 C o n s e q u e n t l y , t h e a n e r o b i c t h r e s h o l d i s p o s t u l a t e d t o o c c u r when t h e r e i s a sudden c u r v i l i n e a r i n c r e a s e i n exce s s CC>2 e l i m i n a t i o n , v e n t i l a t i o n r a t e and r e s p i r a t o r y exchange r a t i o , w i t h a c o n c o m i t a n t i n c r e a s e i n b l o o d l a c t a t e l e v e l s (above r e s t i n g v a l u e s ) . ( F i g u r e I) . C o s t i l l and Fox (1969) have shown t h a t marathon r u n n e r s a r e a b l e t o u t i l i z e a p p r o x i m a t e l y 75% o f t h e i r VC>2 max w i t h l i t t l e l a c t i c a c i d p r o d u c t i o n . I n a d d i t i o n , F a r r e l l e t a l (1979) found t h a t t h e "marathoner 1 can m a i n t a i n an average v e l o c i t y d u r i n g a r a c e w h i c h i s o n l y s l i g h t l y a b o v e . h i s a n a e r o b i c t h r e s h o l d . Kinderman e t a l (19 79) found t h a t endurance t r a i n e d a t h l e t e s a c h i e v e h i g h e r work i n t e n s i t i e s b e f o r e l a c t a t e p r o d u c t i o n FIGURE I Common V a r i a b l e s Used f o r A.T. D e t e r m i n a t i o n 5 10 15 20 25 Time (Min.) 5 exceeds i t s r e m o v a l . C o s t i l l e t a l (19 73) found t h a t a t a l l r u n n i n g speeds above 70% max, t h e f a s t e r d i s t a n c e r u n n e r s accumulated l e s s b l o o d l a c t a t e t h a n t h e s l o w e r r u n n e r s a t s i m i l a r speeds and r e l a t i v e p e r c e n t a g e s o f t h e i r a e r o b i c c a p a c i t i e s . I t has been s u g g e s t e d t h a t t h e m e t a b o l i c a d a p t a t i o n s o f t h e r u n n i n g m u s c u l a t u r e have been o x i d a t i v e r a t h e r t h a n g l y c o l y t i c . I n a d d i t i o n , i n t e n s i t i e s above t h e a n a e r o b i c t h r e s h o l d , a c c o r d i n g t o Wasserman e t a l (1973), can be m a i n t a i n e d w i t h s l i g h t l y e l e v a t e d l a c t i c a c i d f o r p r o l o n g e d p e r i o d s o f t i m e . The t e r m i n o l o g y used today t o d e f i n e t h e i n t e r p l a y between a e r o b i c and a n a e r o b i c s o u r c e s i s v a r i e d . These i n c l u d e t h e a n a e r o b i c t h r e s h o l d o f Wasserman e t a l (1964), t h e o n s e t o f plasma l a c t a t e a c c u m u l a t i o n (OPLA) o f F a r r e l l e t a l (19 7 9 ) , an i n t e n s i t y t h r e s h o l d as d e f i n e d by Sady e t a l (1980), t h e l a c t a t e t h r e s h o l d o f I v y e t a l (1980), t h e o n s e t o f b l o o d l a c t a t e a c c u m u l a t i o n (OBLA) o f S j o d i n e t a l (19 8 1 ) , and t h e t h r e e phase double breakaway model o f S k i n n e r and M c L e l l a n (1980) and Kindermann e t a l (1979). ( F i g u r e I I ) I n a d d i t i o n , i n v e s t i g a t i o n s i n Europe by Stegmann e t a l (1981) d i s p l a y the need f o r i n d i v i d u a l a n a e r o b i c t h r e s h o l d (IAT) d e t e r m i n a t i o n , v i a l a c t a t e k i n e t i c s , due t o i n t e r i n d i v i d u a l v a r i a b i l i t y . The c u r v i l i n e a r i n c r e a s e i n ExCO n e l i m i n a t i o n as d e f i n e d FIGURE I I H y p o t h e t i c a l Model o f Three Phase, Double Breakaway Model (adapted from S k i n n e r and M c L e l l a n , 19 80) PHASE I PHASE I I PHASE I I I REST AEROBIC THRESHOLD ANAEROBIC THRESHOLD V 0 2 MAX -Predominant type o f m e t a b o l i s m -Predominant S u b s t r a t e -Predominant Muscle F i b e r Type - R e l a t i v e I n t e n s i t y (% V0 2Max) -He a r t Rate (Beats per min.) - B l o o d L a c t a t e (mM/L) A e r o b i c F a t > Carbohydrate 40 - 60 130 - 150 /v 2 I , I I A A n a e r o b i c C a r b o h y d r a t e > F a t I , I I A , I I B 65 - 90 100 - 180 ^ 4 7 by V o l k o v e t a l (1974) and used by Rhodes e t a l (1981) t o p r e d i c t marathon r a c i n g t i m e s i s a l s o s u g g e s t i v e of a c r i t i c a l i n t e n s i t y above wh i c h m e t a b o l i c a c i d o s i s becomes a l i m i t i n g f a c t o r on p e r f o r m a n c e . The r o l e o f t h e a n a e r o b i c t h r e s h o l d has been used f o r t e s t i n g h o s p i t a l p a t i e n t s (Wasserman and Whipp, \ 19 7.5), a t h l e t e s ( C o s t i l l , 19 70) and models o f t h e hyperpnea o f dynamic m u s c u l a r e x e r c i s e (Whipp, 19 77) . However, t h e study, o f t h e r o l e o f t h e a n a e r o b i c t h r e s h o l d and i t s r e l a t i o n s h i p t o performance o f e l i t e endurance r u n n e r s i s i n s t a g e s of p r e l i m i n a r y i n v e s t i g a t i o n . Statement o f Problem The purpose o f t h i s s t u d y was t o e l u c i d a t e t h e r e l a t i o n s h i p between ExCC^ as a d e t e r m i n a t i o n o f a n a e r o b i c t h r e s h o l d and t h e appearance t o b l o o d l a c t a t e . Hypotheses F o r each o f t h e f o l l o w i n g dependent v a r i a b l e s , i t was h y p o t h e s i z e d t h a t : 1. B l o o d l a c t a t e a t s p e c i f i c V t a__, i e . ( L a V t a m ) (a) LaV ' ,, w i l l have a v a l u e e q u a l t o o r tam-1 lower t h a n LaV, (1 km/hr below V, ); tarn tarn (b) LaV. w i l l have a lower v a l u e t h a n LaV , tarn tam+1 (1 km/hr above V, ); tarn (c) LaV" ,, w i l l have a lower v a l u e t h a n LaV. tam+1 tam+2 (2 km/hr above V ); tarn 8 (LaV, ,~ > LaV^. >'LaV. ^ LaV. m .) tam+2 tam+1 tam tam-1 2. Excess C 0 2 p r o d u c t i o n a t s p e c i f i c ^ t a m ( E x C 0 2 V t a m ^ (a) ExCO„V, . w i l l have a v a l u e e q u a l t o 2 tam-1 or l o w e r t h a n ExCO„V, 2 tam (b) ExCC> 2V t a m w i l l have a lower v a l u e t h a n ExCC> V^ _, , ; 2 tam+1 (c) ExC0 oV. w i l l have a lower v a l u e t h a n ' 2 tam+1 ExCO-V^ ' _; 2 tam+2 (ExCO„ V,. ExCO_V. , _ > ExC0 oV, 35 ExCO_V, ̂  ) 2 tam+2 2 tam+1 2 tam 2 tam-1 3. There w i l l be a s i g n i f i c a n t c o r r e l a t i o n between e x c e s s C0„ and b l o o d l a c t a t e (LaV^ and ExCC" V. ) f o r 2 tam 2 tam V,_ , , V. , , .and V. , n . tam-1 tam tam+, tam+2 R a t i o n a l e The a n a e r o b i c t h r e s h o l d has been d e f i n e d as t h a t work r a t e j u s t below t h e p o i n t a t which t h e r e i s t h e f i r s t s i g n i f i c a n t e l e v a t i o n o f b l o o d l a c t a t e i n e x c e s s o f r e s t i n g l e v e l s , w i t h a c o n c o m i t a n t i n c r e a s e i n e x c e s s C 0 2 e l i m i n a t i o n . S t u d i e s have shown t h a t e l i t e marathon r u n n e r s appear t o u t i l i z e t h e h i g h e s t p e r c e n t a g e o f t h e i r maximal oxygen consumption (70% - 85% VC^max), w i t h a minimum amount o f l a c t i c a c i d p r o d u c t i o n . The a e r o b i c pathways t h e n , a r e a l r e a d y o p e r a t i n g . a t an extreme l e v e l and any i n c r e a s e i n i n t e n s i t y w i l l n e c e s s i t a t e an i n c r e a s i n g c o n t r i b u t i o n t h r o u g h 9 g l y c o l y t i c / a n a e r o b i c m e t a b o l i s m . A l t h o u g h t h e r e i s no d e f i n i t i v e l i n e between a e r o b i c and a n a e r o b i c m e t a b o l i s m , t h e r e does appear t o be a c r i t i c a l work i n t e n s i t y above w h i c h m e t a b o l i c a c i d o s i s i s o b s e r v a b l e . A l t h o u g h m e t a b o l i c a c i d o s i s has; been measured v i a n o n i n v a s i v e (ExCG^) o r d i r e c t venous b l o o d l a c t a t e t e c h n i q u e s , no attempt has been made t o e l u c i d a t e upon th e use o f ExCC>2 t h r o u g h l a c t a t e a n a l y s i s a t c r i t i c a l r u n n i n g speeds i n e l i t e marathon r u n n e r s d u r i n g t r e a d m i l l e x e r c i s e . D e l i m i t a t i o n s T h i s s t u d y i s d e l i m i t e d by: (1) t h e sample t y p e ; (2) t h e sample s i z e (N=5); (3) t h e sample's f i t n e s s l e v e l (endurance t r a i n e d ) ; (4) t h e . s p e e d o f t h e t r e a d m i l l a t w h i c h t h e s u b j e c t w i l l r u n ; L i m i t a t i o n s T h i s s t u d y ' s r e s u l t s a r e l i m i t e d by: (1) d a t a c o l l e c t i o n c a p a b i l i t i e s o f t h e Beckman M e t a b o l i c Meaurement C a r t and t h e H e w l e t t P a c k a r d Data A c q u i s i t i o n system i n t e r f a c e d w i t h i t ; (2) t h e methods.of a n a e r o b i c t h r e s h o l d d e t e r m i n a t i o n ; (3) t h e i n d i v i d u a l ' s m e t a b o l i c response t o t h e p r o t o c o l s ; 10 (4) b l o o d l a c t a t e measurement technique. D e f i n i t i o n s For the purpose of c l a r i f i c a t i o n , the f o l l o w i n g d e f i n i t i o n s and a b b r e v i a t i o n s were c o n s i d e r e d a p p l i c a b l e throughout t h i s study: (1) Anaerobic t h r e s h o l d (AT) - the work r a t e j u s t below the p o i n t a t which l a c t a t e p r o d u c t i o n exceeds i t s removal by o x i d a t i v e means ( i e . f i r s t s i g n i f i c a n t e l e v a t i o n of b l o o d l a c t a t e above r e s t i n g l e v e l ) with which there i s a concomitant i n c r e a s e i n excess CC^. (2) Excess CC>2 (ExCC^) - the r e l a t i o n s h i p between the amount of nonmetabolic CC^ being produced i n p r o p o r t i o n t o the amount of non-metabolic ©2 b e i n g consumed as energy f o r a g i v e n workload. E x C 0 2 - V C 0 2 ~ ( r e s t i n g R.Q. x VC^) where CO^ i s the t o t a l e x p i r e d CO^ O2 i s the t o t a l e x p i r e d R.Q. i s the r e s t i n g r e s p i r a t o r y q u o t i e n t VCC>2 produced 0„ consumed - - (3) v e l o c i t y of t r e a d m i l l (V. ) a t time of onset . tarn of anaerobic metabolism - t r e a d m i l l speed (km/hr) 11 c o r r e s p o n d i n g t o the anaerobic t h r e s h o l d , (as determined by a c u r v i l i n e a r i n c r e a s e i n excess CC^). (a) V\ , = 1 km/hr below AT; tam-1 (b) V,. = t r e a d m i l l v e l o c i t y (km/hr) a t AT; tam J (c) vtam+l = ^ m / n r a D ° v e A T ; (d) ^ 0 = 2 km/hr above AT. tam+2 12 CHAPTER I I REVIEW OF LITERATURE I n t r o d u c t i o n The c a p a b i l i t y o f t h e human body t o p e r f o r m p h y s i c a l work o f v a r y i n g i n t e n s i t i e s and d u r a t i o n i n v o l v e s the r e c r u i t m e n t o f muscle, c o n s e q u e n t l y , any f a c t o r s w h i c h l i m i t t h i s w i l l l i m i t performance (Wenger and Reed, 19 7 6 ) . One o f t h e m e t a b o l i c f a c t o r s a s s o c i a t e d w i t h m u s c l u a r f a t i g u e d u r i n g a e r o b i c .and a n a e r o b i c work i s an i n c r e a s e i n l a c t a t e p r o d u c t i o n . T h i s i n c r e a s e can r e s u l t i n a de c r e a s e i n muscle and b l o o d pH w h i c h i n h i b i t s t he r e a c t i o n v e l o c i t y o f p h o s p h o f r u c t o k i n a s e t h u s s l o w i n g down t h e r a t e o f ATP p r o d u c t i o n (Edgerton e t a l , 1973), d e c r e a s e s C a + + s e n s i t i v i t y i n h i b i t i n g the c o n t r a c t i l e p r o c e s s and i n h i b i t s t he c o n v e r s i o n o f p h o s p h o r y l a s e b t o a t h u s d e c r e a s i n g g l y c o g e n d e g r a d a t i o n , (Hultman and S a h l i n , 19 8 1 ) . F u r t h e r m o r e , t h e e f f e c t s o f t h e i n c r e a s e d l a c t a t e w i l l , i n h i b i t f a t m o b i l i z a t i o n from a d i p o s e t i s s u e t h u s s t r a i n i n g the l i m i t e d g l y c o g e n s t o r e s (Boyd e t a l , 19 74). I t w i l l be t h e purpose o f t h i s r e v i e w t o p r e s e n t c u r r e n t r e s e a r c h p e r t a i n i n g t o l a c t i c a c i d and i t s subsequent r e l a t i o n s h i p t o CO^ p r o d u c t i o n , the a n a e r o b i c t h r e s h o l d c o n c e p t and t h e endurance a t h l e t e . L a c t i c A c i d In t he n i n e t e e n t h c e n t u r y , B e r z e l i u s (180 7) demonstrated 13 the p r e s e nce o f l a c t i c a c i d i n human and muscle t i s s u e . V i r t u a l l y a l l t i s s u e s o f the body a r e c a p a b l e o f p r o d u c i n g l a c t i c a c i d , a l t h o u g h the b e s t known p h y s i o l o g i c a l example i s m u s c u l a r e x e r c i s e d u r i n g w h i c h l a c t a t e accumulates i n th e t i s s u e s and b l o o d s t r e a m . The a c c u m u l a t i o n i s because o f r e l a t i v e oxygen l a c k and the i n a b i l i t y o f l a c t a t e removal mechanisms t o keep up w i t h p r o d u c t i o n , t h u s c a u s i n g m e t a b o l i c a c i d o s i s (Cohen e t a l , 19 76) . The removal o f accumulated l a c t a t e i s n e c e s s a r y s i n c e l a c t i c a c i d may i n h i b i t the performance o f subsequent e x e r c i s e ( K a r l s o n e t a l , 1975). T h i s may r e s u l t from t h e i n h i b i t o r y a c t i o n t h a t l a c t i c a c i d has on t h e g l y c o l y t i c enzymes p h o s p h o f r u c t o k i n a s e (Keul e t a l , 19 72; Newsholme, 19 74 ) and p h o s p h o r y l a s e (Hultman and S a h l i n , 1901), and/or on f r e e f a t t y a c i d m o b i l i z a t i o n ( I s s e k u t z and M i l l a r , 1962). D u r i n g e x e r c i s e , t h e muscles go i n t o debt f o r oxygen d e s p i t e an i n c r e a s e i n m e t a b o l i s m . The energy r e q u i r e m e n t s of t h e muscle supersede the a b i l i t y o f the c a r d i o - v a s c u l a r system t o s u p p l y oxygen, c o n s e q u e n t l y energy i s s u p p l i e d by a n a e r o b i c p r o d u c t i o n t h r o u g h t h e breakdown o f g l u c o s e o r g l y c o g e n t o l a c t a t e ( A l p e r t , 1965) . J o b s i s and S t a i n s b y (196 8) however, s t a t e d t h a t the l a c t a t e f o r m a t i o n i s not caused by h y p o x i c s t i m u l a t i o n o f a n a e r o b i c g l y c o l y s i s , b u t r a t h e r an i n b a l a n c e between p y r u v a t e p r o d u c t i o n by a e r o b i c 14 g l y c o l y s i s and p y r u v a t e u t i l i z a t i o n i n the Kreb C y c l e . C o n s e q u e n t l y , p y r u v a t e accumulates and i s c o n v e r t e d t o l a c t a t e . F a r r e l l (19 79) s u g g e s t s t h a t .the plasma l a c t a t e c o n c e n t r a t i o n s a r e the r e s u l t o f t h e p r o d u c t i o n o f l a c t a t e i n m uscle, and d i f f u s i o n o f l a c t a t e from muscle t o b l o o d and t h e uptake o f l a c t a t e by numerous t i s s u e s . The l a c t a t e may be a c t e d upon w i t h i n t h e muscle i t s e l f (Hermanson & Vaage, 1977), or be r e l e a s e d i n t o t h e b l o o d where i t may be removed by t h e h e a r t ( C a r l s t e n , 1 9 6 1 ) , k i d n e y (Mole e t a l , 1973), s k e l e t a l muscle ( J o r f e l d t , 1970; I s s e k u t z e t a l , 1976), b r a i n ( B e l c a s t r o and Bonen, 19 75) and l i v e r ( C o r i and C o r i , 1929) . Forms o f L a c t i c A c i d L a c t i c a c i d o c c u r s i n two s t e r e o i s o m e t r i c forms and i n a s o - c a l l e d r a c e m i c m i x t u r e o f t h e s e two i s o m e r s . The s t e r e o i s o m e r s have been named D(-) L a c t i c A c i d and L(+) L a c t i c A c i d . The L(+) isomer r e p r e s e n t s the form o f l a c t i c , a c i d p r o d u c e d i n muscle m e t a b o l i s m as a r e s u l t o f muscle c e l l a n a e r o b i o s i s and/or t h e o r d i n a r y g l y c o l y t i c o x i d a t i o n of g l u c o s e i n a l l c e l l s . ( C o r i , 1962; Lockwood e t a l , 1965). COOH COOH H^OH C H 3 D(-) L a c t i c A c i d i c A c i d A l t h o u g h M o r i y a i n 1904 s t a t e d t h a t a l m o s t a l l o f the 15 l a c t a t e f o r m e d b y v a r i o u s a n i m a l t i s s u e s was o f t h e L(+) f o r m , D a k i n and D u d l e y (1913) f o u n d t h a t some a n i m a l t i s s u e s f o r m e d D(-) l a c t a t e . C o r i 1 s (1931) c l a s s i c a l e x p e r i m e n t showed t h a t D(-) l a c t a t e i s p o o r l y m e t a b o l i z e d a n d t h a t 30 - 40% o f t h e l a c t a t e i n g e s t e d i s e x c r e t e d i n t h e u r i n e , c o m p a r e d w i t h none o f t h e L(+) f o r m . H o w e v e r , r e c e n t i n v e s t i g a t i o n s h a v e shown t h a t D(-) l a c t a t e c a n be m e t a b o l i z e d b y t h e r a t a n d p r o b a b l y t h e human (Schumer, 19 79) . Thus t h e d e f i n i t i v e - v a l u e s p l a c e d on l a c t a t e d e t e r m i n a t i o n v i a L(+) s p e c i f i c a s s a y s i s q u e s t i o n a b l e i n r e l a t i o n s h i p t o a l l l a c t a t e i n t h e human s e r u m . L a c t i c A c i d A s s a y The p r e f e r r e d s t e r e o s p e c i f i c a n a l y t i c a l m e t h o d f o r L(+) l a c t i c a c i d i s b a s e d on t h e r e d u c t i o n o f n i c o t i n o m i d e a d e n i n e d i n u c l e o t i d e (NAD +) b y L(+) l a c t i c d e h y d r o g e n a s e (LDH) i n t h e p r e s e n c e o f L(+) l a c t i c a c i d , w h e r e t h e c h a n g e i n o p t i c a l d e n s i t y a t 340 n y / i s r e a d ( O l s o n , 1962). C 0 2 H rnu C 0 9 H | - . LDH | 2 + 0=0 + NADH + H => HOCH + NAD C I I 3 " C H 3 ( P y r u v i c a c i d ) L(+) L a c t i c A c i d The l i b e r a t e d h y d r o g e n s a r e t r a n s f e r r e d t o NAD ( n i c o t i n o m i d e a d e n i n e d i n u c l e o t i d e ) t o f o r m NADH. I t i s t h i s r e d u c e d f o r m w h i c h i s c a p a b l e o f a b s o r b i n g l i g h t . The 16 i n c r e a s e i n absorbance i s d i r e c t l y p r o p o r t i o n a l t o l a c t a t e c o n c e n t r a t i o n (Kragenings, 1978). There are a t l e a s t f i v e d i s t i n c t forms of l a c t i c dehydrogenase (LDH) which a r i s e from the combination of two types of p r o t e i n "H" type and "M" type. The LDH form composed of f o u r i d e n t i c a l "M" s u b u n i t s (M^) i s found i n s k e l e t a l muscle and the H^ form i s c h a r a c t e r i s t i c of h e a r t - type t i s s u e s (Cahn e t a l , 1962). The i n t e r m e d i a t e e l e c t r o p h o r e t i c forms of LDH, which are molecular h y b r i d s of muscle and h e a r t - t y p e LDH, i n c l u d e M^H and MH^. The M 4 and M^H isoenzymes are predominantly found i n f a s t - t w i t c h , g l y c o l y t i c s k e l e t a l f i b e r s (Thorstensson e t a l , 19 77; Schumer, 19 79), which f a c i l i t a t e the reduction- of pyruvate t o l a c t a t e ; and the MH^ and isoenzymes predominate i n slow- t w i t c h o x i d a t i v e t i s s u e ( S j o d i n , 1976; Schumer, 1979), which f a c i l i t a t e the o x i d a t i o n of l a c t a t e to pyruvate and i t s subsequent use i n the Krebs C y c l e . The r e s u l t s of a study by Taunton e t a l , 0-981) suggests t h a t the g l y c o l y t i c enzyme a c t i v i t y i s a f u n c t i o n of f i b e r composition r a t h e r than t r a i n i n g . Consequently r e c e n t s t u d i e s have not r e s u l t e d i n LDH enzyme a l t e r a t i o n s i n e i t h e r endurance or power a t h l e t e s (Green e t a l , 1979). L a c t a t e C o n c e n t r a t i o n Cohen and Woods (19 78) s t a t e t h a t the main m e t a b o l i c 17 pathways i n v o l v e d i n l a c t a t e c o n c e n t r a t i o n a r e g l y c o l y s i s , g l u c o n e o g e n e s i s and l a c t a t e o x i d a t i o n . The f u n c t i o n s o f g l y c o l y s i s i n c l u d e the p r o v i s i o n o f energy i n the form o f adenosine t r i p h o s p h a t e and the p r o v i s i o n o f i n t e r m e d i a t e s f o r subsequent b i o s y n t h e s i s o f o t h e r m e t a b o l i t e s . M a r g a r i a (196 7) showed t h a t under c o n d i t i o n s o f maximal e x e r c i s e , when t h e o x y g e n a t i o n o f t i s s u e i s l o w e r e d , energy i s p r o v i d e d v i a g l y c o l y s i s . Under a n a e r o b i c c o n d i t i o n s t h e s o l e p r o d u c t o f g l y c o l y s i s i s l a c t i c a c i d ; whereas under a e r o b i c c o n d i t i o n s t h e l a c t i c a c i d formed can e i t h e r be used f o r t h e r e s y n t h e s i s o f g l u c o s e o r o x i d a t i o n v i a t he t r i c a r b o x y l i c a c i d c y c l e . I t s h o u l d be n o t e d though, t h a t energy s o u r c e s a re seldom s t r i c t l y a e r o b i c o r a n a e r o b i c , i n f e r r i n g a s e r i a l r e l a t i o n s h i p ( A s t r a n d and.Rodahl, 1977). G l u c o n e o g e n e s i s r e f e r s t o t h e f o r m a t i o n o f g l u c o s e from l a c t a t e and amino a c i d s (Cohen and Woods, 1978). The pathway i n c l u d e s some o f t h e g l y c o l y t i c r e a c t i o n s t h r o u g h w h i c h t h e n e t f l u x i s i n t h e r e v e r s e d i r e c t i o n . muscle g l y c o g e n —-> b l o o d l a c t a t e t 4 b l o o d g l u c o s e < l i v e r g l y c o g e n ( C o r i C y c l e ) R e c e n t l y the q u a n t i t a t i v e s i g n i f i c a n c e "of t h e "Himwich- C o r i C y c l e " f o r removal o f l a c t a t e has been q u e s t i o n e d . Hermansen and Vaage (19 80) s t a t e t h a t a l t h o u g h some o f the l a c t a t e produced i n muscle d u r i n g e x e r c i s e d i f f u s e s o u t 18 i n t o t h e b l o o d and o t h e r f l u i d compartments, p a r t o f t h e l a c t a t e produced i s " s t o r e d " w i t h i n t h e mu s c l e . F u r t h e r m o r e , t h e y showed t h a t o n l y about 10% o f the l a c t a t e d i s a p p e a r a n c e from human muscle d u r i n g i t s r e c o v e r y from maximal e x e r c i s e , can be a c c o u n t e d f o r by an e f f l u x from muscle i n t o t h e c i r c u l a t i o n . T h i s s u g gests t h a t 90% i s m e t a b o l i z e d w i t h i n the muscle i t s e l f i e . 15% th r o u g h o x i d a t i o n t o CO^ and ^O; 75% t h r o u g h ( r e ) c o n v e r s i o n t o g l y c o g e n . Both G i s o l f i e t a l (1966) and D a v i e s e t a l (196 8) a l l u d e d t o t h e f a c t t h a t moderate a e r o b i c w o r k l o a d s d u r i n g r e c o v e r y i n c r e a s e d t h e r a t e o f d i s a p p e a r a n c e from b l o o d , s u g g e s t i n g t h a t a g r e a t e r f r a c t i o n o f l a c t a t e may have been u t i l i z e d as s u b s t r a t e . More r e c e n t l y , Bonen and B e l c a s t r o (19 76) demonstrated g r e a t e r l a c t a t e removal d u r i n g r e c o v e r y speeds between s e t s o f one m i l e r u n s : i n h i g h l y t r a i n e d endurance r u n n e r s than i n u n t r a i n e d s u b j e c t s . The i n v e s t i g a t i o n s i n t o t h e f a t e o f l a c t a t e has l e d t o some c o n t r o v e r s y . R o w e l l e t a l (1966) i n d i c a t e d t h a t a p p r o x i m a t e l y 50% o f l a c t a t e produced d u r i n g moderate p r o l o n g e d e x e r c i s e i s r e s y n t h e s i z e d i n t o g l y c o g e n by t h e l i v e r , whereas t h e s t u d i e s by Hermansen and Vaage (19 80) c o n c l u d e t h a t 75% o f l a c t a t e found i n muscles a t the end o f a n a e r o b i c e x e r c i s e i s c o n v e r t e d i n t o g l y c o g e n i n the same muscle. These d a t a s u g g e s t t h a t l a c t a t e c o n c e n t r a t i o n and subsequent 19 removal may be i n t e n s i t y s p e c i f i c . The o x i d a t i o n o f l a c t a t e v i a t h e t r i c a r b o x y l i c a c i d c y c l e t o C 0 2 and H^O depends on the a c t i v i t y o f p y r u v a t e dehydrogenase and not t h a t o f l a c t a t e dehydrogenase. The enzyme i s m a i n t a i n e d i n an i n a c t i v e s t a t e when the c o n c e n t r a t i o n o f ATP and a c e t y l CO-A a r e k e p t h i g h by the o x i d a t i o n o f f u e l s such as f a t t y a c i d s (Cohen and Woods, 19 78) . R e s t i n g man p r o b a b l y produces a l a c t a t e c o n c e n t r a t i o n o f 0.7 -1 mM/L, a 70 k g . man h a v i n g a t o t a l l a c t a t e p r o d u c t i o n a p p r o x i m a t i n g 1300 mM/day. Of t h i s , 53% i s a p p a r e n t l y m e t a b o l i z e d by l i v e r (Cohen, 1975). P r a c t i c a l and p h y s i o l o g i c a l f a c t o r s a l s o i n f l u e n c e t h e c o n c e n t r a t i o n o f l a c t a t e . P r a c t i c a l f a c t o r s i n c l u d e the t e c h n i q u e o f v e n i p u n c t u r e , m u s c l u l a r c o n t r a c t i o n in.'the l i m b from w h i c h t h e b l o o d i s o b t a i n e d , and t h e method o f b l o o d c o l l e c t i o n , a l l w h i c h y i e l d s s p u r i o u s l y h i g h l a c t a t e concentrations (Cohen e t a l , 1976; Huckabee, 1 9 5 8 ( b ) ) . P h y s i o l o g i c a l f a c t o r s i n c l u d e t h e s i t e o f s a m p l i n g , a r t e r i a l v a l u e s b e i n g lower t h a n p e r i p h e r a l venous v a l u e s ( J e r v e l l , 19 28; Huckabee 1 9 6 1 ( a ) ) , and the s t a t e o f an i n d i v i d u a l , s i n c e l a c t a t e c o n c e n t r a t i o n can r i s e f o l l o w i n g a meal o r d u r i n g e x e r c i s e . T u r r e l l and Robinson (19 42) :showed t h a t b l o o d l a c t a t e c o n c e n t r a t i o n s can r e a c h 22 mM/L d u r i n g maximal e x e r c i s e , t h e a c c u m u l a t i o n c a u s i n g a m e t a b o l i c a c i d o s i s w h i c h B a r r 20 e t a l (1923) termed " l a c t i c a c i d a c i d o s i s " . A q u e s t i o n c r u c i a l t o t h e i n t e r p r e t a t i o n o f b l o o d l a c t a t e c o n c e n t r a t i o n , and i t s subsequent use t o i n d i c a t e t h e q u a n t i t y o f a n a e r o b i c work performed i s whether i t b e a r s any r e l a t i o n s h i p t o t i s s u e l a c t a t e c o n c e n t r a t i o n s . S k i n n e r and M c L e l l a n (1981) s t a t e t h a t , depending on t h e time o f b l o o d s a m p l i n g , b l o o d l a c t a t e may o r may not be i n d i c a t i v e o f muscle l a c t a t e . I t would appear t h a t the h i g h e r t h e e x e r c i s e i n t e n s i t y , t h e l a t e r b l o o d l a c t a t e r e a c h e s peak v a l u e s . However, Green e t a l (1982) showed t h a t t h e e l e v a t i o n i n muscle a n a e r o b i c g l y c o l y s i s p r e c e d e s b o t h t h e VC^AT and the b l o o d LaAT i n a p r o g r e s s i v e e x e r c i s e t e s t . F u r t h e r m o r e , Taunton e t a l (19 81) s t a t e d t h a t r a p i d removal r a t e s d u r i n g r e c o v e r y i n l o n g d i s t a n c e r u n n e r s w i l l l e a d t o lower b l o o d l a c t a t e v a l u e s i f t a k e n 5 m i n u tes p o s t e x e r c i s e . F u r t h e r r e s e a r c h i s r e q u i r e d i n t h i s a r e a as r e l a t e d t o s p e c i f i c i t y o f t r a i n i n g . N e i t h e r muscle l a c t a t e c o n c e n t r a t i o n nor t h e m u s c l e - t o - b l o o d g r a d i e n t f o r l a c t a t e was r e l a t e d t o l a c t a t e r e l e a s e d i n t o t h e b l o o d (Graham e t a l , 1976) . I n a d d i t i o n , b l o o d l a c t a t e c o n c e n t r a t i o n i s i n f l u e n c e d by muscle f i b e r c o m p o s i t i o n and r e c r u i t m e n t as mentioned p r e v i o u s l y . Graham (19 78) showed a muscle l a c t a t e c o n c e n t r a t i o n t o be t h r e e t i m e s as h i g h i n Type I I f i b e r s as t h a t found i n 21 Type I f i b e r s . He h y p o t h e s i z e d t h a t t h e Type I I f i b e r s would be more l i k e l y t o become h y p o x i c due t o l o w e r v a l u e s f o r c a p i l l a r y - f i b e r r a t i o , m i t o c h o n d r i a l c o n c e n t r a t i o n and the r a t e o f o x i d a t i v e m e t a b o l i s m . Due t o what appears t o be a p r e f e r e n t i a l r e c r u i t m e n t p a t t e r from Type I t o Type I I A t o Type I I B f i b e r s d u r i n g v a r i o u s phases o f p r o g r e s s i v e e x e r c i s e (Essen, 1977), as r e l a t e d t o g l y c o g e n d e p l e t i o n s t u d i e s , r e c r u i t m e n t may i n f l u e n c e l a c t a t e c o n c e n t r a t i o n . "Thus, i t would appear t h a t b l o o d l a c t a t e l e v e l s r e f l e c t the p r o d u c t i o n , r e l e a s e , and o x i d a t i o n o f l a c t i c a c i d by muscle and t h a t , i n t u r n , i s i n f l u e n c e d by muscle f i b e r c o m p o s i t i o n and t h e t y p e o f f i b e r b e i n g r e c r u i t e d a t any g i v e n t i m e " ( S k i n n e r , P.238, 1981), i n a d d i t i o n t o t h e t y p e o f e x e r c i s e performed and t h e i n t e n s i t y a t t h e o n s e t o f e x e r c i s e . C 0 2 - The c o n t r o l o f pulmonary v e n t i l a t i o n d u r i n g e x e r c i s e , and t h e subsequent CO^ and hydrogen i o n m e d i a t o r s i n t h e b l o o d , are o f s p e c i a l i m p o r t a n c e t o t h e d i s c u s s i o n o f a e r o b i c - a n a e r o b i c m e t a b o l i s m and t h e subsequent d e t e r m i n a t i o n o f the a n a e r o b i c t h r e s h o l d . I n 1905, Haldane and P r i e s t l e y s t a t e d t h a t CO^ p r o d u c t i o n c o u l d f u l l y a c c o u n t f o r t h e i n c r e a s e i n v e n t i l a t i o n o 22 seen d u r i n g e x e r c i s e . I n t h e y e a r s from 1911 - 1914, European r e s e a r c h e r s i n d i c a t e d t h a t t h e hydrogen i o n was the b l o o d borne m e d i a t o r o f v e n t i l a t o r y c o n t r o l i n e x e r c i s e . Today, we r e a l i z e t h a t CC^ can be produced by the a e r o b i c m e t a b o l i s m o f f a t and c a r b o h y d r a t e . D u r i n g a n a e r o b i c m e t a b o l i s m , l a c t i c a c i d i s a l s o formed t h u s c o n s t i t u t i n g an . a d d i t i o n a l s o u r c e o f CO,,. The e n t r y o f l a c t a t e i n t o t h e r e d b l o o d c e l l s i s a s s o c i a t e d w i t h the e n t r y o f hydrogen i o n s w h i c h r e a c t w i t h HCO^ l e a d i n g t o E^CO^ and t h u s the CC>2 w h i c h i s e x c r e t e d by the l u n g s . The q u e s t i o n a t t i m e s i s t h e a v a i l a b i l i t y o f c a r b o n i c anhydrase. There i s no c a r b o n i c anhydrase i n plasma, b u t an abundant s u p p l y i n r e d b l o o d c e l l s . HLa + NaHC0 3~ > NaLa + H 2 C 0 3 ; H„CO_ -—> CO- + H_0 2 3 * 2 2 (Wasserman andiMcIlroy., 1964; Wasserman e t a l , 1973) T u r r e l l and Robinson (19 42) e a r l i e r had shown t h a t an i n c r e a s e i n l a c t a t e i s accompanied by a d e c r e a s e i n base bound as b i c a r b o n a t e , which, causes a decrease i n the CO^ c o m b i n i n g c a p a c i t y o f t h e b l o o d . Some hydrogen i o n s w i l l s t i m u l a t e the chemoreceptors l o c a t e d i n t h e m e d u l l a o b l o n g a t a , t h e c a r o t i d and a o r t i c b o d i e s t h u s c a u s i n g the r e s p i r a t i o n r a t e t o i n c r e a s e (Guyton, 1976) . 23 The d i f f u s i o n c o e f f i c i e n t i s twenty times h i g h e r f o r CC>2 tha n f o r 0 2 t h e r e f o r e C 0 2 d i f f u s e s e a s i l y o u t o f t h e c e l l s i n t o the i n t e r s t i t i a l f l u i d t h e n i n t o the b l o o d . Once i n the b l o o d , C 0 2 i s c a r r i e d v i a t h r e e major forms: (a) 10% o f d i s s o l v e d C© 2 forms some b i c a r b o n a t e i o n s , b u t t h i s i s a v e r y slow p r o c e s s i n t h e plasma; C 0 o + H_0 H„C0^ => H + + HCO ~ Z Z ^ Z 3 ^ -J The H + i s b u f f e r e d by plasma p r o t i e n s : (b) 20% o f C 0 2 c a r r i e d forms a l o o s e c o m b i n a t i o n w i t h carbamine Hb; (c) 70% o f C 0 2 d i f f u s e s i n t o the r e d b l o o d c e l l s w h ich c a r r i e s h i g h c o n c e n t r a t i o n s o f the enzyme c a r b o n i c a n h y d r a s e . C a r b o n i c anhydrase c o n v e r t s C 0 9 t o H„CO,. t h r o u g h t h e f o l l o w i n g r e a c t i o n : CA C 0 2 + H 20 H 2 C 0 3 > H + HC0 3- Once t h e s e r e a c t i o n s o c c u r t h e (H*) i o n s a re p i c k e d up by the Hb and b u f f e r e d i n o r d e r t o c o n t r o l t h e pH and the HCO^ d i f f u s e o u t i n t o the plasma i n exchange f o r CL (CL s h i f t o r Hamburger s h i f t ) . The C 0 2 i s c a r r i e d v i a venous r e t u r n t o be e x c r e t e d by t h e l u n g s . (Ganong, 19 79) . A n a e r o b i c T h r e s h o l d From t h e e a r l y s t u d i e s o f M a r g a r i a e t a l (19 64) and 24 Bang (19 36) t h e c o n c e p t o f " a n a e r o b i c t h r e s h o l d " grew. These r e s e a r c h e r s c o n s i d e r e d t h a t l a c t a t e p r o d u c t i o n would be r e s t r i c t e d t o t h e f i r s t few minutes o f e x e r c i s e when the oxygen s u p p l y would be l i m i t e d . However, r e s e a r c h by Hubbard (197 3) showed t h a t l a c t a t e p r o d u c t i o n c o u l d o c c u r even a t low i n t e n s i t i e s and t h a t uptake p r o b a b l y i n c r e a s e s w i t h i n c r e a s i n g i n t e n s i t y . K n u t t g e n (1962) showed t h a t t h e r e was a " c r i t i c a l " l e v e l o f work where l a c t a t e f i r s t appears i n the b l o o d and i n 1964, Wasserman and M c l l r o y p o s t u l a t e d t h a t the " a n a e r o b i c t h r e s h o l d " was t h e l e v e l o f work j u s t below w h i c h a s u b j e c t c o u l d e x e r c i s e f o r p r o l o n g e d p e r i o d s i n a s t e a d y s t a t e , w i t h o u t d e v e l o p i n g m e t a b o l i c a c i d o s i s . They measured th e AT v i a .an .increase i n b l o o d l a c t a t e c o n c e n t r a t i o n , a decrease i n a r t e r i a l b l o o d HCO and pH, and an i n c r e a s e i n R. 3 I n 19 61, I s s e k u t z and Rodahl s t a t e d t h a t t h e r e was a h i g h c o r r e l a t i o n between b l o o d l a c t a t e l e v e l s and e x c e s s C 0 2 and v e n t i l a t i o n (r=0.92) s u g g e s t i n g t h a t t h e d i f f u s i o n o f b i c a r b o n a t e C 0 2 ( n o n - m e t a b o l i c C0 2) was more r a p i d t h a n l a c t a t e . T h i s showed t h a t e x c e s s C 0 2 f o l l o w s a n a e r o b i c m e t a b o l i s m more c l o s e l y than b l o o d l a c t a t e l e v e l s . However, Bouhuys e t a l (1966) found t h a t R and ExC0 2 were a s s o c i a t e d w i t h l a c t a t e a c c u m u l a t i o n , b u t the r e v e r s e was not always t r u e . As t h e w o r k l o a d i n c r e a s e d , t h e i n c r e a s e i n l a c t a t e 25 was g r e a t e r t h a n the d e c r e a s e i n s t a n d a r d b i c a r b o n a t e c a u s i n g them t o a l l u d e t o t h e f a c t t h a t t h e measurement:of R and ExCG^ would o n l y be an i n d i r e c t s i g n o f the degree o f e x e r c i s e a c i d e m i a . F u r t h e r m o r e , t h e y were unable t o r e p r o d u c e t h e e x c e l l e n t c o r r e l a t i o n found by I s s e k u t z and Rodahl i n 1961. I s s e k u t z , B i r k h e a d and R odahl (196 2) f i r s t r e c o g n i z e d t h a t t h e r e would be a c o n c o m i t a n t i n c r e a s e i n C 0 2 o u t p u t by t h e l u n g s w i t h i n c r e a s e d l a c t i c a c i d p r o d u c t i o n . They su g g e s t e d t h a t an i n c r e a s e i n t h e r e s p i r a t o r y q u o t i e n t w o u l d i n d i c a t e l a c t i c a c i d p r o d u c t i o n , where, R = volume o f CO^ produced/volume o f CC^ consumed Wasserman-and M c l l r o y (1964) expanded t h i s c o n c e p t i n c a r d i a c p a t i e n t s and i n 196 7, C l o d e , C l a r k and Campbell q u a n t i f i e d the a pproach, r e c o g n i z i n g t h a t t h e volume o f e x c e s s CC^ r a t h e r t h a n R would be s t o i c h i o m e t r i c a l l y e q u i v a l e n t t o l a c t i c a c i d p r o d u c t i o n , i e . t h e n u m e r i c a l r e l a t i o n s o f c h e m i c a l elements/compounds and t h e m a t h e m a t i c a l laws o f c h e m i c a l changes.. V o l k o v i n 19 75 s u p p o r t e d I s s e k u t z and Rodahl (19 61) when he found t h a t l a c t a t e a c c u m u l a t i o n l e d t o a d e c r e a s e i n HCO^ and t o t h e appearance o f e x c e s s i v e amounts o f CC^ • He s t a t e s t h a t i t i s p o s s i b l e t o determine th e l e v e l o f a n a e r o b i c m e t a b o l i s m from t h e e x c e s s o f r e l e a s e C0„ t h r o u g h the f o l l o w i n g 26 e q u a t i o n : E xC0 2 = O R • V 0 2 = VC0 2 — [ R ( r e s t ) x V c J -1 -1 • where ExC0 2 i s e x c e s s C 0 2 (ml* kg • min ), V 0 2 i s the l e v e l o f oxygen consumption d u r i n g work (ml-kg - min "*") . Diamont e t a l (1968) found muscle t i s s u e l a c t a t e t o d i f f e r from b l o o d l a c t a t e (19.1 t o 11.4 mM/L r e s p e c t i v e l y ) : a f t e r maximal e x e r t i o n t h e r e f o r e s u g g e s t i n g a p o s s i b l e d e l a y i n d i f f u s i o n c a p a c i t y f o r l a c t a t e from muscle t i s s u e t o the b l o o d . T h i s was s u p p o r t e d by Graham (19 78) . J o r f e l d t e t a l (19 78) s u g g e s t e d t h a t the< d e l a y may be due t o t h e i n a d e q u a t e r e l a t i o n s h i p between r e c r u i t e d f i b e r s and a v a i l a b l e d r a i n i n g c a p i l l a r i e s . Wasserman e t a l (19 73) used a b r e a t h by b r e a t h t e c h n i q u e f o r d e t e r m i n i n g t h e a n a e r o b i c t h r e s h o l d and found t h a t the e n d - t i d a l CC>2 and C>2 t e n s i o n s were more s e n s i t i v e i n d i c a t o r s , because t h e y a l l o w e d f o r t h e d e t e c t i o n o f h y p e r v e n t i l a t i o n . T h i s h y p e r v e n t i l a t i o n may o b s c u r e the gas exhange p a r a m e t e r s , i e . V C0 2, V , and R. T h i s was s u p p o r t e d by Wasserman and Whipp (19 75) who a l s o s u g g e s t e d t h a t f o r n o n - i n v a s i v e AT d e t e r m i n a t i o n , a one minute work i n c r e m e n t would be o p t i m a l f o r showing the change i n m e t a b o l i s m a t t h e s t a r t o f a n a e r o b i o s i s . Kao (1977) however, s u g g e s t s t h a t t h e h y p e r v e n t i l a t i o n i s p a r t i a l l y due t o a l t e r a t i o n s o f t h e n e u r a l component and t o the a l t e r e d r e c r u i t m e n t o f f i b e r . 27 Today the a n a e r o b i c t h r e s h o l d t e r m i n o l o g y has been d i s p u t e d by v a r i o u s i n v e s t i g a t o r s (Kinderman e t a l , 19 79; S k i n n e r and M c L e l l a n , 1980) who s u g g e s t t h a t t h e r e i s a t h r e e phase two breakaway model d u r i n g t h e p r o g r e s s i v e t r a n s i t i o n from e x e r c i s e o f low t o maximal i n t e n s i t y . The phases are c o n v e n i e n t l y termed a e r o b i c phase, a e r o b i c - a n a e r o b i c t r a n s i t i o n phase, and a n a e r o b i c phase. The f o l l o w i n g p a t t e r n w o u l d be o b s e r v e d : 1) A e r o b i c Phase: a t low i n t e n s i t i t y e x e r c i s e , t h e r e i s a l i n e a r i n c r e a s e i n oxygen i n t a k e (VO^), v e n t i l a t i o n (JJ^) , volume o f CO^ e x p i r e d (VC0 2) and h e a r t r a t e , w i t h an R o f .7 t o .8 and l i t t l e o r no l a c t a t e formed; i n a d d i t i o n , t h e r e would be a decrease i n F e 0 2 and an i n c r e a s e i n F e C 0 2 ; 2) A e r o b i c - A n a e r o b i c T r a n s i t i o n a l Phase: a t an e x e r c i s e i n t e n s i t y o f 40 - 60% o f V 0 2 max, the » V 0 2 and h e a r t r a t e c o n t i n u e t o r i s e l i n e a r l y and t h e r e i s a r i s e i n l a c t a t e t o a p p o x i m a t e l y 2 mM/L; due t o b u f f e r i n g o f t h e H + produced by the l a c t a t e by the b i c a r b o n a t e , t h e r e w i l l be an i n c r e a s e d VCC>2 and a c o n t i n u i n g r i s e i n FeCC>2 c o n s e q u e n t l y V and VCC>2 w i l l be g r e a t e r t h a n the r i s e i n VC>2; s i n c e t h e r e i s an i n c r e a s e d V t o compensate f o r t h e m e t a b o l i c a c i d o s i s t h e r e w i l l be a decrease i n FeO„; t h i s 2 8 breakaway p o i n t c o r r e s p o n d s t o the AT o f Wasserman e t a l (19 73) and t h e a e r o b i c t h r e s h o l d o f S k i n n e r and M c L e l l a n (1981). 3) A n a e r o b i c Phase: a t an e x e r c i s e i n t e n s i t y o f 6 5 - 90% V0 2max the VC>2 and h e a r t r a t e c o n t i n u e t o r i s e l i n e a r l y t o maximal p l a t e a u s ; t h e l a c t i c a c i d i s a p p r o x i m a t e l y 4 mM/L and t a k e s a c u r v i l i n e a r i n c r e a s e accompanied by a n o t h e r V breakaway and a c o n t i n u i n g r i s e i n VC0 2; t h e r e i s a d r o p - o f f i n F e C 0 2 due t o h y p e r v e n t i l a t i o n w h i l e F e 0 2 c o n t i n u e s t o r i s e ; t h i s breakaway p o i n t c o r r e s p o n d s t o t h e AT o f MacDougall (1978) . . • Rupp e t a l (1982) l o o k e d s p e c i f i c a l l y a t n o n - i n v a s i v e measures o f the a e r o b i c t h r e s h o l d and AT and found the b e s t p r e d i c t i o n o f a e r o b i c t h r e s h o l d t o be t h e i n i t i a l i n c r e a s e i n V"e out o f p r o p o r t i o n t o V 0 2 . They f u r t h e r s t a t e d t h a t no e f f e c t i v e n o n - i n v a s i v e p r e d i c t i o n c o u l d be found when u s i n g the second breakaway V"e and/or a d e c r e a s e i n F e C 0 2 . Sucec e t a l (19 82) demonstrated t h a t b l o o d l a c t a t e measurement o f AT i s r e p r o d u c i b l e and t h a t gas exchange may be v a l i d l y employed t o det e r m i n e AT f o r e x e r c i s e . Ponton e t a l (19 82) s u p p o r t e d t h e s e f i n d i n g s and a l s o s u g g ested t h a t d i f f e r e n t w o r k l o a d d u r a t i o n s o f one t o t h r e e minutes do n o t 29 seem t o a f f e c t t h e t h r e s h o l d p o i n t . The Marathoner The marathon i s a 42.195 km. (26 m i l e , 385 yard) r u n n i n g r a c e . The pace, s e t t h r o u g h t h e eyes o f t h e moder e l i t e marathoner, i s between 17.74 km/hr and 19.35 km/hr;. The p h y s i o l o g i c a l consequence o f t h e b i o c h e m i c a l a d a p t a t i o n s t o t h i s form o f e x e r c i s e from an u n t r a i n e d s t a t e t o a t r a i n e d s t a t e i s w e l l documented ( H o l l o s z y e t a l , 1977; H o l l o s z y , 1973). These i n c l u d e i n c r e a s e s i n m i t o c h o n d r i a l c o n t e n t and r e s p i r a t o r y c a p a c i t y o f s k e l e t a l m u scle, i n c r e a s e d VG^niax and subsequent a b s o l u t e work r a t e s , i n c r e a s e d r a t e o f m y o c a r d i a l p r o t e i n s y n t h e s i s r e s u l t i n g i n a p h y s i o l o g i c a l c a r d i a c h y p e r t r o p h y , a lo w e r u t i l i z a t i o n o f g l y c o g e n i n t h e w o r k i n g m u s c l e s , an enhanced c a p a c i t y t o o x i d i z e f a t t y a c i d s (which h e l p s t o p r o t e c t a g a i n s t g l y c o g e n d e p l e t i o n ) , i n c r e a s e s i n number o f c a p i l l a r i e s p e r number o f muscle f i b e r s and i n c r e a s e s i n t y p e I I muscle f i b e r m i t o c h o n d r i a l volume ( H o l l o s z y e t a l , 1977; Howald e t a l , 1982) . C o s t i l l and Fox (1969) have shown t h a t marathon r u n n e r s were a b l e t o u t i l i z e 75% o f t h e i r VC^max w i t h l i t t l e l a c t i c a c i d p r o d u c t i o n . L a t e r i n 197 3, C o s t i l l e t a l found t h a t a t a l l r u n n i n g speeds above 70% VC^max, t h e f a s t e r d i s t a n c e r u n n e r s accumulated l e s s b l o o d l a c t a t e t h a n the s l o w e r r u n n e r s a t s i m i l a r speeds and r e l a t i v e • p e r c e n t a g e s o f t h e i r a e r o b i c c a p a c i t i e s . 30 The a b i l i t y o f t h e endurance r u n n e r t o m a i n t a i n a h i g h v e l o c i t y d u r i n g a r a c e w h i c h i s o n l y s l i g h t l y above h i s a n a e r o b i c t h r e s h o l d was r e p o r t e d by F a r r e l l e t a l (1979). Rhodes e t a l (19 81) demonstrated t h a t t h e r e was i n d e e d a h i g h c o r r e l a t i o n between t h e v e l o c i t y a t t h e a n a e r o b i c t h r e s h o l d and t h e marathon r u n n i n g pace. T h i s appears t o be a p p r o p r i a t e f o r s p e c i f i c s p e c i a l t i e s as Svendenhag and S j o d i n (19 82) found t h a t t h e r u n n i n g v e l o c i t y c o r r e s p o n d i n g t o a b l o o d l a c t a t e c o n c e n t r a t i o n o f 4 mM/L was the b e s t s i n g l e parameter i n d i f f e r e n t i a t i n g between r u n n e r s w i t h d i f f e r e n t d i s t a n c e s p e c i a l t i e s . E f f e c t s o f T r a i n i n g on AT The e f f e c t s o f t r a i n i n g on the a n a e r o b i c t h r e s h o l d has r e c e i v e d some a t t e n t i o n as o f l a t e . D a n i e l s e t a l (1980) s u g g e s t s t h a t t r a i n i n g d e l a y s t h e on s e t o f b l o o d l a c t a t e a c c u m u l a t i o n "as a f u n c t i o n o f e x e r c i s e i n t e n s i t y " , i n d i c a t i n g t h a t the a c c u m u l a t i o n o f venous l a c t a t e i s r e v e r s i b l e d u r i n g s t e a d y s t a t e e x e r c i s e . M a c D o u g a l l (19 77) and Robinson and Sucec (1980) , s t a t e t h a t b o t h moderate (85% VO^max) and i n t e n s i v e (125% VOc,max) t r a i n i n g i n c r e a s e t h e a n a e r o b i c t h r e s h o l d . They i n c l u d e d b o t h h i g h i n t e n s i t y endurance- i n t e r v a l and l o n g d u r a t i o n sub-maximal t r a i n i n g . L a f o n t a i n e e t a l (19 82) found t h a t f o r moderate f i t i n d i v i d u a l s , medium i n t e n s i t y / h i g h q u a n t i t y and h i g h i n t e n s i t y / l o w q u a n t i t y 31 i n c r e a s e d the a n a e r o b i c t h r e s h o l d o v er o t h e r c o m b i n a t i o n s o f low/medium/high i n t e n s i t y w i t h low o r h i g h q u a n t i t y o v er a 10 week, 5 s e s s i o n s p e r week, t r a i n i n g s c h e d u l e . R e p r o d u c i b i l i t y o f AT The r e p r o d u c i b i l i t y o f t h e AT v i a gas exchange and venous b l o o d l a c t a t e measurements has been i n v e s t i g a t e d . Sucec e t a l (1982), u s i n g V , VCC>2, v" e/V0 2 and FeC>2 f o r t h e gas exhange v a r i a b l e s and venous b l o o d l a c t a t e s drawn 15 seconds p r i o r t o c h a n g i n g t h e work r a t e , t o d e t e r m i n e the AT, found the b l o o d l a c t a t e measurements o f AT t o be r e p r o d u c i b l e and t h a t n o n - i n v a s i v e d e t e r m i n a t i o n may be v a l i d l y employed i n a s s e s s i n g AT f o r e x e r c i s e on the b i c y c l e e rgometer. . Ponton e t a l (1982) s t u d i e d t h e v a l i d i t y and r e p r o d u c i b i l i t y o f t h e l a c t a t e t h r e s h o l d f o r a c o n t i n u o u s p r o t o c o l on t h e t r e a d m i l l f o r t r a i n e d r u n n e r s and found the l a c t a t e t h r e s h o l d t o be a v a l i d and r e l i a b l e measure. The r o l e o f t h e a n a e r o b i c t h r e s h o l d has been used f o r t e s t i n g h o s p i t a l p a t i e n t s (Wasserman and Whipp, 19 75), a t h l e t e s ( C o s t i l l , 1970) and models of hyperpnea i n non- a t h l e t e s (Whipp, 19 77) . However, the s t u d y o f t h e r o l e o f the a n a e r o b i c t h r e s h o l d and i t s r e l a t i o n s h i p t o performance o f e l i t e endurance r u n n e r s i s . i n s t a g e s o f . p r e l i m i n a r y i n v e s t i g a t i o n . 32 CHAPTER I I I METHODS AND PROCEDURES S u b j e c t s F i v e male s u b j e c t s (mean age = 30.6 - 5.64 y e a r s ) were s e l e c t e d from t r a c k t r a i n i n g c l u b s i n the Vancouver l o w e r m a i n l a n d . Each s u b j e c t had a VO^max o f a p p r o x i m a t e l y 65 ml-kg •min o r g r e a t e r , and had r u n a sub 2:30 marathon. I n f o r m a t i o n r e g a r d i n g t r a i n i n g program, b e s t time a t v a r i o u s d i s t a n c e s and m e d i c a l h i s t o r y was a l s o c o m p i l e d . T e s t i n g P r o c e d u r e s The s u b j e c t s were t e s t e d on f i v e s e p a r a t e days w i t h a t l e a s t one day between each s e s s i o n . They were asked t o r e f r a i n from any heavy t r a i n i n g 24 hours p r i o r t o and on th e t e s t day. T e s t i n g was a d m i n i s t e r e d a t a p p r o x i m a t e l y the same time o f day and under s i m i l a r e n v i r o n m e n t a l c o n d i t i o n s . D u r i n g t h e f i r s t s e s s i o n a f t e r an a p p r o p r i a t e consent form had been s i g n e d (see A p p e n d i x ) , h e i g h t , w e i g h t , body c o m p o s i t i o n ; assessment ( H y d r o s t a t i c w e i g h i n g ) , a n a e r o b i c t h r e s h o l d and maximal oxygen consumption (V02max) were d e t e r m i n e d . The r e m a i n i n g f o u r s e s s i o n s c o n s i s t e d o f a s h o r t warm-up, f o l l o w e d by a 10 minute c o n s t a n t speed r u n , a f t e r w h i c h 2 ml. o f b l o o d was drawn from an a n t i - c u b i t a l v e i n (every minute f o r f o u r minutes) i n t h e arm o f each s u b j e c t . 33 T e s t i n g P r o t o c o l s A l l t e s t i n g was p e r f ormed i n t h e J . M. Buchanan F i t n e s s and R esearch C e n t r e a t U.B.C H e a r t r a t e was m o n i t o r e d by d i r e c t ECG u t i l i z i n g an A v i o n i c s 4000 E l e c t r o c a r d i o g r a p h w i t h o s c i l l o s c o p e and ST d e p r e s s i o n computer and d i s p l a y . E x p i r e d gases were c o n t i n u a l l y sampled and a n a l y z e d by a Beckman M e t a b o l i c Measurement C a r t (BMMC) i n t e r f a c e d i n t o a H e w l e t t P a c k a r d 30 52A Data A c q u i s i t i o n system f o r f i f t e e n second d e t e r m i n a t i o n o f r e s p i r a t o r y gas exchange v a r i a b l e s . P h y s i c a l c h a r a c t e r i s t i c s i n c l u d e d h e i g h t , w e i g h t and p e r c e n t body f a t . Assessment o f p e r c e n t body f a t was c a r r i e d out v i a h y d r o s t a t i c w e i g h i n g (Katch e t a l , 196 7) . VC^max and a n a e r o b i c t h r e s h o l d were d e t e r m i n e d u s i n g a c o n t i n u o u s t r e a d m i l l p r o t o c o l . Each s u b j e c t w a l k e d on the t r e a d m i l l a t 8.06 km/hr (for.' f i v e m inutes) as a warm-up. The speed was t h e n i n c r e a s e d t o .81 km/hr a t t h e end o f each minute w i t h s u b j e c t r u n n i n g u n t i l v o l i t i o n a l , f a t i g u e . Maximal oxygen consumption and ExCC^ a t max were d e t e r m i n e d by a v e r a g i n g t h e h i g h e s t f o u r c o n s e c u t i v e f i f t e e n second v a l u e s . V a l u e s r e p o r t e d f o r the 10 minute c o n s t a n t speed r u n s were mean i S.D. The a n a e r o b i c t h r e s h o l d and t h e V t a m w e r e d e t e r m i n e d by v i s u a l i n s p e c t i o n o f t h e ExCC^ e l i m i n a t i o n c u r v e ( V o l k o v , 19 75) . Three i n v e s t i g a t o r s c a r r i e d o u t t h e d e t e r m i n a t i o n and came t o an agreed p o i n t o f break away. 34 The d e t e r m i n a t i o n o f t h e a n a e r o b i c t h r e s h o l d was c o n s i s t e n t w i t h the d e f i n i t i o n by Wasserman e t a l (19 64) . The b l o o d samples were drawn from an a n t i - c u b i t a l v e i n v i a a 21 gauge b u t t e r f l y c a t h e t e r , a t the end o f the 10 minute c o n s t a n t speed r u n , and each subsequent minute f o r f o u r m i n u t e s . Samples were i m m e d i a t e l y c e n t r i f u g e d and plasma p i p e t t e d and f r o z e n f o r f u t u r e a n a l y s i s . B l o o d l a c t a t e was c a l c u l a t e d i n mM/L v i a a s t a n d a r d e n z y m a t i c method, and peak l a c t a t e s were r e c o r d e d (Gutmann and W a h l e f e l d , 1974) . E x p e r i m e n t a l D e s i g n and Data A n a l y s i s There were two dependent v a r i a b l e s : B l o o d l a c t a t e and ExCC^. The independent v a r i a b l e was the speed o f t h e t r e a d m i l l w i t h f o u r l e v e l s o f v a r i a t i o n : 1. 1 km/hr below V. tarn 2. a t V_ tarn 3. 1 km/hr above V" ' tam 4. 2 km/hr above V, ' tam A l a t i n square was used t o a s s i g n t h e s u b j e c t s t o t h e s e v a r i a t i o n s . A n a l y s i s o f v a r i a n c e w i t h p r e p l a n n e d o r t h o g o n a l comparisons and S c h e f f e p o s t hoc c o n t r a s t s were used t o dete r m i n e t h e e f f e c t s o f the t r e a d m i l l v a r i a t i o n s on La and ExCC^• The Pearson product-moment c o r r e l a t i o n c o e f f i c i e n t u s i n g raw s c o r e s was employed, i n c o r r e l a t i n g La and ExCC^. 35 CHAPTER IV RESULTS AND DISCUSSION R e s u l t s The p h y s i c a l c h a r a c t e r i s t i c s o f the f i v e s u b j e c t s a r e summarized i n T a b l e I . The p e r t i n e n t v a r i a b l e s f o r f o u r o f t h e s u b j e c t s a re r e p r e s e n t e d i n T a b l e I I . The r e s u l t s o f the s t a t i s t i c a l a n a l y s i s f o r b l o o d l a c t a t e (La) and e x c e s s CQ 2 (ExCO,,) are d i s p l a y e d i n Ta b l e I I I . The c o r r e l a t i o n c o e f f i c i e n t s between La and ExC0 2 are r e p r e s e n t e d i n T a b l e IV. T a b l e V c o n t a i n s a summary o f t h e hypotheses t e s t i n g . F i g u r e s I I I and IV r e p r e s e n t the means and s t a n d a r d d e v i a t i o n o f La v e r s u s t r e a t m e n t s and ExC0 2 v e r s u s t r e a t m e n t s r e s p e c t i v e l y . F i g u r e V shows t h e r e l a t i o n s h i p between La and E x C 0 2 . I n d i v i d u a l summary s h e e t s f o r t h e m e t a b o l i c parameters and t h e subsequent a n a e r o b i c t h r e s h o l d c u r v e s , f o r d e t e r m i n a t i o n o f V t a m appear i n Appendix A. I t was r e v e a l e d d u r i n g t h e b l o o d l a c t a t e d e t e r m i n a t i o n t h a t s u b j e c t NW had been a s s e s s e d a t a V, wh i c h was w e l l J tam above t h e a c c e p t e d v a l u e s f o r a n a e r o b i c t h r e s h o l d d e t e r m i n a t i o n , as o u t l i n e d by Wasserman e t a l (1964) . The f o l l o w i n g v a l u e s f o r La (mM/L) were found: V,. . • V ' V" , , V̂ _ , „ tam-1 < tam tam+1 tam+2 NW 5.096 8.261 11.927 14.053 LH 1.479 2.493 4.570 9.263 JT 2.05 3.397 4.191 6.978 JH .1.747 3.837 8 .077 8 .945 SP 2.774 2.908 4.277 9.385 36 TABLE 1 • / PHYSICAL CHARACTERISTICS OF SUBJECTS (SUBJECT AGE HEIGHT WEIGHT % V D ^ A.T.- MARATHON TIME (YRS.) (CM.) (KG.) BODY . . ., % VO„ (hr: min: sec) F A T (ml-kg 'rain ' 2 m a x NW 34 171.7 67.1 5.2 69.80 88 2:29:27 LH 36 182.1 72.0 - 67.01 86 2:29:00 JT 34 182.2 68.5 11.2 64.11 87 2:26:14 JH 25 177.1 70.5 8.7 67.47 91 2:18:33 SP 24 182.0 68.5 7.9 72.42 82 2:15:56 X 30.6 179.02 69.32 8.25 68.16 86.8 2:23:50 +S.D. -5.64 ±4.63 ±1.93 ±2.47 ±3.12 ±3.27 ±6:13 37 TABLE I I RELEVANT DATA VARIABLES V, tam-1 V tam V tam+1 V, tam+2 MAX Velocity of treadmill (KPH) VCL -1 -1 (ml «kg -min ) |vo2 (percent MAX) iExC02 (ml-kg - 1-min - 1) |ExC02 (percent MAX) [Blood lactate (irM/L) (Heart Rate Xb.p.m.) \J (STPD) e 16.61±.77 J7.58-.77 18.55±.77 19.52±.77 22.74±.77 52.67±1.48 58.64±2.42 62.05±1.96 63.32^4.54 67.75±3.45 77±3 87±3 91-5 93±4 100 11.09±1.54 14.35±1.34 17.06±3.15 21.61±2.53 28.8si4.55 39±10 50-7 59-2 15-8 100 2.01±.56 3.16±.58 5.28±1.87 8.64±1.13 162±8 167±9 174±9 182±8 +_ .+ . pfeight (kg.) 76.49-2.8 89.90-2.66 99.08-8.59 113.89-7.74 130.55-4.35 69.3 ±1.5 69.2 ±1.4 69.2 ±1.6 69.-1 ±2 67.7 ±2 * - + (All values are X - S.D.; N=4 unless *, where N=3) 38 . TABLE I I I ANALYSIS OF VARIANCE WITH PREPLANNED ORTHOGONAL COMPARISONS AND SCHEFFE'S POST HOC CONTRASTS F Pr o b a b i l i t y (p*) Blood Lactate'. F Pro b a b i l i t y (p^) ExC0 2 Between Groups V,. ,, V, , tam-1' tam 24.95 0.01 15.46 0.01 Vtam+1' Vtam+2 Comparison 1 tam-1 tam/ 56.24 0.01 34.15 o;oi tam+1 tam+2 Comparison 2 tam-1 tam 1.93 non-sig. 4.15 non-sig. Comparison 3 V - V tam+1 tam+2 16.65 0.01 7.89 ; .0.05 Scheffe's V, , and V, .. tam-1 -:.. tam+1 11.62 0.05 2.33 non-sig. V̂ , . , and V, .„ tam-1 tam+2 47.78 0.01 43.23 0.01 V̂ . and V. tam tam+1 4.88 non-sig. 2.87 non-sig. v and V̂_ . . tam tam+2 32.64 0.01 20.59 0.05 TABLE TV CORRELATION COEFFICIENTS: HLa and ExCO. SUBJECT r LH .949* JT .998** JH .995** SP .948* OVERALL .886** ** p<*.005 40 TABLE V SUMMARY OF HYPOTHESES TESTING DEPENDENT VARIABLES PROPOSED RELATIONSHIPS RESULTS ExC0 2 (ml*kg "'"•min 1 ) tam-1-" tam V • y V tam tam+1 V V tam+1^ tam+2 Supported Non-Supported Supported HLa (iriM/L) V t a m - 1 — V t a m V ^ V tam ^- tam+1 V ^ V Tam+1 *~ tam+2 Supported Non-Supported Supported ExC0 2/HLa High C o r r e l a t i o n Supported FIGURE I I I Means - s.D. F o r Four S u b j e c t s Over Four C o n d i t i o n s  43 i rH I • H 30 25'- •2,0 h FIGURE V C o r r e l a t i o n Between ExCC^ and La (r = .89) 15 C N O U w -1.0 2 5: 1) '9 i'O- B l o o d L a c t a t e (mM\L ) O LH + JT" O JH' * S P 44 In a d d i t i o n , s u b j e c t NW was able t o complete o n l y 7:30 ;(min) of the 10 (min) v t a m + 2 w o r k t a s k . Subsequently, he was i n j u r e d and unable t o f u r t h e r complete a second t e s t i n g . Consequently, h i s data o n l y appears i n Appendix A and was not i n c l u d e d i n any s t a t i s t i c a l a n a l y s i s . Blood l a c t a t e s and ExC0 2 demonstrate a s i g n i f i c a n t F f o r the between group; . v a r i a t i o n ( p ^ O . 0 1 ) . T h i s i n d i c a t e s t h a t the v e l o c i t y of the t r e a d m i l l ( V ^ ^ , " V ^ , V t a m + 1 , V t a m + 2 ) a f f e c t e d both the La and ExC0 2 v a l u e s . The between groups v a r i a n c e was then d i v i d e d i n t o preplanned o r t h o g o n a l comparisons and . s t a t i s t i c a l s i g n i f i c a n c e was found f o r both La and ExCO„ f o r the comparison V. , and V. versus 2 tam-1 tam V_ ,. and V_ , „ • ( p * 0 .01 f o r La; p*0.05 f o r ExCC- ). tam+1 tam+2 c c 2 No s i g n i f i c a n c e was found f o r V. . and V. f o r e i t h e r La 3 tam-1 tam or ExC0 2. S c h e f f e ' s m u l t i p l e comparison of means was computed on both La and ExCC>2. t o f u r t h e r l o c a t e s i g n i f i c a n c e . V t a m _ i and V\ , , were found t o be s i g n i f i c a n t l y d i f f e r e n t (p^-0.05 tam+1 3 f o r b l o o d l a c t a t e , whereas V, , and V. (p-J 0.01) and tam-1 tam+_ a l s o V_ and V. (p^eO.Ol f o r La; p-<0.05 f o r ExCOJ tam tam+2 - > c . 2 demonstrated s i g n i f i c a n t d i f f e r e n c e s f o r both La and ExC0 2. No s i g n i f i c a n c e was found f o r v t a m _ j a n d Vtam+1 f o r E x C 0 2 ' nor f o r v\ and V\ ,, f o r both La and ExC0 o. tam tam+1 , 2. • The i n d i v i d u a l c o r r e l a t i o n s between La and ExC0 2 are 45 h i g h l y s i g n i f i c a n t . The o v e r a l l c o r r e l a t i o n , o f .886 (p<0.05) demonstrates a h i g h p o s i t i v e c o r r e l a t i o n between La and E x C 0 2 . D i s c u s s i o n The main o b j e c t i v e o f t h i s s t u d y was t o e l u c i d a t e the p r o c e d u r e o f u t i l i z i n g t h e n o n - l i n e a r i n c r e a s e i n ExCC>2, as o u t l i n e d by V o l k o v (1975), f o r t h e subsequent d e t e r m i n a t i o n o f t h e a n a e r o b i c t h r e s h o l d , as d e f i n e d by Wasserman e t a l (1964). A l t h o u g h t h e sample s i z e (N=4) l i m i t e d s t a t i s t i c a l t r e a t m e n t , a n a l y s i s o f v a r i a n c e w i t h p r e p l a n n e d o r t h o g o n a l comparisons and Sc h e f f e ' p o s t hoc c o n t r a s t s r e v e a l s i m i l a r p a t t e r n s between La and ExCC^ o v e r t h e f o u r c o n d i t i o n s , i e . tam-1 tam tam+1 tam+2 The s u b j e c t s a r e r e p r e s e n t a t i v e o f t h e u s u a l e l i t e c l a s s marathoner. They have a low p e r c e n t a g e o f body f a t (X = 8.25-^ 2.47%); a r e c a p a b l e o f consuming l a r g e volumes o f oxygen (VG^max) d u r i n g an e x h a u s t i v e e f f o r t (X =67.76 - 3.45 ml-kg • min "'") ; and have t h e a b i l i t y t o m a i n t a i n a l a r g e f r a c t i o n o f t h e i r V0 2max (AT - % VC>2max) f o r p r o l o n g e d p e r i o d s . . ( C o s t i l l , 1967, 1979; S a l t i n arid A s t r a n d , 1967; C o s t i l l e t a l , 1970). A c c o r d i n g t o V o l k o v (1975), the more a e r o b i c a l l y t r a i n e d a r u n n e r i s , t h e h i g h e r V,_ (or AT - % VO.max) . T h i s s t u d y r e p o r t e d tam 2 an AT - % V0 2max of 86 .8 - 3.27 %. (17.58 km/hr) wh i c h i s h i g h e r t h a n most d i s t a n c e r u n n e r s who employ 75 - 80%. 46 However, some e l i t e r u n n e r s have been r e c o r d e d a t 86 - 90% V0 2max ( C o s t i l l and Fox, 1969; C o s t i l l , 1970'; MacDougalL 1977). F u r t h e r r e s e a r c h s h o u l d c o n s i d e r t h e AT - %V0 2max as an a d d i t i o n a l i n d i c a t o r o f performance p o t e n t i a l . The c r i t i c a l p e r c e n t o f VG^max w h i c h one can m a i n t a i n f o r p r o l o n g e d p e r i o d s o f time has been d e f i n e d as the a n a e r o b i c t h r e s h o l d (Wasserman e t a l , 1964) . The v e l o c i t y o f t h e t r e a d m i l l j u s t below the p o i n t o f a n o n - l i n e a r i n c r e a s e i n . ExCC>2 e l i m i n a t i o n was used as t h e a n a e r o b i c t h r e s h o l d d e t e r m i n a n t and l a b e l l e d V\ (Volkov e t a l , 19 74) . tam ' P r i o r r e s e a r c h has a l r e a d y i n d i c a t e d an i n c r e a s e i n l a c t a t e a t a c r i t i c a l l e v e l o f work (K n u t t g e n , 1962; M a r g a r i a e t a l , 19 63; I s s e k u t z and Ro d a h l , 19 61; Naimark e t a l , 1964; Bouhuys e t a l , 1966), above which t h e l i m i t e d energy from a n a e r o b i c m e t a b o l i s m and t i s s u e a c i d o s i s p r o b a b l y d e t e r m i n e s o p t i m a l r u n n i n g pace. I n e a r l i e r s t u d i e s , t h i s c r i t i c a l l e v e l w ould be r e v e a l e d v i a a d r a m a t i c i n c r e a s e i n R ( r e s p i r a t o r y q u o t i e n t ) , i n c r e a s e d La and a d e c r e a s e i n HCO^ . The i n c r e a s e i n R i s a t t r i b u t e d t o t h e E x C 0 2 produced by m e t a b o l i c a c i d o s i s w h i c h d i s p l a c e s C 0 2 from b i c a r b o n a t e (Naimark e t a l , 19 6 4 ) . Wasserman and M c l l r o y (1964) a l l u d e d t o t h e f a c t t h a t ExCC»2 was r e l e a s e d when a c i d s formed d u r i n g a n a e r o b i c m e t a b o l i s m were b u f f e r e d , p r i n c i p a l l y by HCO . T h e r e f o r e , 47 an i n c r e a s e i n t h e volume o f C 0 2 produced and e l i m i n a t e d . w o u l d y i e l d a h i g h e r v a l u e f o r ExCC^ s i n c e : E x C 0 2 = [vC0 2 - ( R ( r e s t ) x VO^j ( V o l k o v , 19 75) I t s h o u l d be p o i n t e d o u t t h a t i n m e t a b o l i c a c i d o s i s o n l y 15 - 20% o f t h e a c i d l o a d i s b u f f e r e d by t h e H 2C0 3-HC0 3~ system i n the i n t e r s t i t i a l f l u i d . The m a j o r i t y o f t h e b u f f e r i n g o c c u r s as an i n t r a c e l l u l a r p r o c e s s , l a r g e l y by p r o t i e n and o r g a n i c phosphates w h i c h b i n d H + and l i b e r a t e N a + and K +. (Ganong, 19 81; Hultman and S a h l i n , 19 81) . I n a c t u a l i t y t he r i s e i n plasma H + s t i m u l a t e s t h e v e n t i l a t i o n r a t e e n a b l i n g t h e l e v e l o f H 2 C 0 3 t o be reduced o t h e r w i s e an uncompensated a c i d o s i s would be e v i d e n t w i t h a dec r e a s e i n pH. C r a n d a l l and B i d a n i (19 81) have shown t h a t a r e d u c t i o n i n P J J C Q 3 ~ l e a d s t o a r e d u c t i o n i n pulmonary C 0 2 e l i m i n a t i o n o f up t o 30%, whether o r n o t c a r b o n i c anhydrase a c t i v i t y i s a v a i l a b l e t o plasma. They s u g g e s t e d t h a t t h e r e d c e l l HGp 3 /CL exchange p a r t i a l l y l i m i t s C 0 2 e l i m i n a t i o n o r c a p i l l a r y gas t r a n s f e r when i t s speed i s a b n o r m a l l y s l o w . T h i s may be th e case a t extreme w o r k l o a d s . The measurement o f V t a m can be a f f e c t e d by h y p e r v e n t i l a t i o n (in a d d i t i o n t o e r r o r s i n v i s u a l i n s p e c t i o n ) w h i c h l i b e r a t e s s t o r e d C 0 2 and t r a n s i e n t l y i n c r e a s e s R, t h e r e f o r e due t o t h e 48 d e c r e a s e d R. ̂ _ more C 0 o w i l l be e x c r e t e d and t h e volume ACO2 z o f E x C 0 2 w i l l i n c r e a s e . C o n s e q u e n t l y v t a m maY be o v e r - e s t i m a t e d i n t h e s e cases where a b r e a t h by b r e a t h a n a l y s i s i s n o t employed. (Wasserman e t a l , 19 7 3 ) . W i l e y ( u n p u b l i s h e d M.P.E. T h e s i s , 1980), s t u d y i n g the r e l a t i o n s h i p between oxygen debt and V , showed t h a t V tam tam i s u s e f u l i n d e t e r m i n i n g p r i m a r i l y a e r o b i c work i n t e n s i t y above w h i c h m e t a b o l i c a c i d o s i s o c c u r s . Dunwoody (1981 M.P.E. T h e s i s ) showed t h a t V m was p r o b a b l y e a s i e r t o determine i n t h e h i g h l y t r a i n e d i n d i v i d u a l s as opposed, t o the, l e s s e r t r a i n e d . A l t h o u g h u s i n g d i f f e r e n t v a r i a b l e s f o r the d e t e r m i n a t i o n o f a t h r e s h o l d , o t h e r i n v e s t i g a t o r s have demonstrated s i g n i f i c a n t c o r r e l a t i o n s between t h e o n s e t o f a n a e r o b i c m e t a b o l i s m and r a c e time (Weiser e t a l , 19 78; F a r r e l l e t a l , 19 79, Sucec, 19 79; S j o d i n e t a l , 1981; Sady.et a l , 1981). A r e c e n t a r t i c l e by Rhodes e t a l (19 81, CJASS a b s t r a c t i n p r e s s ) , examined t h e r e l a t i o n s h i p between p r e d i c t e d marathon, t i m e s , c a l c u l a t e d from V , and a c t u a l performance t i m e s , i n a marathon, and found a h i g h l y s i g n i f i c a n t z e r o o r d e r c o r r e l a t i o n (R - .94, p^O.01) between t h e p r e d i c t e d and a c t u a l marathon t i m e s . T h i s r e l a t i o n s h i p e s t a b l i s h e d V, tam as a c r i t i c a l p o i n t i n d e t e r m i n i n g marathon r u n n i n g speed and p o s s i b l y t o the o n s e t o f m e t a b o l i c a c i d o s i s . The p r e s e n t s t u d y n o t o n l y shows h i g h i n d i v i d u a l c o r r e l a t i o n 49 between La and ExCO,,, b u t a h i g h o v e r a l l c o r r e l a t i o n ( r = .886 , p«-0.005), i n d i c a t i n g t h a t t h e r e e x i s t s a h i g h p o s i t i v e r e l a t i o n between La and ExCC^ (Table IV, F i g u r e V ) . R e c e n t l y t h e use o f the term " a n a e r o b i c t h r e s h o l d " has been q u e s t i o n e d (Kinderman e t a l , 19 79; S k i n n e r and M c L e l l a n , 1981) . The a u t h o r s s u g g e s t e d t h a t t h e a b i l i t y o f the a e r o b i c c y c l e t o s u p p l y f u e l t o the w o r k i n g muscle and t o remove any m e t a b o l i c b y - p r o d u c t s w i l l e v e n t u a l l y " be exceeded a t a c r i t i c a l p o i n t l a b e l l e d t h e a e r o b i c t h r e s h o l d (^2 mM/L. La) (the a n a e r o b i c t h r e s h o l d o f Wasserman e t a l , 1964). The t r a n s i t i o n a l s t a g e whereby the p e r c e n t c o n t r i b u t i o n o f a e r o b i c mechanisms i s g r a d u a l l y d i m i n i s h e d and the p e r c e n t c o n t r i b u t i o n o f a n a e r o b i c m e t a b o l i s m i n c r e a s e s was l a b e l l e d t h e a e r o b i c - a n a e r o b i c t r a n s i t i o n (<**'2 - 4 mM/L L a ) . As t h e p e r c e n t o f the a n a e r o b i c c o n t r i b u t i o n i n c r e a s e s , a t h i r d phase becomes e v i d e n t , l a b e l l e d t h e a n a e r o b i c t h r e s h o l d (*M mM/L La)(Mader e t a l , 1976). F o r t h e purpose o f d i s c u s s i o n , t h e t h r e e phase double breakaway model r e p o r t e d by S k i n n e r and M c L e l l a n (19 81) w i l l be used. I n the p r e s e n t s t u d y , V^ demonstrated a La c o n c e n t r a t i o n * 2 tam o f 3.16 mM/L w h i c h i s h i g h e r t h a n the a c c e p t e d v a l u e o f a p p r o x i m a t e l y 2 mM/L d e f i n e d by Wasserman, and more c l o s e l y l o c a t e d i n t h e a e r o b i c - a n a e r o b i c t r a n s i t i o n s t a g e r e p o r t e d by Kinderman e t a l (1979) and S k i n n e r and M c L e l l a n (1981). The 50 La v a l u e o f 5.28 mM/L r e p o r t e d f o r v t a m + ] _ i-s markedly above t h e 4 mM/L mark f o r contemporary t e r m i n o l o g y w h i c h i n d i c a t e s t h a t V\ ,, i s above t h e a n a e r o b i c t h r e s h o l d as tam+1 r e p o r t e d by MacDougall (19 78) and Mader e t a l (19 76) . I n o r d e r t o shew a * t r a n s i t i o n a l zone though, s e r i a l s a m p l i n g may be n e c e s s a r y and d i f f e r e n c e s . m a y be due t o t h e range o f t r e a d m i l l speeds. The f a c t t h a t • s i g n i f i c a n c e was demonstrated between V\ , and V\_ v e r s u s V\ „,, and tam-1 tam tam+1 V. , „ -(p<0.01) f o r b o t h ExCO- and La i n d i c a t e s t h a t t h e tam+2 ^ 2 v a l u e s a r e c l o s e r t o t h e a n a e r o b i c t h r e s h o l d o r t h e upper l i m i t s o f t h e a e r o b i c - a n a e r o b i c t r a n s i t i o n a l s t a g e , above wh i c h m e t a b o l i c a c i d o s i s i s e v i d e n t by the i n c r e a s i n g c o n c e n t r a t i o n o f L a . I n t e r - ^ i n d i v i d u a l v a r i a b i l i t y among t h e r u n n e r s may account f o r d i f f e r i n g . ;La c o n c e n t r a t i o n s . Derek C l a y t o n i n one s e r i e s o f experiments; was r e q u i r e d t o r u n a t a t r e a d m i l l speed w h i c h e q u a l l e d h i s b e s t marathon performance .'(328 m/min. o r 4:54 s e c . / m i l e ) . H i s h e a r t r a t e response was c o n s t a n t d u r i n g t h e r u n a t 16 7 b e a t s / m i n . w h i c h e q u a l s t h e X- h e a r t a t V\ f o r t h i s s t u d y and t h a t r e p o r t e d by Parkhouse tam e t a l (1982) . Venous b l o o d l a c t a t e v a l u e s a t 10 and 30 minutes were 2.1 and 2.3 mM/L. r e s p e c t i v e l y , w h i c h i s s i m i l a r , t o t h e X - La v a l u e r e p o r t e d f o r v t a m _ T _ - H : L S a b i l i t y t o r u n a t 86-9 0% o f V0 2max w i t h La c o n c e n t r a t i o n s o n l y s l i g h t l y above 51 r e s t i n g v a l u e s (1.3 mM/L) i s p r o b a b l y a f u n c t i o n o f m u s c u l a r a d a p t a t i o n s t o endurance t r a i n i n g . I n t h e p r e s e n t s t u d y t h e 3.16 mM/L r e p o r t e d a t v t a m i s above th e a e r o b i c t h r e s h o l d . V. as used by Rhodes • tam -* e t a l (19 81 CJASS .Abstract) has been shown t o have a h i g h c o r r e l a t i o n t o marathon r u n n i n g pace ( r - .9 2 ) . The f a c t t h a t t h e v a l u e s r e p o r t e d d i f f e r from a c c e p t e d t h r e s h o l d c o n c e n t r a t i o n s o f 2 mM/L and 4 mM/L derhonstate t h e n e e d ^ f o r t h e d e t e r m i n a t i o n o f i n d i v i d u a l a n a e r o b i c t h r e s h o l d (IAT) v i a l a c t a t e k i n e t i c s as p o i n t e d out by Stegmann e t a l (1981) . F u r t h e r m o r e , t h e i n c o r r e c t assessment o f s u b j e c t NW's V, J tam s u p p o r t s the need f o r t h e development of a method o f e v a l u a t i n g v t a m which would be more s o p h i s t i c a t e d t h a n v i s u a l i n s p e c t i o n a l o n e . A t t h i s s t a g e , i t s h o u l d be a p p a r e n t t h a t t h e d i s c u s s i o n o f a s p e c i f i c p o i n t o r t h r e s h o l d i s m i s l e a d i n g . S i n c e the plasma l a c t a t e c o n c e n t r a t i o n s a r e t h e r e s u l t o f t h e p r o d u c t i o n o f l a c t a t e i n m uscle, d i f f u s i o n o f l a c t a t e from muscle t o b l o o d , and t h e uptake o f l a c t a t e by numerous t i s s u e s , c a u t i o n must be used i n i n t e r p r e t i n g t h e AT as t h e o n s e t o f a n a e r o b i o s i s (MacDougall, 19 78; F a r r e l l e t a l , 19 79) . I t appears t o be a p o i n t i n a t r a n s i t i o n s t a g e w h i c h v a r i e s from i n d i v i d u a l t o i n d i v i d u a l . Many r e s e a r c h e r s b e l i e v e t h a t t h e r e i s a c r i t i c a l pH w h i c h can a f f e c t r a t e l i m i t i n g enzymes 52 i e . PFK or t h e Ca dependent c o n t r a c t i l e mechanism. As you g e t c l o s e r t o the c r i t i c a l pH a v e r y s m a l l d e c r ease i n pH may be q u i t e i m p o r t a n t . (Roos and Baron, 19 81; Hultman and S a h l i n , 1981) . The s i g n i f i c a n c e demonstrated between v\ 3 tam+1 and v t a m + 2 o f f e r s some i n d i r e c t s u p p o r t f o r t h i s . The h i g h c o r r e l a t i o n o f .886 shown between La and ExCC>2 does not n e c e s s a r i l y i n d i c a t e a c a u s e / e f f e c t s i t u a t i o n s i n c e a t h i r d v a r i a b l e (or more) may be i n v o l v e d . I t does i n d i c a t e t h a t b o t h appear t o i n c r e a s e i n a l i n e a r f a s h i o n as i n t e n s i t y i n c r e a s e s . . A l t h o u g h o u t o f t h e scope o f t h i s s t u d y t h e i n t r a c e l l u l a r b u f f e r i n g and t h e d e t e r m i n a t i o n o f i n t r a m u s c u l a r pH seem t o be o b v i o u s c a n d i d a t e s t o c o n s i d e r . The i n c r e a s e d v e n t i l a t i o n r a t e as a r e s u l t o f H + a c c u m u l a t i o n h e l p s t o compensate f o r an impending a c i d o s i s s h o u l d i n t e n s i t y c o n t i n u e t o i n c r e a s e . Above a c r i t i c a l i n t e n s i t y though e x t r a CC^ i s added t o t h e e x p i r a t e p r i m a r i l y t h r o u g h t h e B^CO^/HCO^ b u f f e r i n g system. C o n s e q u e n t l y , above V, one s h o u l d see f u r t h e r i n c r e a s e s i n ExCO„ e l i m i n a t i o n tam 2 as the body's a b i l i t y t o m a i n t a i n a t o l e r a b l e pH l e a d s t o f a t i g u e . I n a p r a c t i c a l s i t u a t i o n , t h i s w ould n e c e s s i t a t e a s l o w i n g o f pace o r a c e s s a t i o n o f t h e r u n . F a t i g u e i n t h i s case i s i n t e r p r e t e d a c c o r d i n g t o t h e f o u r b a s i c p r o c e s s e s o u t l i n e d by Simonsen (19 81): d e p l e t i o n o f s u b s t a n c e s n e c e s s a r y f o r a c t i v i t y , a c c u m u l a t i o n o f s u b s t a n c e s , changes 53 o f p h y s i c o - c h e m i c a l s t a t e o f s u b s t r a t e and d i s t u r b a n c e o f r e g u l a t i o n and c o o r d i n a t i o n . I n an e x e r c i s e s i t u a t i o n , • t h e m a j o r i t y o f t h e (H+) which r e f l e c t s pH i s from l a c t i c a c i d (97%) and p y r u v a t e m a l a t e , e t c . ( 3 % ) . The use o f ExCC^ i s o f p a r t i c u l a r i m p o r t a n c e f o r d e t e r m i n i n g r u n n i n g pace f o r an endurance a t h l e t e s i n c e i t measures the CC^ produced as a b y - p r o d u c t from m e t a b o l i c a c i d s and i s non- i n v a s i v e t h e r e f o r e much e a s i e r t o a s c e r t a i n t h a n L a . ( I s s e k u t z e t a l , 1962; Naimark e t a l , 1964; Rhodes e t a l , 1981). I t was h y p o t h e s i z e d t h a t V, , _c V, -C V, ,, V. J j r tam-1 tam tam+1 tam+2 f o r both La and ExCC^. R e s u l t s , r e p r e s e n t e d i n T a b l e I I I , s u p p o r t t h i s . A l t h o u g h no s i g n i f i c a n c e was found between v ^ a m and v t a m + j x t m a Y p o s s i b l y be due t o t h e s m a l l N and v a r i a b i l i t y and/or as d i s c u s s e d , p a r t o f a t r a n s i t i o n s t a g e above wh i c h a more s i g n i f i c a n t i n c r e a s e i n La and ExCC^ i s seen. T h i s was s u p p o r t e d by t h e s i g n i f i c a n t d i f f e r e n c e seen between V + ^ and v t a m + 2 ( P ^ O . O l f o r L a ; P < 0 . 0 5 . ExC0 2) . The g r e a t e r t h e w o r k l o a d , t h e g r e a t e r t h e a c c u m u l a t i o n o f La and t h e subsequent ExCC>2 e l i m i n a t i o n . The i m p l i c a t i o n s o f t h i s s t u d y t o the coach and a t h l e t e has y e t t o be e s t a b l i s h e d . The use o f ExCC^ i n d e t e r m i n i n g the p r e s e n t pace s t a t u s o f a marathon r u n n e r , above w h i c h f a t i g u e p r o c e s s e s become l i m i t i n g upon performance, appears t o be adequate. Some r e s e a r c h has been c a r r i e d o ut on 54 t h e e f f e c t s o f i n t e n s i t y and t r a i n i n g q u a n t i t y on t h e A.T. and medium i n t e n s i t y / h i g h q u a n t i t y and h i g h i n t e n s i t y / l o w q u a n t i t y b o t h i n c r e a s e d A.T. ( L a F o n t a i n e e t a l , 19 82).. I n a d d i t i o n t o a h i g h v 0 2 m a x a n d h i g h p e r c e n t V 0 2 m a x ' t r a : L n i n 9 " volume i s a s s o c i a t e d w i t h s u c c e s s i n marathon r u n n i n g . (Hagan and Gettman, 19 82; S j o d i n and J a c o b s , 19 82) . S p e c i f i c g u i d e l i n e s f o r an i n d i v i d u a l would n e c e s s i t a t e t a b u l a t i n g d a t a i n a l a r g e p o p u l a t i o n o f marathon r u n n e r s t o e s t a b l i s h some g e n e r a l norms and t h e n i d e n t i f y i n g t h a t i n d i v i d u a l ' s s t r o n g and weak a r e a s . C e r t a i n l y , t h e moire e l i t e a r u n n e r becomes, th e s m a l l e r the room f o r improvement and the more s o p h i s t i c a t e d t h e t o o l s o f a n a l y s i s . I n summary, a l t h o u g h o t h e r f a c t o r s such as t h e d i f f e r e n c e between s u b j e c t s i n s t o r a g e c a p a c i t y i n muscle f o r l a c t a t e , l a c t a t e t o l e r a n c e and i n d i f f u s i o n o f t h i s l a c t a t e from the muscle t o b l o o d , c o u p l e d t o d i f f e r e n c e s i n f i b e r t y pe and r e c r u i t m e n t , v e n t i l a t o r y r e s p o n s e s , s t o r a g e and b u f f e r c a p a c i t y f o r m e t a b o l i c a c i d s , t h e a n a l y s i s o f La and ExCO^ i n t h i s s t u d y r e v e a l e d s i m i l a r p a t t e r n s o f s i g n i f i c a n c e and a h i g h p o s i t i v e c o r r e l a t i o n . These f i n d i n g s s u p p o r t th e r e l a t i o n s h i p between the i n c r e a s e i n ExCG^ and t h e o n s e t o f plasma l a c t a t e a c c u m u l a t i o n as a l i m i t i n g f a c t o r i n performance o f e l i t e marathon r u n n e r s . ( I s s e k u t z e t a l , 19 62; Naimark e t a l , 1964; V o l k o v , 1975; F a r r e l l e t a l , 19 79; Rhodes e t a l , 1981; S j o d i n and J a c o b s , 19 81). 55 F u r t h e r i n v e s t i g a t i o n i s r e q u i r e d i n t o the range o f t r a n s i t i o n from a e r o b i c t o a n a e r o b i c m e t a b o l i s m v i a b r e a t h by b r e a t h a n a l y s i s o f r e s p i r a t o r y measurements i n c o n j u n c t i o n w i t h La v a l u e s o r perhaps La K i n e t i c s ( s e r i a l sample f o r a b e t t e r l o o k a t t i m e c h a n g e s ) . The e f f e c t o f t r a i n i n g below, a t and above t h i s c r i t i c a l l e v e l as r e l a t e d t o endurance a t h l e t e s may y i e l d o p t i m a l t r a i n i n g s p e c i f i c i t y f o r peak p e r f o r m a n c e s . CHAPTER V .. SUMMARY AND CONCLUSIONS Summary The term " a n a e r o b i c t h r e s h o l d " grew from the e a r l y s t u d i e s o f Bang (1936) and M a r g a r i a e t a l (1964) . I n 1962, K n u t t z e n showed t h a t t h e r e was a c r i t i c a l l e v e l o f work where l a c t a t e f i r s t appears i n t h e b l o o d . The i n c r e a s e i n l a c t a t e i s a s s o c i a t e d w i t h m u s c u l a r f a t i g u e w h i c h l i m i t s performance a t a g i v e n i n t e n s i t y . Wasserman and M c l l r o y (19 64) l a t e r p o s t u l a t e d t h a t t h e a n a e r o b i c t h r e s h o l d was t h e l e v e l o f work j u s t below w h i c h a s u b j e c t c o u l d e x e r c i s e f o r p r o l o n g e d p e r i o d s i n a s t e a d y s t a t e , w i t h o u t d e v e l o p i n g m e t a b o l i c a c i d o s i s . R e c e n t l y t h e use o f ex c e s s CO2 as a n o n - i n v a s i v e measure f o r d e t e r m i n a t i o n o f a n a e r o b i c t h r e s h o l d has been shown t o c o r r e l a t e h i g h l y w i t h marathon r u n n i n g pace (Rhodes.et : a l , 1981). The p r e s e n t s t u d y a t t e m p t e d t o e l u c i d a t e t h e r e l a t i o n s h i p between E x C 0 2 , . a s used i n d e t e r m i n i n g the a n a e r o b i c t h r e s h o l d , and t h e appearance t o b l o o d l a c t a t e i n e l i t e marathon r u n n e r s . S i n c e l a c t a t e has been used t o determine t h e degree o f a c i d e m i a , d u r i n g e x e r c i s e o f v a r y i n g i n t e n s i t i e s , s i m i l a r p a t t e r n s i n EXCO2 may r e v e a l a n o n - i n v a s i v e t o o l i n d i c a t i v e o f m e t a b o l i c a c i d o s i s . F i v e male s u b j e c t s (mean age 30.6) who had a VX^max °^ a p p r o x i m a t e l y 65 ml«kg "'"•min \ and had. r u n a sub 2:30 marathon were tested on f i v e separate days. During the . f i r s t session, a f t e r ah appropriate c o n s e n t form had. been .signed, h e i g h t , weight,, body c o m p o s i t i o n 57 assessment, a n a e r o b i c t h r e s h o l d and maximal oxygen uptake were d e t e r m i n e d . The r e m a i n i n g f o u r s e s s i o n s c o n s i s t e d o f a s h o r t warm-up, f o l l o w e d by a 10 minute c o n s t a n t speed r u n (V\ , , V\ j V. , , , V\ a f t e r w h i c h 2 m l . o f b l o o d was tam-1 tam tam+1' tam+2 drawn from an a n t i - c u b i t a l v e i n . Due t o t h e s m a l l number o f s u b j e c t s under i n v e s t i g a t i o n , s t a t i s t i c a l a n a l y s i s was l i m i t e d . N e v e r t h e l e s s , a n a l y s i s o f v a r i a n c e w i t h p r e p l a n n e d o r t h o g o n a l comparisons and S c h e f f e ' s p o s t hoc c o n t r a s t s r e v e a l e d s i m i l a r p a t t e r n s , o f s i g n i f i c a n c e between ExC0 2 and blood, l a c t a t e o v e r the f o u r t r e a t m e n t s . The o v e r a l l c o r r e l a t i o n c o e f f i c i e n t o f .886 (p<.005) between ExC0 2 and b l o o d l a c t a t e r e v e a l e d a h i g h p o s i t i v e r e l a t i o n s h i p between the two v a r i a b l e s . ExC© 2 (ml-kg "''•min ^) was used as the d e t e r m i n a n t o f the o n s e t o f m e t a b o l i c a c i d o s i s i n the p r e d i c t i o n o f t h e a n a e r o b i c t h r e s h o l d . The s i m i l a r p a t t e r n s o f s i g n i f i c a n c e and h i g h c o r r e l a t i o n , a l t h o u g h i n d i c a t i v e o f a r e l a t i o n s h i p , s h o u l d not be i n t e r p r e t e d as a c a u s e - e f f e c t r e l a t i o n s h i p as o t h e r v a r i a b l e s may be i n v o l v e d ( i e . i n t r a m u s c u l a r b u f f e r i n g ) . I n a d d i t i o n the use o f ExCC>2 i n d e t e r m i n i n g the AT. as d e f i n e d by Wasserman e t a l (1964) needs r e - e v a l u a t i o n as t h e mean l a c t a t e was h i g h e r t h a n a c c e p t e d v a l u e s (3.16 mM/L as opposed t o an a c c e p t e d v a l u e o f a p p r o x i m a t e l y 2.0 mM/L). C o n s e q u e n t l y , when u s i n g 58 contemporary t e r m i n o l o g y t h e e s t i m a t i o n o f AT, v i a ExCC^ i s l o c a t e d s l i g h t l y above t h e a e r o b i c t h r e s h o l d and i n the a e r o b i c a n a e r o b i c t r a n s i t i o n phase. The f a c t t h a t a mean of 3.16 mM/L was r e p o r t e d i n d i c a t e s t h a t e l i t e endurance r u n n e r s a r e a b l e t o r u n a t a pace w h i c h i s s l i g h t l y above t h e i r a e r o b i c t h r e s h o l d and t h a t t h e use o f ExCC^ i n i d e n t i f y i n g t h i s i s an e x c e l l e n t p r e d i c t i o n o f pace. C o n s e q u e n t l y , t h e a p p l i c a t i o n o f t h i s p o i n t t o a t h l e t e and coach needs t o be a s s e s s e d i n terms of. t r a i n i n g r e g i m e s . The f a c t t h a t r e s e a r c h has shown i n c r e a s e i n AT. w i t h t r a i n i n g a t o r above th e AT, i d e n t i f i e s the .ExCC>2 d e t e r m i n a t i o n as a v i a b l e p r e d i c t i o n o f a t h r e s h o l d i n t e n s i t y t h a t the a t h l e t e s h o u l d t r a i n about. C o n c l u s i o n s 1. S i m i l a r p a t t e r n s o f s i g n i f i c a n c e were r e v e a l e d f o r ExCO„ and b l o o d l a c t a t e o v e r the f o u r t r e a t m e n t s (V. n , 2 tam-1' V t a m ' Vtam+1' Vtam+2 ) 2. A h i g h p o s i t i v e c o r r e l a t i o n was d e m o n s t r a t e d between E x C 0 2 and b l o o d l a c t a t e (r=.886 p<.005),- 3. ExCC>2 s i g n i f i e s a rough measure o f m e t a b o l i c a c i d o s i s because o t h e r v a r i a b l e s may account f o r t h e h i g h c o r r e l a t i o n r e p o r t e d . 59 Recommendations 1. S e r i a l measurements of b l o o d l a c t a t e i n c o n j u n c t i o n w i t h ExCC>2 values d u r i n g and f o l l o w i n g a p r o g r e s s i v e t r e a d m i l l run f o r the d e t e r m i n a t i o n of an i n d i v i d u a l anaerobic t h r e s h o l d needs t o be compared i n r e l a t i o n s h i p to other v a r i a b l e s which may c o n t r i b u t e t o me t a b o l i c a c i d o s i s ; i e . pH, b u f f e r i n g c a p a c i t y , f i b e r composition, and so on; 2. The use of an assumed RQ f o r the c a l c u l a t i o n of ExCG^ may vary the a c t u a l ExCG^ values s i n c e : ExC0 2 = VC0 2 - ( r e s t i n g R.Q. x VC>2) ; 3. F u r t h e r r e s e a r c h i s r e q u i r e d i n t o the e f f e c t s of v a r y i n g i n t e n s i t i e s and. d u r a t i o n of t r a i n i n g upon the AT (as assesed by ExCC>2) and subsequent race pace i n marathon runners; 4. 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I n f l u e n c e o f f i b e r t y p e c o m p o s i t i o n and c a p i l l a r y d e n s i t y on o n s e t o f b l o o d l a c t a t e a c c u m u l a t i o n . I n t . J . S p o r t s M e d i c i n e . 2.(4): 252-255, 1981. 68 T h o r s t e n s s o n , A., B. S j o d i n , P. Tesch and J . K a r l s s o n . A c t o m y o s i n ATPase, myokinase, CPK and LDH i n human f a s t and slow t w i t c h muscle f i b e r s . A c t a P h y s i o l . Scan. 99: 225-229, 1977. T u r r e l l , E.S. and S. R o b i n s o n . The a c i d - b a s e e q u i l i b r i u m o f the b l o o d i n e x e r c i s e . Amer. J . P h y s i o l . 137: 742, 1942. V o l k o v , N., E. S h e r k a v e t s and V. B o r i l k e v i c h . Assessment o f a e r o b i c and a n a e r o b i c c a p a c i t y o f a t h l e t e s i n t r e a d m i l l r u n n i n g . E u r . J . A p p l . P h y s i o l . 3 4 ( 2 ) : 121-130, 1975. Wasserman, K.. and M. M c l l r o y . 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The hyperpnea o f dynamic m u s c u l a r e x e r c i s e . Ex. S p t . S c i . Rev. 5: 295-311, 1977. W i l e y , J.P. The r e l a t i o n s h i p o f i n d i v i d u a l a n a e r o b i c t h r e s h o l d s t o t o t a l , a l a c t i c and l a c t i c oxygen debts a f t e r a s e t t r e a d m i l l r u n . U n p u b l i s h e d M.P.E. T h e s i s . U n i v e r s i t y o f B r i t i s h C o lumbia, 1980. 69 A P P E ND I X 70 Subjec t : NW V7ARIART.KS Vtam-1 Vtam Vtam+1 Vtam+2 MAX Velocity of treadmill (KPH) 16.74 17.74 18.74 19.74 13.0 VCL -1 -1 (ml-kg -min ) 55.38±2.4 61.23±2.12 62.86±1.98 66.08±1.78 69.80 vo 2 79 88 90 95 100 (percent MAX) ExCCL (ml-kg -min ) 13.96^1.08 18.83±3.14 23.43±2.26 24.74^1.64 26.57 ExCCL z (percent MAX) 53 71 88 93 100 Blood lactate (mM/L) 5.096 -8.261 11.927 14.053 — Heart Rate (b.p.m.) 168 180 187 184 185 94.31±9.27 (7:30 min. only) V e (STPD) 76.01±3.44 107.28±9.92 114.51- 118.71 height (kg.) 67.5 67.5 67.1 66.7 67.10 71 Subject: LH VARIART.ES v tam-1 Vtam Vtam+1 v tam+2 MAX Velocity of treadmill (KPH) 15.94 16.94 17.94 18.94 14.0 V 02 -1 -1 (ml-kg -min ) 51.29-1.5 57.45-.52 64.66^.62 66.9-1.65 67.01 vo 2 (percent MAX) 76 86 96 100 100 ExC02 (ml-kg-1-min"1) 13.02±.76 15.73±.34 15.24^1.09 20.7±2.08 26.63 ExC02 (percent MAX) 49 59 57 78 100 Blood lactate (rrM/L) 1.479 2.493 4.570 9.263 Heart Rate (b.p .m.) 150 161 167 V (STPD) e 78.6±2.17 93.70-1.47 107.44-3.56 125.03-8.15 130.84 Weight (kg.) 71.0 70.2 70.9 71.2 72.0 72 Subject: JT VAR IART iES V . tam-1 Vtam Vtam+1 V tam+2 MAX Veloc i t y of teeadmill (KPH) 15.94 16.94 17.94 18.94 13.5 V 0 2 -1 -1 (ml-kg -min ) 51.52^1.32 55 .98-1.04 60.12-2.84 57.42^1.32 64.11 vo 2 (percent MAX) 80 87 94 90 100 ExC0 2 (ira-kg^-min - 1) 9.96-1.04 14 .11-.66 15.85-.41 22.9-.80 26.77 ExC0 2 (percent MAX) 37 53 59 85 100 Blood lactate (mM/L) 2.053 3.397 4.191 6.978 Heart Rate (b.p.m.) 164 164 170 176 V ( STPD ) e 73.24^3.9,1 88 .44^4.12 89.13^3.12 111.57-6.36 126.48 Weight (kg.) 68.0 67.5 68.2 67.6 68.5 73 Subject: JH V7ARIART.ES Vtam-1 Vtam V tam+1 V tam+2 MAX Velocity of treadmill (KPH) 17.55 18.55 19.55 20.55 14.5 V 0 2 54.18±.95 61.48±.81 62.36^1.42 62.09±1.24 -1 -1 (ml-kg -min ) 67.47 VO (percent MAX) 80 91 92 92 100 ExC02 (ml-kg^-niin - 1) 9.75±.51 14.95±.93 21.77^1.89 24.3±1.12 35.71 ExC02 27 42 61 68 100 (percent MAX) Blood lactate (mM/L) 1.747 3.837 8.077 8.945 Heart Rate (b.p.m.) 168 180 187 191 200 V (STPD) e 75.09*1.93 87.74±1.44 104.95±5.07 107.10±3.6 128.40 Weight (kg.) 70.1 70.5 70.0 69.6 70.5 74 Subject: SP VARIABLES Vtam-1 Vtam V tam+1 V tam+2 MAX Velocity of treadmill (KPH) 16.74 17.74 18.74 19.74 14.5 VCL -1 -1 (ml'kg -10111 ) 53.7±.48 59.63-1.33 61 .09-1.31 66.87^2.04 72.42 vo 2 (percent MAX) 74 82 84 92 100 ExCCL (ml-kg -min ) LI.62-.85 12.60-.7 15 .37^1.68 18.53-1.01 26.42 ExC02 (percent MAX) 44 48 58 70 100 Blood lactate (mM/L) 2.774 2.908 4.277 9.385 Heart Rate (b.p .m.) 165 164 173 180 V (STPD) e 79.05-1.51 89.73^1.66 94 .80-1.85 111.85^-3.70 136.50 Weight (kg.) 68.1 68.5 67.5 67.9 68.5 ANACIOUIC Tlli'.tjJilOLO CUKVE E x c e s s C02 ( . t i l / k y ) v s r i ' - l i i ( t i n ) & o l ' R G O ( n p i i ) E x c e s s C02 (ml/kg) NW il 1 2 3 4 5 (. 7 1 J 1U L i 12 13 14 ID lf> 17 lrt 19 2J 5 6 7 U 9 10 11 • 12 1J 14 15 ( m i n u t e s ) •;H>KE.J ('jiiii U l ANAEROBIC THRESHOLD CURVE E x c e s s C02 ( m l / k g ) v s TIME ( r a i n ) & S P E E D (mph) E x c e s s C02 ( m l / k g ) 28.00 25.20 22.40 19.60 16.80 14.00 11.20 8.4 0 5.60 2.80 0.00 ** * *• 1- 0 1 2 3 4 5 6 7 8 9 1 0 11 12 13 14 15 16 17 18 19 20 5 6 7 8 9 10 11 12 13 14 15 TIME ( m i n u t e s ) LJJ SPEED (mph) CTl 77 «- 3 LO O r̂ - — co in rg. r-> ANAEROBIC THRESHOLD CURVE E x c e s s C02 ( m l / k g ) v s TIME ( m i n ) & S P E E D (mph) E x c e s s C02 ( m l / k g ) 38.00 34.20 30.40 26.60 22.80 19.00 15.20 11.40. 7. 60- 3.80 0.00 * * * * * * * * **• » ** 5 1 6 3 7 5 I 7 ? 9 " 1 1 1 2 " 14 15 16 17 18 19 20 6 7 8 9 10 11 12 13 14 15 JH 11 12 TIME (minutes) SPEED (mph)  80 JOHN M. BUCHANAN FITNESS & RESEARCH CENTRE Informed Consent: You w i l l p e r f o r m a graded e x e r c i s e t e s t on a m o t o r - d r i v e n t r e a d m i l l . The purpose o f t h i s t e s t i s t o examine the response o f y o u r h e a r t and l u n g s t o e x e r c i s e . The t e s t c o n s i s t s o f r u n n i n g a t one o r more l e v e l s o f d i f f i c u l t y . Your e l e c t r o - c a r d i o g r a m w i l l be m o n i t o r e d t h r o u g h o u t t h e e x e r c i s e and r e c o v e r y p e r i o d s . B l o o d samples w i l l be t a k e n by.way o f a venous p u n c t u r e . I t i s e x p e c t e d t h a t you w i l l c omplete t h e e x e r c i s e t e s t w i t h o u t c o m p l i c a t i o n s . Because o f the v e r y uncommon, u n p r e d i c t a b l e response o f some i n d i v i d u a l s t o e x e r c i s e , u n f o r s e e n d i f f i c u l t i e s may a r i s e w hich would n e c e s s i t a t e t r e a t m e n t . C o m p l i c a t i o n s have been few d u r i n g e x e r c i s e t e s t s and t h e s e u s u a l l y c l e a r q u i c k l y w i t h l i t t l e o r no t r e a t m e n t . You are a s k e d t o r e p o r t any u n u s u a l symptoms d u r i n g the t e s t . We may s t o p t h e t e s t a t any time because o f s i g n s o f f a t i g u e o r you may s t o p when you w i s h t o because o f p e r s o n a l f e e l i n g s o f f a t i g u e o r d i s c o m f o r t . E v e r y e f f o r t w i l l be made t o conduct the t e s t i n such a way as t o m i n i m i z e d i s c o m f o r t and r i s k . However, t h e r e e x i s t s the p o s s i b i l i t y o f p o t e n t i a l r i s k s such a s ; abnormal b l o o d p r e s s u r e , f a i n t i n g , d i s o r d e r s o f h e a r t b e a t and v e r y r a r e i n s t a n c e s o f h e a r t a t t a c k . You w i l l a l s o p e r f o r m t e s t s o f l u n g c a p a c i t y and body c o m p o s i t i o n . In s i g n i n g t h i s c o n s e n t form y o u . s t a t e t h a t you have r e a d and u n d e r s t a n d t h e d e s c r i p t i o n o f the t e s t s and t h e i r c o m p l i c a t i o n s . You e n t e r t h e b a t t e r y o f t e s t s w i l l i n g l y , b u t you may w ithdraw o r r e f u s e t o p a r t i c i p a t e a t any t i m e . F i n a l l y , a l l d a t a c o l l e c t e d about you w i l l be k e p t i n s t r i c t e s t c o n f i d e n c e . CONSENT I have r e a d t h e above comments and u n d e r s t a n d the e x p l a n a t i o n and I w i s h t o p r o c e e d w i t h t h e t e s t s . DATE: SUBJECT: S i g n a t u r e WITNESS:

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{[{ mDataHeader[type] }]} {[{ month[type] }]} {[{ tData[type] }]}

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