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Cardiorespiratory fitness during pregnancy and its relationship to outcome 1985

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CARDIORESPIRATORY FITNESS DURING PREGNANCY AND ITS RELATIONSHIP TO OUTCOME by SUSAN CAROL WONG B . H . E . Univers i ty of B r i t i s h Columbia, 1976. A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER IN PHYSICAL EDUCATION in THE FACULTY OF GRADUATE STUDIES Phys ica l Education and Recreation We accept th i s thes is as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA © October 1985 Susan Carol Wong In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of P h y s i r a l F d u c a t l o n The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date DE-6(3/81) ABSTRACT I n o r d e r t o d e t e r m i n e t h e e f f e c t s o f a e r o b i c f i t n e s s on p r e g n a n c y and t h e newborn 20 p r i m i g r a v i d s u b j e c t s were s t u d i e d t h r o u g h o u t t h e i r g e s t a t i o n a l p e r i o d and i m m e d i a t e l y p o s t - p a r t u m . The s u b j e c t s were c l a s s i f i e d as t r a i n e d (T=10) o r u n t r a i n e d (UT=10) b a s e d on t h e h e a r t r a t e r e s p o n s e t o s u b m a x i m a l c y c l e e r g o m e t r y t e s t i n g done i n e a c h t r i m e s t e r . Case room r e p o r t s were r e v i e w e d a f t e r d e l i v e r y . T h e r e was no d i f f e r e n c e between g r o u p s i n t h e l e n g t h o f g e s t a t i o n a l p e r i o d (T=40.75;UT=40.75 w e e k s ) n o r w e i g h t g a i n e d v e r s u s p r e - p r e g n a n c y m e a s u r e s (T=13.92; UT=13.30 k g s ) . The f i r s t s t a g e o f l a b o u r was e x t e n d e d i n t h e UT, 1 3 h r s . 5 8 . 8 m i n . vs 1 l h r s . 1 8 . O m i n . UT had a l o n g e r s e c o n d s t a g e , 90.57 vs 70.0 m i n s . f o r T. S t a g e 3 was a l s o p r o l o n g e d i n UT, 15.17 vs 7.43 j m i n s . I n b o t h g r o u p s a n a l g e s i a a n d / o r a n a e s t h e s i a was u s e d e q u a l l y . Two o f t h e 10 T f e m a l e s had c a e s a r e a n s e c t i o n s vs 3 o f t h e 10 i n t h e UT g r o u p . The mean a p g a r s c o r e s a t 1 and 5 m i n u t e s w e r e : T=7.70, 9.20; UT=7.90, 9.33, r e s p e c t i v e l y . The b i r t h w e i g h t s o f t h e T b a b i e s were m a r g i n a l l y l a r g e r t h a n t h e UT newborns ( 3 7 3 3 . 0 0 vs 3679.97 gms). The T newborns were 8 m a l e s and 2 f e m a l e s , and t h e UT were 5 m a l e s and 5 f e m a l e s . A l l b a b i e s were h e a l t h y and w i t h o u t a p p a r e n t a b n o r m a l i t i e s . T h e r e a p p e a r s t o be no p o s i t i v e o r n e g a t i v e e f f e c t s o f m a t e r n a l f i t n e s s on t h e n e w b o r n . The r e d u c t i o n i n t h e a c t i v e s t a g e o f l a b o u r i n t h e T g r o u p may r e f l e c t t h e i r i m p r o v e d f i t n e s s l e v e l s . i i TABLE OF CONTENTS Ab s t r a c t L i s t of Tables Acknowledgement I. INTRODUCTION I I . METHODS I I I . RESULTS IV. DISCUSSION V. REFERENCES APPENDIX A - REVIEW OF LITERATURE 26 I n t r o d u c t i o n 26 Animal S t u d i e s 27 U t e r i n e Blood Flow 28 E f f e c t on O f f s p r i n g 33 Human S t u d i e s 46 P h y s i o l o g i c a l Changes duri n g Pregnancy 47 R e s p i r a t o r y Changes 47 C a r d i o v a s c u l a r Changes 48 E f f e c t s of E x e r c i s e and Pregnancy 50 R e p i r a t o r y 50 C a r d i o v a s c u l a r 52 Temperature 57 Work T e s t s 57 E f f e c t s on the f e t u s of maternal e x e r c i s e 66 R e t r o s p e c t i v e s t u d i e s 74 Co n c l u s i o n 79 i i i i i 1 7 9 13 19 APPENDIX B - INDIVIDUAL HEART RATE DATA 82 APPENDIX C - PREDICTED MAXIMUM OXYGEN UPTAKE 84 APPENDIX D - ACTIVITY LOGBOOKS SUMMARIZED 87 iv LIST OF TABLES Mean M a t e r n a l Data Mean Newborn Data Acknowledgements I would l i k e to express my thanks and a p p r e c i a t i o n to my s u b j e c t s f o r t h e i r p a r t i c i p a t i o n , and f o r a l l o w i n g me to f o l l o w t h e i r p r e g n ancies. A s p e c i a l thanks to my committee - Drs. Ken Coutts , Peter Grantham , Jack Taunton t and e s p e c i a l l y Don McKenzie , f o r t h e i r c o n t i n u a l support and guidance throughout the study. Not to be f o r g o t t e n are f r i e n d s and f a m i l y without whose support the p r o j e c t would never have been p o s s i b l e , a very s p e c i a l thank you. v i INTRODUCTION I n c r e a s e d p a r t i c i p a t i o n , by men and women i n p h y s i c a l f i t n e s s programs o f a l l v a r i e t i e s has been a c h a r a c t e r i s t i c of the 1980's. E x e r c i s e has been i n v o l v e d i n i n d u c i n g changes i n a l l p h y s i o l o g i c a l systems and i s r e s p o n s i b l e f o r p o s i t i v e changes i n l i f e s t y l e m o d i f i c a t i o n . With the new emphasis on f i t n e s s , e x e r c i s e programs have been expanded to i n c l u d e the pregnant woman. As e x e r c i s e i s p e r c e i v e d t o promote h e a l t h , then perhaps e x e r c i s e d u r i n g pregnancy might a s s u r e an i d e a l g e s t a t i o n a l p e r i o d and a h e a l t h y f e t u s . The l a c k of w e l l - d e s i g n e d and c o n t r o l l e d s t u d i e s of humans e x e r c i s i n g d u r i n g pregnancy has h e a l t h c a r e p r o f e s s i o n a l s b a s i n g t h e i r a d v i c e t o e x e r c i s i n g pregnant women on a n e c d o t a l s t u d i e s i n humans or a n i m a l models. The p h y s i o l o g i c a l d i f f e r e n c e s between humans and a n i m a l s p r e c l u d e s the d i r e c t a p p l i c a t i o n o f a n i m a l s t u d y r e s u l t s t o humans. The m a j o r i t y o f a n i m a l s t u d i e s have used sheep, guinea p i g s , and r a t s as models f o r o b s e r v i n g r esponses t o e x e r c i s e t e s t i n g or t r a i n i n g d u r i n g g e s t a t i o n . E x e r c i s e t e s t i n g h e a l t h y pregnant sheep on a t r e a d m i l l has had no i l l e f f e c t s on the ewes or t h e i r f e t u s e s ( Orr e t a l . , 1972; Cur e t e t a l . , 1976), but e x e r c i s i n g ewes a t 'moderate to heavy s u s t a i n e d ' l e v e l s (Longo e t a l . , 1978), t o e x h a u s t i o n ( Cl a p p , 1980), or w i t h f e t u s e s w i t h i m p a i r e d u m b i l i c a l blood f l o w (Emmanoulides e t a l . , 1972) 1 produced t r a n s i e n t d e c r e a s e s i n f e t a l pO r e s p o n s e s d u r i n g 2 the e x e r c i s e t e s t i n g s e s s i o n s . The decrease i n u t e r i n e blood f l o w (UBF) i n pregnant sheep was r e l a t e d to the l e v e l and d u r a t i o n of m a t e r n a l e x e r c i s e , but a r e l a t i v e l y c o n s t a n t d e l i v e r y o f oxygen was m a i n t a i n e d to the u t e r u s ( L o t g e r i n g e t a l . , 1983a), and the p r e f e r r e n t i a l s h u n t i n g w i t h i n the u t e r u s m a i n t a i n e d f e t a l and p l a c e n t a l V02 a t , or s l i g h t l y above, the p r e - e x e r c i s e v a l u e s d u r i n g e x e r c i s e ( L o t g e r i n g e t a l . , 1983b). The f e t a l pO l e v e l s were w i t h i n normal l e v e l s 2 because t o t a l u t e r i n e oxygen consumption was m a i n t a i n e d d u r i n g e x e r c i s e due t o h e m o c o n c e n t r a t i o n and i n c r e a s e d oxygen e x t r a c t i o n . S t u d i e s w i t h g u i n e a p i g s , r a t s , and mice have c o n t r o l l e d p h y s i c a l a c t i v i t y p r i o r to c o n c e p t i o n and d u r i n g g e s t a t i o n . T r a i n i n g s t u d i e s w i t h pregnant g u i n e a p i g s found i n c r e a s i n g the time and/or i n t e n s i t y of the e x e r c i s e i n c r e a s e d the a b o r t i o n r a t e , s h o r t e n e d the g e s t a t i o n p e r i o d , d e c r e a s e d the m a t e r n a l weight g a i n , i n c r e a s e d f e t a l m o r t a l i t y , decreased f e t a l weight g a i n , lowered newborn weight and i n c r e a s e d newborn m o r t a l i t y i n the t r a i n e d groups ( G i l b e r t e t a l . , 1980). S t u d i e s on e x e r c i s i n g r a t s b e f o r e and d u r i n g pregnancy have found t h a t i n c r e a s e d m o r t a l i t y i n the e x e r c i s i n g groups' o f f s p r i n g may have been due t o the t e s t i n g p r o t o c o l used, m a t e r n a l c a n n i b a l i s m , o r low b i r t h w e i g h t ( W i l s o n and G i s o l f i , 1 9 8 0 ) . The e f f e c t s on the o f f s p r i n g of e x e r c i s e d pregnant r a t s i n v o l v e d c a r d i o v a s c u l a r and l i p i d m e tabolism changes ( P a r i k o v a 1978., 1979), w h i l e o t h e r s ( M o t t o l a e t a l . , 2 1983) found no dev e l o p m e n t a l changes w i t h m i l d a e r o b i c e x e r c i s e . The human s t u d i e s have f o c u s e d on the p h y s i o l o g i c a l responses t o e x e r c i s e d u r i n g pregnancy or the e f f e c t of e x e r c i s e d u r i n g pregnancy on the outcome of pregnancy. One of the f i r s t s t u d i e s r e p o r t e d reduced u t e r i n e b l o o d f l o w w h i l e c y c l i n g a bed c y c l e ergometer ( M o r r i s e t a l . , 1956). The r e d u c t i o n i n UBF may have been due to the t e s t i n g p r o t o c o l i n t h a t the sup i n e p o s i t i o n a l l o w e d the e n l a r g e d u t e r u s t o p r e s s on the i n f e r i o r vena cava . No c o r r e l a t i o n was found between P h y s i c a l F i t n e s s S c o r e s (PFS) and u t e r o p l a c e n t a l i n s u f f i c i e n c y d e termined from f e t a l h e a r t rate(FHR) i n women t e s t e d on a b i c y c l e ergometer l a t e i n g e s t a t i o n (Pommerance et a l . , 1974a) . E a r l y work u s i n g P h y s i c a l Work Capacity(PWC) as an i n d i c a t i o n of p h y s i c a l f i t n e s s d u r i n g pregnancy ( D a h l s t r o m and Ihrman, 1960) found a c o n s t a n t v a l u e through g e s t a t i o n which decr e a s e d s h a r p l y a few days a f t e r d e l i v e r y . A s e r i e s of s t u d i e s u s i n g PWC, ( E r k k o l a 1975, 1976a, 1976b) found t h a t t h i s v a r i a b l e i n c r e a s e d 10% w i t h pregnancy and a f u r t h e r 17.6% w i t h e x e r c i s e t r a i n i n g , and r e t u r n e d t o pre-pregnancy v a l u e s 2 weeks p r i o r t o d e l i v e r y . E x p r e s s i n g the pregnant PWC v a l u e s as a p e r c e n t a g e of the non-pregnant PWC v a l u e , E r k k o l a (1976b) found t h a t those women w i t h g r e a t e r than normal PWC v a l u e s had s i g n i f i c a n t l y s h o r t e r spontaneous l a b o u r s , h e a v i e r newborns and p l a c e n t a s . 3 Pommerance and co-workers(1974b) s t u d i e d pregnant women who were c l a s s i f i e d as " f i t " using t h e i r pre-pregnancy weights, c y c l e ergometer t e s t responses, and compared them to the l e v e l s of p h y s i c a l f i t n e s s based on non-pregnant women using Astrand's nomogram f o r c a l c u l a t i o n of VO max from submaximal 2 measurements (Astrand and Rodah.1,1970 ). They found that the " f i t " m u l t i p a r a s had s h o r t e r labour - stages were not s p e c i f i e d . Recent s t u d i e s have found that a e r o b i c f i t n e s s can be maintained through r e g u l a r a e r o b i c t r a i n i n g during pregnancy ( S i b l e y et a l . , 1981, C o l l i n g s et a l . , 1983). Healthy primiparas and mu l t i p a r a s were a e r o b i c a l l y t r a i n e d f o r 10 to 12 weeks during g e s t a t i o n . A l l the pregnancies were problem- f r e e and the newborns were h e a l t h y . Two case s t u d i e s have been repo r t e d on e x e r c i s i n g during pregnancy but data from these works are only a p p l i c a b l e to the s u b j e c t s analyzed. One study r e p o r t e d no problems with running during pregnancy and l a c t a t i o n where VO max in c r e a s e d 20% during pregnancy 2 i n d i c a t i n g an improvement i n endurance performance (Dressendorfer,1979). The other work suggested that i t was necessary to decrease running and i t s i n t e n s i t y during pregnancy due to the metabolic s t r e s s i t caused (Hutchinson et al.,1981) . In the l a t e r study the i n c r e a s e i n VO was 2 p r o p o r t i o n a l to weight gain and a e r o b i c c a p a c i t y was concluded to be constant throughout g e s t a t i o n . 4 There have been r e t r o s p e c t i v e s t u d i e s r e p o r t e d i n the l i t e r a t u r e on e x e r c i s e throughout pregnancy i n v o l v i n g j o g g i n g , scuba d i v i n g , and a combination of cr o s s - c o u n t r y s k i i n g , a e r o b i c dance and running. With a l l r e t r o s p e c t i v e s t u d i e s the accuracy of s u b j e c t ' s r e c a l l of p h y s i c a l a c t i v i t y p a t t e r n s i n t r o d u c e s c o n s i d e r a b l e e r r o r . Women reported d e c r e a s i n g t h e i r jogging as pregnancy progressed due to mechanical f a c t o r s a s s o c i a t e d with g e s t a t i o n - u t e r i n e enlargement, changes i n weight d i s t r i b u t i o n , and the suggested decrease i n c i r c u l a t o r y r e s e r v e ( J a r r e t t and Spel l a c y , 1 9 8 3 ) . They had a lower a b o r t i o n r a t e and i n c i d e n c e of maternal and f e t a l c o m p l i c a t i o n s than normal which may have been due to t h e i r healthy c o n d i t i o n , but f e t a l a b n o r m a l i t i e s were higher than expected (6% versus the norm of 2-4%). In women who dove during pregnancy, the frequency and depth of dive s decreased as pregnancy progressed, and the in c i d e n c e of the p r e - s e l e c t e d b i r t h c o m p l i c a t i o n s was higher i n women who dove (5.5% vs 0% ; Bolton,1980). Women who p a r t i c i p a t e d i n a combination of endurance a c t i v i t i e s during g e s t a t i o n at or near pre-pregnancy l e v e l s gained l e s s weight , d e l i v e r e d e a r l i e r , and had l i g h t e r newborns than those who stopped before the 28th week (Clapp and D i c k s t e i n , 1 9 8 4 ) . Reasons f o r stopping a c t i v i t y were extreme f a t i g u e , lower abdominal d i s c o m f o r t , m u s c u l o s k e l e t a l i n j u r y , f e a r of a f f e c t i n g the pregnancy, and l a c k of time . 5 Given the problems i n h e r e n t to r e t r o s p e c t i v e s t u d i e s , t h i s i n v e s t i g a t i o n was designed to determine the e f f e c t s of e x e r c i s e throughout g e s t a t i o n on the course of pregnancy and i t s outcome i n healthy p r i m i p a r a s . 6 METHODS S u b j e c t s ; T w e n t y - s i x h e a l t h y C a u c a s i a n , p r i m i g r a v i d women (ages 25 - 35) w i t h no m e d i c a l c o n t r a i n d i c a t i o n s to e x e r c i s e v o l u n t e e r e d t o be s t u d i e d p r o s p e c t i v e l y through g e s t a t i o n . They were r e c r u i t e d through f a m i l y p r a c t i o n e r s , p r e n a t a l e d u c a t i o n c l a s s e s , pre and p o s t n a t a l f i t n e s s c l a s s e s , and the media: r a d i o , newspaper a d v e r t i s e m e n t and p o s t e r s . The s u b j e c t s were made aware of the t e s t i n g p r o t o c o l and any p o t e n t i a l r i s k s ; i n f ormed consent was o b t a i n e d from the s u b j e c t s , and t h e i r p h y s i c i a n s were a d v i s e d of t h e i r p a r t i c i p a t i o n i n the s t u d y . S i x of the s u b j e c t s d i d not complete the study : 3 developed m e d i c a l c o n t r a i n d i c a t i o n s t o e x e r c i s e , 2 l e f t the study due t o l a c k of time and i n t e r e s t , and 1 changed g e o g r a p h i c l o c a t i o n . T h i s was a d e s c r i p t i v e study o n l y ; no attempt was made to modify t h e i r a c t i v i t y p a t t e r n . The s u b j e c t s were asked t o keep a l o g of t h e i r p h y s i c a l a c t i v i t y d u r i n g g e s t a t i o n . T h i s i n c l u d e d the type of e x e r c i s e , f r e q u e n c y , d u r a t i o n , and i n t e n s i t y of a c t i v i t y . F i t n e s s Assessment; The s u b j e c t s e n t e r e d the study a t 10-14 weeks or 22-24 weeks g e s t a t i o n . They completed a q u e s t i o n n a i r e on t h e i r pre-pregnancy p h y s i c a l a c t i v i t y p a t t e r n s , the consent form, and had t h e i r f i t n e s s a s s e s s e d v i a h e a r t r a t e response t o a submaximal t e s t on a Monark c y c l e ergometer. D u r i n g the i n i t i a l t e s t i n g s e s s i o n (10-14 weeks or 22-24 weeks) and the subsequent s e s s i o n s (22-24 weeks and 34-36 weeks), b l o o d p r e s s u r e , w e i g h t , and p r e - t e s t 7 heart r a t e s were recorded. The c y c l e ergometry t e s t i n v o l v e d determining a steady heart r a t e response while c y c l i n g 50 rpm at each of the four designated workloads f o r 5 to 6 minutes : 25, 50, 75, 100 watts.The maternal heart r a t e s were recorded during the c y c l i n g and the p o s t - t e s t p e r i o d by d i r e c t ECG. The t e s t i n g ended when the s u b j e c t ' s heart r a t e reached 150 beats per minute (bpm) or the f o u r t h workload was completed. F e t a l heart r a t e s were not assessed. The s u b j e c t s were c l a s s i f i e d as " f i t " (n=10) i f t h e i r heart r a t e was 130 bpm or l e s s at 1.5 kpm i n the second t r i m e s t e r s e s s i o n (22-24 weeks), or " u n f i t " (n=10) i f t h e i r heart r a t e was g r e a t e r than 130 bpm. The d i f f e r e n c e between the two groups i n the heart r a t e response to the c y c l e ergometery was determined i n the second and t h i r d t r i m e s t e r s using a student's t t e s t with the c o n f i d e n c e l i m i t set at 0.05. With such a small sample s i z e f u r t h e r s t a t i s t i c a l treatment was not deemed a p p r o p r i a t e and the r e s u l t s t r e a t e d as d e s c r i p t i v e data o n l y . Postpartum data: The data was obtained from 6 h o s p i t a l s - 5 i n the Lower Mainland and 1 i n V i c t o r i a . The p a t i e n t s ' r e c o r d s were examined s p e c i f i c a l l y f o r : l e n g t h of l a b o u r , use of medication, s u r g i c a l procedures, p l a c e n t a l weight, newborn weight, apgar scores at 1 and 5 minutes, and sex of the newborn. 8 RESULTS The age i n each group was s i m i l i a r (T=29.50years, UT=28.70years).The lengths of g e s t a t i o n (T=40.75 weeks,UT=40.75 weeks),and weight gained versus pre-pregnancy measures (T=13.92 kg., UT=13.30 kg) i n the two groups were e q u i v a l e n t . The f i r s t stage of labour decreased i n the T group (T«=ll hrs 18.0 min., UT= 13 hrs 58.8 min.). The second stage of labour i n the t r a i n e d group was l e s s than 80% of the un t r a i n e d group (T=70.Omin., UT=90.57min.). A d i f f e r e n c e was a l s o seen i n the t h i r d stage of labour between the two groups (T=7.43 min., UT=15.17 min.). Medication was administered to 8 of 10 t r a i n e d and u n t r a i n e d s u b j e c t s . There were 2 Caesarean s e c t i o n s i n the t r a i n e d group and 3 Caesarean s e c t i o n s i n the u n t r a i n e d group. The maternal data with the means and ranges of the r e s u l t s are presented i n TABLE 1. The mean heart r a t e s d u r i n g the ergometry t e s t s i n the second and t h i r d t r i m e s t e r s i n d i c a t e d a s i g n i f i c a n t d i f f e r e n c e between the two groups. In the second and t h i r d t r i m e s t e r s the mean heart r a t e s were T=121.78 + 9.4, UT=147.11 + 5.3 bpm (p < 0.05); T= 133.22 + 12.0, UT=147.33 + 5.9 bpm (p < 0.05), r e s p e c t i v e l y , t h e r e f o r e d i f f e r e n t l e v e l s of f i t n e s s e x i s t e d between the s u b j e c t s i n each category throughout g e s t a t i o n . The T group i n c r e a s e d i t s mean heart r a t e from the second t r i m e s t e r to the t h i r d t r i m e s t e r , T=121.78 + 9.4 and 133.22 + 12.02 bpm (p<0.05), whereas the UT group's mean heart r a t e s d i d not change, UT= 147.11 + 5.3 and 147.33 + 9 5.9 bpm. Based on these heart r a t e responses, using Astrand's nomogram (de V r i e s , 1968), the s u b j e c t s were c l a s s i f i e d as being h i g h , good, average, f a i r , or low based on t h e i r p r e d i c t e d maximum oxygen uptake (VO max). The T 2 group had more above average VO max r a t i n g s , at 75 watts, i n 2 the second and t h i r d t r i m e s t e r s (T=5 High, 2 Good, UT=1 Good, A Average, A F a i r ; T=l High, A Good, 3 Average, UT=8 Average, 1 F a i r , r e s p e c t i v e l y ) . The a c t i v i t y logbooks (T=9, UT=8) i n d i c a t e d s i m i l i a r p a r t i c i p a t i o n i n a e r o b i c a c t i v i t y , 3 > hours per weeks, i n the second t r i m e s t e r (T=6;UT=6), but the T s u b j e c t s were more a c t i v e i n the t h i r d t r i m e s t e r (T=5;UT=2). (See appendices C and D). The newborns from the t r a i n e d mothers were s l i g h t l y h eavier (T=3733.00 gms., UT=3679.97 gms), but t h e i r p l a c e n t a l weights were lower (T=6A7.A0 gm;UT=812.86 gm). The apgar scores a t 1 minute and 5 minutes were s i m i l i a r (T=7.70,UT=7.90;T=9.20,UT=9.33, r e s p e c t i v e l y ) . T h e r e were more males i n the t r a i n e d newborns whereas the sexes were evenly d i s t r i b u t e d i n the u n t r a i n e d newborns (T:M=8,F=2;UT:M=5,F=5). The newborn data i s summarized i n TABLE 2. 10 TABLE 1 Mean Maternal Data (range of values) T (n=10) Age (ye a r s ) 29.50 (25 - 33) UT (n«*10) 28.76 (25 - 31) G e s t a t i o n a l P e r i o d Length (wks) Weight gain (kgs) Labour Stage Stage Stage 40.75 (40.0 - 41.0) 13.92 (8.64 - 20.90) l l h r s 18.0 min. ( 3 h r s - 15hrs20min.n=9) 70.0 min. ( l l m i n . - 110rain.n=8) 40.75 (38.0 - 42.0) 13.30 (11.82 - 16.36) 13hrs 58.8 min. (4hrs - 48hrs) 90.57 min. (45min.- 150min.n=7) 7.43 min. 15.17 min. (4min.- 16min.n=7) (3min.- 40 min.,n=10) P l a c e n t a Weight (gm) 647.40 812.86 (482 - 820,n=5) (700 - 1050,n=7) Me d i c a t i o n Administered 8/10 8/10 Caesarean S e c t i o n s 2 3 1 K j e l l a n d s r o t a t i o n and e x t r a c t i o n 11 TABLE 2 Mean Newborn Data £ range of values J_ T (n=10) UT (n-10) Apgar 1 minute 7.70 7.90 (5 - 9) (5 - 9, n=9) 5 minute 9.20 9.33 (8 - 10) (9 - 10, n=9) Weight 3733.00 3679.97 (gms) (3200 - 4460) (2980 - 5320) Sex M 8 F 2 5 5 12 DISCUSSION The l i t e r a t u r e on the e f f e c t s of e x e r c i s e during pregnancy has r e p o r t e d changes i n the le n g t h of g e s t a t i o n and maternal weight g a i n . The s i m i l i a r l e n g t h s of g e s t a t i o n i n these two groups confirms previous f i n d i n g s ( C o l l i n g s et a l . , 1983; Dibblee and Graham, 1983; E r k k o l a , 1976; Pommerance et a l . , 1974), but c o n f l i c t s with those of Clapp and D i c k s t e i n (1984) who observed that women who e x e r c i s e d to terra had s h o r t e r l e n g t h s of g e s t a t i o n s . The maternal weight gain r e p o r t e d here was s i m i l i a r i n the two groups which d i f f e r s with the g r e a t e r body f a t and weight i n the u n f i t group i n Dibblee and Graham's (1983) study, and lower maternal weight gain i n women who e x e r c i s e d to term as reported by Clapp and D i c k s t e i n (1984). I t was p o s s i b l e to d i f f e r e n t i a t e l e v e l s of c a r d i o v a s c u l a r f i t n e s s based on the heart r a t e response to submaximal e x e r c i s e d u r i n g g e s t a t i o n . The twenty p r i m i g r a v i d s u b j e c t s i n t h i s study were grouped, s i m i l i a r to Dibblee and Graham(1983), who c l a s s i f i e d f i t n e s s l e v e l s i n p r i m i g r a v i d s u b j e c t s by a s t e p - t e s t and E r k k o l a (1976) who used P h y s i c a l Work C a p a c i t y (PWC) v a l u e s . The maj o r i t y of human t r a i n i n g s t u d i e s ( S i b l e y et al.,1981; C o l l i n g s et a l . , 1983; Er k k o l a 1976, 1976a) placed the s u b j e c t s i n t o an experimental ( t r a i n i n g ) or a c o n t r o l (sedentary) group at the beginning of t h e i r i n v e s t i g a t i o n . T h i s study i n v e s t i g a t e d the e f f e c t of d i f f e r e n t f i t n e s s c l a s s i f i c a t i o n s on pregnancy and i t s outcome, whereas, the other s t u d i e s analyzed the e f f e c t of 13 t h e i r t r a i n i n g programs on f i t n e s s l e v e l s , pregnancy, and outcome. Dibblee and Graham (1983) c l a s s i f i e d the s u b j e c t s i n the f i r s t t r i m e s t e r , but no d i f f e r e n c e s between the T and UT groups e x i s t e d by the t h i r d t r i m e s t e r . In t h i s i n v e s t i g a t i o n we c l a s s i f i e d the s u b j e c t s i n the second t r i m e s t e r and found the groups to be d i s t i n c t throughout the t h i r d t r i m e s t e r . E x e r c i s i n g a c y c l e ergometer has been used as a means of s t u d y i n g pregnant s u b j e c t s by those i n t e r e s t e d i n s p e c i f i c p h y s i o l o g i c a l responses - r e s p i r a t o r y ( P e r n o l l et a l . , 1975; Edwards et a l . , 1981), c a r d i o v a s c u l a r (Ueland et a l . , 1969; Guzman and Caplan, 1970 ), hormonal (Rauramo et al.,1982), and f o r e s t a b l i s h i n g (Pommerance et a l . , 1974) and/or monitoring ( C o l l i n g s et a l . , 1983; E r k k o l a 1976, 1976a) a e r o b i c f i t n e s s l e v e l s during g e s t a t i o n . I t i s a safe procedure f o r determining a e r o b i c f i t n e s s with no known adverse e f f e c t s experienced by the s u b j e c t s . C y c l i n g the c y c l e ergometer ,a non-weight bearing a c t i v i t y , was not a f f e c t e d by the s u b j e c t s ' i n c r e a s i n g weight, s h i f t s i n c e n t r e of g r a v i t y , and/or changes i n body c o n f i g u r a t i o n during g e s t a t i o n -which would a f f e c t other t e s t i n g p r o t o c o l s such as the s t e p - t e s t ( D i b b l e e and Graham ,1983), walking ( S i b l e y et a l . , 1981), or running on a t r e a d m i l l ( Dressendorfer 1978; Hutchinson et a l . , 1981). A l l these t e s t i n g p r o t o c o l s c l a s s i f y the s u b j e c t s based on one aspect of f i t n e s s - c a r d i o v a s c u l a r or a e r o b i c f i t n e s s , and do not attempt to 14 measure the s u b j e c t s ' anaerobic c a p a c i t y , s t r e n g t h , or f l e x i b i l i t y which combined with the a e r o b i c component comprise " p h y s i c a l f i t n e s s " . The s u b j e c t ' s f i t n e s s l e v e l s i n t h i s study does not give any o b j e c t i v e measurement of the c o n d i t i o n of the muscle or ligamentous s t r u c t u r e s and, t h e r e f o r e does not a l l o w s p e c u l a t i o n as to the e f f e c t of strong or t i g h t p e l v i c f l o o r muscles and t h e i r r o l e i n the d e l i v e r y p r o c e s s . The f i r s t stage of labour i n d i c a t e d d i f f e r e n c e s i n the two groups which d i s a g r e e s with the f i n d i n g s reported i n the l i t e r a t u r e ( S i b l e y et a l . , 1981; Dibblee and Graham, 1983; C o l l i n g s et a l . , 1983). T h i s stage of labour i s i n v o l u n t a r y and would not be a f f e c t e d by the s u b j e c t ' s a e r o b i c f i t n e s s l e v e l . A major f i n d i n g of t h i s study i s the r e d u c t i o n i n the second stage of labour i n the T group. T h i s d i s a g r e e s with other s t u d i e s ( C o l l i n g s et al.,1983; Dibblee and Graham, 1983; Pommerance et al.,1974) where no d i f f e r e n c e i n the l e n g t h of labour had been observed i n p r i m i g r a v i d s u b j e c t s . Zaharieva (1972) and E r d e l y i (1960) however, found the second stage of labour to be s h o r t e r i n e l i t e a t h l e t e s compared to n o n - a t h l e t e s . T h i s was d i s p u t e d by Berg and co-workers (1984) who r e p o r t e d t h a t high-performance (endurance and power- t r a i n e d ) a t h l e t e s ' l e n g t h s of labour (not separated i n t o stages) were longer than those r e p o r t e d i n a n a t i o n a l p e r i n a t a l study. The a c t i v e stage of labour may have been reduced by the T s u b j e c t s ' higher l e v e l of a e r o b i c f i t n e s s and, t h e r e f o r e , the s u b j e c t s ' a b i l i t y to a i d the b i r t h 15 process. Fatigue p l a y s a major r o l e i n the process of labour and i t has been demonstrated that i n c r e a s e d a e r o b i c f i t n e s s can postpone the onset of f a t i g u e (Brooks and Fahey, 1984). Thus a f i t woman i s more capable of d e a l i n g with the p h y s i c a l o r d e a l of labour and t h i s i s r e f l e c t e d i n the r e d u c t i o n of the second stage of labour by 20 percent. The t h i r d stage of labour was a l s o q u i c k e r i n the T group, but t h i s v a r i a b l e i s a f f e c t e d more by the medical management of t h i s stage. Two other v a r i a b l e s of i n t e r e s t , medication administered and caesarean s e c t i o n s , c o u l d not be c o n t r o l l e d or a f f e c t e d by the r e s e a r c h design; the d i f f e r e n c e s between the two groups were not apparent. Thus, i n t h i s p o p u l a t i o n , f i t n e s s does not i n f l u e n c e the need f o r a n a l g e s i a or a f f e c t the i n c i d e n c e of s u r g i c a l procedures r e q u i r e d during d e l i v e r y . T h i s r e l a t i o n s h i p between these v a r i a b l e s and f i t n e s s supports the f i n d i n g s of C o l l i n g s and co-workers (1983) and Dibblee and Graham (1983), but c o n f l i c t s with Berg and co-workers(1984) who found a higher number of abdominal d e l i v e r i e s i n a t h l e t e s . The p l a c e n t a l weight has been r e p o r t e d i n two s t u d i e s ( E r k k o l a 1976: C o l l i n g s et a l . , 1983) where l a r g e r p l a c e n t a s were found i n the T groups. The UT group's l a r g e r p l a c e n t a l weights r e p o r t e d i n t h i s i n v e s t i g a t i o n i s s i m i l a r to animal study f i n d i n g s (Nelson et a l . , 1983) where i n c r e a s e d maternal e x e r c i s e decreased p l a c e n t a weight. The sample s i z e of the p l a c e n t a s weighed i n the T group was smaller(n=5) compared to 16 the UT group (n=7) . The r e l a t i o n s h i p between decreased p l a c e n t a weight and f e t a l weight, as re p o r t e d by Nelson and co-workers (1983), was not observed i n t h i s study s i n c e there was no d i f f e r e n c e i n the newborns' weights. Clapp and D i c k s t e i n (1984) found the T group newborns to be l i g h t e r which may have been r e l a t e d to the re p o r t e d s h o r t e r g e s t a t i o n p e r i o d s . E r k k o l a (1976) r e p o r t e d T o f f s p r i n g to be heavier due to the higher plasma volume, blood volume, and t o t a l hemaglobin i n the T subjects.The one minute apgar scores of the T group and the UT group were e q u i v a l e n t , which c o n f l i c i t s with Dibblee and Graham (1983) and C o l l i n g s and co-workers (1983) whose f i t or e x e r c i s e d newborns' had higher 1 minute apgar s c o r e s . There were no d i f f e r e n c e s i n the 5 minute apgar scores which was a p o s s i b l e r e f l e c t i o n on the he a l t h y , normal pregnancies, and the absence of any long-term e f f e c t s of maternal e x e r c i s e on the f e t u s . There have been no r e p o r t s i n the l i t e r a t u r e of s i g n i f i c a n t d i f f e r e n c e s i n 5 minute apgar s c o r e s . The s m a l l sample s i z e r e p o r t e d here l i m i t s the c o n c l u s i o n s which can be made about e x e r c i s e during pregnancy. The study was d e s c r i p t i v e , no attempt was made to modify the s u b j e c t s ' p h y s i c a l a c t i v i t y p a t t e r n s . T h i s i n v e s t i g a t i o n was c a r r i e d out at 6 h o s p i t a l s with a d i f f e r e n t p h y s i c i a n and caseroom nurse f o r each s u b j e c t , t h e r e f o r e , a l a c k i n c o n s i s t e n c y of r e c o r d i n g apgar s c o r e s , and d e l i v e r y procedures i s apparent. The s u b j e c t s were c l a s s i f i e d on the b a s i s of 17 c a r d i o r e s p i r a t o r y f i t n e s s and no attempt was made to evaluate the other p h y s i o l o g i c a l components of f i t n e s s . E x e r c i s e d u r i n g pregnancy did not a f f e c t l e n g t h of g e s t a t i o n , m a t e r n a l weight g a i n , newborn weight, or the f i r s t stage of l a b o u r . I t d i d decrease the second stage of labour i n t r a i n e d s u b j e c t s . The 1 minute and 5 minute apgar scores were s i m i l i a r i n d i c a t i n g no long-term e f f e c t s of e x e r c i s e during pregnancy. In c o n c l u s i o n , p a r t i c i p a t i o n i n a p h y s i c a l f i t n e s s program r e s u l t e d i n no d e t e r i m e n t a l e f f e c t s on the mother or f e t u s . 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A l o n g i t u d i n a l study of changes i n a e r o b i c f i t n e s s , body composition, and energy i n t a k e i n p r l m i g r a v i d p a t i e n t s . Am.J.Obstet.Gynecol 147 (8),p 908, 1983. D r e s s e n d o r f e r , R.H. P h y s i c a l t r a i n i n g d u r i n g pregnancy and l a c t a t i o n . The P h y s i c i a n and Sportsmedicine 6 ( 2 ) , p 74, 1978. D r e s s e n d o r f e r , R.H. and G o o d l i n , R.C. F e t a l Heart Rate response to maternal e x e r c i s e t e s t i n g . The P h y s i c i a n and Sportsmedicine 8 (11), p 91, 1980. Edwards,M.J., M e t c a l f e , J . , Dunham, M.J., and P a u l , M.S. A c c e l e r a t e d r e s p i r a t o r y response to moderate e x e r c i s e i n l a t e pregnancy. R e s p i r . P h y s i o l . 45, p 229, 1981. Emmanoulides, G.C., Hobel, C.J., Y a s h i r o , K., and Klyman.G. F e t a l responses to maternal e x e r c i s e i n the sheepAm.J.Obstet.Gynecol. 112 ( l ) , p 130, 1972. 20 E r d e l y i , G.J. 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The impact of d a i l y work lo a d d u r i n g pregnancy on l i p i d metabolism i n the l i v e r of o f f s p r i n g . E u r . J . A p p l . P h y s i o l . 39, p 81, 1978. Pernoll,M.L.,Metcalfe,J.,Kovach,P.A.,Watchtel,R.,and Dunham,M.J. V e n t i l a t i o n d u r i n g r e s t and e x e r c i s e i n pregnancy and post - partum. R e s p i r . P h y s i o l . 25, p 295, 1975. 23 P e r n o l l , M . L . , M e t c a l f e , J . , S c h l e n k e r , T . L . , W e l c h , J . E . , a n d Matsumoto,*J.A. Oxygen consumption a t r e s t and d u r i n g e x e r c i s e i n p r e g n a n c y . R e s p i r . P h y s i o l . 25, p 285, 1975 P e r n o l l . M . L . , M e t c a l f e , J . , a n d Paul.M. F e t a l c a r d i a c response to m a t e r n a l e x e r c i s e . I n : C i r c u l a t i o n i n F e t u s and Newborn, ed. L.D.Longo, G a r l a n d P u b l i s h i n g , New York, 1977. P i j p e r s , L., W l a d i m i r o f f , J . W . , and McGhie,J. E f f e c t of s h o r t - t e r m m a t e r n a l e x e r c i s e on m a t e r n a l and f e t a l c a r d i o v a s c u l a r d y n a m i c s . B r i t i s h J . O b s t e t . G y n e c o l . 91, p 1081, 1984. P i a t t , L.D., A r t a l , R . , Serael, J . , S i p o s , L . , and Kammuala,R.K. E x e r c i s e i n pregnancy. I I F e t a l r e s p o n s e s . Am.J.Obstet.Gynecol. 147 ( 5 ) , p 487, 1983. P o k o r n y , J . and Rous,J. The e f f e c t of mother's work on f o e t a l h e a r t sounds. In H o r s k y , J . and S t e m b e r a , Z . ( e d s ) : I n t r a u t e r i n g Dangers to the Fetus E x c e r p t a Medica F o u n d a t i o n 1967, p354. Pommerance, J . J . , Gluck,L.,and Lynch, V.A. M a t e r n a l e x e r c i s e as a s c r e e n i n g t e s t f o r u t e r o p l a c e n t a l i n s u f f i c i e n c y . O b s t e t . G y n e c o l . 44 ( 3 ) , p 383, 1974a. Pommerance,J.J., G l u c k , l . , and Lynch, V.A. P h y s i c a l f i t n e s s i n pregnancy: i t s e f f e c t on pregnancy outcome.Am.J.Obstet.Gynecol. 119 ( 7 ) , p 867, 1974b. Rauramo,I.,Andersson,B., L a a t i k a i n e n , T . , and P e t t e r s s o n , J . S t r e s s hormones and p l a c e n t a l s t e r i o d s i n p h y s i c a l e x e r c i s e d u r i n g p r e g n a n c y . B r i t i s h J . O b s t e t . G y n e c o l . 89, p 921, 1982. S e i t c h i k , J . Body c o m p o s i t i o n and energy e x p e n d i t u r e d u r i n g r e s t and work i n pregnancy. Am.J.Obstet.Gynecol. 97 ( 5 ) , p 701, 1967. S i b l e y , L . . R u h l i n g , R . 0 . , Cameron-Foster, J . , C h r i s t e n s e n , C . , and Bolen,T. Swimming and p h y s i c a l f i t n e s s d u r i n g p r e g n a n c y . J . N u r s e - M i d w i f e r y 26 ( 6 ) , p 3, 1981. Smith,A.D., G i l b e r t , R . D . , Lammers,R.J., and Longo,L.D. P l a c e n t a l exchange a r e a i n g u i n e a p i g s f o l l o w i n g l o n g - t e r m m a t e r n a l e x e r c i s e : a s t e r e o l o g i c a l a n a l y s i s . J . D e v e l o p . P h y s i o l . 5, p 11, 1983. S o i v a , K . , S a l m i , A . , Gronroos,M., and P e l t o n e n , T . P h y s i c a l work c a p a c i t y d u r i n g pregnancy and e f f e c t of p h y s i c a l work t e s t s on f o e t a l h e a r t r a t e . A n n . C h i r . G y n a e c o l . Fenn. 53, p 187, 1964. 24 Stembera,Z.K. and Hodr.J. The " e x e r c i s e t e s t " a s an e a r l y d i a g n o s t i c a i d f o r f o e t a l d i s t r e s s . I n Horsksy.J. and Stembera,Z (eds) I n t r a u t e r i n e Dangers to the Fetus. Excerpta Medica Foundation^ 1967, p 349. Terada.M. E f f e c t of p h y s i c a l a c t i v i t y before pregnancy on f e t u s e s of mice e x e r c i s e d f o r c i b l y d u r i n g pregnancy.Teratology 10, p 141, 1974. Turner, G., and Unsworth.T. I n t r a u t e r i n e bends? Lancet p 905, A p r i l 17, 1982. Ueland,K. t Novy, M.J., and M e t c a l f e , J . C a r d i o r e s p i r a t o r y responses to pregnancy and e x e r c i s e i n normal women and p a t i e n t s with heart disease.Am.J.Obstet.Gynecol. 115 ( 1 ) , p 4, 1969. Ueland.K., Novy,M.J., Peterson,E.N.,and M e t c a l f e , J . Maternal c a r d i o v a s c u l a r dynamicstIV The i n f l u e n c e of g e s t a t i o n a l age on the maternal c a r d i o v a s c u l a r response to posture and e x e r c i s e . Am.J.Obstet.Gynecol. 104 ( 6 ) , p 856, 1969. Ueland,K., Novy,M.J., and M e t c a l f e , J . Hemodynamic responses of p a t i e n t s with heart d i s e a s e to pregnancy and e x e r c i s e . Am.J.Obstet.Gynecol. 113 ( 1 ) , p 47, 1972. V e i l l e , J - C , Hohimer, A.R. , Burry, K., S p e r o f f , L . The E f f e c t o e x e r c i s e on u t e r i n e a c t i v i t y i n the l a s t e i g h t weeks of pregnancy. Am.J.Obstet.Gynecol. 151 ( 6 ) , p727, 1985. Wilson,N.C. and G i s o l f i , C V . E f f e c t s of e x e r c i s i n g r a t s d u r i n g p r e g n a n c y . J . A p p l . P h y s i o l . 48 ( 1 ) , p 34, 1980. Zaha r i e v a . E . Olympic p a r t i c i p a t i o n by women - e f f e c t s on pregnancy and c h i l d b i r t h . J.A.M.A. 221 ( 9 ) , p 992, 1972. 25 APPENDIX A - REVIEW OF LITERATURE I n t r o d u c t i o n In the past e x e r c i s e during pregnancy was r e s t r i c t e d to s t r e t c h and r e l a x a t i o n e x e r c i s e s which were i n p r e p a r a t i o n f o r labour and d e l i v e r y . The recent i n t e r e s t i n f i t n e s s p resents a dilemma f o r p h y s i c a l l y a c t i v e women of c h i l d b e a r i n g age: should she e x e r c i s e during pregnancy? Popular l i t e r a t u r e c i t e s women who were a c t i v e throughout g e s t a t i o n with no or p o s i t i v e e f f e c t s on pregnancy and i t s outcome. Reasons c i t e d f o r encouraging r e g u l a r e x e r c i s e during pregnancy i n c l u d e c o n t r o l l i n g weight gai n , decreased backache, c o n s t i p a t i o n , and/or v a r i c o s e v e i n s , and i n c r e a s e d energy l e v e l s f o r coping with d a i l y l i f e and the s t r e s s e s of pregnancy (Jopke, 1983). However, there are few p r o s p e c t i v e c l i n i c a l t r i a l s on the e f f e c t s of e x e r c i s e on pregnancy women and t h e i r f e t u s e s . Animals s t u d i e s have demonstrated some negative e f f e c t s of e x e r c i s e during pregnancy and the p r a c t i c i c n g p h y s i c i a n has l i t t l e concrete data on which to base a d e c i s i o n when c o n s u l t e d by a woman who questions the merit of c o n t i n u i n g an e x e r c i s e program throughout her g e s t a t i o n a l p e r i o d . T h i s paper reviews the s t u d i e s i n the area i n both animal and human po p u l a t i o n s i n an e f f o r t to gain an o v e r a l l p i c t u r e of the c u r r e n t s t u d i e s of re s e a r c h i n the f i e l d . 26 Animal S t u d i e s Animal s t u d i e s provide models f o r the e f f e c t s of e x e r c i s e d u r i n g pregnancy. The l i t e r a t u r e on e x e r c i s i n g pregnant animals during g e s t a t i o n has o f f e r r e d a v a r i e t y of c o n c l u s i o n s due to the experimental animals used, stages d u r i n g g e s t a t i o n examined, and experimental p r o t o c o l s . The m a j o r i t y of animal s t u d i e s have shown that i n normal, healthy animals, e x e r c i s e t e s t i n g to exhaustion i s w e l l - t o l e r a t e d (Orr et a l . , 1972; Curet et a l . , 1976; Mottola et a l , , 1983) and t h a t the e f f e c t s on the f e t u s from acute e x e r c i s e bouts i s t r a n s i e n t with no d e t r i m e n t a l long-term e f f e c t s . Some s t u d i e s have found that t r a i n i n g to exhaustion w i l l cause s h o r t e r d u r a t i o n of g e s t a t i o n , lower b i r t h w e i g h t s , and i n c r e a s e d f e t a l m o r t a l i t y ( G i l b e r t et a l . , 1980; Wilson and G i s o l f i , 1980) while others have found p o s i t i v e long-term e f f e c t s of p r e n a t a l e x e r c i s e ( P a r i z i k o v a , 1978 and 1979). E x e r c i s e before mating may a f f e c t pregnancy - weight gai n , l i t t e r s i z e - depending when t r a i n i n g occurred i n the females' l i f e c y c l e . The general c o n c l u s i o n from the animal l i t e r a t u r e was t h a t c h r o n i c maternal e x e r c i s e , i n moderation, had no long-term e f f e c t s on the f e t u s , g e s t a t i o n l e n g t h , or the mother. 27 U t e r i n e Blood Flow F e t a l responses f o l l o w e d maternal responses during the pregnant ewe's e x e r c i s e i n work by Emmanoulides et a l . (1972). At the end of maternal e x e r c i s e , there was s i g n i f i c a n t i n c r e a s e i n f e t a l pH and decrease i n f e t a l pCO 2 a s s o c i a t e d with maternal h y p e r v e n t i l a t i o n and a l k a l o s i s . C h r o n i c a l l y - s t r e s s e d f e t u s e s had higher pCO and lower pO 2 2 v a l u e s , before and a f t e r maternal e x e r c i s e , and an e l e v a t e d heart r a t e a f t e r e x e r c i s e f o r a longer p e r i o d compared to normal f e t u s e s . There was gross evidence of f e t a l m a l n u t r i t i o n seen i n the c h r o n i c a l l y - d i s t r e s s e d f e t u s e s (where one u m b i l i c a l a r t e r y was t i e d ) of e x e r c i s i n g ewes and of n o n - e x e r c i s i n g ewes. These f e t u s e s were at an a d d i t i o n a l disadvantage dur i n g maternal e x e r c i s e due to the reduced oxygen a v a i l a b l e . The r e d i s t r i b u t i o n of r e g i o n a l blood flow a s s o c i a t e d with the decreased c i r c u l a t o r y reserve of pregnant animals, and the e f f e c t s of the moderate maternal and f e t a l hemoglobin were causes f o r decreased oxygen. The study assumed t h a t the f e t a l oxygen consumption and the pO 2 g r a d i e n t ( u m b i l i c a l a r t e r y - u m b i l i c a l vein) d i d not change during maternal e x e r c i s e . The authors concluded that moderately severe maternal e x e r c i s e may induce v a r y i n g decreases of f e t a l pO which were t r a n s i e n t and w e l l - 2 t o l e r a t e d by the f e t u s e s with i n t a c t u m b i l i c a l c i r c u l a t i o n where there was a r a p i d r e t u r n of u t e r i n e blood flow (UBF) to p r e - e x e r c i s e l e v e l s d u r i n g r e c o v e r y . 2 8 Orr e t a l . (1972) found UBF i n non-pregnant and pregnant sheep was not i m p a i r e d by m a t e r n a l e x e r c i s e t o e x h a u s t i o n , i f the a n i m a l was h e a l t h y . The i n c r e a s e d heat produced d u r i n g e x e r c i s e was removed by i n c r e a s e d c a r o t i d b l o o d f l o w t o the v a s c u l a r p l e x u s i n the t u r b i n a t e bones. In sheep, the v a s c u l a r p l e x u s i s a heat exchanger. The i l i a c b l ood f l o w was i n c r e a s e d t o meet the i n c r e a s e d oxygen r e q u i r e m e n t s of the s k e l e t a l m u s c l e s . The s i g n i f i c a n t i n c r e a s e i n UBF i n non-pregnant sheep was because the blo o d f l o w a t r e s t was s m a l l and the i n c r e a s e i n UBF d u r i n g e x e r c i s e was a g r e a t e r percentage of the t o t a l UBF than i n pregnant sheep. In pregnant sheep, the UBF would be near maximum v a l u e s a t r e s t and the i n c r e a s e w i t h e x e r c i s e would be a s m a l l e r p ercentage of t o t a l UBF when compared to the i n c r e a s e i n e x e r c i s i n g non- pregnant sheep. Orr d i s a g r e e d w i t h Emmanoulides'(1972) c o n c l u s i o n s t h a t a drop i n f e t a l b l o o d pO i n d i c a t e d t i s s u e 2 h y p o x i a . Orr c o n c l u d e d t h a t the absence of f e t a l a c i d o s i s i n d i c a t e d a l a c k o f f e t a l h y p o x i a . M a t e r n a l e x e r c i s e i n Or r ' s work d i d not cause any hazardous e f f e c t s on the f e t u s because UBF was not i m p a i r e d . L a t e r , i t was c o n f i r m e d by C u r e t e t a l . (1976) t h a t m a t e r n a l e x e r c i s e d i d not a f f e c t u t e r i n e b l o o d f l o w , and t h e r e was no d i f f e r e n c e i n response to e x e r c i s e t e s t i n g i n t r a i n e d and u n t r a i n e d pregnant ewes. Cu r e t q u e s t i o n n e d whether a t h r e e week t r a i n i n g p e r i o d on the t r e a d m i l l was s u f f i c i e n t t o show a d i f f e r e n c e i n s t r o k e volume and h e a r t r a t e d u r i n g the e x e r c i s e t e s t i n g . Sheep responded t o the e x e r c i s e t e s t by 2 9 i n c r e a s i n g c a r d i a c output by i n c r e a s i n g heart r a t e , which d i f f e r s from humans who i n c r e a s e c a r d i a c output by i n c r e a s i n g stroke volume and heart r a t e . Pygmy goats i n c r e a s e c a r d i a c output l i k e humans, by i n c r e a s i n g t h e i r s t r o k e volume. Dhinsda et a l . (1978) found that the r e s t i n g heart r a t e was s i g n i f i c a n t l y higher i n l a t e pregnancy and i n c r e a s e d more with e x e r c i s e compared to postpartum, as expected. The p e r i p h e r a l v a s c u l a r r e s i s t a n c e at r e s t was lower during pregnancy and was s i g n i f i c a n t l y lower with e x e r c i s e , but not enough to account f o r the i n c r e a s e d c a r d i a c output with e x e r c i s e . I t was proposed that the i n c r e a s e i n c a r d i a c output r e s u l t e d from the i n c r e a s e d a r t e r i a l blood pressure during e x e r c i s e and i t s g r e a t e r i n c r e a s e i n pregnancy. The r e s t i n g a-vO d i f f e r e n c e and the 2 amount i t i n c r e a s e d with e x e r c i s e were the same during l a t e pregnancy and postpartum. Pygmy goats were suggested as models f o r human blood flow d i s t r i b u t i o n , t i s s u e oxygen supply, and f e t a l oxgenation s t u d i e s during maternal e x e r c i s e . In the l a s t t r i m e s t e r of pregnancy, the n o n p l a c e n t a l p o r t i o n s of the pygmy goat uterus s u f f e r e d a major r e d u c t i o n i n blood flow d u r i n g e x e r c i s e (Hohimer et a l . , 1982). The v a s c o n s t r i c t i o n may have been due to e x e r c i s e ( walking on an i n c l i n e d t r e a d m i l l at 1.5 to 2.0 mph) or to concommitant hypocapnia or hyperthermia. 30 Longo and a s s o c i a t e s (1978) c o n c l u d e d t h a t "moderate to heavy s u s t a i n e d " m a t e r n a l e x e r c i s e i n pregnant sheep c o u l d r e s u l t ii i n s i g n i f i c a n t f e t a l h y p o x i a and p o s s i b l y cause i n t r a u t e r i n e growth r e t a r d a t i o n . D u r i n g m a t e r n a l e x e r c i s e , f e t a l d escending a o r t i c pO f e l l and UBF dereased a s s o c i a t e d w i t h a 2 decrease i n m a t e r n a l a r t e r i a l pCO s i m i l i a r t o the e a r l i e r •-. 2 f i n d i n g s (Emmanoulides e t a l . , 1972). There was a s i g n i f i c a n t d ecrease i n the weight of f e t u s e s from e x e r c i s i n g ewes compared to the c o n t r o l s . The e x e r c i s i n g ewes had a lower p l a c e n t a l d i f f u s i n g c a p a c i t y f o r carbon monoxide d u r i n g r e s t , than the c o n t r o l s , and d u r i n g e x e r c i s e the d i f f u s i n g c a p a c i t y i n c r e a s e d . The r a t e s of u t e r i n e and u m b i l i c a l b l o o d f l o w and f e t a l pO 2 decreased i n pregnant sheep e x e r c i s e d t o e x h a u s t i o n ( C l a p p , 1980). D u r i n g e x e r c i s e t h e r e was a downward s h i f t i n the oxygen d i s s o c i a t i o n curve a l l o w i n g normal oxygen uptake by u t e r o p l a c e n t a l t i s s u e and the f e t u s . The e x e r c i s e t e s t was a s s o c i a t e d w i t h s i g n i f i c a n t i n c r e a s e s i n m a t e r n a l temperature and r e s p i r a t o r y a l k a l o s i s which l e d to a decrease i n UBF. The i n c r e a s e i n h e a r t r a t e was r e l a t e d t o the decrease i n UBF. The p r e - e x e r c i s e c o n d i t i o n of the ewes might have e f f e c t e d the UBF because the w e l l - t r a i n e d ewes had unchanged u t e r i n e blood f l o w v a l u e s d u r i n g s h o r t term e x e r c i s e on the t r e a d m i l l . R e c e n t l y , L o t g e r i n g and co- w o r k e r s ( 1983a) found a decrease i n pregnant ewe's UBF d u r i n g e x e r c i s e and a very f a s t r e t u r n 31 to normal v a l u e s d u r i n g r e c o v e r y , s i m i l i a r to f i n d i n g s w i t h humans ( M o r r i s e t a l . , 1956). The ewes were accustomed to the e x e r c i s e s t r e s s by w a l k i n g on the t r e a d m i l l a t v a r i o u s speeds f o r 10 m i n u t e s , f o r a week. Cu r e t and a s s o c i a t e s (1976) had q u e s t i o n n e d whether t h r e e weeks were ample t r a i n i n g time to f i n d d i f f e r e n c e s i n sheeps' responses to e x e r c i s e , but L o t g e r i n g f e l t t h a t h i s a c c l i m a t i z a t i o n p e r i o d was adequate and p r e v e n t e d e x c e s s i v e c a t e c h o l a m i n e r e l e a s e b e f o r e or d u r i n g the t e s t . The sudden UBF changes d u r i n g e x e r c i s e s u g g e sted t h a t the i n i t i a l d e crease i n UBF was not due t o h y p e r t h e r m i a or a l k a l o s i s ( both occur i n e x e r c i s e and are a s s o c i a t e d w i t h a d e c r e a s e i n UBF), but a n e u r a l or hormonal mechanism due t o e x e r c i s e . The f u r t h e r d e c rease i n UBF was a t t r i b u t e d t o h y p e r t h e r m i a and a l k a l o s i s . I t was c o n c l u d e d t h a t the d e c r e a s e i n UBF m a i n t a i n e d a r e l a t i v e l y c o n s t a n t oxygen d e l i v e r y to the u t e r u s which was i n v e r s e l y r e l a t e d to the l e v e l and d u r a t i o n of m a t e r n a l e x e r c i s e . I n summary, the m a t e r n a l e x e r c i s e e i t h e r had no e f f e c t on UBF ( O r r e t a l . , 1972; C u r e t e t a l . , 1976;) or i t d e c r e a s e d UBF (Emmanoulides e t a l . , 1972) w i t h a q u i c k r e t u r n to r e s t i n g UBF l e v e l s d u r i n g p o s t - e x e r c i s e r e c o v e r y s i m i l i a r t o the e f f e c t i n humans ( M o r r i s e t a l . , 1956). The i n i t i a l UBF d e c r e a s e was proposed as a n e u r a l or hormonal mechanism due to e x e r c i s e w i t h the f u r t h e r decrease i n UBF r e s u l t i n g from m a t e r n a l h y p e r t h e r m i a and r e s p i r a t o r y a l k a l o s i s ( L o t g e r i n g e t a l . , 1983a). The c o n c e r n f o r the decrease i n UBF was c h r o n i c 32 f e t a l t i s s u e h y p o x i a which c o u l d l e a d to i n t r a u t e r i n e growth r e t a r d a t i o n (Longo e t a l . , 1978). Oxygen a v a i l a b i l i t y to the f e t u s was assumed t o be r e l a t i v e l y c o n s t a n t d u r i n g m a t e r n a l e x e r c i s e w i t h the downward s h i f t i n the oxygen d i s s o c i a t i o n c urve when u t e r i n e and u m b i l i c a l b l o o d f l o w was reduced ( C l a p p , 1980). E x e r c i s i n g the pregnant a n i m a l s t o e x h a u s t i o n d i d not a f f e c t the o f f s p r i n g s ' development which c o u l d be e x p e c ted s i n c e the m a j o r i t y of s t u d i e s i n v o l v e d e x e r c i s e t e s t i n g , not t r a i n i n g , d u r i n g g e s t a t i o n . One study d i d f i n d t h a t o f f s p r i n g from e x e r c i s e d a n i m a l s , a t moderate to s e v e r e l e v e l s , had s i g n i f i c a n t l y l i g h t e r o f f s p r i n g compared to the c o n t r o l s , but the d i f f e r e n c e was not a t t r i b u t e d j u s t to reduced UBF. The m a j o r i t y of s t u d i e s found t h a t the o f f s p r i n g were normal at b i r t h . E f f e c t on O f f s p r i n g Terada (1974) s t u d i e d f o u r groups of mice t o see the e f f e c t s of t r a i n i n g , b e f o r e and d u r i n g g e s t a t i o n on f e t a l development. H a l f of t h e mice t r a i n e d (T) b e f o r e m a ting, and r a n (TR) or were s e d e n t a r y (TC) from the 9 t h to the 16th day of g e s t a t i o n , and t h e o t h e r h a l f e i t h e r r a n a f t e r mating ( C E ) , from the 9 t h to the 16th day, or were a c o n t r o l (CC). Tra-ining b e f o r e mating was advantageous because the TR group had a l ower f e t a l m o r t a l i t y r a t e compared^ to the CE group due to an unknown mechanism. There were no m o r t a l i t y d i f f e r e n c e s 3 3 between TC and CC f e t u s e s . Terada proposed t h a t the lower body w e i g h t s of the t r a i n e d mice a t the s t a r t of g e s t a t i o n wa'.s due to a decreased c a l o r i c i n t a k e i n t h e i r growing phase, when t r a i n i n g o c c u r r e d . E x e r c i s i n g d u r i n g mid-pregnancy ( 9 t h to 16th day) was a t t r i b u t e d t o i n t e r f e r r i n g w i t h the body weight g a i n s i n the TR and CE mice. F e t a l weights i n the CE and TR l i t t e r s were l o w e r . The- h i g h e r m o r t a l i t y and lower f e t a l w e i g h t s i n the CE group was caused by the decrease i n water and food consumption, and the u t e r i n e e n v i r o n m e n t a l m o d i f i c a t i o n s (eg:decreased UBF). Comparing m a t e r n a l e x e r c i s e t o c h r o n i c h y p o x i a i n guinea p i g s G i l b e r t e t a l . , ( 1 9 7 9 ) , found moderate e x e r c i s e d u r i n g g e s t a t i o n d i d not produce any changes i n f e t a l body, organ or p l a c e n t a l w e i g h t s , whereas c h r o n i c h y p o x i a decreased f e t a l body and b r a i n w e i g h t s , and i n c r e a s e d the r a t i o of b r a i n , h e a r t , and p l a c e n t a w e i g h t s t o body w e i g h t s when compared to c o n t r o l r a t i o s . P r e v i o u s work ( T e r a d a , 1974) found a decrease i n f e t a l weight w i t h m a t e r n a l e x e r c i s e , but the d i f f e r e n c e s i n the two s t u d i e s were p r o b a b l y due to a h i g h e r l e v e l of e x e r c i s e i n the p r e v i o u s s t u d y . The f i r s t i n d i c a t i o n of s t r e s s produced by m a t e r n a l e x e r c i s e was a decrease i n p l a c e n t a l d i f f u s i n g c a p a c i t y , found w i t h h i g h e r workloads and the changes i n f e t a l body and organ w e i g h t s found i n o t h e r s t u d i e s ( T e r a d a , 1974; Longo et a l . , 1978; Nelson e t a l . , 1983). Based on w e i g h t , the a u t h o r s f e l t the e x e r c i s e l e v e l was w e l l - t o l e r a t e d by the e x e r c i s i n g a n i m a l s , but 15 of the 20 e x e r c i s i n g a n i m a l s a b o r t e d or d e l i v e r e d e a r l y ( i n d i c a t i n g 34 the e x e r c i s e l e v e l was s e v e r e ) . E x e r c i s i n g d u r i n g pregnancy d i d not i n d u c e c h r o n i c h y p o x i a because the w e i g h t s - f e t a l body, organ, p l a c e n t a - of the e x e r c i s i n g a n i m a l s d i d not change as they d i d i n the a n i m a l s exposed to c h r o n i c h y p o x i a . A subsequent s t u d y w i t h g u i n e a p i g s , ( G i l b e r t e t a l . , 1980) used d i f f e r e n t l e v e l s of m a t e r n a l e x e r c i s e to determine the e f f e c t s on p l a c e n t a l and f e t a l w e i g h t s , and d i f f u s i n g c a p a c i t y . P l a c e n t a l and k i d n e y w e i g h t s decreased as the e x e r c i s e i n t e n s i t y i n c r e a s e d and the r a t i o of b r a i n and h e a r t weight t o body weight i n c r e a s e d a t h i g h e r l e v e l s of e x e r c i s e . The b r a i n and h e a r t w e i g h t s had no r e l a t i o n s h i p t o the e x e r c i s e l e v e l s which may be due to " r e l a t i v e s p a r i n g " of t hese o r g a n s . The d i f f u s i n g c a p a c i t y decreased w i t h more i n t e n s e e x e r c i s e l e v e l s s u p p o r t i n g G i l b e r t ' s (1978) e a r l i e r h y p o t h e s i s . The f e t u s , i t was c o n c l u d e d , was compromised by a s m a l l e r p l a c e n t a , t h e r e f o r e w i t h l e s s d i f f u s i n g c a p a c i t y per k i l o g r a m of f e t a l t i s s u e which was s u p p o r t e d l a t e r by N e l s o n e t a l . , 1983. C h a n d l e r and B e l l (1981) suggested f e t a l o x y g e n a t i o n was compromised by the e f f e c t s of reduced UBF and m a t e r n a l a l k a l o s i s on p l a c e n t a l t r a n s f e r d u r i n g e x e r c i s e i n pregnant ewes. M i l d e x e r c i s e caused the development of m i l d hypocapnea w i t h no e f f e c t s on f e t a l gases. Moderate e x e r c i s e d i d not a f f e c t the u t e r i n e oxygen uptake s i g n i f i c a n t l y because an i n c r e a s e i n t h e a-vO d i f f e r e n c e a c r o s s the u t e r u s 2 was about e q u a l to the d e c r ease i n blood f l o w . The 35 s i g n i f i c a n t changes i n maternal hemoblobin c o n c e n t r a t i o n , f e t a l and maternal blood gases were gre a t e r with moderate e x e r c i s e than mild e x e r c i s e . There were i n c r e a s e s i n maternal blood glucose and l a c t a t e l e v e l s , and f e t a l glucose and l a c t a t e c o n c e n t r a t i o n s a f t e r mild maternal e x e r c i s e . Reasons f o r f e t a l hyperglycemia were 1) i n c r e a s e d u m b i l i c a l glucose uptake, 2) s t i m u l a t i o n of g l y c o g e n o l y s i s i n f e t a l l i v e r , and 3) reduced f e t a l glucose u t i l i z a t i o n due to reduced blood flow. The e x t r a c t i o n of glucose i n c r e a s e d s i g n i f i c a n t l y with e x e r c i s e as the UBF decreased, but e f f e c t s on p l a c e n t a l oxygen t r a n s f e r were balanced by the i n c r e a s e i n maternal hemoconcentration. Maternal r e s p i r a t o r y a l k a l o s i s during moderate e x e r c i s e could reduce p l a c e n t a l t r a n s f e r due to 1) a s i g n i f i c a n t s h i f t i n the maternal oxyhemaglobin d i s s o c i a t i o n curve, t h e r e f o r e i n c r e a s i n g the oxygen a f f i n i t y of maternal a r t e r i a l blood which i s g r e a t e r than f e t a l blood, or 2) f e t a l hypocapnia and a l k a l e m i a from maternal r e s p i r a t o r y a l k a l o s i s could decrease u m b i l i c a l blood flow. In c o n c l u s i o n , the authors f e l t t h a t short-term r e a l i s t i c l e v e l s of e x e r c i s e caused s i g n i f i c a n t d i s t u r b a n c e s i n r e s p i r a t i o n and carbohydrate metabolism i n f e t a l sheep, t h e r e f o r e , e x e r c i s e c l o s e to term could a f f e c t f e t a l w e l l - being and " b i r t h v i g o u r " more than gross e f f e c t s on f e t a l growth. The lambs i n the study were born w i t h i n f i v e ( 5 ) days of term and i n the normal weight range. 3 6 Maternal e x e r c i s e produced d e t r i m e n t a l e f f e c t s on f e t a l growth and development i n guinea pigs (Nelson et a l . , 1983). Lower l e v e l s of e x e r c i s e (15 or 30 minutes/day) decreased p l a c e n t a l weight whereas d i f f u s i n g c a p a c i t y and higher l e v e l s of e x e r c i s e (45 or 60 minutes/day) decreased f e t a l weights. Nelson 's f i n d i n g s agreed with G i l b e r t ' s e a r l i e r statement (1979) t h a t i n c r e a s e d workloads could be s t r e s s f u l , a f f e c t i n g d i f f u s i n g c a p a c i t y , and f e t a l weights. The d i f f u s i n g c a p a c i t y had a d i f f e r e n t response to e x e r c i s e due to 1) a s e l e c t i o n process whereby the f e t u s e s with low p l a c e n t a l d i f f u s i n g c a p a c i t i e s aborted before term, or 2) the appearance of some adapt i v e mechanisms not present at the lower l e v e l s . The mechanisms proposed f o r the changes i n p l a c e n t a l d i f f u s i n g c a p a c i t y during e x e r c i s e were an a l t e r a t i o n i n p l a c e n t a l morphology with a decrease i n exchange s u r f a c e , based on other work i n t h e i r lab (Smith et a l . , 1983) and a decrease i n f e t a l blood volume or decrease i n maternal and f e t a l p l a c e n t a l blood volume. Pa r i z k o v a (1978) used r a t s to study the e f f e c t of p r e n a t a l and p o s t n a t a l e x e r c i s e on c a r d i a c m i c r o s t r u c t u r e . The pregnant r a t s e i t h e r e x e r c i s e d (E) or d i d not e x e r c i s e (C) during g e s t a t i o n , and t h e i r male o f f s p r i n g e i t h e r e x e r c i s e d (EE,CE) or d i d not e x e r c i s e (EC.CC). The highest d e n s i t y of c a r d i a c muscle f i b e r was i n the EE group and the lowest d e n s i t y was i n the CC group. P a r i z k o v a suggested that with r e g u l a r o p t i m a l workloads during pregnancy (E) the p o s i t i v e 37 e f f e c t s of e x e r c i s e c o u l d be t r a n s f e r r e d t o the f e t u s , and the e f f e c t s of e x e r c i s e on c a r d i a c muscle would i n c r e a s e i f the o f f s p r i n g (EE) c o n t i n u e d r e g u l a r o p t i m a l e x e c i s e . The CE group i n c r e a s e d t h e i r c a r d i a c m i c r o s t r u c t u r e w i t h p o s t n a t a l e x e r c i s e compared to the CC o f f s p r i n g , but the i n c r e a s e d d e n s i t y was not the same as the EE group. There were two suggested r e a s o n s f o r the changes i n the f e t a l development. F i r s t , the i n c r e a s e i n p l a c e n t a l b l o o d f l o w d u r i n g m a t e r n a l e x e r c i s e and change i n d i s t r i b u t i o n of b l o o d t o the p l a c e n t a m o d i f i e d the f e t a l h e a r t and i t s f u t u r e development. Second, the changes were due to i n c r e a s e d d a i l y workloads which i n c r e a s e d g l y c o l y s i s , l i p o l y s i s , r e l e a s e of c a t e c h o l a m i n e s , and b l o o d l e v e l s of p y r u v i c a c i d , l a c t i c a c i d , and f r e e f a t t y a c i d s , t h e r e b y i n c r e a s i n g the f e t u s ' exposure t o these elements and m o d i f y i n g i t s development. P a r i z k o v a (1979) r e p e a t e d the s t u d y w i t h male and female o f f s p r i n g and found no d i f f e r e n c e s i n c a r d i a c m i c r o s t r u c t u r e development between the s e x e s . The e f f e c t o f m a t e r n a l e x e r c i s e on s e l e c t e d f a c t o r s of l i p i d m e t abolism - l i p i d and f a t t y a c i d c o n c e n t r a t i o n , serum c h o l e s t e r o l l e v e l s of f r e e f a t t y a c i d s ( F F A ) , c h o l e s t e r o l and l i p i d s y n t h e s i s was i n v e s t i g a t e d by P a r i z k o v a and P e t r a s e k (1978) i n f o u r groups of male and female o f f s p r i n g (35-108 days o l d ) who e x e r c i s e d (E) or were s e d e n t a r y ( C ) . At 35 days, the E o f f s p r i n g had h i g h e r serum c h o l e s t e r o l l e v e l s of FFA's and c h o l e s t e r o l . The E females had a h i g h e r l i p i d and f a t t y a c i d c o n c e n t r a t i o n i n t h e i r l i v e r , whereas the E males 38 had a lower or no change i n l i p i d c o n c e n t r a t i o n compared to the other groups. L i p o s y n t h e s i s was lower i n E females at 35 and 90 days, and i t was v a r i e d i n E males. The E males had a higher c o n c e n t r a t i o n of c h o l e s t e r o l , s y n t h e s i s of f a t t y a c i d s , and lower c h o l e s t e r o g e n e s i s i n the sma l l i n t e s t i n e at 100 days. P a r i s k o v a and Petrasek proposed that l i p i d metabolism changed i n the E o f f s p r i n g s ' l i v e r s because repeated maternal a e r o b i c e x e r c i s e i n c r e a s e d maternal FFA blood l e v e l s , t h e r e f o r e , l e a d i n g to i n c r e a s e d l i p i d m e t a b o l i t e s i n f e t a l blood which may have caused a higher c o n c e n t r a t i o n i n the o f f s p r i n g s ' l i v e r s . The i n c r e a s e d serum l e v e l s of FFA and other l i p i d m e tabolites from the mother may have caused the i n c r e a s e l i p i d metabolism i n the f e t u s during development r e g a r d l e s s of p h y s i c a l a c t i v i t y p o s t n a t a l l y . I t was suggested that the females'increased l i v e r l i p i d c o n c e n t r a t i o n may be evidence of a p o s s i b l e dimorphism of l i p i d metabolism due to the a c t i o n of female sex hormones. The f a t d e p o s i t s i n females have a v a r i e t y of purposes - pregnancy and l a c t a t i o n - t h e r e f o r e , t h e i r l i p i d metabolism has an i n c r e a s e d s e n s i t i v i t y to s t i m u l i compared to the males, even d u r i n g p r e n a t a l l i f e . E x e r c i s e was the suggested s t i m u l i t h a t caused the i n c r e a s e d l i p i d and f a t t y a c i d c o n c e n t r a t i o n . Wilson and G i s o l f i (1980) s t u d i e d r a t s who e x e r c i s e d before and/or dur i n g pregnancy, and t h e i r o f f s p r i n g . r a t s who continued t r a i n i n g through pregnancy (TT) had a higher 39 o x i d a t i v e enzyme ( s o l e u s cytochrome o x i d a s e ) a c t i v i t y than the o t h e r 3 groups. The r a t s who s t a r t e d t r a i n i n g d u r i n g pregnancy (NT-T) had a h i g h e r o x i d a t i v e enzyme c a p a c i t y than the group t h a t stopped t r a i n i n g d u r i n g pregnancy (T-NT) and the c o n t r o l ( C ) , whereas o t h e r s ( C o r b e t t e t a l . , 1 9 7 9 ) found no d i f f e r e n c e s i n o x i d a t i v e , g l y c o l y t i c or c o n t r a c t i l e p r o p e r t i e s of s k e l e t a l muscle between o f f s p r i n g of r a t s t r a i n e d d u r i n g g e s t a t i o n and the c o n t r o l . The VO max of the 2 c o n t r o l groups was lower a t the end of g e s t a t i o n than the TT group, but no d i f f e r e n c e i n VO max was found between the NT-T 2 and C groups. There was no d i f f e r e n c e between pregnancy and non-pregnant r a t s when oxygen consumption was a d j u s t e d f o r weight g a i n e d d u r i n g g e s t a t i o n , which agreed w i t h human s t u d i e s on energy needs of pregnant and non-pregnant women based on f a t - f r e e w e i g ht ( S e i t c h i k , 1972). The o f f s p r i n g of the T-T r a t s had the h i g h e s t m o r t a l i t y i n the f i r s t 28 days. The p o s s i b l e causes f o r i n c r e a s e d m o r t a l i t y i n the T-T r a t s were 1) unknown e f f e c t s of shock a v o i d a n c e t e c h n i q u e s used to f o r c e r a t s t o e x e r c i s e , 2) m a t e r n a l c a n n i b a l i s m which was observed but ,not c o n t r o l l e d , and/or 3) low b i r t h w e i g h t . The T-T r a t s g a i n e d l e s s w e i g h t , but had the same l i t t e r s i z e as the o t h e r groups. W i l s o n and G i s o l f i found no s i g n i f i c a n t d i f f e r e n c e s i n t h e weight of male o f f s p r i n g between 45 and 65 days, t h e r e f o r e t h e i r growth was not a f f e c t e d by m a t e r n a l e x e r c i s e . P a r i z k o v a (1978) found male o f f s p r i n g of e x e c i s i n g mothers to be l i g h t e r than the male o f f s p r i n g of n o n - e x e r c i s i n g mothers. 4 0 There was no d i f f e r e n c e i n c a p i l l a r y or c a r d i a c muscle d e n s i t i e s i n male o f f s p r i n g i n W i l s o n and G i s o l f i ' s study (1980) whereas P a r i z k o v a ' s study (1978) found a g r e a t e r c a p i l l a r y and muscle d e n s i t y i n o f f s p r i n g of e x e r c i s i n g mothers. W i l s o n and G i s o l f i (1980) suggested the d i f f e r e n c e between the two s t u d i e s was t h a t they c o n t r o l l e d the g e n e t i c i n f l u e n c e s . and the t e c h n i q u e s used t o p r e s e r v e the t i s s u e specimens. E x e r c i s i n g d u r i n g pregnancy had no e f f e c t on mean f e t a l w eight or development of the diaphragm muscle i n the r a t s s t u d i e d ( M o t t o l a e t a l . , 1983). Female r a t s were a c c l i m a t i z e d t o r u n n i n g on a t r e a d m i l l b e f o r e m a ting. A f t e r m a t i n g , the r a t s c o n t i n u e d t o run a t a lower r a t e (PR) or were s e d e n t a r y ( P C ) . The t r a i n i n g b e f o r e mating d i d not a l t e r the r a t s ' normal development, based on weight g a i n , when compared t o c o n t r o l r a t s , who were not a c c l i m a t i z e d or mated. The PC r a t s had l a r g e r l i t t e r s i z e s which may have a t t r i b u t e d t o t h e i r g r e a t e r weight g a i n d u r i n g g e s t a t i o n . The d i f f e r e n c e i n l i t t e r s i z e s between PC and PR r a t s was s t a t i s t i c a l l y i n s i g n i f i c a n t . The diaphragm muscle was examined because of i t s r o l e i n f e t a l b r e a t h i n g movements (FBM). As an i n d i c a t i o n of the f e t u s ' c o n d i t i o n FBM's were c o n s i d e r e d more s e n s i t i v e than FHR, s i m i l i a r t o human f e t a l c o n d i t i o n s ( M a r s a l , 1979). I t was proposed t h a t changes i n the diaphragm muscle would o n l y o c c u r under s e v e r e c o n d i t i o n s w i t h p o s s i b l e p r e f e r r e n t i a l \ 41 t r e a t m e n t s i m i l i a r t o the h e a r t , b r a i n , and l i v e r . M o t t o l a suggested e xamining a more s e n s i t i v e muscle f o r s i g n s of n u t r i t i o n a l ( c h e m i c a l ) d e p r i v a t i o n d u r i n g m a t e r n a l e x e r c i s e . Another r e a s o n o f f e r e d f o r the l a c k of f e t a l changes w i t h matermal e x e r c i s e was the s m a l l sample s i z e (n=5) which may have missed s l i g h t changes which would have been e v i d e n t i n a l a r g e r sample s i z e . I n c o n c l u s i o n , M o t t o l a e t a l . (1983) found t h a t m i l d a e r o b i c e x e r c i s e d u r i n t pregnancy d i d not cause any d e v e l o p m e n t a l changes. E x p o s i n g pregnant sheep t o a i r a t i n c r e a s e d a t m o s p h e r i c p r e s s u r e d u r i n g peak development of t h e i r f e t u s e s (12 t o 40 days) was a s i m u l a t i o n of the e f f e c t of d i v i n g d u r i n g g e s t a t i o n , B o l t o n - K l u g ( 1 9 8 3 ) . Sheep were s e l e c t e d as a model f o r humans because t h e i r r e sponses to h y p e r b a r i c e x p o s u r e , and the s i z e and number of o f f s p r i n g were comparable. The s e r i e s of m a r g i n a l l y - t o l e r a t e d d i v e s by the pregnant sheep d i d not a f f e c t the f e t u s e s h e a l t h . B o l t o n - K l u g e x p l a i n e d the l a c k of e f f e c t s from the h y p e r b a r i c exposure as p h y s i o l o g i c a l a l t e r a t i o n s t h a t were e i t h e r r e v e r s e d d u r i n g development, ' or the e f f e c t s occured i n f r e q u e n t l y t o show i n the s m a l l sample s i z e (n=14), and/or were not found i n g r o s s a n a t o m i c a l e x a m i n a t i o n s . In B o l t o n - K l u g ' s e a r l i e r work ( B o l t o n , 1980) she a d v i s e d d i v i n g t o s h a l l o w e r depths or no d i v i n g a t a l l about the time of c o n c e p t i o n o r i n t h e 1 s t t r i m e s t e r . L o t g e r i n g e t a l . ( 1 9 8 3 b ) examined t e m p e r a t u r e , u t e r i n e oxygen 42 consumption, and b l o o d gases i n f e t a l sheep. The d i f f e r e n c e between f e t a l and m a t e r n a l t e m p e r a t u r e , a t r e s t , was 0.5 C and changed d u r i n g m a t e r n a l e x e r c i s e . The h i g h e r f e t a l t e m p e r a t u r e s were r e l a t e d t o the h i g h e r r a t e of metabolism \ and r e q u i r e m e n t t o d i s s i p a t e heat t o the mother. There was a r e l a t i v e l y slow r e s p o n s e i n f e t a l t emperature d u r i n g r a p i d temperature changes i n the mother, due to the heat c a p a c i t y of the a m n i o t i c f l u i d and the f e t u s , w i t h o u t changes i n heat t r a n s f e r e f f i c i e n c y a c r o s s the p l a c e n t a . There was no major i n c r e a s e i n f e t a l m e t a b o l i c r a t e . The decreased UBF d u r i n g e x e r c i s e demonstrated the o c c u r r e n c e of p r e f e r r e n t i a l s h u n t i n g w i t h i n the u t e r u s as p l a c e n t a l VO was m a i n t a i n e d a t 2 or s l i g h t l y above the c o n t r o l v a l u e s . The oxygen r e q u i r e m e n t s of the f e t u s and p l a c e n t a i n p r o l o n g e d e x e r c i s e were not met t o the same e x t e n t as a t r e s t . I t was not p o s s i b l e t o a s s e s s a c c u r a t e l y t o what e x t e n t f e t a l - p l a c e n t a l oxygen r e q u i r e m e n t s s h o u l d have i n c r e a s e d d u r i n g e x e r c i s e . The f e t a l o x y g e n t a t i o n l e v e l s were w i t h i n normal l e v e l s d u r i n g m a t e r n a l e x e r c i s e because t o t a l u t e r i n e oxygen consumption was m a i n t a i n e d d u r i n g e x e r c i s e due to h e m o c o n c e n t r a t i o n and i n c r e a s e d oxygen e x t r a c t i o n . L o t g e r i n g c o n c l u d e d t h a t m a t e r n a l e x e r c i s e was not a major s t r e s s f u l or h y p o x i c event f o r the f e t u s . The a n i m a l l i t e r a t u r e has had a n i m a l s f o r c e d t o e x e r c i s e f o r s p e c i f i e d p e r i o d s of time d u r i n g g e s t a t i o n . One study documented the e f f e c t s of v o l u n t a r y e x e r c i s e of mice d u r i n g 43 g e s t a t i o n and l a c t a t i o n , on l a c t a t i o n (Karasawa e t a l . , 1981). The d a i l y a c t i v i t y of the mice - t r e a d w h e e l r o t a t i o n s - was t a l l i e d d u r i n g t h e i r growing phase. The mice were d i v i d e d i n t o the e x e r c i s i n g group (cages w i t h t r e a d w h e e l s ) or the s e d e n t a r y group a f t e r mating. V o l u n t a r y e x e r c i s e g r a d u a l l y d e c r e a s e d as g e s a t a t i o n p r o g r e s s e d and i t decreased markedly b e f o r e d e l i v e r y . The a c t i v i t y l e v e l d i d not i n c r e a s e d u r i n g l a c t a t i o n because s u c k l i n g the young l i m i t e d the f e m a l e s ' f r e e movement. E x e r c i s e d u r i n g pregnancy d i d not a f f e c t l a c t a t i o n . I t was not p o s s i b l e t o study the e f f e c t of e x e r c i s e d u r i n g l a c t a t i o n on l a c t a t i o n because the f e m a l e s ' a c t i v i t y l e v e l s were too low. J e n k i n s and Ciconne (1980) used t h r e e groups of r a t s - c o n t r o l , f o r c e d and v o l u n t a r y e x e r c i s e - t o study the e f f e c t of e x e r c i s e d u r i n g g e s t a t i o n on the o f f s p r i n g ' s b r a i n n u c l e i c a c i d s . Rats who e x e r c i s e d v o l u n t a r i l y , on a t r e a d w h e e l , d i d more t o t a l work than r a t s who were f o r c e d t o e x e r c i s e , on a t r e a d m i l l . The e x e r c i s e dose f a i l e d to a l t e r b r a i n n u c l e i c a c i d s , t h e r e f o r e the dose was not i n t e n s e engough t o produce a change or c e r t a i n p h y s i o l o g i c a d a p t a t i o n s o c c u r e d t o ' p r o t e c t b r a i n n u c l e i c a c i d s of the o f f s p r i n g . The poorer motor performance of the t r e a d m i l l run dams' o f f s p r i n g , on the Rotacone, i n d i c a t e d t h a t m a t e r n a l e x e r c i s e d i d have some e f f e c t s , p o s s i b l y i n d i c a t i n g s e l e c t i v e i n v o l v e m e n t of c e r e b e l l u m or v e s t i b u l a r system. The dams who e x e r c i s e d v o l u n t a r i l y had a lower w e i g h t g a i n p o s s i b l y i n d i c a t i n g t h e i r g r e a t e r t o t a l work compared t o those who were f o r c e d t o e x e r c i s e , t h e r e f o r e they c o u l d reduce t h e i r weight 44 s i g n i f i c a n t l y without obvious e f f e c t s on their, o f f s p r i n g s ' b r a i n n u c l e i c a c i d s and/or motor performance. In c o n c l u s i o n , the animal s t u d i e s found that acute e x e r c i s e bouts to exhaustion d u r i n g prenancy of normal healthy animals with normal healthy f e t u s e s d i d not have any long-term e f f e c t s . Chronic e x e r c i s e during pregnancy produced v a r i e d e f f e c t s on the f e t u s , g e s t a t i o n and i t s outcome. There was some concern whether f e t u s e s s u f f e r e d from hypoxia i n pregnant ewes e x e r c i s e d to exhaustion , but a l l o f f s p r i n g were normal at b i r t h . Rat o f f s p r i n g s t u d i e s found that e x e r c i s e during pregnancy may a f f e c t c a r d i a c m i c r o s t r u c t u r e , c a p i l l a r y d e n s i t y , and l i p i d metabolism. One study found that e x e r c i s e at a high i n t e n s i t y before and during pregnancy l e d to a higher o f f s p r i n g m o r t a l i t y which may have been due to experimental design or the e f f e c t s of maternal e x e r c i s e . The animal s t u d i e s provide a model from which to study humans e x e r c i s i n g d u r i n g pregnancy. Drawing d i r e c t c o n c l u s i o n s from animal l i t e r a t u r e to humans must be done with c a u t i o n s i n c e these s t u d i e s had animals f o r c e d to e x e r c i s e , and the d u r a t i o n of e x e r c i s e with animals does not equate to the same time p e r i o d i n a human. In a d d i t i o n , d i f f e r e n c e s i n phy s i o l o g y between animals and humans could r e s u l t i n d i f f e r e n t e f f e c t s on a human pregnancy. 45 The major d i f f e r e n c e with human s t u d i e s i s that the pregnant s u b j e c t would e x e r c i s e v o l u n t a r i l y , thereby e l i m i n a t i n g the p o s s i b l e consequences of f o r c e d e x e r c i s e and accompanying s t r e s s . Human St u d i e s Human s t u d i e s , most of which are anecdotal or too s m a l l f o r s t a t i s t i c a l a n a l y s i s , have not shown the same r e s u l t s as many of the animal s t u d i e s - s h o r t e r g e s t a t i o n , lower i n f a n t b i r t h w e i g h t . 46 P h y s i o l o g i c a l Changes during Pregnancy The p h y s i o l o g i c a l changes with pregnancy are s i m i l i a r to changes duri n g submaximal a e r o b i c e x e r c i s e i n an endurance t r a i n e d i n d i v i d u a l - i n c r e a s e d c a r d i a c output, i n c r e a s e d blood volume and red blood c e l l volume and decrease i n p e r i p h e r a l r e s i s t a n c e . The changes which would occur during t r a i n i n g and pregnancy are u s u a l l y noted i n the l i t e r a t u r e i n a n e c d o t a l or p o o r l y c o n t o l l e d s t u d i e s . In pregnancy, major p h y s i o l o g i c a l changes i n v o l v e the r e s p i r a t o r y , c a r d i o v a s c u l a r systems, and the uterus to accommodate the growing f e t u s . R e s p i r a t o r y Changes Anatomical changes duri n g pregnancy e f f e c t the r e s p i r a t o r y system. The i n c r e a s i n g s i z e of the uterus presses up a g a i n s t the diaphragm, thereby d e c r e a s i n g the depth of the thorax, but t h i s decrease i s counterbalanced by the broadening of the t h o r a c i c cage. The r e s p i r a t o r y changes i n pregnancy i n c l u d e an i n c r e a s e i n t i d a l volume(30%), i n s p i r a t o r y c a p a c i t y ( 5 % ) , and decrease i n e x p i r a t o r y c a p a c i t y (15%), r e s i d u a l volume(20%), l e a d i n g to a decrease i n f u n t i o n a l r e s i d u a l c a p a c i t y (FRC),(18%). The higher l e v e l s of c i r c u l a t i n g progesterone, a known r e s p i r a t o r y s t i m u l a n t , are thought to s t i m u l a t e the r e s p i r a t o r y c e n t r e s and lead to the i n c r e a s e i n minute v e n t i l a t i o n . The p h y s i o l o g i c a l shunt and dead space 4 7 do not change u s u a l l y during pregnancy. The h y p e r v e n t i l a t i o n of pregnancy decreases PaCO (29-31mmHg) which i n c r e a s e s pH 2 to the 7.43 - 7.46 range l e a d i n g to compensatory l o s s or sodium bicarbonate (21 m E q / l i t e r ) . At term, the oxygen uptake has s i g n i f i c a n t l y i n c r e a s e d (32%), the pulmonary compliance i n c r e a s e d , and r e s i s t a n c e decreased. The c l o s i n g volume (CV) - the lung volume at which the airways begin to c l o s e - does not change, but with the decrease i n FRC, CV maybe g r e a t e r than the FRC, t h e r e f o r e a f f e c t i n g t i d a l volume. A l v e o l a r c o l l a p s e may occur during t i d a l b r e a t h i n g i n c r e a s i n g the p o s s i b i l i t y of hypoxemia, and could account f o r the high r a t e of dyspnea r e p o r t e d i n pregnant women. C a r d i o v a s c u l a r Changes The most dramatic changes i n pregnancy are i n blood volume (BV), c a r d i a c output (Q), and the u t e r u s . Blood volume i n c r e a s e s (30-50%) from the end of the f i r s t t r i m e s t e r u n t i l the 30th week, pl a t e a u s f o r a s h o r t p e r i o d before decreasing to pre-pregnancy val u e s 2 weeks postpartum. The l a r g e i n c r e a s e i n blood volume i s to meet the metabolic needs of the f e t u s and to compensate f o r blood l o s s a t d e l i v e r y . The red blood c e l l volume i n c r e a s e s d u r i n g g e s t a t i o n , but not to the same extent as plasma, t h e r e f o r e a " d i l u t i o n a l anemia" r e s u l t s . The hematocrit (Hct) and hemaglobin c o n c e n t r a t i o n ([Hb]) are lowered i n pregnancy ( to values of 33-38% and 11- 48 12mg/100ml, r e s p e c t i v e l y ) . The c a r d i a c output i n c r e a s e s (30-50%) and l i k e blood volume, peaks between 28-32 weeks, and d e c l i n e s to pre-pregnancy values the l a s t few weeks of g e s t a t i o n . The decrease i n Q at term depends on the p o s i t i o n of the women when measurements occurred s i n c e s m a l l e r decreases are found i n the l a t e r a l p o s i t i o n versus supine or s i t t i n g . The c a r d i a c output decreases as the s i z e of the uterus i n c r e a s e s and presses on the i n f e r i o r vena cava. The i n c r e a s e i n venous pressure i n the lower e x t r e m i t i e s due to the pressure of the uterus on the i n f e r i o r vena cava reaches a maximum at term and f a l l s to pre-pregnancy values at d e l i v e r y . The decrease i n t o t a l p e r i p h e r a l r e s i s t a n c e i s probably secondary to s t e r o i d hormones, e s p e c i a l l y estrogen a c t i n g on blood v e s s e l s (Gibbs, 1981). U t e r i n e blood flow i n c r e a s e s t e n - f o l d (10X) from the pre- pregnancy s t a t e to term. In the non-pregnant s t a t e the uterus i s 30 to 60 gm, but becomes v e s s e l - r i c h with pregnancy with 80% of the u t e r i n e blood flow to the p l a c e n t a and 20% to the uterus muscle. UBF i s not r o u t i n e l y measured i n humans because of the i n v a s i v e techniques i n v o l v e d , t h e r e f o r e , i t i s necessary to r e f e r to o l d e r s t u d i e s ( M o r r i s et a l . , 1956) or animals s t u d i e s f o r data. U t e r i n e blood v e s s e l s are thought to be maximally d i l a t e d at term with the blood flow being pressure dependent, t h e r e f o r e a l a c k of a u t o r e g u l a t i o n (Gibbs, 1981). 49 E f f e c t s of E x e r c i s e and Pregnancy St u d i e s of e x e r c i s e d u r i n g pregnancy have r e p o r t e d responses of pregnant women to e x e r c i s e s t r e s s t e s t i n g at one in s t a n c e or s e r i a l l y through g e s t a t i o n . The s t u d i e s provide the expected responses of a he a l t h y pregnant woman to a b i c y c l e ergometer or t r e a d m i l l submaximal t e s t . A few s t u d i e s have repor t e d maximal responses to e x e r c i s e t e s t i n g . The v a r i a b l e s of i n t e r e s t can be c l a s s i f i e d i n to s i x main c a t e g o r i e s r e s p i r a t o r y responses, c a r d i o v a s c u l a r responses, thermal responses, work c a p a c i t y , p h y s i c a l t r a i n i n g e f f e c t on the outcome of pregnancy, and e f f e c t s on the f e t u s of maternal e x e r c i s e . R e s p i r a t o r y P e r n o l l et a l . (1975a) s t u d i e d pregnant women throughout pregnancy and postpartum to compare oxygen consumption during submaximal b i c y c l e t e s t i n g . They found that the oxygen consumption (VO ), at r e s t and during e x e r c i s e , i n c r e a s e d 2 g r a d u a l l y as the pregnancy progressed with VO reaching peak 2 values new term. At the peak, the VO at r e s t was 33% above 2 non-pregnant v a l u e s , and du r i n g e x e r c i s e i t was s i g n i f i c a n t l y above non-pregnant v a l u e s . The average VO during the post- 2 e x e r c i s e p e r i o d s i n c r e a s e d throughout the pregnancy. P e r n o l l assumed the i n c r e a s e d oxygen consumption was due to the cost of the e x e r c i s e . Minimal work was i n v o l v e d i n the movement 50 and c a r r y i n g o f the e x t r a weight gained during pregnancy s i n c e c y c l i n g i s a non-weight bearing a c t i v i t y . Increased oxygen cost would a l s o be a t t r i b u t e d to 1) work of the muscles i n h y p e r v e n t i l a t i o n during pregnancy and 2) i n c r e a s e i n myocardial VO due to i n c r e a s e d Q. The i n c r e a s e i n VO 2 2 during l a t e pregnancy was g r e a t e r than the estimated amount f o r r e s p i r a t o r y and myocardial work. The authors could not e x p l a i n why the e f f f i c i e n c y of mild muscular work d e c l i n e d during pregnancy. In a subsequent study on v e n t i l a t i o n r a t e s at r e s t and e x e r c i s e , P e r n o l l and a s s o c i a t e s (1975b) found a s i g n i f i c a n t i n c r e a s e i n e x p i r a t o r y minute v e n t i l a t i o n (VE), at r e s t and e x e r c i s e , which was due to a s i g n i f i c a n t l y g r e a t e r t i d a l volume (TV). The carbon d i o x i d e p r o d u c t i o n i n c r e a s e d s i g n i f i c a n t l y at r e s t and with e x e r c i s e during the second t r i m e s t e r (22-26 weeks). The r e s p i r a t o r y q u o t i e n t d i d not change s i g n i f i c a n t l y with e x e r i c s e . The end t i d a l volume carbon d i o x i d e c o n c e n t r a t i o n was lower at r e s t and e x e r c i s e during pregnancy than postpartum, s i g n i f y i n g r e l a t i v e a l v e o l a r h y p e r v e n t i l a t i o n both at r e s t and e x e r c i s e during pregnancy. Edwards et al.(1981) focused t h e i r work on r a t e s of changes of VE, VO , VCO , before and a f t e r s t e a d y - s t a t e e x e r c i s e , 2 2 l a t e i n pregnancy (38 weeks) and postpartum (3 months). Pregnant s u b j e c t s s i g n i f i c a n t l y higher VO , VE, and VCO at 2 2 r e s t and a s i g n i f i c a n t l y g r e a t e r absolute i n c r e a s e i n VE from 51 r e s t to e x e r c i s e (steady s t a t e ) than postpartum s u b j e c t s . In the f i r s t 90 seconds of the 6 minute b i c y c l e t e s t , VCO , and 2 VE i n c r e a s e d more r a p i d l y i n pregnancy than postpartum, but recovery r a t e s f o r both c o n d i t i o n s (pregnancy and postpartum) were the same. A f t e r s i t t i n g on the b i c y c l e f o r 6 minute during the p r e - e x e r c i s e r e s t p e r i o d , Edwards suggested that the sudden c o n t r a c t i o n of the lower extremity muscles of the l e g s would cause an i n c r e a s e of pressure on the blood v e s s e l s and venous r e t u r n to the h e a r t . The s i m i l i a r recovery r a t e s i n pregnancy and postpartum maybe due to the slow r e f i l l i n g of the lower e x t r e m i t y v e i n s . The i n c r e a s e s i n VE during pregnancy were g r e a t e r , t h e r e f o r e , the same workload and e f f i c i e n c y would e l i c i t a v e n t i l a t o r y response g r e a t e r than i n postpartum. The VE p a t t e r n during e x e r c i s e was s i m i l i a r to VCO and VO suggesting an unusual r e g u l a t o r y method where 2 2 the blood flow c a r r y i n g deoxyheraaglobin and CO to the lungs 2 r e g u l a t e d VE. T h e r e f o r e , the a c c e l e r a t e d v e n t i l a t o r y increment with e x e r c i s e during pregnancy was due to i n c r e a s e d CO flow. 2 C a r d i o v a s c u l a r Some of the c i r c u l a t o r y changes i n pregnancy were the same as those from p h y s i c a l t r a i n i n g - i n c r e a s e d red blood c e l l v o l u m e , t o t a l blood volume, c a r d i a c output, and f a l l i n p e r i p h e r a l r e s i s t a n c e (Ihrman, 1960;Gibbs, 1981). Ihrman (1960) s t u d i e d c i r c u l a t o r y changes with p h y s i c a l 52 t r a i n i n g i n pregnancy. P h y s i c a l t r a i n i n g was 35 minutes of e x e r c i s e , where the heart r a t e was 140 bpm p o s t - e x e r c i s e twice a week f o r 10 weeks. Ihrman found no d i f f e r e n c e i n pulse frequency between the t r a i n e d and un t r a i n e d pregnant women on the b i c y c l e ergometer. There was a s l i g h t i n c r e a s e i n c a r d i a c output i n the e x e r c i s e d group, but the other c i r c u l a t o r y adjustments were not a f f e c t e d which l e d to the c o n c l u s i o n t h a t pregnancy was c h a r a c t e r i z e d by a c i r c u l a t o r y adjustment not i n f l u e n c e d by heavy e x e r c i s e , between the 20th and 30th week. The term "heavy" to d e s c t i b e the e x e r c i s e i n t e n s i t y maybe q u e s t i o n a b l e s i n c e i t was not s p e c i f i e d how long the heart r a t e was e l e v a t e d . The program c o n s i s t e d of three bouts of very high i n t e n s e a c t i v i t y f o r s e v e r a l minutes - 3 times per 35 minute s e s s i o n - perhaps the work was more anaerobic than a e r o b i c . The schedule would not i n c r e a s e a e r o b i c f i t n e s s i n a non-pregnant woman un l e s s the s e s s i o n s were more frequent than 2 time per week (as i n S i b l e y et a l . , 1981), longer d u r a t i o n , and/or i n c r e a s e d i n t e n s i t y . M i l d e x e r c i s e 100 kpm per minute ) on the b i c y c l e ergometer produced c a r d i o v a s c u l a r responses t h a t were constant throughout pregnancy. During moderate e x e r c i s e (200kpm per minute), there was a p r o g r e s s i v e d e c l i n e i n the c a r d i o v a s c u a l r response ( r e s e r v e ) due to the p e r i p h e r a l p o o l i n g of blood and o b s t r u c t i o n of venous r e t u r n , as the uterus pressed a g a i n s t the i n f e r i o r vena cava (Ueland , 1969). C a r d i a c output peaked 20-24 weeks and was maintained 53 u n t i l the 32nd week when Q began to drop to non-pregnant l e v e l s between 38 - 40 weeks. The maternal heart rate i n c r e a s e d s l i g h t l y at the beginning of g e s t a t i o n and reached maximum values at 28 - 32 weeks. The e a r l y i n c r e a s e i n c a r d i a c output confirmed the accepted o p i n i o n that hemodynamic changes were not due to the metabolic and n u t r i t i o n needs of the f e t u s , but perhaps estrogen could induce these changes proposed i n an e a r l i e r work by Ueland and Parer (1966). Guzman and Caplan (1970) f o l l o w e d c a r d i o r e s p i r a t o r y responses to e x e r c i s e i n pregnant women from the f i r s t t r i m e s t e r to three months postpartum; they proposed t h a t the p h y s i o l o g i c a l responses to e x e r c i s e were the same i n both s t a t e s . The small i n c r e a s e i n VO , at 29 weeks, was accounted f o r by the 2 uterus and f e t u s , which l e d the authors to suggest that pregnant women had no decrease i n muscular e f f i c i e n c y or no s i g n i f i c a n t i n c r e a s e i n metabolic demands during mild and moderate e x e r c i s e on the b i c y c l e ergometer. Adequate myocardial r e s e r v e was suggested from the i n c r e a s e i n e x e r c i s e c a r d i a c output per u n i t i n c r e a s e of oxygen uptake, s i n c e the i n c r e a s e i n Q was the same i n pregnancy and postpartum. The higher demands on the pregnant woman's heart at the given workloads r e s u l t e d i n pregnant women reaching t h e i r maximum heart r a t e s at lower workloads than postpartum. The c a r d i a c output i n c r e a s e u n t i l the 20th week and was maintained u n t i l d e l i v e r y , which d i f f e r s from Ueland's f i n d i n g s on c a r d i a c output which dropped to normal l e v e l s 54 near term. Guzman and Caplan (1970) suggested the changes i n c a r d i a c output were due to o v a r i a n and p l a c e n t a l hormones, as di d Ueland and Parer(1969), and not due to blood volume which reached peak values betwen 30 - 36 weeks. I t was concluded that the h y p e r k i n e t i c s t a t e of pregnancy i n the f i r s t t r i m e s t e r d i d not change with the i n c r e a s i n g uterus and f e t u s , but stayed i n a s t a b l e s t a t e u n t i l d e l i v e r y . P i j p e r s et al.(1984) found an i n c r e a s e i n maternal heart r a t e , and s y s t o l i c and d i a s t o l i c blood pressure d u r i n g c y c l i n g a bed-type c y c l e ergometer , at 25 watts f o r 5 minutes, l a t e i n g e s t a t i o n (34-36 weeks) , an i n c r e a s e i n heart r a t e would be expected when e x e r c i s i n g compared to r e s t i n g v a l u e s . A r t a l et al.(1981) found l i g h t e x e r c i s e d u r i n g pregnancy i n c r e a s e d maternal heart r a t e , decreased the R time i n t e r v a l (a continuous c a r d i o v a s c u l a r technique, proposed by Koh et al.,1979), i n c r e a s e d c o n c e n t r a t i o n s of glucagon, n o r e p i n e p h r i n e , and e p i n e p h r i n e , but these r e s u l t s were expected because blood r e d i s t r i b u t i o n i s catecholamine- mediated. A l l values r e t u r n e d to b a s e l i n e values 30 minutes a f t e r e x e r c i s e stopped. The n o r e p i n e p h r i n e which i n c r e a s e d with e x e r c i s e a l s o s t i m u l a t e d the uterus with the p o s s i b i l i t y of t r i g g e r i n g labour i n women a t r i s k of premature d e l i v e r y . A r t a l had four s u b j e c t s who experienced mild i r r e g u l a r u t e r i n e a c t i v i t y during the e x e r c i s e t e s t i n g , but the a c t i v i t y ceased when the 55 n o r e p i n e p h r i n e l e v e l s were decreased during the p o s t - e x e r c i s e p e r i o d . In a study of s t r e s s hormones and p l a c e n t a l s t e r i o d s i n p h y s i c a l e x e r c i s e during pregnancy (Rauramo et a l . f 1982) found i n c r e a s e s of norepinephrine and epinephrine during submaximal workloads, g r e a t e r than those reported p r e v i o u s l y by A r t a l et a l . , 1981. The i n c r e a s e i n plasma catecholamine l e v e l s were s i g n i f i c a n t l y c o r r e l a t e d with the i n c r e a s e d pulse r a t e , s u p p o r t i n g the r o l e of the catecholamines i n blood r e - d i s t r i b u t i o n and hemodynamics. The catecholamine response d i d not change with pregnancy versus non-pregnancy. Serum l e v e l s of p r o l a c t i n i n c r e a s e d s i g n i f i c a n t l y 30 minutes a f t e r the e x e r c i s e t e s t and the l e v e l s were s t i l l e l e v a t e d a t 60 minutes p o s t - t e s t . The p r o l a c t i n l e v e l s i n the s u b j e c t s were higher than non-pregnant p r o l a c t i n l e v e l s . The mean serum o e s t e r i o l c o n c e n t r a t i o n s were e l e v a t e d s i g n i f i c a n t l y 30 minutes p o s t - t e s t , but were at b a s e l i n e by 60 minutes p o s t - t e s t . Rauramo assummed that e x e r c i s e d i d not change the r a t e of p l a c e n t a l s e c r e t i o n of o e s t e r i o l but the i n c r e a s e d serum l e v e l s were due to i n c r e a s e d flow of u t e r o p l a c e n t a l blood i n t o maternal c i r c u l a t i o n soon a f t e r e x e r c i s e ceased. M o r r i s et al.(1956) demonstrated u t e r i n e blood flows decreased d u r i n g e x e r c i s e , but blood flow was compensated when e x e r c i s e stopped. The a b l i l i t y of the f e t u s to cope with v a r y i n g oxygen a v a i l a b i l i t y depended on 56 e f f i c i e n t development of the p l a c e n t a . Pommerance et a l . (1974a) found no c o r r e l a t i o n between P h y s i c a l F i t n e s s Scores (PFS) and u t e r o p l a c e n t a l i n s u f f i c i e n c y from FHR r e c o r d i n g s . Subjects were t e s t e d , on a b i c y c l e at 35-37 weeks g e s t a t i o n and maximum oxygen uptake were p r e d i c t e d from A s t r a n s ' s p r o t o c o l , g i v i n g the PFS. F i v e f e t u s e s had " p o s i t i v e " t e s t s between pre and p s o t - e x e r c i s e FHR r e c o r d i n g and four of these i n f a n t s had problems i n labour and d e l i v e r y . Seven a d d i t i o n a l f e t u s e s had i n d i c a t i o n s of f e t a l d i s t r e s s and s i x of the seven had compromised u n b i l i c a l c i r c u l a t i o n . Temperature Rec e n t l y , Jones et a l . , (1985) followed the changes i n maternal body temperature and heat storage (heat content/kg) i n f o u r women durin g a e r o b i c e x e r c i s e throughout g e s t a t i o n . They found t h a t heat storage d i d not i n c r e a s e during e x e r c i s e , and concluded t h a t the s u b j e c t s ' thermal balance was maintained with advancing pregnancy due to t h e i r i n d i v i d u a l e x e r c i s e p r e s c r i p t i o n s . Work T e s t s E a r l y work by Dahlstrom and Ihrman (1960), on f i t n e s s assessment i n pregnancy, u t i l i z e d p h y s i c a l work c a p a c i t y (PWC). PWC was a constant value throughout pregnancy, 57 d e c r e a s i n g s h a r p l y a few days a f t e r d e l i v e r y . A p o s i t i v e c o r r e l a t i o n between the PWC and the pregnant women's age was e s t a b l i s h e d and two p o s s i b l e reasons were 1) p h y s i c a l l y s t r o n g e r women conceive more c h i l d r e n , t h e r e f o r e they were over - r e p r e s e n t e d i n an o l d e r group of pregnant women, and 2) ol d e r women grew up during the second world war and had d i f f e r e n t a c t i v i t y p a t t e r n s than younger women. The PWC values were s i m i l i a r i n pregnant women with and without toxemia, t h e r e f o r e the c a r d i o r e s p i r a t o r y system had adapted to the work t e s t i n hypotensive p a t i e n t s a c c o r d i n g to Soiva et a l . ( 1 9 6 9 ) . There was no c o r r e l a t i o n between age and PWC, as i n Dahlstrom and Ihrman (1960) or between b i r t h w e i g h t and PWC. Soiv a found a p o s i t i v e c o r r e l a t i o n between maternal weight and PWC which was c o n t r a d i c t e d by l a t e r works, who found PWC and weight were n e g a t i v e l y c o r r e l a t e d (Pommerance, et al.,1974b). The normal pregnant women had PWC values s i m i l i a r to the c o n t r o l (non-pregnant women), but the toxemic women had the g r e a t e s t PWC. The expected r a n k i n g of PWCs, from lowest to h i g h e s t , was toxemic, normal pregnancy, non-pregnant women of the same age. The c o n t r o l s were not matched f o r weight-based on the pregnant women's pre-pregnancy weights.Severe p h y s i c a l a c t i v i t y was a suggested c o n t r a i n d i c a t o r l a t e i n pregnancy e s p e c i a l l y f o r women with toxemia because of the great i n c r e a s e i n s y s t o l i c blood p r e s s u r e . Soiva f e l t the sudden i n c r e a s e s i n blood pressure i n toxemic p a t i e n t s could l e a d to 58 premature s e p a r a t i o n of the p l a c e n t a . The myometrial flow was taken as adequate dur i n g r e s t i n g because the FHR returned to normal l e v e l s 5 minutes p o s t - e x e r c i s e . E r k k o l a (1976b) found PWC i n c r e a s e d 10% spontaneously with pregnancy, and a f u r t h e r 17.6% with p h y s i c a l t r a i n i n g , whereas Dalhstrom and Ihrman (1960) found PWC was constant i n pregnancy. The t r a i n i n g program was longer (26 vs 10 weeks), higher frequency 3 vs 2 times per week), and grea t e r d u r a t i o n (60 minutes p l u s 10 minutes d a i l y a t home vs 35 minutes per se s s i o n ) i n E r k k o l a ' s study compared to Dahlstrom and Irhraan, t h e r e f o r e a g r e a t e r change i n p h y s i c a l f i t n e s s was p o s s i b l e . The PWC l e v e l s r e t u r n e d to pre-pregnancy l e v e l s about 2 weeks p r i o r to d e l i v e r y . E r k k o l a ' s work demonstrated that i t was p o s s i b l e to improve PWC without harming the pregnancy . I t concluded t h a t t r a i n i n g d u r i n g pregnancy had l i t t l e i n f l u e n c e on heart r a t e and blood p r e s s u r e , there was an i n s i g n i f i c a n t decrease i n the t r a i n e d group. The pregnant women's PWC's were expressed as a percentage of non-pregnant PWC's. E r k k o l a found that healthy pregnant women (n=51) whose PWC value was gr e a t e r than normal had s i g n i f i c a n t l y s h o r t e r spontaneous l a b o u r s , more newborns over 3500 grams, s i g n i f i c a n t l y h e a v i e r p l a c e n t a s , and fewer low values of r e l a t i v e p l a c e n t a l weight. These high PWC pregnant women had high e r plasma volume, higher blood volume, and t o t a l hemaglobin which l e d to t h e i r newborns gre a t e r weight. The i n c r e a s e d plasma volume was a s s o c i a t e d with the l a r g e r p l a c e n t a , improved c i r c u l a t i o n , and gas exchange which 59 b e n e f i t e d the f e t u s . The d u r a t i o n of the pregnancy was not viewed an an important f a c t o r by E r k k o l a et a l . , (1976a). They found the d u r a t i o n of pregnancy was not r e l a t e d to the PWC, but due to the design of the experiment - t e s t i n g at the 38th week e l i m i n a t e d premature d e l i v e r i e s , women who developmed medical problems were e l i m i n a t e d - and the high number of pregnancies (27%) which were terminated a t 40 weeks, e l e c t i v e l y . In a r e t r o s p e c t i v e study, women who threatened premature labour had lower PWC's ( E r k k o l a , 1976) . Increased bedrest was p r e s c r i b e d f o r women with threatened premature labour and t h i s f a c t o r probably a f f e c t e d the PWC values which r a p i d l y decreased with i n a c t i v i t y . PWC and r e l a t i v e h e art volume (RHV) were p o s i t i v e l y c o r r e l a t e d by E r k k o l a and Makela (1976), c o n f i r m i n g E r k k o l a ' s other work (1976b)on improving p h y s i c a l f i t n e s s during pregnancy. RHV was used as an i n d i c a t o r of improved p h y s i c a l f i t n e s s based on the r e l a t i o n s h i p of heart volume i n c r e a s i n g with p h y s i c a l t r a i n i n g i n non-pregnant s u b j e c t s (Astrand and Rodahl, 1970). The authors c i t e d one study ( K l e p z i g and F r i s c h , 1965) that p o s i t i v e l y c o r r e l a t e d RHV with p h y s i c a l f i t n e s s . The RHV va l u e s of the t r a i n e d women were g r e a t e r than the the c o n t r o l group I, who were t e s t e d throughout g e s t a t i o n , but s i m l i a r to the c o n t r o l group I I , who were t e s t e d at 38 weeks. C o n t r o l group I I was s l i g h t l y more f i t than the c o n t r o l group I . The PWCs were s i g n i f i c a n t l y 60 g r e a t e r i n the t r a i n e d group as was expected. No c o r r e l a t i o n was evident between RHV or PWC and l e n g t h of g e s t a t i o n or b i r t h weight. E r k k o l a ' s work found PWC had no i n f l u e n c e on d u r a t i o n of pregnancy, induced l a b o u r , time the baby's head was v i s i b l e u n t i l d e l i v e r y , apgar scores at 1 minute, development of toxemia or threatened premature l a b o u r . Pommerance et al.(1974b) used Astrand's t a b l e s to c a l c u l a t e maximum a e r o b i c c a p a c i t y . The values obtained from a submaximal b i c y c l e t e s t were used to compare p h y s i c a l f i t n e s s l e v e l s of pregnant women at the same stage of pregnancy. The standard t a b l e was not accurate i n p r e d i c t i n g pregnant s u b j e c t s maximum oxygen uptake because they were based on non-pregnant s u b j e c t s . Pommerance assumed that the p h y s i c a l f i t n e s s s c o r e s (PFS) from the t e s t s would represent an equal i n t e r v a l s c a l e f o r use of parametric s t a t i s t i c a l t e s t s of s i g n i f i c a n c e . The PFSs were i n v e r s e l y r e l a t e d with l e n g t h of labour i n m u l t i p a r a s . The l e n g t h of pregnancy, and the apgar sc o r e s at 1 minute were not r e l a t e d to PFS which agreed with p r e v i o u s f i n d i n g s with PWC and pregnancy by E r k k o l a . Pommerance found no s i g n i f i c a n t c o r r e l a t i o n of PFS with labour i n p r i m l p a r a s , b i r t h weight, newborn l e n g t h or head c i r c u m f e r e n c e . The authors d i d not view the d u r a t i o n of g e s t a t i o n as an important outcome of pregnancy, s i m i l i a r to the o p i n i o n l a t e r expressed by E r k k o l a (1976a). The t e s t i n g of PFS between 35 and 37 e l i m i n a t e d premature d e l i v e r i e s and the s u b j e c t s were e l i m i n a t e d whose pregnancies d e l i v e r e d 61 a f t e r 42 weeks plus a day, or developed medical problems. A h i g h l y s i g n i f i c a n t negative c o r r e l a t i o n between Astrand's index and pre-pregnancy weight ( E r k k o l a , 1975) confirmed Pomraerance's work. The Astrand t e s t supposedly avoids weight i n f l u e n c e , but i t was expected t h a t an obese mother would be l e s s f i t than a normal weight mother. E r k k o l a presumed pregnancy had t r a i n i n g e f f e c t on maternal c i r c u l a t i o n which c o n f l i c t e d with Ihrman's (1960) work f o r reasons mentioned p r e v i o u s l y . E r k k o l a used Borg's P e r c e i v e d E x e r t i o n Rating s c a l e (PER) to determine the s u b j e c t ' s v o l u n t a r y maximal t e s t on a b i c y c l e . A submaximal b i c y c l e t e s t i s l i m i t e d to a maternal heart r a t e of 150 bpm, t h e r e f o r e making i t a l e s s r e l i a b l e t e s t of p h y s i c a l c o n d i t i o n than PER, ac c o r d i n g to E r k k o l a . When p r i m i g r a v i d a e women were t e s t e d 2 weeks before d e l i v e r y t h e i r mean p h y s i c a l c o n d i t i o n was s i m l i a r to non- pregnant women of the same age. L a t e r s t u d i e s by E r k k o l a (1976b) found that PWC i n c r e a s e d 10% with pregnancy, t h e r e f o r e a PWC at 38 weeks would not r e f l e c t the non- pregnant PWC, but the PWC due to pregnancy. The p r e d i c t e d maximal VO two days before and 10 days a f t e r d e l i v e r y were 2 n e a r l y i d e n t i c a l ( D r e s s e n d o r f e r , 1978), but 4 months a f t e r d e l i v e r y the value s were h i g h e r . D r e s s e n d o r f e r ' s case study found that the maximal 0 uptake and endurance performance 2 could be improved during a normal pregnancy and l a c t a t i o n by p h y s i c a l t r a i n i n g without harmful e f f e c t s to the mother or newborn. A l i n e a r r e l a t i o n s h i p between VO max and running speed i n non-pregnant s t a t e s was estab - 2 l i s h e d except 2 weeks postpartum when i t appeared that the 62 s u b j e c t had l o s t her r a c i n g pace sense and had run too slow. Most women are not encouraged to e x e r c i s e two to four weeks postpartum, the s u b j e c t probably had not run s i n c e d e l i v e r y and c o u l d not be expected to be i n the same s t a t e of f i t n e s s as b e f o r e d e l i v e r y . D r e s s e n d o r f e r ' s case study approach l e d to three major f i n d i n g s about running and pregnancy. F i r s t , the s u b j e c t ' s pregnancies and milk p r o d u c t i o n were not a f f e c t e d by t r a i n i n g and i t s high c a l o r i c c o s t s and f l u i d l o s s e s . Second, the t r e a d m i l l t e s t s , which e l e v a t e d the s u b j e c t ' s heart r a t e to 90% of her non-pregnant maximum heart r a t e , d i d not produce any s e r i o u s e f f e c t s on the pregnancy . T h i r d , the decrease i n the estimated maximum oxygen uptake during the f i r s t t r i m e s t e r of the second pregnancy, when mileage decreased, suggested a d e t r a i n i n g e f f e c t . I t would be unreasonable to assume t h a t running has no c o n t r a i n d i a t i o n s i n pregnancy. Since D r e s s e n d o r f e r ' s r e p o r t was a case study the c o n c l u s i o n s can o n l y be a p p l i e d to the s u b j e c t examined. Hutchinson et a l . (1981) used the case study method to examine the m e t a b o l i c , r e s p i r a t o r y , and c i r c u l a t o r y responses to running d u r i n g pregnancy. The metabolic s t r e s s , i n d i c a t e d by the percentage maximum VO to perform the work t e s t (a ten 2 minute submaximal t r e a d m i l l t e s t ) , i n c r e a s e d during pregnancy. The authors suggested that running speed should be decreased d u r i n g pregnancy due to the i n c r e a s e s t r e s s seen from the s u b s t a n t i a l i n c r e a s e s i n oxygen uptake, heart r a t e , 63 and v e n t i l a t i o n as the pregnancy continued. The i n c r e a s e i n oxygen uptake was p r o p o r t i o n a l to the weight g a i n , but the i n c r e a s e s i n heart r a t e and r e s p i r a t o r y exchange r a t i o were not p r o p o r t i o n a l . The a e r o b i c c a p a c i t y was assumed to be constant throughout g e s t a t i o n , 61% of maximum a t 3 months to 70% at 8 months. S i b l e y et a l .(1981) found pregnant women were able to maintain t h e i r i n i t i a l p h y s i c a l f i t n e s s l e v e l over a 12 week pe r i o d by p a r t i c i p a t i n g i n a 10 week i n d i v i d u a l i z e d t r a i n i n g (swimming) program. The c o n t r o l group became l e s s e f f i c i e n t over the study p e r i o d with oxygen consumption and work r a t e d e c r e a s i n g - 10% and 20.8%, r e s p e c t i v e l y . A l l the s u b j e c t s were t e s t e d w i t h i n three weeks of d e l i v e r y and were a l l able to reach 72% of t h e i r maximum oxygen consumption values on the t r e a d m i l l (determined by a modified Blake M u l t i s t a g e P r o g r e s s i v e T r e a d m i l l t e s t ) without u n d e s i r a b l e e f f e c t s . The f e t a l heart r a t e s before and a f t e r the t r e a d m i l l t e s t were w i t h i n c l i n i c a l norms. The apgar scores of the t r a i n e d mothers' i n f a n t s were hi g h with 6 of the 7 i n f a n t s s c o r i n g 8 and 9 and one i n f a n t s c o r i n g 9 and 10 at one and f i v e minutes, r e s p e c t i v e l y . The apgar scores of the c o n t r o l group were not p u b l i s h e d , but i t is.assumed a l l i n f a n t s were h e a l t h y . R e c e n t l y , C o l l i n g s et al.(1983) compared pregnant women t r a i n e d f o r an average of 13 weeks on a b i c y c l e ergometer at 64 submaximal workloads. The s u b j e c t s were placed i n the t r a i n i n g (n=12) and c o n t r o l (n=8) groups i n i t i a l l y by t h e i r c h o i ce and the remaining women were randomly assigned to the two groups when i t became apparent the authors had an i n t e r e s t e d p o p u l a t i o n . There were no d i f f e r e n c e s i n the p r e d i c t e d maximal VO from the Astrand's p r o t o c o l between the 2 groups at the beginning of the study. The submaximal b i c y c l e t e s t found an i n c r e a s e i n the t r a i n i n g group and decrease i n the c o n t r o l group of a b s o l u t e a e r o b i c c a p a c i t y and f u n c t i o n a l c a p a c i t y . The s t a t i s t i c a l a n a l y s i s (ANOVA with post hoc S c h e f f e ' s t e s t ) found the t r a i n e d group's i n c r e a s e (18%) i n a b s o l u t e a e r o b i c c a p a c i t y (1/min) over the u n t r a i n e d group's decrease (4%) was s i g n i f i c a n t as was the t r a i n e d group's t h i r d t r i m e s t e r f u n d t i o n a l c a p a c i t y (ml/kg/min) versus the u n t r a i n e d group's f u n c t i o n a l c a p a c i t y . The f e t a l h e a r t r a t e i n c r e a s e d s i g n i f i c a n t l y , during e x e r c i s e and p o s t - e x e r c i s e , over r e s t i n g v a l u e s . The i n c r e a s e i n f e t a l h e art r a t e was a t t r i b u t e d to three p o s s i b l e f a c t o r s : 1) the e x e r c i s e woke the f e t u s and i n c r e a s e d i t s heart r a t e , 2) p l a c e n t a l t r a n s f e r of maternal catecholamines or r e l e a s e of f e t a l catecholamines secondary to maternal e x e r c i s e , and/or 3) i n c r e a s e d maternal and f e t a l temperatures may i n f l u e n c e f e t a l h e a r t r a t e , s i n c e FHR has a p o s i t i v e c o r r e l a t i o n with f e t a l temperature. C o l l i n g s et a l . (1983) found no c o r r e l a t i o n between t r a i n i n g and outcome of pregnancy. The r e s u l t s of the study may have been a f f e c t e d by the s m a l l sample s i z e and f a c t o r s of labour which c o u l d not be c o n t r o l l e d , such as maternal medication, 65 i n a c c u r a t e d e t e r m i n a t i o n of the onset of labour, and f e t a l p r e s e n t a t i o n . Maternal e x e r c i s e had no e f f e c t on f e t a l growth. Dibblee and Graham (1983) used the Canadain home F i t n e s s Test (CHFT) to group 16 p r i m i g r a v i d s i n t o " f i t " and " u n f i t " groupings. The women were not i n v o l v e d i n any organized p h y s i c a l a c t i v i t y . The " f i t " group (CHFT scores >8) had a constant a b s o l u t e VO max (1/min) and the changes i n a e r o b i c 2 f i t n e s s (VO max i n ml/kg/min) were due to changes i n body 2 mass with pregnancy. The " u n f i t " group (CHFT scores< 8) had an i n c r e a s i n g a b s o l u t e VO max(l/min) during e x e r c i s e which 2 decreased d u r i n g post-partum and a constant a e r o b i c f i t n e s s (ml/kg/min) which was a t t r i b u t e d to cardiopulmonary demands. The i n c r e a s e d body mass provided a s u f f i c i e n t workload f o r the u n f i t group to i n c r e a s e t h e i r VO max (1/min). Greater 2 gains i n body f a t weight i n the u n f i t group were a t t r i b u t e d to lower l e v e l s of a c t i v i t y compared to the f i t group. D i b b l e and Graham found the only s i g n i f i c a n t d i f f e r e n c e between the groups was a higher apgar score at one minute i n the f i t group's newborns a f i n d i n g s i m i l i a r to C o l l i n g s et a l . (1983). E f f e c t s on the f e t u s of maternal e x e r c i s e In the l i t e r a t u r e , the e f f e c t of maternal e x e r c i s e on the f e t u s has been documented as part of s t u d i e s on maternal 6 6 responses to e x e r c i s e t e s t i n g or t r a i n i n g , and these r e s u l t s have been d i s c u s s e d p r e v i o u s l y . The l i t e r a t u r e t h a t focused on f e t a l responses only to maternal e x e r c i s e w i l l be reviewed. One of the f i r s t s t u d i e s to e v a l u a t e the e f f e c t s of maternal e x e r c i s e on f e t a l h e art r a t e (FHR) was by Hon and Wohlgemuth (1961) who recorded FHRs before and a f t e r a three minute step t e s t . The authors f e l t t h a t maternal e x e r c i s e may have decreased u t e r i n e blood flow (UBF), t h e r e f o r e p u t t i n g a temporary a d d i t i o n a l l o a d on the u t e r o p l a c e n t a l oxygen t r a n s f e r mechanism which caused the abnormal FHR p a t t e r n found i n 6 of the 26 s u b j e c t s . The p o s t - e x e r c i s e FHR r e c o r d i n g s were put i n t o 3 c a t e g o r i e s : 1) no remarkable change (4/26), 2) minor changes (17/26), and 3) i r r e g u l a r i t i e s , t a c h y c a r d i a , b r a d y c a r d i a (6/26). In s u b j e c t s t h a t were t e s t e d weekly, the FHRs f l u c t u a t e d between c a t e g o r i e s 1 and 2. The frequency of changing from one group to another was not p o s s i b l e to determine s i n c e the s e r i a l l y t e s t e d sample s i z e was small(n=6). Hon and Wohlgemuth's data was c o l l e c t e d between the 33rd and 43rd weeks of g e s t a t i o n from low and high r i s k pregnancies. I t would have been p r e f e r a b l e to have FHR r e c o r d i n g s from a s p e c i f i e d week i n g e s t a t i o n ( P e r n o l l et a l . , 1977), pregnancies of the same r i s k l e v e l , and a l a r g e r sample t e s t e d s e r i a l l y . In h i g h r i s k pregnancies the FHR may have r e f l e c t e d f a c t o r s other than maternal e x e r c i s e . 67 Pokorny and Rous (1967) s t u d i e d how p h y s i c a l work durin g the l a s t four weeks of pregnancy was expressed i n 1 f e t a l heart sounds. Three d i f f e r e n t f e t a l heart r a t e r e a c t i o n s to e x e r c i s e were 1) no change, which was a t t r i b u t e d to mothers who were well-adapted to the workload, 2) a gradual i n c r e a s e of the FHR to a maximum at the beginning of steady s t a t e e x e r c i s e , but r e t u r n i n g to b a s e l i n e by the end of the e x e r c i s e p e r i o d , and 3) a continuous i n c r e a s e i n FHR u n t i l the end of the e x e r c i s e p e r i o d a f t e r which the FHR and maternal heart r a t e s f e l l below normal v a l u e s . A l a r g e r sample was needed to determine whether there were three d i f f e r e n t r e a c t i o n s or v a r i a t i o n s of a s i n g l e r e a c t i o n to the maternal e x e r c i s e . I t was assumed a l a r g e r sample would i n d i c a t e whether FHR was dependent on maternal heart r a t e , and/or her r e a c t i o n to the workload. Stembera and Hodr (1967) used an e x e r c i s e t e s t to see the d i f f e r e n c e s i n FHR of h e a l t h y and p o t e n t i a l l y d i s t r e s s e d f e t u s e s i n normal and abnormal pregnancies. In p o t e n t i a l hypoxia d i s t r e s s e d f e t u s e s , there was a g r e a t e r i n f l u e n c e of extreme v a r i a t i o n s i n the FHR, more to t a c h y c a r d i a than b r a d y c a r d i a . The stage of g e s t a t i o n should be considered when i n t e r p r e t i n g FHRs a f t e r maternal e x e r c i s e ( P e r n o l l et a l . , 1977). E a r l y i n g e s t a t i o n the p o s t - e x e r c i s e FHR decreased, but l a t e r i n g e s t a t i o n the p o s t - e x e r c i s e FHR i n c r e a s e d , i l l u s t r a t i n g that when FHRs i s taken i s important. P e r n o l l and a s s o c i a t e s 68 found no d i f f e r e n c e s i n FHRs recorded monthly, from low r i s k pregnancies, and those with mild c o m p l i c a t i o n s , a f t e r c y c l i n g on an ergometer f o r 6 minutes. Since the maternal c a r d i a c output and u t e r i n e blood flow decreased near term due to i n f e r i o r vena cava compression, p o o l i n g of the blood i n the l e g s may cause, a c c o r d i n g to the authors, f e t a l hypoxemia, and t h e r e f o r e , t a c h y c a r d i a . Near term, t a c h y c a r d i a c o u l d be i n t e r p r e t e d as a p o s s i b l e i n c r e a s e i n f e t a l c a r d i o v a s c u l a r system responsiveness to autonomic s t i m u l i , and p l a c e n t a l " r e s p i r a t o r y r e s e r v e " d e c r e a s i n g i n r e l a t i o n to f e t a l requirements. Older f e t u s e s would be more s t r e s s e d due to the d i v e r s i o n of u t e r i n e blood flow. Dressendorfer and G o o d l i n (1980) found t h a t maternal e x e r c i s e at 80% of maximum oxygen uptake d i d not produce f e t a l b r a d y c a r d i a or t a c h y c a r d i a . FHR was about 142 beats per minute (bpm) before a submaximal b i c y c l e t e s t and reached peak val u e s of 146 bpm. These values were i n the same range as Stembera and Hodr's which were 140 -180 bpm before and a f t e r t e s t i n g . The pregnant women t r a i n e d by swimming 3 times per week. They had above average c a r d i o r e s p i r a t o r y f i t n e s s , were i n e x c e l l e n t h e a l t h , and were non-competitive swimmers. FHR p r i o r to maternal j o g g i n g was 140-150 bpm and a f t e r j o g g i n g (1.5 m i l e s and c l i m b i n g three f l i g h t s of s t a i r s ) the FHR was 180 -204 bpm i n Hauth et a l . (1982). In t h i s study, 69 n e i t h e r the speed or the joggi n g was not c o n t r o l l e d and the f i t n e s s l e v e l s of the p a r t i c i p a n t s was not determined at the s t a r t of the t e s t p e r i o d . Hauth used a non-stress t e s t (NST) to e v a l u a t e the p o t e n t i a l l y acute e f f e c t s of maternal e x e r c i s e on f e t a l w e l l - b e i n g . The r e a c t i v e NST (at l e a s t two f e t a l a c c e l e r a t i o n s of at l e a s t 10 bpm i n a s s o c i a t i o n with f e t a l movement ) had s i m i l i a r mean times before and a f t e r j o g g i n g , t h e r e f o r e the f e t u s e s were not compromised duri n g the e x e r c i s e . Hauth proposed two c o n c l u s i o n s from the r e s u l t s - 1) i n humans the u t e r i n e blood flow remained adequate with maternal (non-exhaustive) e x e r c i s e and/or 2) p o s t - e x e r c i s e f e t a l t a c h y c a r d i a represented f e t a l compensatory s t a t e , which was supported l a t e r by A r t a l et a l . ( 1 9 8 4 ) . F e t a l b r a d y a c a r d i a was observed dur i n g maternal e x e r c i s e i n the t h i r d t r i m e s t e r (Dale et a l . , 1982; A r t a l et a l . , 1984). Dale and a s s o c i a t e s ( 1 9 8 2 ) found t h a t the f e t a l heart r a t e s decreased f o r the f i r s t 3 to 3.5 minutes of maternal e x e r c i s e , a t r e a d m i l l t e s t , and retu r n e d to the b a s e l i n e r a t e p r i o r to the s u b j e c t s r e a c h i n g 80% of t h e i r p r e d i c t e d maximum heart r a t e s . A r t a l et a l (1984) found f e t a l b r a d y c a r d i a continued through e x e r c i s e ,a symptom-limited max VO 2 t r e a d m i l l t e s t . One of t h e i r s u b j e c t s went i n t o premature labour at 37.5 weeks, and agreed to an i n t e r n a l FHR monitoring d u r i n g a submaximal c y c l e ergometer t e s t up to 65% VO max. The FHR i n c r e a s e d s l o w l y during e x e r c i s e from 140 2 bpm pre to 150 bpm p o s t - e x e r c i s e . The d i f f e r e n c e i n the FHR 70 responses to e x e r c i s e l e d the authors to q u e s t i o n whether f e t a l b r a d y c a r d i a was a normal p h y s i o l o g i c a l responses to e x e r c i s e and , i f so, was the i n c r e a s e i n FHR p o s t - e x e r c i s e a compensatory mechanism f o r b r i e f p e r i o d s of hypoxia during e x e r c i s e . The recovery time, r e t u r n to normal FHR, could be dependent on the s t a t u s of the f e t u s . A r t a l and a s s o c i a t e s p o s t u l a t e d t h a t f e t a l response depended on g e s t a t i o n a l age, l e v e l of catecholamines r e l e a s e d by mother and consequently by the f e t u s , maternal s t r e s s and l e v e l of f i t n e s s probably i n f l u e n c e d the l e v e l of sympathetic a c t i v i t y . C o l l i n g s and Curet (1985) found no evidence of the r e l a t i o n s h i p of g e s t a t i o n a l age on FHR ( A r t a l et a l . , 1984) when they t e s t e d s u b j e c t s s e r i a l l y from the 28th to 38th week to 70% of maximum a e r o b i c c a p a c i t y . In comparison to t h e i r p r e v i o u s work ( C o l l i n g s et a l . , 1983) the p o s t - e x e r c i s e heart r a t e s were higher due to 1) d i f f e r e n t types of e x e r c i s e 2) l o n g e r d u r a t i o n of e x e r c i s e . There were no FHR >180bpm s i n c e the s u b j e c t s e x e r c i s e t e s t s were s e t a c c o r d i n g to t h e i r maximum a e r o b i c c a p a c i t y i n t e n s i t y , others (Hauth et a l . , 1982) d i d not s t a n d a r d i z e the t e s t , t h e r e f o r e unknown s t r e s s per s u b j e c t . P e r n o l l (1977) used 6 minutes of mild c y c l i n g to i l l u s t r a t e t h a t i n normal and m i l d l y abnormal pregnancies, that FHR decreased p o s t - e x e r c i s e <35 weeks g e s t a t i o n , but a f t e r 35 weeks i t i n c r e a s e d . C o l l i n g s and Curet t r i e d to monitor FHR w h i l e c y c l i n g and found too much " n o i s e " from the movement of l e g s and trunk. They d i d count the FHR during e x e r c i s e by u s i n g the a m p l i f i c a t i o n system of the FHR monitor 71 and found FHR was normal with moderate t a c h y c a r d i a . The F e t a l B r e a t h i n g Movements (FBM), i n study by Marsal et a l . , (1979) were more s e n s i t i v e to maternal c h a l l e n g e than FHR. The FBM i n c r e a s e d with maternal dynamic work ( submaximal b i c y c l e t e s t ) , d i d not change with s t a t i c work and p a s s i v e movements , and decreased with maternal h y p e r v e n t i l a t i o n and hyperoxygenation. The FHR d i d not change during the f i v e maternal c h a l l e n g e s . The changes i n FBM p a r a l l e l e d the maternal pCO l e v e l s s u p p o r t i n g CO as a 2 2 major s t i m u l a t o r of b r e a t h i n g movements even i n neonatal l i f e . There were no d i r e c t c o r r e l a t i o n s betwen mi l d maternal e x e r c i s e (walking at 2 mph) and f e t a l body (FB) or breathing movements (FBM) i n a study by P i a t t et a l . (1983). A r e l a t i o n s h i p between maternal sympathetic a c t i v i t y and degree of f e t a l a c t i v i t y was confirmed. Fetuses with i n c r e a s e d FM or FBM p o s t - e x e r c i s e had s i g n i f i c a n t l y h igher mean pre and p o s t - e x e r c i s e e p i n e p h r i n e l e v e l s . The mean norepinephrine and e p i n e p h r i n e l e v e l s i n c r e a s e d s i g n i f i c a n t l y from pre to p o s t - e x e r c i s e , but a f t e r 30 minutes p o s t - e x e r c i s e the e p i n e p h r i n e l e v e l s were s t i l l e l e v a t e d . The f i v e reasons suggested f o r the f i n d i n g s were 1) one l e v e l of s t i m u l u s may i n c r e a s e FM or FBM while a higher l e v e l would decrease i t , 2) the f e t u s a c t s independently of the mother, t h e r e f o r e v a r i e d o b s e r v a t i o n s were due to i n d i v i d u a l i z e d a d a p t a t i o n to changes 72 i n maternal environment, 3) r e d u c t i o n i n UBF could be due to the i n c r e a s e i n catecholamines which would a f f e c t FBM, 4) fe t u s e s had fou r b a s i c behaviour s t a t e s r e l a t e d to f e t a l age, and wakefulness and these stages were organized at 36 weeks ( t e s t i n g was a t a mean g e s t a t i o n a l age - 34.6 weeks), and 5) during p e r i o d s of low heart r a t e v a r i a b l i l i t y , shaking the f e t u s , as i n maternal e x e r c i s e , would s i g n i f i c a n t l y i n c r e a s e i t s r e a c t i v i t y . P i a t t concluded that mild e x e r c i s e produced v a r i a b l e f e t a l b i o p h y s i c a l responses. The f e t a l a c t i v i t y (measured as FM and FBM) seemed to be a s s o c i a t e d with an i n c r e a s e d maternal sympathetic a c t i v i t y and independent of maternal a c t i v i t y . The changes i n FM, FBM, and catecholamine l e v e l s due to e x e r c i s e were r e v e r s i b l e . J a k o b o v i t s (1983) r e p o r t e d a s i g n i f i c a n t negative r e l a t i o n s h i p between maternal e x e r c i s e - cl i m b i n g 2 f l i g h t s of s t a i r s - and FBM i n a m a j o r i t y of the s u b j e c t s (24 out so 33) t e s t e d . The purpose of the study was to e s t a b l i s h the v a l i d i t y of FBM as a t e s t of f e t a l w e l l - b e i n g . The FBM t e s t was u s e f u l i f p o s t - e x e r c i s e data was analyzed. The v a r i e d r e s u l t s of the study- 24/33 with negative c o r r e l a t i o n of maternal e x e r c i s e to FBM, 6/33 p o s i t i v e c o r r e l a t i o n , and 3/33 with no c o r r e l a t i o n - could have been due to the f i t n e s s l e v e l s of the women before or du r i n g g e s t a t i o n , the r a t e at which women climbed the s t a i r s , the r i s k l e v e l of the pregnancies, and the time dur i n g the t e s t p e r i o d (35-42 weeks) t h a t the women were e v a l u a t e d . P e r n o l l et a l . , (1977) p r e v i o u s l y suggested the time of t e s t i n g was important i n FHR 73 and Marsal et a l . , (1979) supported FBM as more s e n s i t i v e than FHR. J a k o b i v i t i s added t h a t the week of g e s t a t i o n should be s p e c i f i e d when comparing and an a l z y i n g ( y FBM, i f they are to be read l i k e FHRs. Ut e r i n e a c t i v i t y d i d not change a f t e r maternal e x e r c i s e ; weight-bearing (running) and non-weight-bearing ( c y c l i n g ) during the l a s t 8 weeks of g e s t a t i o n ( V e i l l e et al.,1985). Maternal heart r a t e was higher , as expected, p o s t - e x e r c i s e . F e t a l heart r a t e i n c r e a s e d d u r i n g the f i r s t 15 minutes post- e x e r c i s e , but returned to b a s e l i n e i n the next 15 minutes. The authors concluded that moderate e x e r c i s e i n h i g h l y motivated, t r a i n e d pregnant s u b j e c t s d i d not i n c r e a s e u t e r i n e a c t i v i t y p o s t - e x e r c i s e . R e t r o s p e c t i v e S t u d i e s Researchers have used q u e s t i o n n a i r e s to study the e f f e c t s of scuba d i v i n g , j o g g i n g , and a combination of endurance a c t i v i t i e s on the outcomes of pregnancy. A r e t r o s p e c t i v e study has a b u i l t i n drawback, the s u b j e c t ' s a b i l i t y to remember events r e q u i r e d , e s p e c i a l l y i f over a long p e r i o d of time as 9 months g e s t a t i o n . A p r e - s e l e c t i o n of s u b j e c t s occurs by the women who answer an advertisement f o r s u b j e c t s . Q u e s t i o n n a i r e s were mailed to 208 women, who responded to advertisements i n n a t i o n a l d i v i n g magazines, and pos t e r s i n 74 d i v i n g shops ( B o l t o n , 1980). The s u b j e c t s had been pregnant w i t h i n 5 years of completing a scuba course. The d e s c r i p t i v e q u e s t i o n n a i r e compared the extent of d i v i n g to o b s t e t r i c and f e t a l outcome . One hundred t h i r t y - s i x of 208 women dove one or more pregnancies to an average depth of 42.6 f e e t ; 24 of the 136 women dove deeper than 99 f e e t during the f i r s t t r i m e s t e r . The women who dove (D) durin g pregnancies had a s i g n i f i c a n t l y higher l e v e l of d i v e r c e r t i f i c a t i o n and approval of t h e i r p h y s i c i a n s and f a m i l i e s than women who did not d i v e (ND) du r i n g t h e i r pregnancies. The frequency and depths of the d i v e s decreased as the pregnancy progressed. B o l t o n found no r e l a t i o n between the r i s k of the pregnancy and the frequency of the s i x p r e - s e l e c t e d c o m p l i c a t i o n s of pregnancy - neonatal deaths, s t i l l b i r t h , low b i r t h weight, v a g i n a l b l e e d i n g d u r i n g pregnancy, spontaneous a b o r t i o n , and b i r t h d e f e c t s . There were s i g n i f i c a n t l y more b i r t h d e f e c t s i n the D group than the ND group ,but the percentage of d e f e c t s i n the D group was w i t h i n the norms of the general p o p u l a t i o n . The r e s u l t s of the study may not be r e p r e s e n t a t i v e of the d i v i n g p o p u l a t i o n because women who had c o m p l i c a t i o n s or u n d e s i r a b l e outcomes may not have answered the a d v e r t i s e m e n t s . B o l t o n recommended t h a t 1) every woman d i v e r of c h i l d b e a r i n g age should be informed of the p o t e n t i a l r i s k s of d i v i n g during pregnancy, and 2) the p h y s i c i a n should aquaint her with the problems and encourage her to decide before becoming pregnant whether to dive and what l i m i t a t i o n s r egarding depth, d u r a t i o n , and c h a r a c t e r of di v e s should be made. I t 75 was f e l t that many women would dive a g a i n s t medical advice or before pregnancy was confirmed. The Undersea Medical S o c i e t y o f f i c i a l l y d iscourages d i v i n g during pregnancy u n t i l f u r t h e r s t u d i e s are a v a i l a b l e . Bolton's g u i d e l i n e s f o r d i v i n g during pregnancy were 1) l i m i t d i v e s to 60 f e e t and d u r a t i o n to one- h a l f the l i m i t s of the U.S.Navy no-decompression t a b l e s , 2) avoid strenous d i v e s , h y p o v e n t i l a t i o n , and c h i l l i n g , or 3) s n o r k e l l i n g under optimal c o n d i t i o n s as an a l t e r n a t i v e to scuba d i v i n g . I f women suspected they were pregnant , Turner and Unsworth (1982) suggested no d i v i n g below 30 f e e t or no d i v i n g at a l l was p r e f e r r e d . They presented a case study of a pregnant i woman who dove 20 times between her 40th and 50th days a f t e r her l a s t menstrual c y c l e . Most of the dive s were to s i x t y f e e t or l e s s (as sugggested by B o l t o n , 1980), three d i v e s were to 100 f e e t , and one dive to 110 f e e t . There was one problem dive where the ascent r a t e was de s c r i b e d as "very r a p i d " , but the remaining ascents were estimated at 60 f e e t per minute, The pregnancy was normal, but the newborn had a number of a b n o r m a l i t i e s - a r t h r o g r y p o s i s , and some dysgenic f e a t u r e s . Turner and Unsworth i m p l i e d that the a b n o r m a l i t i e s were due to the d i v i n g . A s i m i l i a r time course as thali d o m i d e , where the upper limbs were a f f e c t e d about the 40th day and the lower limbs about the 45th day due to the drug a f f e c t i n g the m i g r a t i o n of c e l l s used to form the p o s t e r i o r root 'ganglia was a proposed reason f o r the 76 a b n o r m a l i t i e s seen from d i v i n g between the 40th and 50th day. A r t h r o g r y p o s i s was supposedly due to a muscle disease or a b n o r m a l i t i e s of c e l l s forming the a n t e r i o r root g a n g l i o n . T h e o r e t i c a l l y , d i v i n g i s a d e t r i m e n t a l f a c t o r to the f e t u s e i t h e r through the bubble formation a f f e c t i n g the pl a c e n t a ' s f u n c t i o n or the f e t u s ' c i r c u l a t i o n , or a secondary e f f e c t through hypoxia because of i t s e f f e c t on p l a c e n t a l f u n c t i o n . J a r r e t t and S p e l l a c y (1983) found women decreased t h e i r j o g g i n g as t h e i r pregnancies progressed. Mechanical f a c t o r s of pregnancy - u t e r i n e enlargement, changes i n weight d i s t r i b u t i o n , and the suggested decrease i n c i r c u l a t o r y r e s e r v e - were a t t r i b u t e d to reduced a c t i v i t y l e v e l s which was s i m i l a r to f i n d i n g s with v o l u n t a r y e x e r c i s e i n mice (Karasawa et a l . , 1981). The a b o r t i o n r a t e was lower than normal, but f e t a l a b n o r m a l i t i e s were higher than expected. A l a r g e r sample s i z e was suggested to f i n d whether the f e t a l a b n o r m a l i t i e s o c c u r r e d more o f t e n i n pregnant women who jogged. The r a t e of a b n o r m a l i t i e s , 4 out 67 s u b j e c t s or 6% was above the norms f o r the ge n e r a l p o p u l a t i o n , 2-4%. The anomalies r e p o r t e d were not a l l c l a s s i c anomalies and g e n e r a l l y not l i f e - t h r e a t e n i n g (hypospadias, metatarus adductus, r i g h t arm phocomelia, c o g e n i t a l h i p d y s p l a x i a , t o r t i c o l l i s , f a c i a l asymmetry).The low i n c i d e n c e of maternal and f e t a l c o m p l i c a t i o n s could probably be a t t r i b u t e d to the healthy c o n d i t i o n of the s u b j e c t s . The author had some r e s e r v a t i o n s about the data 1) women with poor outcomes may or may not 77 have responded, and 2) r e c a l l accuracy was unknown. The general c o n c l u s i o n was women who were t r a i n e d and continued to run during pregnancy d i d not a d v e r s e l y a f f e c t t h e i r pregnancies. Subjects who continued to p a r t i c i p a t e i n a combination of endurance a c t i v i t i e s - running, a e r o b i c dance, c r o s s - c o u n t r y s k i i n g - at or near pre-pregnancy i n t e n s i t i e s u n t i l term gained l e s s weight, had l i g h t e r i n f a n t s , and s h o r t e r lengths of g e s t a t i o n than s u b j e c t s who ceased p a r t i c i p a t i o n i n these a c t i v i t i e s before t h e i r 28th week (Clapp and D i c k s t e i n , 1984). P a r t i c i p a t i o n i n endurance e x e r c i s e p r i o r to pregnancy was no a s i g n i f i c a n t determinant i n pregnancy weight g a i n , as was the continued and s u s t a i n e d p a r t i c i p a t i o n i n ; endurance e x e r c i s e . The l i g h t e r newborns f o r g e s t a t i o n a l age may have been r e l a t e d to the lower maternal weight gain of e x e r c i s i n g s u b j e c t s , but i t was important to note that with the decrease i i n the v a r i a b l e s mentioned , there was no i n c r e a s e i n m o r b i d i t y . The r e t r o p s e c t i v e s t u d i e s with e l i t e a t h l e t e s ( E r d e l y i , 1962; Zaharieva 1972; Berg et a l 1983) who t r a i n e d p r i o r to and/or during pregnancy have found r e s u l t s which are s i m i l i a r to those mentioned p r e v i o u s l y . The second stage of labour was s h o r t e r i n e l i t e a t h l e t e s compared to non-athletes ( E r d e l y i , 1 9 6 0 ; Z a h a r i e v a , 1972) which was a t t r i b u t e d to t h e i r b e t t e r t r a i n e d musculature and nervous systems f o r p h y s i c a l 78 s t r a i n , g e n e r a l l y ( E r d e l y i , 1962).Berg et a l . (1983) noted the second stage was longer i n a t h l e t e s than n a t i o n a l p e r i n a t a l r e s u l t s , no reason f o r the d i f f f e r e n c e was proposed. Z a h a r i e v a (1972) noted that the f i r s t stage was prolonged i n the Olympic a t h e l e t e s due to r i g i d i t y of the ute r u s , s t r o n g e r muscle tone, and an unusual l a c k of f l e x i b i l i t y i n the s o f t p a r t s of the b i r t h t r a c t . E r d e l y i found a t h l e t e s had a 50% r e d u c t i o n i n the number of c e s a r i a n s e c t i o n s , but Berg et a l . found an i n c r e a s e i n abdominal d e l i v e r i e s and higher percentage of h i g h - r i s k pregnancies i n a t h l e t e s compared . to n a t i o n a l data and lower b i r t h w e i g h t of newborn, t h e r e f o r e a p o s s i b l e i n f l u e n c e of t r a i n i n g h i s t o r y on course of pregnancy and l a b o u r . C o n c l u s i o n The human s t u d i e s suggest t h a t normal healthy pregnant women can be p h y s i c a l l y a c t i v e without a f f e c t i n g the outcome of t h e i r pregnancy or the f e t u s i f the i n t e n s i t y l e v e l i s not exha u s t i n g . A pregnant woman w i l l reach her maximum heart r a t e at a lower workload than a non-pregnant woman, but a pregnant woman should be able to maintain her a e r o b i c f i t n e s s l e v e l or i n c r e a s e her f i t n e s s l e v e l s compared to a non- e x e r c i s i n g pregnant woman. The t r a i n i n g p e r i o d could be 10 or more weeks, but the frequency should be at l e a s t 3 times per week f o r a s i g n i f i c a n t d i f f e r e n c e to show between the e x e r c i s i n g and n o n - e x e r c i s i n g pregnant women. The d u r a t i o n 79 of pregnancy was not viewed by a number of the r e s e a r c h e r s as an important q u e s t i o n , but t h e i r s t u d i e s e l i m i n a t e d premature d e l i v e r i e s by t e s t i n g l a t e i n g e s t a t i o n or e l i m i n a t i n g s u b j e c t s who d e l i v e r e d beyond the normal g e s t a t i o n p e r i o d of 40 weeks. Small sample s i z e s prevented f i n d i n g s i g n i f i c a n c e , i f one e x i s t s , i n the apgar scores and b i r t h weights of the i n f a n t s of e x e r c i s i n g and n o n - e x e r c i s i n g women. Further s t u d i e s on e x e r c i s e during pregnancy should have a sample s i z e l a r g e enough to show whether the f e t u s v i a f e t a l heart r a t e or f e t a l b r e a t h i n g movements, and/or the i n f a n t at b i r t h v i a apgar scores are i n any way a f f e c t e d by maternal e x e r c i s e . An i d e a l study of e x e r c i s e during pregnancy would monitor p h y s i c a l a c t i v i t y and a e r o b i c f i t n e s s l e v e l s from e a r l y i n the pregnancy, such as the f i r s t t r i m e s t e r . Since most of the f e t u s * development occurs i n the f i r s t t r i m e s t e r , maternal e x e r c i s e should e f f e c t the f e t u s more during t h i s t r i m e s t e r than the l a s t t r i m e s t e r . The outcomes of e x e r c i s e during pregnancy such as the apgar s c o r e s , b i r t h weight, and other f a c t o r s i n d i c a t i n g how the f e t u s adapted to the mother's r e g u l a r p h y s i c a l a c t i v i t y would a l s o be of i n t e r e s t to the mothers and those i n v o l v e d i n her p r e n a t a l care and a c t i v i t i e s . The sample s i z e s should be l a r g e enough to show any s i g n i f i c a n t changes due to maternal e x e r c i s e . Animal s t u d i e s have f o l l o w e d the o f f s p r i n g of e x e r c i s i n g 80 pregnant animals f o r d i f f e r n c e s i n growth and s t r u c t u r e . In f u t u r e , as more work i s done i n e x e r c i s e during pregnancy, a follow-up on the i n f a n t s to f i n d long-term e f f e c t s of the e x e r c i s e during t h e i r f e t a l development should be undertaken. In reviewing the l i t e r a t u r e on e x e r c i s e d u r i n g pregnancy, a number of the papers on human pregnancy have been p u b l i s h e d i n the past 10 years and with t h i s i n c r e a s e d i n t e r e s t i n the area, a number of questions pregnant women have about p h y s i c a l a c t i v i t y d u r i n g pregnancy should be answered w i t h i n the near f u t u r e . There should be some standard workloads or values used i n t e s t i n g pregnant women to make the comparison of v a r i o u s p h y s i o l o g i c a l v a r i a b l e s and p h y s i c a l a c t i v i t i e s p o s s i b l e among the s t u d i e s p u b l i s h e d e n a b l i n g d e f i n i t e c o n c l u s i o n s to be drawn on the e f f e c t s of the p h y s i c a l a c t i v i t y on the pregnancy and i t s outcome. 81 APPENDIX B Raw D a t a S u b j e c t Mean H e a r t R a t e s ( b p m ) d u r i n g C y c l e E r g o m e t e r T e s t a t f o u r w o r k l o a d s ( k g ) ( s e e n o t e ) 1 s t T r i m e s t e r 2nd T r i m e s t e r 3 r d T r i m e s t e r 0 . 5 1 .0 1 .5 2 . 0 0 . 5 1 .0 1 .5 2 . 0 0 . 5 1 .0 1 .5 2 . 0 A B ( . n 66) 90 ( 1 . 3 ) 110 130 100 n 106 98 125 n 131 150 109 100 1 2 2 . 120 5 138 142 144 * C - - - - 95 105 125 1 4 7 . 5 101 115 135 150 D - - - • - 89 100 120 135 90 110 122 138 E - - - - 83 8 7 . 5 103 123 89 94 110 125 F 81 98 108 134 80 87 110 125 98 120 130 147 G 93 110 133 150 94 110 125 150 110 125 138 144 H ( . 6 6 ) n 1 0 5 . 5 ( 1 . 3 ) 1 2 7 . 5 146 ( . n 66 ) 115 ( 1 . 3 ) 130 170 9 7 . 5 105 132 1 4 7 . 5 I 93 107 120 1 4 2 . 5 98 110 130 150 121 1 3 6 . 5 152 * J - - - - 87 110 128 145 113 150 * * K 98 123 143 * 99 125 140 150 110 129 147 * L 9 7 . 5 133 1 3 2 . 5 150 105 125 150 * 122 138 150 * M 113 135 150 * 109 130 150 * 117 138 150 * N - - - - 103 125 150 * 105 125 147 * 0 98 112 133 155 110 129 153 * 130 158 * * P - - - - 105 146 * * 108 132 156 * Q - - - - 125 142 150 * 115 125 150 * R 1 0 2 . 5 125 138 150 93 110 138 150 95 110 138 150 S - - - - 95 110 143 * 105 114 138 150 T _ 113 125 150 * 110 135 150 * 82 Note: The workloads 0.05, 1.0, 1.5, 2.0 kg at 50rpm on the Monark c y c l e ergometer equal 150, 300, 450, 600 kgm/m, which are e q u i v a l e n t to 25, 50, 75, 100 watts r e s p e c t i v e l y . "-" no heart r a t e data because the s u b j e c t s t a r t e d the study i n the second t r i m e s t e r . "*" no data a t t h i s workload because the t e s t had been terminated at the pr e v i o u s workload when the s u b j e c t ' s heart r a t e had approached or reached 150 bpm. "n" due to changes i n t e s t i n g p r o t o c o l - s u b j e c t B was not evaluated at 0.5 kg i n the 1st t r i m e s t e r , and 0.5 kg and 1.5 kg i n the 2nd t r i m e s t e r , and s u b j e c t H was not evaluated at 0.5 kg i n the 1st adn 2nd t r i m e s t e r s . 83 APPENDIX C:PREDICTED MAXIMUM OXYGEN UPTAKES Maximum oxygen uptake (V02max) values were p r e d i c t e d from the heart r a t e s during the submaximal c y c l e ergometry t e s t s , at 75 and/or 100 watts i n the second and t h i r d t r i m e s t e r s , using Astrand's nomogram (de V r i e s , 1968). The V02max values were r a t e d (low, f a i r , average, good, high) a c c o r d i n g to Astrand's t a b l e of norms f o r women 20-29, and 30-39. The T group ( s u b j e c t s A-J) had p r e d i c t e d V02 values g r e a t e r than the UT group ( s u b j e c t s K-T) at each workload dur i n g the second and t h i r d t r i m e s t e r s . FITNESS CLASSIFICATION Second T r i m e s t e r : Group Workload High Good Average F a i r Low (watts) T 75 5 2 100 4 5 UT 75 1 100 2 T h i r d T r i m e s t e r : T 75 1 4 100 3 4 UT 75 8 1 100 1 1 84 V 0 2 ( l / m i n ) R a t i n g ( L o w , F a i r , A v e r a g e , G o o d , H i g h ) a t s e l e c t e d w o r k l o a d s (75 w a t t s , 100 w a t t s ) S e c o n d T r i m e s t e r S u b j e c t W o r k l o a d ( w a t t s ) 75 100 A 3 . 0 H i g h 3 . 4 H i g h B n n 2 . 5 Good C 3 . 0 H i g h 2 . 6 Good C 3 . 4 H i g h 3 .1 H i g h E * 3 . 9 H i g h F * 3 . 7 H i g h G 3 . 0 H i g h 2 . 5 Good H 2 . 5 Good 2 . 0 A v e r a g e I 2 . 7 Good 2 . 5 Good J 2 . 8 H i g h 2 . 7 Good K 2 . 4 Good 2 . 5 Good L 2 . 0 A v e r a g e ** ** M 2 . 0 F a i r 2 . 0 A v e r a g e N 2 . 0 F a i r ** ** 0 2 . 0 A v e r a g e ** ** P ** ** ** ** Q 2 . 0 F a i r ** ** R 2 . 4 A v e r a g e 2 . 5 Good S 2 . 2 A v e r a g e * ** T 2 . 0 F a i r 2 . 7 F a i r T h i r d t r i m e s t e r : A 2 . 4 A v e r a g e 2 . 7 Good B 2 . 3 A v e r a g e ** ** C 2 . 6 Good 2 . 5 Good D 3 . 2 H i g h 3 . 0 H i g h E * 3 . 7 H i g h F 2 . 7 Good 2 . 6 Good G 2 . 4 Good 2 . 7 H i g h H 2 . 7 Good 2 . 6 Good I 2 . 0 A v e r a g e ** ** J ** ** ** ** K 2 .1 A v e r a g e ** ** L 2 . 0 A v e r a g e ** ** M 2 . 0 A v e r a g e ** ** N 2 .1 A v e r a g e ** ** 0 ** ** ** ** P 1 .9 F a i r ** ** Q 2 . 0 A v e r a g e ** ** R 2 . 4 A v e r a g e 2 . 5 A v e r a g e S 2 . 4 A v e r a g e 2 . 5 Good T 2 . 0 A v e r a g e ** ** 85 * The s u b j e c t ' s heart r a t e at t h i s workload was too low to p r e d i c t a maximum oxygen uptake from Astrand's t a b l e and nomogram. ** The submaximal c y c l e ergometry t e s t had been terminated at the previous workload when the s u b j e c t ' s heart r a t e approached or reached the designated maximum of 150 bpm, t h e r e f o r e no p r e d i c t e d maximum oxygen uptake. "n" Subject B was not t e s t e d at 75 watts i n the second t r i m e s t e r , t h e r e f o r e no data f o r p r e d i c t i n g maximum oxygen uptake. 86 APPENDIX D - ACTIVITY LOGBOOKS SUMMARIZED F i r s t T r i m e s t e r ( i f a v a i l a b l e ) S u b j e c t * A c t i v i t i e s Comments >3hr/wk Type D u r a t i o n Freq/wk A s t a r t e d l o g b o o k i n s e c o n d t r i m e s t e r B * A e r o b i c s C l a s s l h r 3 C * W e i g h t T r a i n i n g 90min 2-3 D s t a r t e d l o g b o o k i n s e c o n d t r i m e s t e r E s t a r t e d l o g b o o k i n s e c o n d t r i m e s t e r F * Swimming 3-5 1-2.4km G s t a r t e d l o g b o o k i n s e c o n d t r i m e s t e r H s t a r t e d l o g b o o k i n s e c o n d t r i m e s t e r I no l o g b o o k J s t a r t e d l o g b o o k i n s e c o n d t r i m e s t e r K no l o g b o o k L * S w i m m i n g / t e n n i s l h r 1-2 / o r s k a t i n g P r e n a t a l f i t n e s s l h r 1-2 M s t a r t e d l o g b o o k i n t h e s e c o n d t r i m e s t e r N s t a r t e d l o g b o o k i n t h e s e c o n d t r i m e s t e r 0 no l o g b o o k P * C y c l i n g 2-3 l O m i l e s S o f t b a l l 2 R * A e r o b i c s c l a s s e s l h r 3 S s t a r t e d l o g b o o k i n s e c o n d t r i m e s t e r T s t a r t e d l o g b o o k i n s e c o n d t r i m e s t e r S e c o n d T r i m e s t e r A no a c t i v i t y r e c o r d e d B * A e r o b i c s C l a s s e s l h r 2-3 W a l k i n g 30min 1 l - l / 2 m i l e s C * W e i g h t t r a i n i n g 90min 2-3 W a l k i n g l - 2 h r 1 D * P r e n a t a l f i t n e s s l h r 1 W a l k i n g 30-90min 1-2 E * A e r o b i c s C l a s s e s l h r 1 Swimming 1-2 1km W i n d s u r f i n g 1 4 87 F * Swimming 4-5 1.5-4.8km L i f e c y c l e 24-36rain 1-3 G no a c t i v i t y r e c o r d e d H * P r e n a t a l f i t n e s s 90min 1 Swimming 20-30min 1-4 1km W a l k i n g 30min 1 I no l o g b o o k J no a c t i v i t y r e c o r d e d K L no * l o g b o o k P r e n a t a l f i t n e s s l h r 3 M * W a l k i n g C y c l i n g 30-45min 30min 3-4 i r r e g u l a r b a s i s N * P r e n a t a l f i t n e s s T e n n i s l h r 45-60min 2 3 0 no l o g b o o k P * B a d m i n t o n W a l k i n g 1 2 Q * A e r o b i c s c l a s s e s R u n n i n g W a l k i n g 40-60min 30min 45min 1-3 2- 4 3- 4 l i g h t - m o d . R * P r e n a t a l f i t n e s s W a l k i n g l h r l h r 2-3 1-2 S J a z z e r c i s e T e n n i s l h r 30min 1-2 1 T Swimming V o l l e y b a l l 30rain 15-20min 1 . 1 T h i r d T r i m e s t e r A B no * a c t i v i t y r e c o r d e d A e r o b i c s c l a s s e s P r e n a t a l f i t n e s s l h r l h r 1 2 u n t i l t e r m u n t i l t e r m C * P r e n a t a l f i t n e s s W a l k i n g l h r l h r 1-2 1-2 t o 3 7 t h wk D P r e n a t a l f i t n e s s Swimming l h r 1- 2 2- 3 t o 3 7 t h wk 3 5 - 4 0 t h wk E * A e r o b i c s c l a s s e s l h r 3 t o 3 7 t h wk Swimming W a l k i n g W i n d s u r f i n g 4 0-60min 1-2 60-90min 1 l h r 1 t o 3 4 t h wk 3 3 - 3 7 t h wk t o 29nd wk 88 C y c l i n g 1-2 20km 31-32nd wk ( d i d n o t keep l o g b o o k beyond 3 7 t h week) F * Swimming L i f e c y c l e A8-60min 2-A A 1.5-3.0km t o t e r m t o t e r m G no a c t i v i t y . r e c o r d e d H P r e n a t a l Swimming W a l k i n g f i t n e s s 90min 20-30min 30-90min 1-2 1 1-3 t o 3 7 t h wk t o 3 6 t h wk t o t e r m I no l o g b o o k J * P r e n a t a l f i t n e s s 60min 1-2 t o 3 8 t h wk K L no no l o g b o o k a c t i v i t y r e c o r d e d i n t h i r d t r i m e s t e r M - W a l k i n g 30min d a i l y t o t e r m N 0 no P r e n a t a l l o g b o o k f i t n e s s l h r 2 t o t e r m P - W a l k i n g 20-30min 20-A0min 1-2 3 2 A - 3 6 t h wk 3 8 - A 0 t h wk Q * A e r o b i c s W a l k i n g c l a s s e s AOmin AOmin 1-3 3-A 2 5 - 3 3 r d wk t o t e r m R * P r e n a t a l W a l k i n g c l a s s e s l h r l h r 2-3 1-2 t o t e r m t o t e r m S — J a z z e r c i s e l h r T e n n i s 30-A5min W a l k i n g 30-90min 1-2 t o 3 6 t h wk 1-2 2 8 - 3 9 t h wk i r r e g u l a r b a s i s T — P r e n a t a l f i t n e s s 30min A e r o b i c s c l a s s e s l h r V o l l e y b a l l 15-20min 1 1 1 2 7 - 3 1 s t wk 3 6 - 3 8 t h wk 2 7 - 3 1 s t wk 3 A - 3 8 t h wk 89

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