Open Collections

UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

The effect of exercise during pregnancy and lactation on maternal food intake, body weight and body composition,… Courant, Geneviève Thérèse 1986

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1987_A6_7 C68_7.pdf [ 4.38MB ]
Metadata
JSON: 831-1.0096869.json
JSON-LD: 831-1.0096869-ld.json
RDF/XML (Pretty): 831-1.0096869-rdf.xml
RDF/JSON: 831-1.0096869-rdf.json
Turtle: 831-1.0096869-turtle.txt
N-Triples: 831-1.0096869-rdf-ntriples.txt
Original Record: 831-1.0096869-source.json
Full Text
831-1.0096869-fulltext.txt
Citation
831-1.0096869.ris

Full Text

THE EFFECT OF EXERCISE DURING PREGNANCY AND LACTATION ON MATERNAL FOOD INTAKE, BODY WEIGHT AND BODY COMPOSITION, AND ON LACTATION PERFORMANCE IN RATS By GENEVIEVE THERESE COURANT B.N.Sc., Queen's U n i v e r s i t y , 1980 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES D i v i s i o n of Human N u t r i t i o n School of Family and N u t r i t i o n a l Sciences We accept t h i s t h e s i s as conforming to the r e q u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA November 1986 (g) Genevieve Therese Courant In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 DE-6(3/81) ABSTRACT During pregnancy, body f a t s t o r e s i n c r e a s e i n p a r t to s u b s i d i z e the h i g h energy c o s t of l a c t a t i o n . One e f f e c t of e x e r c i s e , on the other hand, i s to lower percent body f a t . The e f f e c t of e x e r c i s e d u r i n g preg-nancy and l a c t a t i o n on body f a t , and on body composition in g e n e r a l , i s not w e l l documented. There i s a l s o a p a u c i t y of data on the e f f e c t of e x e r c i s e d u r i n g these p h y s i o l o g i c a l s t a t e s on food i n t a k e and body weight. I f e x e r c i s e d u r i n g pregnancy decreases body f a t s t o r e s , would l a c t a t i o n performance subsequently be compromised? T h i s study was designed to determine the e f f e c t of moderately strenuous a e r o b i c e x e r c i s e , d u r i n g r a t preg-nancy and l a c t a t i o n , on food i n t a k e , body weight, body composition and l a c t a t i o n performance. V i r g i n female Sprague-Dawley r a t s were d i v i d e d i n t o e x e r c i s e d (n=40) and sedentary (n=40) groups. E x e r c i -s i n g r a t s were t r a i n e d over three weeks to run on a t r e a d m i l l at 30 m/min, 2 hours/day, 5 days/week. W i t h i n each group, two subgroups were then mated and three subgroups remained as v i r g i n age c o n t r o l s (n=8 per sub-group). Of the mated subgroups, one was terminated w i t h i n 24 hours of p a r t u r i t i o n and the other on day 14 of l a c t a t i o n . Subgroups of v i r g i n sedentary and exer-c i s i n g c o n t r o l s were terminated at times corresponding to each of mating, p a r t u r i t i o n and day 14 of l a c t a t i o n i i of mated animals. C a r c a s s e s were assayed f o r f a t , water, ash and p r o t e i n . Ad l i b i t u m food i n t a k e and body weight were monitored throughout the study, as was the weight gain of pups of l a c t a t i n g dams. MANOVA showed the e f f e c t of a c t i v i t y to be s i g n i f i -cant on food intake at week three of t r a i n i n g and d u r i n g the pregnancy p e r i o d (p<0.00l) and at week one (p<0.0l) and two (p<0.05) of l a c t a t i o n . The e f f e c t of a c t i v i t y was h i g h l y s i g n i f i c a n t (p<0.00l) on body weight from week three of t r a i n i n g and throughout the pregnancy and l a c t a t i o n p e r i o d s , as w e l l as on the percent f a t , water and ash of the r a t c a r c a s s e s . Post hoc multimean com-p a r i s o n s (Scheffe) at the p<0.05 l e v e l r e v e a l e d that e x e r c i s e r e s u l t e d i n a s i g n i f i c a n t i n c r e a s e i n the food intake of v i r g i n r a t s , and n o n s i g n i f i c a n t i n c r e a s e s i n the food intake of pregnant and l a c t a t i n g r a t s . Body weights of v i r g i n , pregnant and l a c t a t i n g e x e r c i s i n g r a t s were s i g n i f i c a n t l y g r e a t e r than t h e i r r e s p e c t i v e sedentary c o n t r o l s . D e s p i t e t h e i r h e a v i e r body weights and g r e a t e r food i n t a k e , the estimated c a r c a s s energy content of e x e r c i s i n g animals was lower than that of sedentary animals. T h i s f i n d i n g was r e f l e c t e d i n the c a r c a s s composition whereby e x e r c i s i n g r a t s , whether v i r g i n , pregnant or l a c t a t i n g , c o ntained c o n s i s t e n t l y l e s s f a t and more water than sedentary c o n t r o l s . At p a r t u r i t i o n , pregnant animals c o n t a i n e d s i g n i f i c a n t l y l e s s f a t , more water and more ash than sedentary preg-nant c o n t r o l s . A f t e r 14 days of l a c t a t i o n , there were 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 c a r c a s s composition be-tween e x e r c i s i n g and sedentary dams. However, l a c t a t i n g r a t s , whether e x e r c i s i n g or sedentary, c a t a b o l i z e d approximately 50 percent of the body f a t present a t p a r t u r i t i o n . Pup weight gains were not s i g n i f i c a n t l y d i f f e r e n t between e x e r c i s i n g and sedentary dams. From these f i n d i n g s i t was concluded that the e f f e c t of e x e r c i s e d u r i n g pregnancy and l a c t a t i o n on food i n t a k e , body weight and body composition was com-parable to i t s e f f e c t i n non-gravid r a t s . Moderately strenuous e x e r c i s e d u r i n g pregnancy prevented the i n -crease i n body f a t d e p o s i t i o n normally present at t h i s time. D e s p i t e these d e p l e t e d f a t s t o r e s , the energy s u p p l i e d by the m o b i l i z a t i o n of the remaining f a t and the i n c r e a s e i n food i n t a k e was adequate to support normal pup growth. i v TABLE OF CONTENTS Page A b s t r a c t i i T a b l e of C o n t e n t s v L i s t of T a b l e s v i i i L i s t of F i g u r e s x Acknowledgements x i CHAPTER I INTRODUCTION 1 I I LITERATURE REVIEW 5 A) The E f f e c t of E x e r c i s e on Food I n t a k e , Body Weight and Body C o m p o s i t i o n 1) Human S t u d i e s 5 2) A n i m a l S t u d i e s 10 B) The E f f e c t of Pregnancy and L a c t a t i o n on Food I n t a k e , Body Weight and Body C o m p o s i t i o n 1) Human S t u d i e s 14 2) A n i m a l S t u d i e s 17 C) The E f f e c t of E x e r c i s e D u r i n g Pregnancy and L a c t a t i o n on Food I n t a k e , Body Weight and Body C o m p o s i t i o n 1) Human S t u d i e s 19 2) A n i m a l S t u d i e s 22 D) The E f f e c t of E x e r c i s e D u r i n g Pregnancy and L a c t a t i o n on Pregnancy Outcome and L a c t a t i o n Performance 1 ) Human S t u d i e s 26 2) A n i m a l S t u d i e s 29 E) Summary 33 I I I EXPERIMENTAL DESIGN AND METHODOLOGY 35 A) E x p e r i m e n t a l D e s i g n 35 B) A n i m a l s '. . 38 v C) D i e t 39 D) Experimental Procedures 1 ) E x e r c i s e 39 2) T r e a d m i l l 41 3) Mating and C u l l i n g of Pups 42 4) M i l k C o l l e c t i o n 43 5) Termination 44 6) Rat E x c l u s i o n C r i t e r i a 44 E) Measurements 1 ) Food Intake 46 2) Body Weight 46 F) Assay Procedures 1) P r e p a r a t i o n of Carcass f o r A n a l y s i s .. 46 2) Sample P r e p a r a t i o n f o r the Ash, Fat and P r o t e i n Assays 48 3) Water 48 4) Ash 50 5) Fat 51 6) P r o t e i n 54 G) Carcass Energy Content 55 H) S t a t i s t i c a l A n a l y s i s 55 IV RESULTS 57 A) Food Intake 57 B) Body Weight 63 C) Body Composition 70 D) Carcass Energy Content 78 E) Pregnancy Outcome and L a c t a t i o n Performance 79 V DISCUSSION 83 A) Food Intake 83 B) Body Weight 85 C) Body Composition 89 1 ) V i r g i n Rats 91 2) Rats at P a r t u r i t i o n 91 3) L a c t a t i n g Rats 93 v i D) Pregnancy Outcome and Lactation Performance • 9 7 BIBLIOGRAPHY v i i L I S T OF T A B L E S Page Table I T r e a d m i l l running t r a i n i n g p r o t o c o l f o r experimental r a t s 40 Table II C r i t e r i a used to exclude r a t s from the experiment and the f i n a l data a n a l y s i s 45 Table I I I F values a s s o c i a t e d with the e f f e c t s of ' a c t i v i t y ' and 'mated' on food intake f o r each week of the t r a i n i n g , pregnancy and l a c t a t i o n p e r i o d s 59 Table IV Comparison of weekly food i n t a k e s of sedentary and e x e r c i s i n g r a t s d u r i n g the t r a i n i n g p e r i o d 60 Table V Comparison of weekly food i n t a k e s of mated sedentary and e x e r c i s i n g r a t s and t h e i r v i r g i n c o n t r o l s d u r i n g the pregnancy p e r i o d 61 Table VI Comparison of weekly food i n t a k e s of mated sedentary and e x e r c i s i n g dams and t h e i r v i r g i n c o n t r o l s d u r i n g the l a c t a t i o n p e r i o d 62 Table VII F values a s s o c i a t e d with the e f f e c t s of ' a c t i v i t y ' and 'mated' on body weight f o r each of the t r a i n i n g , pregnancy and l a c t a t i o n p e r i o d s 66 Table VIII Comparison of i n i t i a l and weekly body weights of sedentary and e x e r c i s i n g r a t s d u r i n g the t r a i n i n g p e r i o d 67 Table IX Comparison of weekly body weights of mated sedentary and e x e r c i s i n g r a t s and t h e i r v i r g i n c o n t r o l s d u r i n g the pregnancy p e r i o d and at p a r t u r i t i o n . . . . 68 Table X Comparison of weekly body weights of mated sedentary and e x e r c i s i n g dams and t h e i r v i r g i n c o n t r o l s d u r i n g the l a c t a t i o n p e r i o d 69 Table XI F values a s s o c i a t e d with the e f f e c t s of ' a c t i v i t y ' 'mated' and 'stage' (P and L) on the percent of water, f a t , ash and p r o t e i n of r a t c a r c a s s e s . . 72 v i i i Table XII F values a s s o c i a t e d with the e f f e c t s of ' a c t i v i t y ' and 'stage' (T, P and L) on the percent of water, f a t , ash and pro-t e i n of v i r g i n and mated r a t c a r c a s s e s . 73 Table XIII Body composition a n a l y s i s summary f o r a l l r a t groups 74 Tabl e XIV Comparison of estimated c a r c a s s energy content of sedentary and e x e r c i s i n g , v i r g i n and mated r a t s t erminated a t , or corresponding t o , the time of mating, at p a r t u r i t i o n and on day 14 of l a c t a t i o n 80 Table XV Comparison of mean pup number per l i t t e r and mean pup b i r t h w e i g h t before c u l l i n g , of sedentary and e x e r c i s i n g dams 81 Table XV Comparison of mean pup b i r t h w e i g h t a f t e r c u l l i n g and mean weight gain of pups a f t e r 14 days of l a c t a t i o n of sedentary and e x e r c i s i n g dams 82 ix LIST OF FIGURES Page F i g u r e 1 Diagrammatic r e p r e s e n t a t i o n of the m o d i f i e d 2*2*3 f a c t o r i a l e x p e r i m e n t a l design 36 F i g u r e 2 Experimental p r o t o c o l 37 F i g u r e 3 Flow diagram o u t l i n i n g r a t c a r c a s s p r e p a r a t i o n procedure f o r body composition a n a l y s i s 49 F i g u r e 4 Least-squares f i t of the f a t recovery t e s t data 53 F i g u r e 5 Weekly mean food intakes of r a t s d u r i n g the t r a i n i n g , pregnancy and l a c t a t i o n p e r i o d s 58 F i g u r e 6 Weekly mean body weights of r a t s d u r i n g the t r a i n i n g , pregnancy and l a c t a t i o n p e r i o d s and at p a r t u r i t i o n 65 F i g u r e 7 Frequency d i s t r i b u t i o n of the t o t a l of water, f a t , ash and p r o t e i n of the 80 experimental r a t c a r c a s s e s 71 F i g u r e 8 Experimental data superimposed on the best f i t l i n e of Cox et a l . (1985) 90 x ACKNOWLEDGEMENTS I wish to thank the f o l l o w i n g people f o r t h e i r c o n t r i b u t i o n to t h i s p r o j e c t : Dr. Susan Barr, f o r her e x c e l l e n t guidance as a r e s e a r c h a d v i s o r and her u n f a i l i n g support and encouragement throughout my graduate s t u d i e s , I am most g r a t e f u l ; Dr. Joseph L e i c h t e r and Dr. Don McKenzie, f o r s e r v i n g on my t h e s i s committee; Dr. R i c h a r d Beames, f o r g i v i n g of h i s time, suggestions and a d v i c e regarding r a t c a r c a s s a n a l y s i s ; Ms. V i r g i n i a Green, f o r her a s s i s t a n c e with the s t a t i s t i c a l a n a l y s i s of the d a t a ; Diana Vos, f o r her t e c h n i c a l a s s i s t a n c e and good-humored companionship dur i n g the many hours spent i n the animal room; C l a r e n c e J . V i r t u e , my p a r t n e r i n l i f e , f o r the hours spent doing emergency r e p a i r s and m o d i f i c a t i o n s to the t r e a d m i l l which saved me much time and f r u s t r a t i o n ; f o r h i s h e l p i n computer programming and f a c i l i t a t i n g the p l o t t i n g of the f i g u r e s f o r the t h e s i s ; and whose a d v i c e , support and encouragement d u r i n g t h i s p r o j e c t are immeasurable. T h i s study was supported by Grant No. A0019 to Dr. Susan Barr from the N a t u r a l S c i e n c e s and E n g i n e e r i n g Research C o u n c i l of Canada. The f i n a n c i a l support of the Summer Graduate Student Research Bursary (1985), U n i v e r s i t y Teaching A s s i s t a n t s h i p s (1984-5 and 1985-6) and the T i n a and M o r r i s Wagner Foundation F e l l o w s h i p (1985) are g r a t e -f u l l y acknowledged. x i CHAPTER I INTRODUCTION The growing emphasis p l a c e d on e x e r c i s e and f i t n e s s i n our s o c i e t y i s r e f l e c t e d i n the i n c r e a s i n g p a r t i c i p a -t i o n of i n d i v i d u a l s of a l l ages, i n c l u d i n g pregnant and l a c t a t i n g women, i n s p o r t s and p h y s i c a l f i t n e s s programs ( A r t a l and Gardin, 1985). Although the p h y s i c a l and p s y c h o l o g i c a l b e n e f i t s of e x e r c i s e are w e l l documented -for nonpregnant i n d i v i d u a l s , the i n t e r a c t i o n of the in c r e a s e d metabolic demands of p h y s i c a l a c t i v i t y with those of pregnancy i s p o o r l y understood ( L o t g e r i n g et a l . , 1985). Thus the a v a i l a b l e data on the e f f e c t s of e x e r c i s e on v a r i o u s maternal and f e t a l p h y s i o l o g i c a l v a r i a b l e s and on f e t a l outcome i n general are i n s u f f i -c i e n t on which to base d e f i n i t e a c t i v i t y g u i d e l i n e s f o r the pregnant woman. The e f f e c t of e x e r c i s e d u r i n g preg-nancy and l a c t a t i o n on l a c t a t i o n performance i s a l s o not known. One e f f e c t of p h y s i c a l e x e r c i s e i s to lower the percent body f a t content ( O s c a i , 1973; Drinkwater, 1984). Pregnancy, on the other hand, i s normally accompanied by the d e p o s i t i o n of three to four kilograms of f a t over the f i r s t two t r i m e s t e r s (Naismith, 1979). The energy needed f o r milk p r o d u c t i o n i s provided by these f a t s t o r e s , other t i s s u e r e s e r v e s and by the maternal d i e t . The degree to which each of these energy 1 sources c o n t r i b u t e s to milk p r o d u c t i o n i s not known, nor i s i t c l e a r to what extent one energy source can compensate f o r a d e f i c i t i n the other (Butte et a l . , 1984). The r a t has been one of the animal models used to study 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 m a j o r i t y of the i n v e s t i g a t i o n s using t h i s model have found t h a t , even at strenuous l e v e l s , maternal a e r o b i c e x e r c i s e does not s i g n i f i c a n t l y a f f e c t gross f e t a l development or pregnancy outcome, while i t does appear to lower maternal weight g a i n (Wilson and G i s o l f i , 1980; B a g n a l l et a l . , 1983; M o t t o l a et a l . , 1983; Mottola et a l . , 1984). T h i s has been suggested to r e f l e c t a r e d u c t i o n i n maternal f a t s t o r e s but has not been i n v e s t i g a t e d f u r t h e r . None of the above s t u d i e s r e p o r t e d on the food i n t a k e of t h e i r animals. Although there are no s t u d i e s which have looked at the e f f e c t of a e r o b i c e x e r c i s e d u r i n g pregnancy on the food intake of the r a t dam, such s t u d i e s have been c a r r i e d out on the nonpregnant female r a t . The r e s u l t s of these s t u d i e s have been c o n t r a d i c t o r y , a f a c t most probably stemming from the d i s s i m i l a r i t i e s of the experimental c o n d i t i o n s employed (Mayer et a l . , 1954; Ring et a l . , 1970; Oscai et a l . , 1973; Nance et a l . , 1977; Applegate et a l . , 1982). Thus t h e i r r e s u l t s do not help p r e d i c t how e x e r c i s e might a f f e c t food intake of pregnant and l a c t a t i n g r a t s . Throughout g e s t a t i o n , food intake of the r a t dam 2 normally r i s e s , the energy balance becomes p o s i t i v e , and f a t s t o r e s are i n c r e a s e d by 40-50% (Spray, 1950; Naismith, 1966; Knopp et a l . , 1973; Naismith et a l . , 1982). These f a t s t o r e s are thought to c o n t r i b u t e to the energy c o s t s of l a c t a t i o n as evidenced by the drama-t i c decrease i n the body f a t of the dam d u r i n g l a c t a -t i o n , d e s p i t e a 200-300% i n c r e a s e i n energy i n t a k e dur-ing t h i s time ( C r i p p s and W i l l i a m s , 1975). The present study was designed to determine the e f f e c t of strenuous a e r o b i c e x e r c i s e d u r i n g pregnancy and l a c t a t i o n on the food i n t a k e , body weight and body composition of Sprague-Dawley r a t s . In a d d i t i o n , l a c t a -t i o n performance was assessed i n d i r e c t l y by pup weight gain over a two week p e r i o d of l a c t a t i o n . L i s t e d below are the primary and secondary hypotheses t e s t e d i n t h i s study. Primary Hypotheses 1) Food intake of e x e r c i s i n g pregnant and l a c t a t i n g r a t s w i l l be higher than that of sedentary c o n t r o l s . 2) Body weight of e x e r c i s i n g pregnant and l a c t a t i n g r a t s w i l l be l e s s than that of sedentary c o n t r o l s . 3) Percent body f a t w i l l be lower i n e x e r c i s i n g pregnant and l a c t a t i n g r a t s than i n sedentary c o n t r o l s . 4) L a c t a t i o n performance, as r e f l e c t e d by pup weight g a i n , w i l l not be a f f e c t e d by e x e r c i s e d u r i n g pregnancy and l a c t a t i o n . 3 Secondary Hypothesis 1) Pregnancy outcome, as r e f l e c t e d by l i t t e r s i z e and weight, w i l l not be a f f e c t e d by e x e r c i s e d u r i n g pregnancy. 4 CHAPTER II LITERATURE REVIEW The f o l l o w i n g review w i l l focus p r i m a r i l y on what i s and i s not known about the e f f e c t of a e r o b i c e x e r c i s e d u r i n g pregnancy and l a c t a t i o n on maternal food i n t a k e , body weight, body composition, pregnancy outcome and l a c t a t i o n performance. Since e x e r c i s e alone and preg-nancy and l a c t a t i o n alone may each a f f e c t food i n t a k e , body weight, and body composition, they w i l l be reviewed s e p a r a t e l y as to t h e i r e f f e c t on these v a r i a b l e s i n the female. A l s o reviewed are s t u d i e s on the e f f e c t s of a e r o b i c e x e r c i s e d u r i n g pregnancy and l a c t a t i o n on preg-nancy outcome and l a c t a t i o n performance. Human and animal data w i l l be reviewed with the emphasis being on s t u d i e s u s i n g the r a t s i n c e i t has been one of the most widely used animal models i n these areas of i n v e s t i g a -t i o n . A) The E f f e c t of E x e r c i s e on Food Intake, Body Weight and Body Composition 1) Human S t u d i e s Due to inhe r e n t problems a s s o c i a t e d with a c c u r a t e measurements of both energy intake and energy expendi-t u r e , the q u e s t i o n as to whether e x e r c i s e i n c r e a s e s , d e c r e a s e s , or has no e f f e c t on a p p e t i t e i n humans, remains to be answered (O s c a i , 1973; Wilmore, 1983). T h i r t y years ago, Mayer et a l . (1956) demonstrated that 5 an increment i n energy expenditure by e x e r c i s e was not n e c e s s a r i l y accompanied by a p r o p o r t i o n a l i n c r e a s e i n energy i n t a k e . He observed the r e l a t i o n s h i p between c a l o r i c i n t a k e , body weight, and p h y s i c a l work i n a group of 213 m i l l workers in West Bengal, I n d i a . The workers covered a wide range of p h y s i c a l a c t i v i t y , from sedentary to very hard work. The i n v e s t i g a t o r s found that c a l o r i c i n t a k e i n c r e a s e d with a c t i v i t y o n l y w i t h i n a c e r t a i n zone i . e . , normal a c t i v i t y . With sedentary employees, the a c t u a l food intake was higher than that of the employees i n the normal a c t i v i t y zone. For those employees i n the medium to very heavy work zones, the c a l o r i c i n t a k e i n c r e a s e d i n p r o p o r t i o n to the energy expenditure demands of the job. T h i s has l e d to the theory that a c e r t a i n minimum l e v e l of p h y s i c a l a c t i v i t y i s necessary b e f o r e the body can p r e c i s e l y r e g u l a t e food intake to balance energy expenditure. Since t h i s study, others l o o k i n g at the same ques-t i o n have conducted t h e i r i n v e s t i g a t i o n s mainly i n males and p a r t i c u l a r l y i n obese s u b j e c t s . In reviewing the e f f e c t s of e x e r c i s e - t r a i n i n g on energy balance, Tremblay et a l . (1985) concluded that g e n e r a l l y s t u d i e s of t h i s nature tend to support the n o t i o n t h a t energy intake f a i l s to adapt immediately to a new regimen of p h y s i c a l a c t i v i t y . R e c e n tly the e f f e c t of i n c r e a s e d p h y s i c a l a c t i v i t y was assessed on v o l u n t a r y food i n t a k e i n f i v e non-obese, u n t r a i n e d women (Woo and Pi-Sunyer, 1985). In a h i g h l y 6 c o n t r o l l e d metabolic ward s i t u a t i o n , the women's energy i n t a k e and energy expenditure were determined d u r i n g each of three 19-day experimental p e r i o d s . T o t a l d a i l y e x p e n d i t u r e was i n c r e a s e d to 114% of the sedentary ( f i r s t ) treatment f o r the m i l d (second) e x e r c i s e p e r i o d and to 129% f o r the moderate ( t h i r d ) p e r i o d . The volun-t a r y i n t a k e s i n c r e a s e d with the in c r e a s e i n a c t i v i t y and energy balance was maintained d u r i n g each of the pe-r i o d s . These f i n d i n g s are i n c o n t r a s t to a comparable study by Woo et a l . (1982) done on obese women. These women d i d not change t h e i r food consumption i n response to d i f f e r e n t l e v e l s of a c t i v i t y . These f i n d i n g s suggest that the degree of response i n intake to a l t e r e d l e v e l s of e x e r c i s e may be i n f l u e n c e d by the s i z e of f a t s t o r e s . It i s a l s o p o s s i b l e that e x e r c i s e may have d i f f e r -ent e f f e c t s depending on i t s i n t e n s i t y and d u r a t i o n . Thus while Karvonen et a l . (1961) r e p o r t e d that lumber-jacks working e i g h t or more hours per day had double the d a i l y c a l o r i c i n take of sedentary i n d i v i d u a l s of normal weight i n c a l o r i c balance, Dempsey (1964) found that more v i g o r o u s e x e r c i s e of sh o r t e r d u r a t i o n (one hour per day) d i d not appear to st i m u l a t e the a p p e t i t e . S i n c e s t u d i e s conducted on l a b o r a t o r y animals s t r o n g l y suggest that the a p p e t i t e of female animals responds d i f f e r e n t l y to r e g u l a r l y performed e x e r c i s e than that of male animals (Nance e t . a l . , 1977; Tokuyama e t . a l . , 1982; P i t t s , 1984), sex i s an important f a c t o r to c o n s i d e r i n s t u d i e s of t h i s nature. 7 For example, c o n s i d e r a b l e evidence e x i s t s to support the hyp o t h e s i s that e x e r c i s e or p h y s i c a l t r a i n i n g r e s u l t s i n some l o s s of t o t a l body weight, a decrease i n body f a t and an i n c r e a s e i n lean body weight (Wilmore, 1983). T h i s evidence however has been d e r i v e d p r i m a r i l y from s t u d i e s using male s u b j e c t s . The r e s u l t s of i n v e s t i g a t i o n s u s i n g female s u b j e c t s have been l e s s c o n c l u s i v e . Indeed there have been few s t u d i e s using female s u b j e c t s and even fewer on normal weight women. G i r a n d o l a (1976) i n v o l v e d 20 young women i n a ten week p h y s i c a l t r a i n i n g program i n v o l v i n g two i n t e n s i t i e s of e x e r c i s e on a b i c y c l e ergometer. Eleven women t r a i n e d a t a r e l a t i v e l y high i n t e n s i t y (HI) of 840 kgm/min, 7 1/2 min/day, while nine women t r a i n e d at a lower e x e r c i s e i n t e n s i t y (LI) of 420 kgm/min, 15 min/day. Both groups e x e r c i s e d three times per week. No s i g n i f i c a n t changes i n body weight, body d e n s i t y , percent body f a t or lean body weight were found f o r the HI group. The LI group e x h i b i t e d a s i g n i f i c a n t i n c r e a s e in body d e n s i t y and s i g n i f i c a n t decreases i n percent body f a t . I t i s suggested that the LI s u b j e c t s were t r a i n i n g a e r o b i c a l l y while the HI s u b j e c t s were t r a i n i n g a n a e r o b i c a l l y f o r some p o r t i o n of each minute of work. Since a n a e r o b i c energy p r o d u c t i o n u t i l i z e s l i t t l e , i f any f a t as a f u e l , t h i s may be the reason f o r the lack of body f a t changes in the HI group. Food intake was not measured i n t h i s study. G e t c h e l l and Moore (1975) s u b j e c t e d 11 u n t r a i n e d 8 women (average age 35.5 years) to a ten week t r a i n i n g program c o n s i s t i n g of a 30 minute walking and jogging e x e r c i s e , three to four days per week. These workouts approximated a t r a i n i n g i n t e n s i t y of 75 to 85% heart r a t e maximum. A f t e r ten weeks there was no s i g n i f i c a n t weight l o s s although there was a s i g n i f i c a n t decrease i n the estimate of body f a t . The e f f e c t of seven weeks of t r a i n i n g and seven weeks of d e t r a i n i n g on the body composition of ten young women was s t u d i e d by Smith and Stransky (1976). The c o n d i t i o n i n g program c o n s i s t e d of continuous r i d i n g on a s t a t i o n a r y b i c y c l e ergometer f o r 16 minutes per day, three days per week. T r a i n i n g h e a r t r a t e averaged 73% of the maximum heart rate range d u r i n g the study. The s u b j e c t s gained a s i g n i f i c a n t amount of weight (1.4 kg) d u r i n g the t r a i n i n g p e r i o d , most of which was l o s t d u r i n g subsequent d e t r a i n i n g (1.1 kg). Lean body.mass i n c r e a s e d s i g n i f i c a n t l y (1.1 kg) f o l l o w i n g t r a i n i n g , but r e t u r n e d to near p r e t r a i n i n g l e v e l s d u r i n g d e t r a i n i n g . Percent body f a t d i d not change s i g n i f i c a n t l y d u r i n g the study. In reviewing the e f f e c t s of p h y s i c a l a c t i v i t y and n u t r i t i o n a l s t a t u s on the body composition of humans, Forbes (1985) s t r e s s e s the f a c t t h a t although e x e r c i s e and/or t r a i n i n g can augment maximum oxygen consumption, muscle s t r e n g t h , and endurance, i t has not been shown to markedly i n c r e a s e lean body mass or to markedly decrease body f a t . On the other hand lean body mass and body f a t 9 are a l t e r e d by both under- and o v e r n u t r i t i o n , and the a l t e r a t i o n s are g r e a t e r i n magnitude than those produced by changes i n p h y s i c a l a c t i v i t y (Forbes, 1982; Forbes and Welle, 1983). I t i s un f o r t u n a t e t h e r e f o r e , that none of the aforementioned s t u d i e s on p h y s i c a l e x e r c i s e have i n c l u d e d c a r e f u l m o n i t o r i n g of food i n t a k e . The e f f e c t of e x e r c i s e on food intake i n humans has yet to be f u l l y e l u c i d a t e d . The s t u d i e s reviewed showed th a t the e f f e c t of e x e r c i s e on body weight i n women i s i n c o n s i s t e n t and may w e l l depend on the s p e c i f i c type of e x e r c i s e , i t s d u r a t i o n and i n t e n s i t y . E x e r c i s e appears to lower the percent body f a t while i n c r e a s i n g the lean body mass of normal weight women although these changes have not always been c o n s i s t e n t and may again depend on the type, d u r a t i o n and i n t e n s i t y of the e x e r c i s e per-formed . 2) Animal S t u d i e s The human model s u f f e r s from lack of c o n t r o l and p r e c i s i o n and t h e r e f o r e animal models, and i n p a r t i c u l a r the r a t , have been used e x t e n s i v e l y i n s t u d i e s i n v e s t i -g a t i n g e x e r c i s e and food i n t a k e , body weight and compo-s i t i o n . While the animal model used to i n v e s t i g a t e the r e l a t i o n s h i p between e x e r c i s e and a p p e t i t e i n p a r t i c u l a r s u f f e r s from the b a s i c f a c t t h at "man i s not a r a t " , and the a p p l i c a b i l i t y of data d e r i v e d from s t u d i e s on r a t s to humans i s not w e l l e s t a b l i s h e d (Wilmore, 1983), t h i s model has provided some i n s i g h t i n t o the problem. The 10 r a t i s e s p e c i a l l y w e l l s u i t e d f o r body composition ana-l y s i s because i t s r e l a t i v e l y small body can be s u b j e c t e d to whole body a n a l y s i s . One of the f i r s t s t u d i e s i n v e s t i g a t i n g the r o l e of e x e r c i s e and food intake on body weight was that of Mayer e t . a l . (1954). When mature female r a t s accus-tomed to a sedentary e x i s t e n c e were e x e r c i s e d on a t r e a d m i l l f o r i n c r e a s i n g d u r a t i o n s , i t was found that at low d u r a t i o n s of e x e r c i s e (20 minutes to one hour), there was a s l i g h t but s i g n i f i c a n t decrease i n food i n t a k e and body weight as compared to sedentary c o n t r o l s . At d u r a t i o n s of one to s i x hours the r a t s i n c r e a s e d t h e i r food intake l i n e a r l y with the d u r a t i o n of the e x e r c i s e while m a i n t a i n i n g t h e i r body weight at c o n t r o l l e v e l s . At d u r a t i o n s of more than s i x hours the r a t s became exhausted, t h e i r food intake decreased, and they r a p i d l y l o s t weight. Ring e t . a l . (1970) s t u d i e d female F i s c h e r r a t s , 50 days o l d , doing v o l u n t a r y e x e r c i s e on a r e v o l v i n g wheel. These r a t s consumed s i g n i f i c a n t l y more food and gained weight s i g n i f i c a n t l y more q u i c k l y over ten weeks than d i d t h e i r sedentary c o n t r o l s . Whole body l i p i d and water content were not s i g n i f i c a n t l y d i f f e r e n t between the e x e r c i s e r s and sedentary c o n t r o l s . Body l e n g t h i n -c r e a s e d s i g n i f i c a n t l y more i n the a c t i v e than i n the i n a c t i v e r a t s . O s cai e t . a l . (1973) t r a i n e d six-week o l d female Wistar r a t s to swim f o r s i x c o n s e c u t i v e hours, f i v e days 1 1 per week, f o r 16 weeks. The swimmers ate approximately 46% more than the sedentary c o n t r o l s while m a i n t a i n i n g t h e i r body weight at the c o n t r o l l e v e l . Whole c a r c a s s a n a l y s i s showed f a t content to be s i g n i f i c a n t l y l e s s and l e a n body mass s i g n i f i c a n t l y g r e a t e r when compared to t h e i r sedentary c o n t r o l s . The food i n t a k e and body weight of 80-day o l d female Sprague-Dawley r a t s were s t u d i e d d u r i n g seven days of f o r c e d e x e r c i s e on a t r e a d m i l l (Nance et a l . , 1977). Workloads were g r a d u a l l y i n c r e a s e d a c r o s s the seven day t e s t p e r i o d to 1.0 mph, 60 min/day on a 18% grade. Sedentary c o n t r o l s were maintained at the same l e v e l used d u r i n g the p r e v i o u s 3-day t r a i n i n g p e r i o d (0.8 mph, 15 min/day, 0% grade). The body weights of e x e r c i s i n g r a t s were comparable to c o n t r o l s throughout the e n t i r e seven day p e r i o d although they ate s i g n i f i c a n t l y more than the c o n t r o l s on days three, f o u r , f i v e and seven of the t e s t p e r i o d . F i f t y - d a y o l d female Wistar r a t s , allowed f r e e access to a running wheel f o r 50 days, i n c r e a s e d t h e i r food i ntake as a f u n c t i o n of the amount of running but gained s i g n i f i c a n t l y l e s s weight than the sedentary c o n t r o l s (Tokuyama e t . a l . , 1982). T h i s suggested that the i n c r e a s e i n food i n t a k e was not s u f f i c i e n t to com-pensate f o r the i n c r e a s e i n energy expenditure. The body f a t contents of e x e r c i s i n g r a t s were s i g n i f i c a n t l y lower than those of sedentary animals, but no s i g n i f i -cant d i f f e r e n c e was observed i n the body water and non-1 2 f a t s o l i d contents of sedentary and e x e r c i s i n g groups. Applegate e t . a l . (1982) showed that female Osborne-Mendel r a t s , ten weeks of age, e x e r c i s e d f o r 12 days at 21.3 meters/minute on a 18% grade f o r 60 minutes per day, d i d not i n c r e a s e t h e i r food intake and t h e i r body weight was not a f f e c t e d as compared to the seden-t a r y c o n t r o l s . E x e r c i s e d i d promote a s i g n i f i c a n t i n -crease i n t o t a l body water which i s u s u a l l y i n v e r s e l y r e l a t e d to body f a t (Cox et a l . , 1985). Percent body ash and p r o t e i n were not a f f e c t e d by e x e r c i s e . Twenty female lean Zucker r a t s ran on a t r e a d m i l l for f i v e c o n s e c u t i v e days per week f o r s i x months at 20 meters/minute. T h i s l e v e l of t r a i n i n g s i g n i f i c a n t l y suppressed weight gain i n the runners as compared to u n t r a i n e d c o n t r o l s , a l t h o u g h they ate s i g n i f i c a n t l y more food (Mahle e t . a l . , 1986). Female, weanling Sprague-Dawley r a t s allowed f r e e access to a running wheel f o r s i x weeks s i g n i f i c a n t l y i n c r e a s e d t h e i r food i n t a k e by the f o u r t h week of the study while m a i n t a i n i n g s i m i l a r body weights when compared to sedentary c o n t r o l s (Barr, 1986). Thus, although the m a j o r i t y of s t u d i e s on female r a t s report that e x e r c i s e i s accompanied by an i n c r e a s e i n food intake while body weight i s maintained, these f i n d i n g s have not been c o n s i s t e n t . The s t u d i e s however do tend to agree that e x e r c i s e d female r a t s have a lower percent body f a t content than t h e i r sedentary c o n t r o l s . 1 3 B) The E f f e c t of Pregnancy and Lactation on Food Intake, Body Weight and Body Composition 1) Human Studies The p h y s i o l o g i c a l s t a t e s of pregnancy and l a c t a t i o n n e c e s s i t a t e a major m o d i f i c a t i o n of the woman's energy balance, a f f e c t i n g her energy i n t a k e , body weight and body c o m p o s i t i o n . F o l l o w i n g i s a summary of f i n d i n g s and cu r r e n t hypotheses r e g a r d i n g these e f f e c t s of pregnancy and l a c t a t i o n i n the average w e l l - n o u r i s h e d woman. ' Although the energy i n t a k e s and weight gains that support h e a l t h y pregnancies vary widely, the average, he a l t h y , pregnant woman, e a t i n g to a p p e t i t e i s expected to gain approximately 11 to 13 kg (Worthington-Roberts, 1985). S t u d i e s which have looked at the a c t u a l energy intakes of pregnant women r e v e a l that they are o f t e n l e s s than recommended (Blackburn and Calloway, 1976; Field-Zimmer and M i l e s , 1980), d e s p i t e average or great e r than average weight gains and i n f a n t s of ade-quate b i r t h w e i g h t . These f i n d i n g s may be due to methodological problems, extremely sedentary l i f e s t y l e s , p u r p o s e f u l r e s t r i c t i o n of food intake or recommendations that have been set too hi g h . These s t u d i e s however do not t e l l us whether or not we l l - n o u r i s h e d women a c t u a l l y have an i n c r e a s e i n a p p e t i t e above prepregnancy l e v e l s . The components of the weight gained in pregnancy have been e s t i m a t e d by Hytten and L e i t c h (1971), assum-ing an average g a i n of 12.5 kg, to in c l u d e the f e t u s 1 4 (3.4 kg), the p l a c e n t a (0.45 kg), amniotic f l u i d (0.9 kg), uterus (1.1 kg weight i n c r e a s e ) , b r e a s t t i s s u e (1.4 kg weight i n c r e a s e ) , blood volume (1.8 kg weight i n -crease) and maternal s t o r e s (3.5 kg). Of p a r t i c u l a r i n t e r e s t are these "maternal s t o r e s " which are b e l i e v e d to c o n s i s t p r i m a r i l y of f a t (Hytten and L e i t c h , 1971). The d e p o s i t i o n of t h i s f a t i s b e l i e v e d to begin d u r i n g the f i r s t t r i m e s t e r of pregnancy, and cease s h o r t l y a f t e r the end of the second t r i m e s t e r (Hytten and L e i t c h , 1971; Naismith, 1979). T h i s p a t t e r n i s supported by anthropometric measurements of 84 normal pregnant women by Taggart et a l . (1967) which showed a p r o g r e s s i v e i n c r e a s e i n s k i n f o l d t h i c k n e s s at seven s i t e s up to approximately 30 weeks g e s t a t i o n , a f t e r which there was no f u r t h e r change. Thus a pregnant women w i l l l a y down f a t e a r l i e r i n pregnancy when the maintenance c o s t s of e x t r a metabolism are r e l a t i v e l y s m a l l and enter the l a s t t r i m e s t e r of pregnancy, d u r i n g which time the f e t u s w i l l almost t r i p l e i t s weight, with a c o n s i d e r a b l e b u f f e r a g a i n s t poor energy intake and/or i n c r e a s e d energy e x p e n d i t u r e . However the w e l l - n o u r i s h e d women w i l l end her pregnancy with a net weight g a i n of 3 to 4 kg which i s b e l i e v e d to be depot f a t (Hytten and L e i t c h , 1971). The s t i m u l u s to f a t storage i s b e l i e v e d to be hormonal i n nature. I t has been suggested on the b a s i s of animal experiments that f a t d e p o s i t i o n r e s u l t s from the a c t i o n of progesterone (Naismith, 1979). Proges-1 5 terone i s the most abundant s t e r o i d hormone produced d u r i n g pregnancy. In women, s y n t h e s i s by the ovary i s overtaken by the p l a c e n t a by the end of the second month, and p r o d u c t i o n r i s e s s t e a d i l y u n t i l term (Csapo et a l . , 1972). The t e r m i n a t i o n of f a t d e p o s i t i o n d u r i n g the t h i r d t r i m e s t e r , d e s p i t e the c o n t i n u i n g r i s e i n progesterone s e c r e t i o n , has been a t t r i b u t e d to anta-gonism by e s t r i o l , a l s o produced by the f e t o p l a c e n t a l u n i t , the s e c r e t i o n of which r i s e s a b r u p t l y at t h i s time (Klopper and B i l l e w i c z , 1963). Such an antagonism a l -lows the f e t u s to r e d i r e c t the use of a v a i l a b l e energy from f u r t h e r i n g maternal storage to s a t i s f y i n g i t s own i n c r e a s i n g demands. Almost a l l the evidence f o r t h i s p a t t e r n of f a t d e p o s i t i o n was d e r i v e d by Naismith from s t u d i e s of w e l l nourished Western women. Whether very a c t i v e women or women l i v i n g and working i n more arduous c o n d i t i o n s s t o r e f a t while they can and then use i t l a t e r i n preg-nancy as a subsidy, whether they eat more than u s u a l , and whether they are a b l e to economize t h e i r energy output are not known. A woman who gains 11 to 13 kg durin g pregnancy may be assumed to terminate i t with an e x t r a r e s e r v e of 2 to 4 kg of body f a t , which can be used to supply energy f o r l a c t a t i o n . During a l a c t a t i o n p e r i o d of 100 days, t h i s r e s e r v e would y i e l d 200 to 300 kcal / d a y . Approximately 750 ml of milk/day i s produced, which i s e q u i v a l e n t to 570 k c a l . Since the e f f i c i e n c y of human 1 6 milk p r o d u c t i o n i s about 80%, the supplementary energy requirement f o r l a c t a t i o n i s 710 kcal/day. I f 200 to 300 kc a l comes from the women's energy s t o r e s , 450 k c a l should be s u p p l i e d by the d i e t . The recommended supple-ment f o r l a c t a t i o n i s t h e r e f o r e 450 kcal/day (Health and Welfare Canada, 1983). Recently however, s e v e r a l s t u d i e s have suggested that l a c t a t i o n performance i s not compromised by energy intakes l e s s than c u r r e n t recommendations and i s compa-t i b l e with g r a d u a l weight r e d u c t i o n (Butte et a l . , 1984; 01iva-Rasbach et a l . , 1985; Manning-Dalton and A l l e n , 1983). 2) Animal S t u d i e s Pregnancy i n r a t s i s c h a r a c t e r i z e d by i n c r e a s e d food intake and s u b s t a n t i a l weight gain ( S h i r l e y , 1984). At term, the food consumption of Sprague-Dawley r a t s i s approximately 60% g r e a t e r than that of non-pregnant c o n t r o l s ( C r i p p s and W i l l i a m s , 1975; Naismith, 1966). As i n humans, i t i s e s t a b l i s h e d that the weight of the conceptus, the i n c r e a s e i n bloo d volume, and the development of the mammary glands do not account f o r the t o t a l weight g a i n d u r i n g pregnancy. Spray (1950), N a i s -mith (1966) and Naismith et a l . (1982) have shown that part of t h i s a d d i t i o n a l i n c r e a s e i n weight, o f t e n r e -f e r r e d to as the "maternal s t o r e s " , can be accounted f o r by f a t d e p o s i t i o n i n the r a t du r i n g pregnancy. From analyses of the bodies of r a t s at d i f f e r e n t stages of 1 7 g e s t a t i o n , Naismith (1966) concluded that the changes in the composition of the maternal body occur i n two phases. During the f i r s t phase, a r e s e r v e of p r o t e i n and f a t i s b u i l t up at a time when c o m p e t i t i o n from the f e t u s e s i s minimal. During the second phase, the p e r i o d of r a p i d f e t a l growth, p r o t e i n reserves are c a t a b o l i z e d and l i p i d s t o r e s i n c r e a s e no f u r t h e r . At p a r t u r i t i o n , Spray (1950) and Naismith (1966) found an i n c r e a s e i n the number of grams of c a r c a s s f a t , of approximately 40%, as compared to v i r g i n c o n t r o l s . However t h i s i n -crease of c a r c a s s f a t was accompanied by a 10 to 30% i n c r e a s e i n t o t a l body weight thereby r e d u c i n g the per-cent c a r c a s s f a t i n c r e a s e to 30 to 10%. N e i t h e r study commented on the s t a t i s t i c a l s i g n i f i c a n c e of the ob-served percent c a r c a s s f a t i n c r e a s e s . Kanto and Clawson (1980) examined the body composition of r a t s two days a f t e r p a r t u r i t i o n and compared i t to nonpregnant age c o n t r o l s . Except f o r a s i g n i f i c a n t l y lower percent c a r c a s s p r o t e i n i n the pregnant r a t s , the percent c a r c a s s f a t , water and ash were not s i g n i f i c a n t l y d i f f e r e n t between groups. In g e n e r a l , d u r i n g l a c t a t i o n , food consumption i n c r e a s e s d r a m a t i c a l l y , c a r c a s s f a t i s c a t a b o l i z e d and body weight changes more sl o w l y . Spray (1950) found that by day 15 of l a c t a t i o n the body weight of r a t dams had decreased 20% from that at p a r t u r i t i o n . Of t h i s l o s s i n body weight 76% was a s s o c i a t e d with l o s s of c a r c a s s f a t . The remainder was accounted f o r by a 14% 18 decrease i n c a r c a s s water and a 10% decrease i n c a r c a s s p r o t e i n . Naismith et a l . (1982) found that a f t e r 14 days of l a c t a t i o n the r a t dams had l o s t no body p r o t e i n but that 60% of the t o t a l c a r c a s s f a t had been mobi-l i z e d , d e s p i t e the marked i n c r e a s e i n food i n t a k e . Food consumption i n l a c t a t i n g dams peaks around day 14 post-partum at a l e v e l two to three times that of non-preg-nant, n o n - l a c t a t i n g r a t s ( C r i p p s and W i l l i a m s , 1975; S h i r l e y , 1984). These s t u d i e s a l s o found a gradual i n c r e a s e i n weight duri n g the l a c t a t i o n p e r i o d in con-t r a s t with the 20% decrease at day 15 of l a c t a t i o n noted by Spray (1950). Kanto and Clawson (1980) found that t h e i r l a c t a t i n g r a t s l o s t weight d u r i n g the three week l a c t a t i o n p e r i o d . At t h i s time c a r c a s s a n a l y s i s r e v e a l e d a n o n s i g n i f i c a n t i n c r e a s e i n both percent water and p r o t e i n , and a s i g n i f i c a n t decrease i n percent f a t when compared to n o n - l a c t a t i n g age c o n t r o l s . Carcass ash d i d not change between groups. A comparison of l a c t a t i n g r a t s to those an a l y s e d at p a r t u r i t i o n , showed that l a c t a t i o n caused a s i g n i f i c a n t decrease i n percent c a r c a s s f a t and a s i g n i f i c a n t decrease i n percent water and p r o t e i n . C) The E f f e c t of E x e r c i s e d u r i n g Pregnancy and L a c t a t i o n on Food Intake, Body Weight and Body Composition 1) Human St u d i e s Working muscles can i n c r e a s e energy requirements d r a s t i c a l l y d u r i n g e x e r c i s e . S i m i l a r l y , pregnancy i n -19 c r e a s e s energy requirements as the f e t u s grows and maternal t i s s u e s and reserves expand. To what extent the i n c r e a s e d demands of pregnancy might compete with those of e x e r c i s e i s not known ( L o t g e r i n g e t . a l . , 1985). D i f f e r e n c e s i n age, body weight, body composi-t i o n , p h y s i c a l c o n d i t i o n , m o t i v a t i o n and e x e r c i s e r e g i -men w i l l r e s u l t i n d i f f e r i n g responses to e x e r c i s e i n any i n d i v i d u a l . In the pregnant i n d i v i d u a l s e v e r a l of these f a c t o r s , i n p a r t i c u l a r body weight and body compo-s i t i o n , change simultaneously (Hytten and L e i t c h , 1971). Because so many v a r i a b l e s a f f e c t the responses to both pregnancy and e x e r c i s e , very few w e l l - c o n t r o l l e d s t u d i e s on the s u b j e c t of e x e r c i s e i n pregnancy can be found i n the l i t e r a t u r e ( L o t g e r i n g e t . a l . , 1985). Even fewer s t u d i e s have examined the e f f e c t of e x e r c i s e i n preg-nancy on food i n t a k e , body weight and body composition. To date the e f f e c t of e x e r c i s e throughout pregnancy and l a c t a t i o n on these v a r i a b l e s and a l s o on l a c t a t i o n per-formance has not been adequately addressed i n w e l l -nourished women. In the f o l l o w i n g study data were examined a c c o r d i n g to the i n i t i a l f i t n e s s l e v e l c l a s s i f i c a t i o n of pregnant women i n order to gain some understanding concerning the p o s s i b l e e f f e c t of f i t n e s s (not e x e r c i s e per se) on energy i n t a k e , body weight and body composition i n these women. Dib b l e e and Graham (1983) c l a s s i f i e d 16 p r i m i -g r a v i d a e as f i t or u n f i t using a f i t n e s s t e s t . None of the s u b j e c t s ( e i g h t per group) was a c t u a l l y i n v o l v e d i n 20 s p o r t s or organized f i t n e s s c l a s s e s . C a l o r i c intake ( u s i n g three day food r e c o r d s ) , body weight and percent body f a t (measured a n t h r o p o m e t r i c a l l y ) , were measured once each t r i m e s t e r and four weeks postpartum. The energy i n t a k e s d i d not d i f f e r over time or between the two groups. The mean weight g a i n of 14.7 kg du r i n g pregnancy d i d not d i f f e r between groups, nor d i d postpartum weights. However at a l l stages of pregnancy and postpartum the u n f i t group had a s i g n i f i c a n t l y g r e a t e r percent body f a t than the f i t group. I t should be noted that seven of the f i t , and onl y three of the u n f i t mothers b r e a s t f e d t h e i r i n f a n t s , a f a c t o r which may have c o n t r i b u t e d t o the lower percent body f a t of the f i t mothers postpartum. Since neonatal weights were not d i f f e r e n t , the f i t mothers had l e s s f a t , and the q u a n t i t y and q u a l i t y of energy i n t a k e d i d not d i f f e r between groups, the authors suggest that the u n f i t women had lower l e v e l s of a c t i v i t y and/or b a s a l metabolic r a t e s . I t i s noteworthy that both groups of women had adequate weight gains d u r i n g pregnancy, and i n f a n t s of adequate b i r t h w e i g h t s , although t h e i r energy in t a k e s (8,820 kJ) were below the recommended 10,040 kJ. A c t i -v i t y l e v e l d u r i n g t h i s study was not ass e s s e d . T h i s study was l i m i t e d by a r e l a t i v e l y small sample s i z e and by a la c k of prepregnancy c o n t r o l d a ta. The recommended a d d i t i o n a l energy f o r pregnancy p r o v i d e s only f o r i n c r e a s e d b a s a l metabolic needs. At present these recommendations i n c l u d e no a d d i t i o n f o r 21 the i n c r e a s e d energy cost of a c t i v i t y because i t i s assumed that pregnant women decrease t h e i r l e v e l of a c t i v i t y d u r i n g pregnancy (Health and Welfare Canada, 1983). However surveys of the a c t i v i t y p a t t e r n s of pregnant women do not show t h a t they become more seden-t a r y (Blackburn and Calloway, 1976). Instead they tend to maintain the same p a t t e r n of a c t i v i t y throughout pregnancy, and the energy r e q u i r e d f o r a c t i v i t i e s i n v o l -v i n g movement of the body, e.g. walking, i s g r e a t e r l a t e i n pregnancy than i n midpregnancy (Nagy and King, 1983). Although i t might be assumed t h a t very a c t i v e pregnant and l a c t a t i n g women would r e q u i r e an energy intake above th a t p r e s e n t l y recommended f o r t y p i c a l sedentary women, data are l a c k i n g on the v o l u n t a r y intake of a c t i v e pregnant and l a c t a t i n g women. 2) Animal Studies Although the m a j o r i t y of animal s t u d i e s on the e f f e c t of e x e r c i s e d u r i n g pregnancy have looked more s p e c i f i c a l l y at f e t a l outcome, some data on food i n t a k e , body weight and body composition have emerged. T r a i n e d Sprague-Dawley r a t s which ran durin g preg-nancy on a t r e a d m i l l at 30 m/min on a 18% i n c l i n e (80% V02 max) f o r one or two hours per day were found to gain weight more slowly than pregnant sedentary c o n t r o l s ( B a g n a l l et a l , 1983; Mottola et a l , 1984). The authors suggest that e x e r c i s i n g dams d e p o s i t e d l e s s f a t d u r i n g pregnancy s i n c e the number of pups per l i t t e r and aver-22 age pup b i r t h w e i g h t s d i d not d i f f e r between the two groups. Body composition however was not measured. Since food intake was not measured i t i s not known whether the d i f f e r e n c e i n weight gain was a f f e c t e d by c a l o r i c i n t a k e . U n t r a i n e d Wistar r a t s e x e r c i s e d on a t r e a d m i l l at 14 to 16 m/min f o r one hour per day d u r i n g pregnancy had s i m i l a r weight gains when compared to sedentary c o n t r o l s ( P a r i z k o v a and Petrasek, 1978). Terada (1974) looked at the e f f e c t of t r a i n i n g b efore pregnancy on f e t a l development i n female 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. Groups c o n s i s t e d of females t r a i n e d before pregnancy and e x e r c i s e d d u r i n g midpregnancy (9th to 16th day) (TE), females t r a i n e d but not e x e r c i s e d d u r i n g pregnancy (TC), females only exer-c i s e d (CE) and females n e i t h e r t r a i n e d nor e x e r c i s e d (CC). T r a i n i n g c o n s i s t e d of running on a t r e a d m i l l at 15 m/min, 30 min/day, s i x days/week, f o r four weeks, while mice e x e r c i s e d d u r i n g midpregnancy ran at the same speed 30 min/day. Maternal body weights on day one of pregnancy i n the TE and TC groups were s i g n i f i c a n t l y lower than those i n the CE and CC groups. Near term TE mice weighed l e s s than TC mice while CE mice weighed l e s s than CC mice. Food i n t a k e was not s i g n i f i c a n t l y d i f f e r e n t between groups. Nelson et a l . ( l 9 8 3 ) , u s i n g guinea p i g s , found that t o t a l maternal body weight c o r r e c t e d f o r l i t t e r s i z e , decreased s i g n i f i c a n t l y with i n c r e a s i n g d u r a t i o n of run-23 ning time on a t r e a d m i l l at 9.7 m/min up a 12% i n c l i n e . I t was c a l c u l a t e d that the maternal body, separate from the f e t u s e s and p l a c e n t a s , grew at a slower r a t e d u r i n g g e s t a t i o n i n the e x e r c i s e groups than i n the sedentary group. Whether t h i s lowered r a t e of growth o c c u r r e d i n one or more body components i s not known s i n c e c a r c a s s composition a n a l y s i s was not done. Food i n t a k e was not measured in t h i s study. In a recent a b s t r a c t , Savard et a l (1985) are the f i r s t to report on the e f f e c t of strenuous e x e r c i s e d u r i n g pregnancy on body c o m p o s i t i o n . T r a i n e d l e a n Zucker r a t s swam three hours per day, s i x days per week. In g u i n a l adipose t i s s u e weight and c e l l s i z e i n c r e a s e d i n sedentary c o n t r o l s but by day 21 of g e s t a t i o n these values were s i g n i f i c a n t l y lower i n the e x e r c i s i n g preg-nant r a t s than i n the sedentary pregnant r a t s . Para-m e t r i a l adipose t i s s u e weight and c e l l s i z e i n c r e a s e d i n sedentary pregnant r a t s but remained at nonpregnant c o n t r o l l e v e l s i n the e x e r c i s i n g pregnant r a t s . Food intake and body weights d i d not d i f f e r between the t r a i n e d and sedentary pregnant r a t s . Since b i r t h -weights, pup number and pup c a r c a s s composition d i d not d i f f e r between the two groups, the authors concluded that intense e x e r c i s e performed d u r i n g pregnancy r e s u l t -ed i n decreased a d i p o s i t y without a f f e c t i n g f e t a l d e v e l -opment in r a t s . Thus, s t u d i e s of animals e x e r c i s i n g d u r i n g preg-nancy have g e n e r a l l y found no change in food i n t a k e and 24 e i t h e r no change or a decrease i n maternal body weight when compared to sedentary c o n t r o l s . In the s i n g l e study l o o k i n g at the e f f e c t of e x e r c i s e during pregnancy on body composition, there was a tendency to a decrease i n body f a t . The few s t u d i e s which have attempted to examine 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 are presented below. Karasawa et a l (1981) documented the e f f e c t s of vo l u n t a r y e x e r c i s e d u r i n g pregnancy and l a c t a t i o n on body composition i n mice. V o l u n t a r y e x e r c i s e on a treadwheel g r a d u a l l y decreased a f t e r mating and i n l a t e pregnancy running a c t i v i t y decreased markedly and was maintained at t h i s lower l e v e l d u r i n g l a c t a t i o n . Body weight and body f a t of dams with access to the t r e a d -wheel were not s i g n i f i c a n t l y d i f f e r e n t from those of sedentary c o n t r o l s (who had no access to a treadwheel) a f t e r 14 days of l a c t a t i o n . I t should be emphasized that the a c t i v i t y l e v e l s of the dams durin g l a c t a t i o n were very low because of the time spent s u c k l i n g the pups. A recent a b s t r a c t r e p o r t e d the e f f e c t of strenuous a e r o b i c e x e r c i s e d u r i n g pregnancy and l a c t a t i o n i n Wis-t a r r a t s (Lederman et a l . 1985). Rats were t r a i n e d to swim f o r two hours/day, f i v e days/week with a three percent t a i l weight. By day 15 of l a c t a t i o n ad l i b i t u m fed e x e r c i s i n g r a t s weighed s i x percent l e s s than seden-t a r y c o n t r o l s . E x e r c i s e r s a l s o had a greater food i n -take than c o n t r o l s throughout the study, although the 25 intake d i f f e r e n c e narrowed d u r i n g l a c t a t i o n . Whether or not these d i f f e r e n c e s were s t a t i s t i c a l l y s i g n i f i c a n t i s not known. Although maternal body composition was ana-l y z e d i n t h i s study, the r e p o r t i s not c l e a r as to whether e x e r c i s e had an e f f e c t . D) The E f f e c t of E x e r c i s e d u r i n g Pregnancy and L a c t a t i o n on Pregnancy and F e t a l Outcome, and L a c t a t i o n Performance 1) Human S t u d i e s U l t i m a t e l y , i t i s the i n f l u e n c e of maternal exer-c i s e on the course of pregnancy, labor and f e t a l outcome which i s of primary concern. E x e r c i s e i s but a s i n g l e f a c t o r that may have an e f f e c t on pregnancy and f e t a l outcome. I t s e f f e c t c o u l d e a s i l y be obscured by the normal wide v a r i a t i o n i n these outcomes as a r e s u l t of a multitude of v a r i a b l e s , i n c l u d i n g g e n e t i c and s o c i o e c o -nomic f a c t o r s , environmental f a c t o r s , n u t r i t i o n , and o b s t e t r i c a l c a r e , to name j u s t a few ( L o t g e r i n g et a l . , 1985). Thus l a r g e , w e l l c o n t r o l l e d p r o s p e c t i v e e p i d e -m i o l o g i c a l s t u d i e s are needed to he l p answer the ques-t i o n of whether p h y s i c a l a c t i v i t y can a f f e c t pregnancy and f e t a l outcome. No such study has been conducted to date, however some r e t r o s p e c t i v e and s m a l l e r p r o s p e c t i v e s t u d i e s have been performed. Six t y - s e v e n women who had been jogging f o r an aver-age of 3.8 years b e f o r e t h e i r pregnancy and ran an average of 470 m i l e s d u r i n g t h e i r pregnancy were s t u d i e d r e t r o s p e c t i v e l y by use of a q u e s t i o n n a i r e ( J a r r e t t and 26 S p e l l a c y , 1983). No c o r r e l a t i o n was found between the number of m i l e s ran d u r i n g the pregnancy, or i n the t h i r d t r i m e s t e r alone, and e i t h e r i n f a n t b i r t h w e i g h t or g e s t a t i o n a l age. Dale et a l . (1982) a l s o looked at the e f f e c t of running d u r i n g pregnancy on f e t a l outcome u s i n g both r e t r o s p e c t i v e and p r o s p e c t i v e data which were compared to data from n o n e x e r c i s i n g pregnant c o n t r o l s . The runners had run an average of four years p r i o r to the pregnancy. No s i g n i f i c a n t d i f f e r e n c e s between the groups with regard to b i r t h w e i g h t or o b s t e t r i c a l or neonatal c o m p l i c a t i o n r a t e s were found. In a small p r o s p e c t i v e study C o l l i n g s et a l . (1983) s t u d i e d 20 pregnant women du r i n g the second and t h i r d t r i m e s t e r s . Twelve of the women p a r t i c i p a t e d i n an ae r o b i c e x e r c i s e program which was i n d i v i d u a l l y p r e s -c r i b e d i n order to o b t a i n a t r a i n i n g i n t e n s i t y a p p r o x i -mating 65-70% of maximum oxygen consumption (V02 max) and a t r a i n i n g heart r a t e averaging 152 beats per minute. E i g h t women served as the c o n t r o l group. A comparison of pregnancy outcome of the two groups showed no d i f f e r e n c e s i n l a b o r d u r a t i o n , Apgar s c o r e s , or f e t a l growth. Using i n t e r v i e w data, Clapp and D i c k s t e i n (1984) p r o s p e c t i v e l y s t u d i e d the e f f e c t s of e x e r c i s e (running, a e r o b i c dance and c r o s s - c o u t r y s k i i n g ) on 336 pregnant women. The women were d i v i d e d i n t o three groups on the b a s i s of e x e r c i s e performance p r i o r to and d u r i n g preg-27 nancy. I t was found that women who c o n t i n u e d e x e r c i s i n g at or near p r e c o n c e p t u a l l e v e l s throughout the pregnancy d e l i v e r e d e a r l i e r (an average of e i g h t d a y s ) , and had l i g h t e r weight o f f s p r i n g (an average of 500g) than those who stopped e x e r c i s i n g p r i o r to the twenty-eighth week of g e s t a t i o n . The l a t t e r group d e l i v e r e d i n f a n t s of s i m i l a r b i r t h w e i g h t at a s i m i l a r g e s t a t i o n a l age as the sedentary c o n t r o l s . Kaufman and H a l l (1985) r e p o r t e d the e f f e c t s of low, medium and high i n t e n s i t y p h y s i c a l c o n d i t i o n i n g programs as compared to c o n t r o l s with no p h y s i c a l c o n d i t i o n i n g , on the pregnancy and f e t a l outcome of 860 women. Workouts were i n d i v i d u a l i z e d a c c o r d i n g to f i t n e s s s t a t u s and c o n s i s t e d of a walk-jog warmup, Nau-t i l u s e x e r c i s e s and one to two m i l e s on a b i c y c l e ergometer at 300 kpm. B i r t h w e i g h t s were p r o g r e s s i v e l y higher i n the low, medium and high groups over the c o n t r o l group (p<0.06). The i n c i d e n c e r a t e of Caesarean s e c t i o n was 6.7% i n the high group as compared to 28.1% in the c o n t r o l group. Kulpa et a l . (1986) in a two and a h a l f year pros-p e c t i v e study looked at the e f f e c t of moderate maternal e x e r c i s e i n 134 low r i s k s u b j e c t s given i n d i v i d u a l exer-c i s e p r e s c r i p t i o n s based on a t a r g e t heart r a t e of 75% V02 max. The s u b j e c t s were randomized i n t o c o n t r o l (C) and e x e r c i s e (E) groups, d i f f e r i n g only i n the frequency of a e r o b i c e x e r c i s e . I t was found that p r i m i p a r a s i n the E group had shortened l a b o r , a c t i v e phase and second 28 stage when compared to the p r i m i p a r a s i n the C group. These f i n d i n g s are comparable to those i n a s m a l l e r p r o s p e c t i v e study (Wong and McKenzie, 1985) i n which ten p r i v i g r a v i d 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 (n=4) or u n t r a i n e d (n=6), based on t h e i r heart r a t e response to submaximal c y c l e ergometry t e s t i n g . The u n t r a i n e d sub-j e c t s had a s i g n i f i c a n t l y longer second stage and a longer t h i r d stage when compared to the t r a i n e d group. T h i s r e d u c t i o n i n time spent i n the a c t i v e stage of l a b o r i n the t r a i n e d group was f e l t to r e f l e c t t h e i r improved f i t n e s s l e v e l . I t appears from these s t u d i e s that most e x e r c i s e regimens d u r i n g pregnancy do not have a d e t r i m e n t a l e f f e c t on pregnancy or f e t a l outcome and may even be b e n e f i c i a l . I t should be noted that there have been no s t u d i e s to date r e p o r t i n g on the e f f e c t s 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 performance i n humans . 2) Animal S t u d i e s D i f f e r i n g f e t a l outcomes have been r e p o r t e d f o r e x e r c i s i n g pregnant animals depending on the s p e c i e s and e x p e r i m e n t a l p r o t o c o l s . In the study by Terada (1974) d e s c r i b e d e a r l i e r , 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 l i t t e r s i z e s or i n the number of f e t a l malformations were found among the groups. Mean f e t a l weight of the mice t r a i n e d b e f o r e pregnancy and e x e r c i s e d d u r i n g midpregnancy (TE) was s i g n i f i c a n t l y lower than those of the mice t r a i n e d but not e x e r c i s e d 29 d u r i n g pregnancy (TC); and the mean f e t a l weight of the mice which were e x e r c i s e d but not t r a i n e d (CE) was s i g n i f i c a n t l y lower when compared with the group that was n e i t h e r t r a i n e d nor e x e r c i s e d (CC), suggest i n g that e x e r c i s e p r i o r to or durin g pregnancy can a f f e c t f e t a l weight. The TE group had a lower f e t a l m o r t a l i t y r a t e than the CE group suggesting t h a t t r a i n i n g p r i o r to pregnancy i s advantageous to e x e r c i s i n g d u r i n g preg-nancy . M aternal e x e r c i s e d u r i n g pregnancy was a l s o found to be d e t r i m e n t a l to f e t a l outcome i n guinea p i g s ( N e l -son et a l . , 1983). Pregnant guinea p i g s were e x e r c i s e d on a t r e a d m i l l at 9.7 meters per minute on a 6.5% grade for 0, 15, 30, 45 or 60 minutes per day f i v e days per week. No e f f e c t on l i t t e r s i z e was observed although f e t a l weights were s i g n i f i c a n t l y reduced when the mothers were e x e r c i s e d f o r 45 or 60 minutes per day. In a d d i t i o n , p l a c e n t a l weight per kilogram of f e t a l weight was s i g n i f i c a n t l y reduced at a l l e x e r c i s e l e v e l s when compared to c o n t r o l s . T h i s decrease i n p l a c e n t a l weight, al o n g with the o b s e r v a t i o n that the 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 per kilogram of p l a c e n t a l weight a l s o decreased with i n c r e a s i n g maternal e x e r c i s e l e v e l , suggests t h a t the f e t u s might be compromised by a small e r p l a c e n t a with l e s s d i f f u s i n g c a p a c i t y per u n i t mass of t i s s u e . Wilson and G i s o l f i (1980) s t u d i e d Sprague-Dawley r a t s who e x e r c i s e d before pregnancy (TN), before and 30 d u r i n g pregnancy (TT), during pregnancy on l y (NT), and r a t s who d i d not e x e r c i s e at a l l (C). No d i f f e r e n c e s between groups were found i n l i t t e r s i z e s , body dimen-s i o n s , or organ weights of the o f f s p r i n g . The TT r a t s had a s i g n i f i c a n t l y higher number of progeny deaths than the other groups i n the f i r s t 28 days of l i f e . The authors suggest that t h i s l a t t e r f i n d i n g might have been a t t r i b u t a b l e t o : i ) low b i r t h w e i g h t , a l t h o u g h the pups were not weighed at b i r t h ; i i ) p r e m a t u r i t y , although the exact date of conception was not determined i n the mothers; i i i ) unknown e f f e c t of shock avoidance t e c h n i -ques used to f o r c e the r a t s to e x e r c i s e ; or i v ) maternal n e g l e c t or c a n n i b a l i s m , both of which were r e p o r t e d l y observed but were not c o n t r o l l e d f o r i n the study. P a r i z k o v a and Petrasek (1978) found no s i g n i f i c a n t d i f f e r e n c e between l i t t e r weights of female Wistar r a t s e x e r c i s e d f o r one hour per day at a speed of 14-16 meters per minute (considered to be m i l d a e r o b i c exer-c i s e ) and t h e i r sedentary c o n t r o l s . A f i n a l group of s t u d i e s i n v o l v e d female Sprague-Dawley r a t s a c c l i m a t i z e d to run on a t r e a d m i l l at 20 meters per minute (Mottola et a l , 1983) or 30 meters per minute ( B a g n a l l et a l , 1983; M o t t o l a et a l , 1984; Motto-l a et a l . , 1986) f o r one or two hours per day, f i v e days per week on a 18% i n c l i n e before pregnancy. These r a t s were then d i v i d e d i n t o two groups and mated. One group c o n t i n u e d to run at the t r a i n i n g l e v e l (PE) while the other remained sedentary (PC) throughout g e s t a t i o n . 31 These v a r y i n g i n t e n s i t i e s of a e r o b i c e x e r c i s e , ranging from m i l d to strenuous, had no e f f e c t on l i t t e r number or pup b i r t h w e i g h t when compared to the PC group. Fur-ther i n v e s t i g a t i o n s demonstrated no s i g n i f i c a n t d i f f e r -ences between groups i n the development of the f e t a l diaphragm muscle (Mottola et a l , 1983); on pup organ weights (Mottola et a l , 1984); or on f e t a l number per l i t t e r , f e t a l weight, f e t a l l e n g t h or p l a c e n t a l weight. There were a l s o no d i f f e r e n c e s between the groups with regards to f e t a l p o s i t i o n w i t h i n the u t e r i n e horns and f e t a l a b n o r m a l i t i e s on day 20 of g e s t a t i o n (Mottola et a l , 1986). These s t u d i e s suggest that whether or not pregnant animals are t r a i n e d before pregnancy may a f f e c t f e t a l outcome when e x e r c i s e d d u r i n g pregnancy, with t r a i n i n g appearing to have a p r o t e c t i v e e f f e c t . More s p e c i f i c a l l y , however, s t u d i e s done on Sprague-Dawley r a t s suggest that m i l d to strenuous e x e r c i s e d u r i n g pregnancy does not a f f e c t f e t a l outcome. In the only r e p o r t e d study of the e f f e c t of e x e r c i s e d u r i n g pregnancy and l a c t a t i o n on l a c t a t i o n performance, the mean pup weight and t o t a l l i t t e r weight of ad l i b i t u m fed Wistar r a t s e x e r c i s e d d u r i n g pregnancy and l a c t a t i o n were 14% lower on day 15 of l a c t a t i o n than i n sedentary c o n t r o l s (Lederman et a l . , 1985). Although milk y i e l d , as measured by pup and dam weighing a f t e r f e e d i n g , were not found to d i f f e r between these groups, milk l a c t o s e was lower i n e x e r c i s e d r a t s (Treadway and 32 Lederman, 1985). E) Summary In summary i t can be s a i d t h a t the e f f e c t of e x e r c i s e d u r i n g pregnany and l a c t a t i o n on food i n t a k e , body weight and body composition i n humans has not been adequately e x p l o r e d . Whether or not the f a t r e s e r v e s which are thought to accumulate under hormonal c o n t r o l d u r i n g pregnancy would be reduced i n those p a r t i c i p a t i n g i n strenuous a e r o b i c e x e r c i s e regimens at t h i s time has not been determined. If indeed these f a t s t o r e s do s u b s i d i z e the energy cost of l a c t a t i o n , i t i s not known to what extent energy intake c o u l d compensate f o r reduced s t o r e s i n m a i n t a i n i n g adequate l a c t a t i o n performance. E x e r c i s e tends to cause female r a t s to i n c r e a s e t h e i r food i n t a k e . The s t a t e s of pregnancy and l a c t a t i o n a l s o cause an i n c r e a s e i n food i n t a k e . Whether or not these e f f e c t s are a d d i t i v e i n e x e r c i s i n g pregnant and l a c t a t i n g r a t s has not been shown. Although e x e r c i s i n g female r a t s tend to maintain t h e i r body weights at c o n t r o l l e v e l s , these f i n d i n g s are not c o n s i s t e n t . I t i s w e l l documented however that e x e r c i s e causes a decrease i n body f a t and an i n c r e a s e i n lean body mass. Pregnancy, on the other hand, i s accompanied by an i n c r e a s e i n body weight. Part of t h i s weight gain i s due to an i n c r e a s e i n body f a t or "mater-33 n a l s t o r e s " . Although the m a j o r i t y of s t u d i e s i n v e s t i -g a t i n g the e f f e c t of e x e r c i s e d u r i n g pregnancy have been concerned with f e t a l outcome, lowered maternal body weight gains have g e n e r a l l y been r e p o r t e d . Although i t has been suggested that t h i s lowered weight gain i s due to a r e d u c t i o n i n body f a t d e p o s i t i o n , as would be the expected e f f e c t of e x e r c i s e , body composition a n a l y s i s has yet to be performed to c o n f i r m t h i s assumption. Very few s t u d i e s to date have examined the e f f e c t of e x e r c i s e d u r i n g pregnancy and l a c t a t i o n on l a c t a t i o n performance. T h i s i s of i n t e r e s t s i n c e maternal f a t s t o r e s are thought to c o n t r i b u t e t o the energy cost of l a c t a t i o n . Both human and animal s t u d i e s have suggested that e x e r c i s e d u r i n g pregnancy has l i t t l e or no e f f e c t on pregnancy or f e t a l outcome i n t r a i n e d i n d i v i d u a l s . T h i s e f f e c t may even be p o s i t i v e . U n t r a i n e d animals f o r c e d to e x e r c i s e d u r i n g pregnancy, however, were found to have reduced l i t t e r weights or other evidence of compromise. 34 CHAPTER III EXPERIMENTAL DESIGN AND METHODOLOGY A) Experimental Design The experiment was a m o d i f i e d 2*2*3 f a c t o r i a l de-si g n which i s summarized i n F i g u r e 1. The f i r s t f a c t o r , " a c t i v i t y " , c o n s i s t e d of two l e v e l s , e x e r c i s e (E) and sedentary ( S ) . The female r a t s were evenly d i v i d e d between these two l e v e l s . The e x e r c i s i n g r a t s ran on a t r e a d m i l l while the sedentary ones followed a normal l a b o r a t o r y r o u t i n e . The second f a c t o r , "mated" a l s o c o n s i s t e d of two l e v e l s , mated (M) and v i r g i n (V). The t h i r d f a c t o r , "stage", c o n s i s t e d of three l e v e l s . Each of the three l e v e l s , t r a i n i n g ( T ) , pregnancy (P) and l a c t a t i o n ( L ) , d e s i g n a t e time p e r i o d s i n the e x p e r i -mental p r o t o c o l (see F i g u r e 2 ) . Rats were terminated at the end of these time p e r i o d s . The end of the t r a i n i n g p e r i o d was taken to be the time of mating of the mated animals; the time of p a r t u r i t i o n ( w i t h i n 24 hours) pro-v i d e d a n a t u r a l end f o r the pregnancy p e r i o d ; and the l a c t a t i o n p e r i o d ended 14 days a f t e r d e l i v e r y . Due to the f a c t o r i a l nature of the experimental design, EM, EV, SM and SV r a t s were a l l f u r t h e r d i v i d e d a c c o r d i n g to t h e i r stage, or time of t e r m i n a t i o n . Hence the l e v e l l a b e l s of T, P and L do not n e c e s s a r i l y imply that the r a t s so c l a s s i f i e d e i t h e r t r a i n e d ; were pregnant or l a c t a t e d . Rats, f o r i n s t a n c e , i n the pregnancy l e v e l 35 FIGURE 1 VIRGIN FEMALE SPRAGUE DAWLEY RATS (N=80) EXERCISING (E) SEDENTARY (S) (N=40) (N=40) VIRGIN (V) MATED (M) VIRGIN (V) MATED (M) (N=24) (N=16) (N=24) (N=16) TRAINING CO PREGNANCY (P) LACTATION (L) PREGNANCY (P) LACTATION (L) TRAINING (T) PREGNANCY (P) LACTATION (L) PREGNANCY (P) LACTATION (L) (N-8) (N-8) (N-8) (N-8) (N-8) (N-8) (N-8) (N-8) (N-8) (N-8) Diagrammatic representation of the modified 2X2X3 factorial experimental design. FIGURE 2 ACCLIMATIZATION TRAINING MATING (1-8 days) PREGNANCY LACTATION •A CO WEEK 0 Randomize  Rats Into  Groups Train on Treadmill EVT EVP EVL EMP EML 0 Terminate EVT SVT Mate EMP SMP EML SML (PARTURITION) Terminate EVP EMP SVP SMP (LACTATION DAY 14) Milk EML SML Terminate EVL EML SVL SML Experimental protocol which were v i r g i n served as age c o n t r o l s f o r the preg-nancy time p e r i o d . In f a c t , a l l v i r g i n r a t s were u t i l i z e d as age c o n t r o l s f o r the three time p e r i o d s i n the experiment. There would have been no d i f f e r e n c e between EMT and EVT r a t s , and between SMT and SVT r a t s , s i n c e they were te r m i n a t e d d u r i n g the mating p e r i o d without having a c t u a l l y mated. For t h i s reason the f a c t o r i a l design was m o d i f i e d to combine these four groups i n t o an ET and an ST group, reducing the t o t a l number of r a t s i n the experiment. Because of the l i m i t e d number of animals which c o u l d be e x e r c i s e d per day, two r e p e t i t i o n s of the experiment were performed. B) A n i m a l s One hundred and twenty-nine v i r g i n female Sprague-Dawley r a t s , weighing between 170 and 190 grams, were obtained from the C h a r l e s River Breeding L a b o r a t o r i e s , Quebec. F i f t y - s e v e n r a t s were ordered f o r the f i r s t run of the experiment and seventy-two f o r the second run. On a r r i v a l they were housed i n groups i n p l a s t i c cages with ground corn cob ( S a n - i - c e l ) bedding and a wire g r i d top. Two days l a t e r the r a t s were randomized i n t o the ten experimental subgroups and housed i n d i v i d u a l l y i n s t a i n l e s s s t e e l screen bottom cages. During the a d j u s t -ment p e r i o d , a t o t a l of f i v e days, the animals were a c c l i m a t i z e d to an i n v e r t e d 12-hour on, 12-hour o f f l i g h t c y c l e (with l i g h t s on at 1:00 pm), and to a room 38 temperature of 21°C. During the experiment pregnant r a t s were p l a c e d i n i n d i v i d u a l p l a s t i c cages with S a n - i - c e l bedding on day nineteen of pregnancy where they remained u n t i l they were te r m i n a t e d . C) Diet During the adjustment p e r i o d and throughout the experiment, a l l animals were given ad l i b i t u m a ccess to ground, stand a r d l a b o r a t o r y chow (Purina Rat Chow) and f r e s h water, except d u r i n g the e x e r c i s e p e r i o d , as d e s c r i b e d below. The ground food was c o n t a i n e d i n a metal cup t i g h t l y covered with a l i d having a 3 cm diameter opening i n order to minimize s p i l l a g e . D) Experimental Procedures 1) Exercise A f t e r the adjustment p e r i o d , the r a t s a s s i g n e d to e x e r c i s i n g groups were t r a i n e d over a p e r i o d of 3 weeks, 6 days per week, to run on a t r e a d m i l l at a speed of 30 meters per minute on a 0% grade f o r 2 c o n s e c u t i v e hours per day (Table I summarizes the t r a i n i n g p r o t o c o l ) . T h i s was d e s i g n a t e d as the t r a i n i n g p e r i o d . On the b a s i s of measurements of oxygen uptake of Sprague-Dawley r a t s running at v a r i o u s speeds and on v a r i o u s grades (Brooks and White, 1978 and Shepherd and G o l l -n i c k , 1976), i t was estimated that the r a t s i n t h i s study were consuming oxygen at the rate of approximately 39 TABLE I T r e a d m i l l running t r a i n i n g p r o t o c o l f o r experimental r a t s . Rats were accustomed to run on the t r e a d m i l l at g r a d u a l l y i n c r e a s i n g speeds f o r in c r e a s e d lengths of time over a three week p e r i o d . Shown are the speeds and d u r a t i o n of running time a c h i e v e d on days 1 to 6 and by the end of weeks 2 and 3 of t r a i n i n g . T r a i n i n g Time Increase over 5 To (m/min) speed min For (min) Decrease over 1 To (m/m i n) speed min For (min) day 1 0 10 - -2 1 0 10 5 5 3 1 0 20 5 10 4 1 2 40 1 0 10 5 1 3 60 1 1 1 5 6 1 5 75 1 2 1 5 week 2 25 90 20 30 3 30 120 40 60 1/kg/min, c o r r e s p o n d i n g to about 70% V02 max (Bedford et a l . , 1979), a moderately strenuous a e r o b i c workload. In order to prevent the p o s s i b l e o v e r h e a t i n g of the animals, an e l e c t r i c fan was d i r e c t e d over the t r e a d m i l l during the e n t i r e e x e r c i s e p e r i o d . A f t e r the t r a i n i n g p e r i o d the r a t s c o n t i n u e d to run at t h i s speed 2 hours per day, 5 days per week u n t i l they were t e r m i n a t e d . Pregnant r a t s ran up to and i n c l u d i n g day 20 of pregnancy and then resumed e x e r c i s e on day 2 of l a c t a t i o n . Throughout the experiment records were kept f o r each animal of running time missed due to r e f u s a l to run. During the d a i l y e x e r c i s e p e r i o d of 2 hours, access to food and water was removed from a l l the animals. Sedentary l a c t a t i n g dams were a l s o removed from t h e i r pups dur i n g the e x e r c i s e p e r i o d . Pup l i t t e r s aged 7 days or l e s s were kept covered with a f l a n n e l c l o t h to keep them warm while separated from t h e i r mothers. In order to mimic the n o c t u r n a l behaviour of r a t s , the e x e r c i s e was conducted i n the mornings near the end of the dark c y c l e . I t i s p o s s i b l e that e x e r c i s i n g d u r i n g the l i g h t c y c l e may d i s r u p t the r a t s ' normal a c t i v i t y p a t t e r n and t h e r e f o r e p o s s i b l y i n f l u e n c e behavior such as food intake (Applegate et a l . , 1982). 2) T r e a d m i l l The t r e a d m i l l was designed by the author, based on a model operated at Simon F r a s e r U n i v e r s i t y (Model 20-41 40, Quinton T r e a d s ) , and b u i l t by E s t r i n Manufacturing L t d . , Vancouver, B.C. I t cou l d accomodate up to 14 animals i n two rows of seven compartments each. Each compartment measured 48 cm long, 10 cm wide and 15 cm hi g h , being formed by aluminum sheet d i v i d e r s . Each compartment was covered by a g r i d to prevent the r a t s from jumping out. The r a t s were run on a te x t u r e d neoprene b e l t d r i v e n by a h a l f horsepower motor which c o u l d be run at c o n t i n u o u s l y v a r i a b l e speeds. Speed was monitored using a c a l i b r a t e d b i c y c l e speedometer. The compartments were equipped with e l e c t r i c shock g r i d s made of copper wires strung p a r a l l e l to one another approximately 0.5 cm a p a r t . Shock g r i d s were powered by a r a p i d l y p u l s a t i n g high v o l t a g e , low c u r r e n t s i g n a l o b t a i n e d by adapting a commercial fence c o n t r o l l e r . The exact v o l t a g e and c u r r e n t c o u l d not be measured because of the ada p t a t i o n made to the fence c o n t r o l l e r ; however i t was t e s t e d on r a t s and a d j u s t e d to p r o v i d e a s u f f i c i e n t l y strong negative r e i n f o r c e m e n t without c a u s i n g e x c e s s i v e pain or i n j u r i n g the animal. No animals were i n j u r e d or l o s t due to the shock system. 3) Mating and C u l l i n g of Pups F o l l o w i n g the three week t r a i n i n g p e r i o d , sedentary and e x e r c i s i n g r a t s a s s i g n e d to mated subgroups were housed o v e r n i g h t on a one-to-one b a s i s with male Sprague-Dawley r a t s . The f i n d i n g of a v a g i n a l p l u g 42 and/or the presence of sperm in the vaginal washings the following morning was taken as day 0 of pregnancy. The number of days to mating was recorded. L i t t e r s of l a c t a t i n g dams were c u l l e d to eight, including four males and four females per l i t t e r where possible. Fostering was ca r r i e d out when necessary, using pups from dams of the same subgroup. 4) M i l k C o l l e c t i o n Lactating dams were separated from th e i r pups for four hours p r i o r to milking. This four hour separation included the two hours of running time for the exercising r a t s . Rats were milked between one and three p.m. only. One half hour before milking, 5.0 IU of oxytocin (Sandoz) was given i n t r a p e r i t o n e a l l y to f a c i l i t a t e milk e j e c t i o n . The animal was anaesthetized with ether during the twenty minute milking procedure. Droplets of milk were expressed from the nipples by manual manipulation of the glands and c o l l e c t e d using a 2.0 mm diameter bore soft p l a s t i c tubing held close to the nipple. The tubing was attached to very low suction which allowed the milk to be c o l l e c t e d in a small polyethylene v i a l . The v i a l was then capped and stored immediately at -80°C u n t i l ready for anal y s i s . One-half to 2 ml of milk per rat could be c o l l e c t e d by thi s method (to be used for analysis in a la t e r study). 43 5) T e r m i n a t i o n Animals were weighed immediately p r i o r to being a n a e s t h e t i z e d with ether and then d e c a p i t a t e d . Approxi-mately 5 to 10 ml of t r u n c a l blood was c o l l e c t e d ( to be used f o r a n a l y s i s i n a l a t e r s t u d y ) . The c a r c a s s , i n c l u d i n g the head, was reweighed and then s t o r e d i n a heavy duty f r e e z e r bag at -20°C u n t i l i t was prepared f o r body composition a n a l y s i s . 6) Rat E x c l u s i o n C r i t e r i a E i g h t y of the o r i g i n a l one hundred and twenty-nine r a t s were i n c l u d e d i n the f i n a l data a n a l y s i s . Table II d e s c r i b e s the c r i t e r i a used to exclude f o r t y - n i n e r a t s from the experiment. I t should be noted that Innovar, an i n t r a m u s c u l a r a n a e s t h e t i c c o n t a i n i n g as i t s a c t i v e i n g r e d i e n t f e n t a n y l c i t r a t e , was o r i g i n a l l y used f o r the m i l k i n g procedure. However i t was found that one or more pups of dams milked with t h i s agent d i e d w i t h i n one or two days a f t e r the m i l k i n g procedure. F e n t a n y l , being l i p o p h i l i c , was probably being t r a n s f e r r e d to the r a t pups v i a the milk causing r e s p i r a t o r y d e p r e s s i o n (Hug and Murphy, 1981). Thus ether was used to r e p l a c e Innovar as the a n a e s t h e t i c f o r the m i l k i n g procedure. O r i g i n a l l y r a t dams were to be mil k e d on days 2 and 14 of l a c t a t i o n . However because of the danger of l o s i n g r a t pups due to the a n a e s t h e t i c agent e n t e r i n g the milk supply, the experimental p r o t o c o l was changed e a r l y on to m i l k i n g on day 14 o n l y . 44 TABLE II C r i t e r i a used to exclude r a t s from the experiment and the f i n a l data a n a l y s i s . C r i t e r i a # r a t s A) Excluded d u r i n g the experiment - R e f u s a l to run * 3 - Pseudopregnancy 4 - U n s u c c e s s f u l mating f o r 8 or more days 4 - Died of i n j u r i e s obtained when housed with male r a t f o r mating 1 - Died of i n j u r i e s obtained from p a s s i n g under back end of t r e a d m i l l 1 - Pups eaten by dam as they were d e l i v e r e d 1 - Rat death of unknown cause 1 B) Excluded a f t e r the experiment - E x e r c i s i n g r a t s l o s i n g more than 3 1/2 hours of t o t a l running time over d u r a t i o n of ex-periment due to r e f u s a l to run ...11 - L a c t a t i n g dams milked using Innovar or milked any day other than day 14 of l a c t a t i o n 10 - Randomly excluded i n order to reduce the t o t a l number of r a t s i n each group to 8 12 - Rat homogenate l o s t due to blendor problem 1 45 E) Measurements 1) Food Intake Food intake was measured and recorded d a i l y f o r a l l r a t s d u r i n g the experimental p e r i o d . S p i l l a g e was measured and accounted f o r i n these r e c o r d s . 2) Body Weight A l l animals were weighed every t h i r d day. Pregnant r a t s were a l s o weighed on day 0 of pregnancy and then every t h i r d day. A postpartum weight was taken w i t h i n 24 hours of d e l i v e r y and dams p e r m i t t e d t o l a c t a t e c o n t i n u e d to be weighed every t h i r d day and on day 14 of l a c t a t i o n . Rat pups were weighed w i t h i n 24 hours of b i r t h and then every t h i r d day and on day 14. F) Assay Procedures 1) P r e p a r a t i o n of Carc a s s f o r A n a l y s i s The f o l l o w i n g method of p r e p a r i n g the c a r c a s s f o r sampling and a n a l y s i s was based on the method of Hart-sook and Hershberger (1963). I t should be noted that the gut c o n t e n t s of the animals was not removed i n t h i s study. The f r o z e n c a r c a s s of each r a t was emptied i n t o a two l i t e r beaker to which approximately 150 ml of d i s t i l l e d water was added. The beaker was covered with aluminum f o i l and p l a c e d i n an a u t o c l a v e (Model STM-E, Market Forge Co.) f o r 3 hours at 115°C and 2 atm. T h i s p r o c e s s s o f t e n s the t i s s u e s i n order to f a c i l i t a t e 46 homogenizat i o n . The content of the beaker was then emptied i n t o a preweighed 4 l i t e r c a p a c i t y Waring blendor (Commercial Model CB-6). Enough d i s t i l l e d water was added to a c h i e v e approximately a 1:1 r a t i o of c a r c a s s weight:water added. The blendor c o n t a i n e r and contents were weighed. The mixture was then homogenized at h i g h speed f o r a t o t a l of 10 minutes, s t o p p i n g i n t e r m i t t e n t l y to prevent o v e r h e a t i n g of the m a t e r i a l . The mixture was allowed to c o o l f o r 20 minutes and was then poured i n t o a beaker through a household wire mesh s i e v e i n order to separate the h a i r from the homogenate. (The l a t t e r step was necessary because i t was found i n p r e l i m i n a r y t r i a l s of t h i s procedure that the h a i r tended to clump and sampling of a t r u l y homogenous mixture from the blendor, as o u t l i n e d below, was not p o s s i b l e ) . The h a i r mass and adhering homogenate was p l a c e d on a preweighed p e t r i d i s h , weighed, and s t o r e d at -20°C u n t i l i t was f r e e z e -d r i e d . The homogenate c o l l e c t e d i n the beaker was q u a n t i t a t i v e l y t r a n s f e r r e d back i n t o the Waring blendor, u s i n g as l i t t l e water ( d i s t i l l e d ) as p o s s i b l e . The blendor and contents were weighed. The homogenate was blended again at high speed f o r 30 seconds to assure homogenization. F i v e samples were then q u i c k l y taken from the blendor using a l a r g e bulb s y r i n g e and p l a c e d i n each of 5 preweighed p e t r i d i s h e s . T h i s amount of sample, approximately 250 g t o t a l wet weight, assured an 47 adequate amount of d r i e d c a r c a s s powder f o r two to three repeats of each assay f o r each c a r c a s s . The p e t r i d i s h e s were then reweighed with t h e i r contents and s t o r e d at -20°C u n t i l f r e e z e - d r i e d . The remaining homo-genate was d i s c a r d e d . Frozen r a t homogenate samples, i n c l u d i n g the h a i r mass, were f r e e z e - d r i e d f o r 22 to 28 hours i n a model 75150 Labconco Tray Freeze Dryer. The f r e e z e - d r i e d r a t homogenate samples (not the h a i r mass) were then ground to a f i n e powder u s i n g a household c o f f e e g r i n d e r (Moulinex). The powder from each r a t and the f r e e z e -d r i e d h a i r mass were each s t o r e d i n a p l a s t i c bag at -20°C u n t i l r e q u i r e d f o r assay procedures. F i g u r e 3 summarizes the c a r c a s s p r e p a r a t i o n procedure. 2) Sample P r e p a r a t i o n f o r the Ash, Fat and P r o t e i n Assays Samples of f r e e z e - d r i e d r a t homogenate or h a i r mass were d r i e d i n a g r a v i t y c o n v e c t i o n oven ( P r e c i s i o n Model 18EG) at 110°C f o r a minimum of 2 hours and then s t o r e d i n a d e s i c c a t o r under vacuum u n t i l they were weighed i n t o the a p p r o p r i a t e v e s s e l f o r the assay. C r u c i b l e s used f o r as h i n g were prepared by soaking i n a 2N HC1 bath f o r a minimum of 2 hours followed by f i r i n g f o r 2 hours at 800°C. A l l glassware used f o r the p r o t e i n assay was a c i d washed. 3) Water A measure of the water l o s t d u r i n g f r e e z e - d r y i n g of 48 FIGURE 3 Terminate Freeze carcass (—20 C) water Autoclave (3 hrs, 115 C, 2 atm) water s^J Homogenize (10 min @ high speed) Sieve water Homogenate Hair Mass N Homogenize (30 sec) Remove samples discard remainder Freeze (-20 C) Freeze-dry (22-28 hrs) Grind to powder Frozen storage (-20 C) Freeze (-20 C) Freeze-dry (22-28 hrs) Frozen storage (—20 C) Ash Pro tein I Fat (triplicate) (duplicate) (duplicate) Ash Pro em Fat (triplicate) (duplicate) (duplicate) Flow diagram outlining rat carcass preparation procedure for body composition analysis. 49 the homogenate and h a i r samples f o r each r a t and the weights taken d u r i n g the p r e p a r a t i o n of the r a t c a r c a s s f o r a n a l y s i s , as d e s c r i b e d above, allowed the c a l c u l a t i o n of the r a t ' s t o t a l body water c o n t e n t . T h i s c a l c u l a t i o n , shown below, accounts f o r the blood l o s s d u r i n g d e c a p i t a t i o n . % water = 100 - % dry matter where % dry matter = ( t o t a l homogenate dry matter + 0.07 * b l o o d l o s s + dry h a i r weight) * 100/ r a t wt where blood i s approximately 7% dry matter and t o t a l homogenate dry matter = (blendor + homogenate wt - dry blendor wt) * average % dry matter of samples/100 where average % dry matter of samples 5 = 100 * f r e e z e - d r i e d sample w t ( i ) 5 i=1 sample w t ( i ) The c a l c u l a t i o n of the percent h a i r content of the dry r a t c a r c a s s i s shown below. T h i s number was needed f o r c a l c u l a t i n g the percent ash, f a t and p r o t e i n of each r a t . I t i s not r e p r e s e n t a t i v e of the a c t u a l h a i r content of the animal, because of adhering c a r c a s s homogenate, and f o r t h i s reason w i l l be d e s i g n a t e d as " h a i r " . % " h a i r " of r a t = dry " h a i r " wt * 100 ( r a t wt * %dry matter/100) 4) Ash T r i p l i c a t e samples, approximately one gram each, of 50 both powdered homogenate and h a i r mass were ashed i n a muffle furnace (Thermolyne Model 2000) at 650°C f o r 18 hours. The percent ash weight of the r a t was c a l c u l a t e d as f o l l o w s : % ash = (% ash of " h a i r " and homogenate) * (100 - %water)/l00 where % ash of " h a i r " and homogenate = (( % a s h of " h a i r " * % " h a i r " of r a t ) + (%ash of homogenate * (100 - % " h a i r " of r a t ) ) ) / 1 0 0 where % ash of " h a i r " or homogenate 3 = 100 * 12 ( c r u c i b l e p l u s ash w t ( i ) - c r u c i b l e w t ( i ) ) / 3 i=1 ( c r u c i b l e p l u s " h a i r " or homogenate w t ( i ) - c r u c i b l e w t ( i ) ) Approximately 10 percent of each of the homogenate and " h a i r " ash assays were repeated. The assays repeated were those with the maximum d i f f e r e n c e between the h i g h e s t and lowest d e t e r m i n a t i o n of the three that made up each assay. For the homogenate assays, those with a d i f f e r e n c e g r e a t e r than 0.25% were repeated, and fo r the " h a i r " assays the f i g u r e was 2.0%. 5) Fat The percent f a t content of d u p l i c a t e samples of both powdered homogenate and h a i r mass was determined by the method of At k i n s o n et a l (1972). The percent f a t weight of the r a t was c a l c u l a t e d as f o l l o w s : % f a t = (%fat of " h a i r " and homogenate) * (100 - %water)/l00 51 where % f a t of " h a i r " and homogenate = ( ( % f a t of " h a i r " * % " h a i r " of r a t ) + (%fat of homogenate * (100 - % " h a i r " of r a t ) ) ) / ! 0 0 where % f a t of " h a i r " or homogenate 2 = 100 * £ (volume of c h l o r o f o r m * f a t w t ( i ) * 100)/ 2 i=1 ((volume of subsample - ( f a c t o r * f a t w t ( i ) ) ) * s a m p l e w t ( i ) ) where f a t wt = (wt of d i s h + f a t ) - wt of d i s h f a c t o r = 0.86 = volume of 1 gm of f a t when d i s s o l v e d i n 1 gm of c h l o r o f o r m volume of subsample = 5 ml volume of c h l o r o f o r m = 10 ml Approximately 10 percent of each of the homogenate and " h a i r " f a t assays were repeated. The assays repeated were those with the maximum d i f f e r e n c e between the two d e t e r m i n a t i o n s . For the homogenate assays those with a d i f f e r e n c e g r e a t e r than 0.4% were repeated and f o r the " h a i r " a ssays, the f i g u r e was 1.0%. A study was done to determine the percent recovery of f a t from f r e e z e - d r i e d r a t homogenate u s i n g the method of Atkinson et a l (1972). E x t r a c t e d r a t f a t was c o l l e c t e d from approximately 25 randomly chosen f r e e z e -d r i e d r a t homogenates. T h i s f a t was added to a p p r o x i -mately one gram samples of the r a t homogenate ( r a t number 3) i n i n c r e a s i n g amounts. F i g u r e 4 shows a l i n e a r r e l a t i o n s h i p between percent f a t added and the percent f a t recovered. The slope of the l e a s t squares 52 FIGURE 4 Least—squares fit of the fat recovery test data. 53 f i t l i n e i s 1.02 i n d i c a t i n g 102 percent recovery. Within e r r o r the recovery of f a t was taken to be 100 perc e n t . 6) P r o t e i n T r i p l i c a t e d e t e r m i n a t i o n s of the n i t r o g e n content of d u p l i c a t e samples were done f o r both the r a t homogenate and h a i r mass us i n g the method of Fukomoto and Chang (1982). Standards were prepared with an ammonium s u l f a t e s o l u t i o n and standard curves were performed any time a new s o l u t i o n was prepared, or a t l e a s t weekly. The percent p r o t e i n content of the r a t was c a l c u l a t e d as f o l l o w s : % p r o t e i n = (%protein of " h a i r " and homogenate) * (100 - %water)/!00 where % p r o t e i n of " h a i r " and homogenate = ( ( % p r o t e i n of " h a i r " * % " h a i r " of r a t ) + (%protein of homogenate * (100 - % " h a i r " of r a t ) ) / 1 0 0 and % p r o t e i n of homogenate or " h a i r " 2 3 = 100 E / L (%nitrogen of homogenate or " h a i r " ( i , j ) ) 4 i=1 j=1 * 6.25/wt of dry s a m p l e ( i , j ) where i= sample j= d e t e r m i n a t i o n (The h i g h e s t and lowest of the 6 determinations were excluded) and % n i t r o g e n of homogenate or " h a i r = (A655 - B)/M 54 where A655 = absorbance at 655 nm B = i n t e r c e p t of standard curve M = s l o p e of standard curve Approximately 10 percent of the p r o t e i n assays were repeated. The c r i t e r i o n f o r the s e l e c t i o n of assays to be repeated was a g r e a t e r than 5 percent d i f f e r e n c e between the averages of the three d e t e r m i n a t i o n s of the two samples. The same c r i t e r i o n a p p l i e d to both the homogenate and the h a i r mass assays. G) Carcass Energy Content A rough approximation of the c a r c a s s energy content (CEC) was c a l c u l a t e d f o r each r a t . T h i s was c a l c u l a t e d as f o l l o w s : CEC = ( c a r c a s s wt (g) * % f a t * 0.0945 kcal/g) + ( c a r c a s s wt (g) * % p r o t e i n * 0.0435 kcal/g) H) S t a t i s t i c a l A n a l y s i s A l l s t a t i s t i c a l a n a l y s e s were conducted using com-puter f a c i l i t i e s and programmes at the U n i v e r s i t y of B r i t i s h Columbia. The SPSSx package of programmes (Nie, 1983) was used to perform the m u l t i v a r i a t e a n a l y s i s of v a r i a n c e (MANOVA) and the Scheffe t e s t . To determine whether the f a c t o r s a c t i v i t y or mated had an e f f e c t on the weekly food intake and the weekly body weight of r a t s d u r i n g each of the T, P and L stages, a MANOVA was performed. Since o n l y one f a c t o r , a c t i v i t y , was i n v o l v e d at the t r a i n i n g stage, a simple t 55 t e s t was performed between the two groups. A MANOVA was performed f o r each body component (water, f a t , ash and p r o t e i n ) and f o r the estimated c a r c a s s energy content t o determine whether a c t i v i t y , mated, stage, or i n t e r a c t i o n s between these f a c t o r s , had s i g n i f i c a n t e f f e c t s on these v a r i a b l e s . In the f i r s t a n a l y s i s only two l e v e l s of the stage f a c t o r , P and L, were i n c l u d e d because the m o d i f i e d f a c t o r i a l d e s ign d i d not permit a complete 2*2*3 a n a l y s i s . A MANOVA was then performed on the 2*3 design of the experiment f o r each of the v i r g i n and mated groups i n order to i n c l u d e the T stage f a c t o r not i n c l u d e d i n the a n a l y s i s of the 2*2*2 de s i g n . To determine the e f f e c t of maternal a c t i v i t y on pup outcome (number of pups per l i t t e r , pup b i r t h w e i g h t and pup weight g a i n ) , a t t e s t comparison of the two groups was performed. The S c h e f f e t e s t was performed at the 0.05 l e v e l f o r a l l post hoc multimean comparisons. These compari-sons were performed between r a t groups at the same stage (T, P or L) o n l y . 56 CHAPTER IV RESULTS A) Food Intake R e s u l t s p e r t a i n i n g to food i n t a k e are presented g r a p h i c a l l y i n F i g u r e 5 and i n t a b u l a r form i n Tables III to VI. F i g u r e 5 summarizes the weekly food intake of r a t s throughout the t r a i n i n g , pregnancy and l a c t a t i o n p e r i o d s . G e n e r a l l y , food i n t a k e i n c r e a s e d over time. While the intake of v i r g i n r a t s s t a b i l i z e d at about the f i r s t week of the pregnancy p e r i o d , mated r a t s c o n t i -nued to in c r e a s e t h e i r food i n t a k e s l i g h t l y during the pregnancy p e r i o d and markedly d u r i n g l a c t a t i o n . R e s u l t s of ANOVA are presented i n Table I I I , and i n d i c a t e that a c t i v i t y s i g n i f i c a n t l y a f f e c t e d food i n -take throughout the experiment, beginning at week two of t r a i n i n g . Mated a l s o had a s t r o n g e f f e c t d u r i n g both the pregnancy and l a c t a t i o n p e r i o d s ( p < 0 . 0 0 l ) . A s i g n i f i c a n t a c t i v i t y / m a t e d i n t e r a c t i o n e f f e c t was d e t e c t e d at week three of pregnancy. Average food i n t a k e data f o r each of the three stages are presented i n T a b l e s IV to VI, along with the r e s u l t s of Sc h e f f e ' s t e s t performed f o l l o w i n g ANOVA. E x e r c i s i n g v i r g i n r a t s consumed s i g n i f i c a n t l y more food than t h e i r sedentary c o n t r o l s d u r i n g the second (p< 0 . 0 5 ) and t h i r d ( p < 0 . 0 0 l ) weeks of t r a i n i n g (Table I V). Weekly food i n t a k e d u r i n g the pregnancy p e r i o d of 57 FIGURE 5 Weekly mean food intake of rats during the training, pregnancy and lactation periods. A sedentary virgin O exercising virgin A sedentary mated • exercising mated 58 TABLE I I I F valu e s a s s o c i a t e d with the e f f e c t s of ' a c t i v i t y ' and 'mated' on food intake f o r each week of the t r a i n i n g , preg-nancy and l a c t a t i o n p e r i o d s . Time P e r i o d E f f e c t a c t i v i t y mated a c t i v i t y / m a t e d T r a i n i n g week 1 0 . 0 0 ns - -(n=40) week 2 6.65* - -week 3 2 6 . 6 1 * * * — -Pregnancy week 1 1 9 . 6 6 * * * 3 2 . 47*** 1 .24 ns (n= l6 ) week 2 1 3 . 5 9 * * * 3 5 . 8 0 * * * 0 . 49 ns week 3 1 1 . 0 9 * * * 5 9 . 8 5 * * * 8 . 3 3 * * L a c t a t ion week 1 1 0 . 3 4 * * 2 6 0 . 2 o * * * 0 .78 ns (n=8) week 2 4 . 6 3 * 6 7 0 . 0 7 * * * 0 .37 ns * p<0.05 ** p<0.0l *** p<0.00l ns not s i g n i f i c a n t 59 TABLE IV Comparison of weekly food i n t a k e s of sedentary (Sed) and e x e r c i s i n g (Ex) r a t s d u r i n g the t r a i n i n g p e r i o d . Mean + S.D. Group Food Intake (g/week) week 1 week 2 week 3 Sed (n=40) 120.8 + 13.8 126.6 + 11.6 126.1 + 14.6 Ex (n=40) 120.8 + 12.2 133.3 + 11.5 143.3 + 15.2 ns * *** * p<0.05 *** p<0.00l ns not s i g n i f i c a n t 60 TABLE V Comparison of weekly food intakes of mated sedentary (Sed) and e x e r c i -s i n g (Ex) r a t s and t h e i r v i r g i n c o n t r o l s d u r i n g the pregnancy p e r i o d . Mean + S.D. Group Food Intake (g/week) week 1 week 2 week 3 V i r g i n Sed (SVP+SVL, n=16) 130.7 + 14.5a 130.5 + 11.9a 126.7 + 12.0a Ex (EVP+EVL, n=16) 150.8 + 12.7b 147.8 + 15.7b 155.1 + 18.3b Mated Sed (SMP+SML, n=16) 155.3 + 14.6bc 156.8 + 14.7bc 175.3 + 19.8c Ex (EMP+EML, n=16) 167.3 + 15.8c 168.6 + 19.7c 177.4 + 21.7c a,b,c F i g u r e s i n the same column not s h a r i n g the same s u p e r s c r i p t a re s i g n i f i c a n t l y d i f f e r e n t (p<0.05). T A B L E V I Comparison of weekly food i n t a k e s of mated sedentary (Sed) and e x e r c i s i n g (Ex) dams and t h e i r v i r g i n c o n t r o l s d u r i n g the l a c t a t i o n p e r i o d . Mean + S.D. Group Food Intake (g/week) week 1 week 2 V i r g i n Sed (SVL, n=8) 129.2 + 8.0a 131.1 + 8.1a Ex (EVL, n=8) 142.3 + 20.1a 155.6 + 17.8a Mated Sed (SML, n=8) 214.8 + 20.3b 366.3 + 33.9b Ex (EML, n=8) 237.9 + 11.4b 380.0 + 31.5b a,b F i g u r e s i n the same column not s h a r i n g the same s u p e r s c r i p t are s i g n i f i c a n t l y d i f f e r e n t (p<0.05). 6 2 sedentary mated and e x e r c i s i n g mated r a t s and t h e i r v i r g i n c o n t r o l s are shown i n Table V. E x e r c i s i n g v i r g i n r a t s continued to eat s i g n i f i c a n t l y more than t h e i r sedentary c o n t r o l s d u r i n g t h i s p e r i o d . While e x e r c i s i n g mated r a t s had a tendency to eat more than t h e i r seden-t a r y c o n t r o l s d u r i n g the f i r s t two weeks of pregnancy, t h i s was not d e t e c t e d by post hoc a n a l y s i s . Evidence of the a c t i v i t y / m a t e d i n t e r a c t i o n d e t e c t e d by ANOVA at week three of pregnancy (Table I I I ) i s shown by the lack of any d i f f e r e n c e i n food i n t a k e between the two groups of mated r a t s and the l a r g e d i f f e r e n c e between the two groups of v i r g i n r a t s at t h i s time. However both groups of mated r a t s consumed s i g n i f i c a n t l y more than t h e i r r e s p e c t i v e v i r g i n c o n t r o l s d u r i n g t h i s p e r i o d . Although ANOVA i n d i c a t e d a s i g n i f i c a n t e f f e c t of a c t i v i t y on food i n t a k e d u r i n g l a c t a t i o n , Table VI r e -v e a l s that the d i f f e r e n c e s between e x e r c i s i n g v i r g i n and e x e r c i s i n g mated r a t s and t h e i r r e s p e c t i v e c o n t r o l s were not s t a t i s t i c a l l y d i f f e r e n t by use of Sc h e f f e ' s t e s t . However, the d i f f e r e n c e between sedentary mated and e x e r c i s i n g mated r a t s d i d approach s t a t i s t i c a l s i g -n i f i c a n c e (p<0.07) d u r i n g week one of the l a c t a t i o n p e r i o d . As d u r i n g the pregnancy p e r i o d , sedentary mated and e x e r c i s i n g mated r a t s consumed more than t h e i r r e s -p e c t i v e v i r g i n c o n t r o l s d u r i n g l a c t a t i o n . B) Body Weight Res u l t s p e r t a i n i n g to.body weight are presented 63 g r a p h i c a l l y in F i g u r e 6 and i n t a b u l a r form i n T a b l e s VII to X. F i g u r e 6 d i s p l a y s the mean body weights of the v a r i o u s r a t groups at weekly i n t e r v a l s throughout the t r a i n i n g , pregnancy and l a c t a t i o n p e r i o d s . G e n e r a l -l y body weights i n c r e a s e d over time. However as ex-pected, the body weights of mated r a t s decreased marked-l y at p a r t u r i t i o n . They then i n c r e a s e d again d u r i n g weeks one and two of l a c t a t i o n . R e s u l t s of ANOVA are presented i n Table V I I , and r e v e a l that both a c t i v i t y and mated had s t r o n g e f f e c t s on body weight. There were no s i g n i f i c a n t i n t e r a c t i o n e f f e c t s . Mean body weights d u r i n g the t r a i n i n g , pregnancy and l a c t a t i o n p e r i o d s are d i s p l a y e d i n Tables VIII through X, along with r e s u l t s of S c h e f f e ' s t e s t . At the s t a r t of the t r a i n i n g p e r i o d , and d u r i n g the f i r s t week of t r a i n i n g , t here was no s i g n i f i c a n t d i f f e r e n c e i n body weight between e x e r c i s i n g and sedentary r a t s (Table V I I I . However, by the end of the second (p<0.05) and t h i r d (p<0.00l) week of t r a i n i n g , e x e r c i s i n g r a t s were s i g n i f i c a n t l y h e a v i e r than t h e i r sedentary c o n t r o l s . Table IX shows t h a t e x e r c i s i n g r a t s , whether mated or v i r g i n , continued to weigh s i g n i f i c a n t l y more than t h e i r r e s p e c t i v e sedentary c o n t r o l s u n t i l the t h i r d week of the pregnancy p e r i o d at which time the d i f f e r e n c e between e x e r c i s i n g and sedentary mated r a t s was not d e t e c t e d by post hoc a n a l y s i s . As expected, mated r a t s , whether e x e r c i s i n g or sedentary, weighed s i g n i f i c a n t l y 64 FIGURE 6 150 I 1 1 1 -i 1 1 i i I i L 0 1 2 3 1 2 3 1 2 Weeks Weekly mean body weight of rats during the training, pregnancy and lactation periods. A sedentary virgin o exercising virgin • sedentary mated • exercising mated 65 TABLE VII F valu e s a s s o c i a t e d with the e f f e c t s of ' a c t i v i t y ' and 'mated' on body weight f o r each week of the t r a i n i n g , preg-nancy and l a c t a t i o n p e r i o d s . Time P e r i o d E f f e c t a c t i v i t y mated act i v i t y / m a t e d T r a i n i n g week 0 1 .41 ns - -(n=40) week 1 0 .08 ns - -week 2 5 .60* - -week 3 30 .40*** - -Pregnancy week 1 42 37*** 19. gg*** 0 .10 ns (n=16) week 2 26 go** * 82. 43*** 0 .26 ns week 3 14 .08*** 228. ]2*** 1 .01 ns p a r t u r i t i o n 22 .51*** 1 . 83 ns 1 .95 ns L a c t a t i o n week 1 23 .84*** 10. 80** 0 .21 ns (n=8) week 2 1 5 # 57*** 37. 1 3*** 0 .08 ns * p<0.05 ** p<0.0l *** p<0.00l ns not s i g n i f i c a n t 66 TABLE V I I I Comparison of i n i t i a l and weekly body weights of sedentary (Sed) and e x e r c i s i n g (Ex) r a t s during the t r a i n i n g p e r i o d . Mean + S.D. Group Body Weight (g) week 0 week 1 week 2 week 3 Sed (n=40) 195.8 + 10.4 Ex (n=40) 193.3 + 7.9 ns * p<0.05 *** p<0.001 ns not s i g n i f i c a n t 212.6 + 10.7 224.9 + 11.7 234.6 + 13.3 211.9 + 10.0 231.6 + 13.3 253.3 + 16.8 ns *** TABLE IX Comparison of weekly body weights of mated sedentary (Sed) and e x e r c i -s i n g (Ex) r a t s and t h e i r v i r g i n c o n t r o l s d u r i n g the pregnancy p e r i o d . Mean + S.D. Group Body Weight (g) week 1 week 2 week 3 p a r t u r i t i o n V i r g i n Sed (SVP+SVL, n=16) 255.2 + 14.8a 260.8 + 16.6a 268.2 + 16.9a 268.2 + 21.6a Ex (EVP+EVL, n=16) 280.6 + 16.2b 287.4 + 20.6b 299.2 + 25.5b 298.7 + 25.1b Mated Sed (SMP+SML, n=l6) 273.0 + 12.2b 305.5 + 16.0b 373.4 + 26.0c 281.9 + 14.2ab Ex (EMP+EML, n=l6) 296.1 + 16.1c 327.2 + 20.7c 391.4 + 33.5c 298.5 + 16.9b a,b,c F i g u r e s i n the same column not s h a r i n g the same s u p e r s c r i p t are s i g n i f i c a n t l y d i f f e r e n t (p<0.05). TABLE X Comparison of weekly body weights of mated sedentary (Sed) and e x e r c i s i n g (Ex) dams and t h e i r v i r g i n c o n t r o l s d u r i n g the l a c t a t i o n p e r i o d . Mean + S.D. Group Body Weight (g) week 1 week 2 V i r g i n Sed (SVL, n=8) Ex (EVL, n=8) 279.3 + 17.8a 306.3 + 19.1 be 284.0 + 16.7a 311.4 + 1 8.9ac Mated Sed (SML, n=8) Ex (EML, n=8) 296.6 + 16.0ab 329.1 + 15.9c 327.4 + 21.6cd 359.0 + 26.2b a,b,c,d F i g u r e s i n the same column not sha r i n g the same s u p e r s c r i p t are s i g n i f i c a n t l y d i f f e r e n t (p<0.05) . 69 more than t h e i r r e s p e c t i v e v i r g i n c o n t r o l s throughout t h i s p e r i o d . At p a r t u r i t i o n , however, the weight of mated r a t s decreased to a l e v e l which was no longer s i g n i f i c a n t l y d i f f e r e n t from that of t h e i r r e s p e c t i v e v i r g i n c o n t r o l s . As i n week three of pregnancy, e x e r c i -s i n g mated r a t s d i d not weigh s i g n i f i c a n t l y more than t h e i r sedentary c o n t r o l s . E x e r c i s i n g v i r g i n r a t s , on the other hand, d i d c o n t i n u e to weigh s i g n i f i c a n t l y more than t h e i r sedentary c o n t r o l s at t h i s time. Although e x e r c i s i n g v i r g i n r a t s continued to weigh more than t h e i r sedentary c o n t r o l s at week one of l a c t a -t i o n , t h i s d i f f e r e n c e was no longer s i g n i f i c a n t at week two (Table X ) . E x e r c i s i n g mated r a t s however, weighed s i g n i f i c a n t l y more than t h e i r sedentary c o n t r o l s throughout the l a c t a t i o n p e r i o d . Although mated r a t s c o ntinued to weigh more than t h e i r r e s p e c t i v e v i r g i n c o n t r o l s , t h i s was s t a t i s t i c a l l y s i g n i f i c a n t only d u r i n g the second week of l a c t a t i o n . C) Body Composition R e s u l t s p e r t a i n i n g to body composition are p r e -sented g r a p h i c a l l y i n F i g u r e 7 and i n t a b u l a r form i n Tables XI to X I I I . F i g u r e 7 shows the frequency d i s t r i -b u tion of the t o t a l ( i n percent) of water, f a t , ash and p r o t e i n f o r each of the 80 r a t c a r c a s s e s . The d i s t r i -b u t i o n i s gaussian i n shape with a mean and standard d e v i a t i o n of 99.5 + 1.1%. The mean was expected to be l e s s than 100% s i n c e the carbohydrate component of the 70 FIGURE 7 94 95 96 97 98 99 100 101 102 103 104 Percent Frequency distribution of the total of water, fat, ash and protein of the 80 experimental rat carcasses. 71 TABLE XI F values a s s o c i a t e d with the e f f e c t s of ' a c t i v i t y ' , 'mated' and 'stage' (P and L) on the percent of water, f a t , ash and p r o t e i n of r a t c a r c a s s e s . E f f e c t C arcass Component water f a t ash p r o t e i n A c t i v i t y 50 .76*** 55. 71*** 20 .89*** 3. 65 ns Mated 58 .35*** 21 . 85*** 40 .76*** 5. 08* Stage 24 .09*** 14. 04*** 12 .53*** 0. 77 ns A c t i v i t y / M a t e d 0 .00 ns 0. 01 ns 2 .93 ns 0. 37 ns Mated/Stage 51 .22*** 38. 89*** 1 . 1 3 ns 3. 81 ns A c t i v i t y / S t a g e 0 .09 ns 0. 00 ns 0 .05 ns 0. 16 ns Act i v i t y / M a t e d / S t a g e 5 .09* 8. 23** 1 .11 ns 1 . 98 ns * p<0.05 ** p<0.0l *** p<0.001 ns not s i g n i f i c a n t TABLE XII F v a l u e s a s s o c i a t e d w i t h (T, P and L) on the p e r c e n t and mated r a t c a r c a s s e s . the e f f e c t s of ' a c t i v i t y ' and ' s t a g e ' of w a t e r , f a t , a s h and p r o t e i n of v i r g i n Group E f f e c t C a r c a s s C o m p o s i t i o n water f a t ash p r o t e i n V i r g i n Mated a c t i v t y stage a c t / s t a g e a c t i v i t y stage a c t / s t a g e 26.26*** 11 .78*** 1.86 ns 27.12*** 38.06*** 2.58 ns 27.80*** 9.55*** 5.29** 30.07*** 31.93*** 5.54** 0.15 ns 3.07 ns 3.06 ns 4.63* 7.39** 7.44** 0.08 ns 0.88 ns 4. 19* 0.21 ns 2.68 ns 3.15 ns * p<0.05 ** p<0.0l *** p<0.00l ns not s i g n i f i c a n t TABLE XIII Body composition a n a l y s i s summary f o r a l l r a t groups. Mean + S.D. e Group Percent water f a t ash p r o t e i n t o t a l T r a i n i n g SVT 68.1 + 2.0a 7.57 + 1.21a 4.02 + 0.31a 19.86 + 1.00a 99.6 EVT 69.5 + 1.0a 6.59 + 1.49a 3.83 + 0.20a 18.75 + 1.02b 98.7 Pregnancy SVP 66.0 + 2.1ab 9.78 + 2.43ab 4.07 + 0.25a 19.44 + 0.94a 99.2 EVP 68.0 + 1.2bc 7.56 + 1.62a 4.1.6 + 0.16a 19.64 + 1.46a 99.4 SMP 65.3 + 1.9a 11.86 + 2.57b 3.70 + 0.17b 19.14 + 1.60a 100.0 EMP 69.1 + 1.9c 6.97 + 2.16a 4.05 + 0.13a 19.77 + 0.73a 99.9 L a c t a t ion SVL 64.4 + 1.5a 12.38 + 1.88c 3.92 + 0.l7abd 19.24 + 1.45ac 99.9 EVL 67.9 + 1.3b 7.34 + 1.96b 4.09 + 0.16a 20.43 + 0.71a 99.8 SML 71.0 + 1.3c 5.72 + 1.39ab 3.55 + 0.25c 18.64 + 0.71 be 98.9 EML 72.8 + 0.7c 3.53 + 0.66a 3.82 + 0.26cd 18.72 + 0.69bc 98.9 a,b,c,d Figures at the same stage (T, P. L ) , not s h a r i n g the same s u p e r s c r i p t , are s i g n i f i c a n t l y d i f f e r e n t (p<0.05). e n=8 for a l l groups c a r c a s s was not ana l y z e d and t h e r e f o r e not i n c l u d e d i n the t o t a l . I n d i v i d u a l c a r c a s s t o t a l s were not c o n s i -dered s u f f i c i e n t l y a c c u r a t e from which to c a l c u l a t e the carbohyrate component by d i f f e r e n c e . The l a s t column i n Table XII shows the mean t o t a l c a r c a s s r e c o v e r y f o r the e i g h t r a t s i n each of the ten experimental groups. These ranged from 98.7 to 100.0%. Table XI p r e s e n t s the r e s u l t s of ANOVA performed on a 2*2*2 design of the experiment i n which the t r a i n i n g (T) stage was dropped from the a n a l y s i s . The main e f f e c t s of a c t i v i t y , mated and stage were h i g h l y s i g n i -f i c a n t (p<0.00l) on the percent water, f a t and ash of rat c a r c a s s e s . Mated a l s o had a s i g n i f i c a n t e f f e c t (p<0.05) on percent c a r c a s s p r o t e i n . A s t r o n g mated/stage i n t e r a c t i o n e f f e c t (p<0.00l) and a weaker but s t i l l s i g n i f i c a n t three-way i n t e r a c t i o n e f f e c t were detected f o r both water and f a t . Table XII pr e s e n t s the r e s u l t s of ANOVA performed on a 2*3 design of the experiment f o r each of the v i r g i n and mated groups. In c o n t r a s t to the ANOVA done on the 2*2*2 design, t h i s a n a l y s i s allowed f o r the i n c l u s i o n of the t r a i n i n g stage. Two f i n d i n g s that were not apparent in the pr e v i o u s ANOVA were det e c t e d by t h i s a n a l y s i s . The f i r s t was an a c t i v i t y / s t a g e i n t e r a c t i o n e f f e c t on percent c a r c a s s f a t i n both v i r g i n and mated r a t s . In both groups, percent f a t i n c r e a s e d i n sedentary r a t s and remained unchanged i n e x e r c i s i n g r a t s from the T to P stage. From the P to L stage, however, the percent 75 c a r c a s s f a t decreased i n mated sedentary and e x e r c i s i n g r a t s , i n c r e a s e d i n v i r g i n sedentary r a t s and remained unchanged i n v i r g i n e x e r c i s i n g r a t s . The other f i n d i n g t h a t emerged from t h i s ANOVA was that a c t i v i t y , stage, and a c t i v i t y / s t a g e i n t e r a c t i o n e f f e c t s on percent c a r -cass ash were c o n f i n e d to mated r a t s . The i n t e r a c t i o n e f f e c t i s accounted f o r by the f a c t that from the T to P stage, percent c a r c a s s ash decreased i n sedentary r a t s and i n c r e a s e d i n mated r a t s , while from the P to L stage, both sedentary and e x e r c i s i n g r a t s had a decrease i n percent c a r c a s s ash. Table XIII shows the r e s u l t s of S c h e f f e ' s t e s t , comparing the a p p r o p r i a t e r a t groups w i t h i n each stage, for each of the body components. A comparison of exer-c i s i n g and sedentary r a t s , whether v i r g i n or mated, shows that e x e r c i s i n g r a t s had a c o n s i s t e n t l y lower percent c a r c a s s f a t and higher percent c a r c a s s water than t h e i r sedentary c o n t r o l s at a l l three stages, a l -though group d i f f e r e n c e s were not always s i g n i f i c a n t by S c h e f f e ' s t e s t (p<0.05). Except f o r a s i g n i f i c a n t l y lower percent c a r c a s s p r o t e i n content i n e x e r c i s i n g v i r g i n r a t s at the end of the t r a i n i n g p e r i o d , no other s i g n i f i c a n t d i f f e r e n c e s i n composition were found between e x e r c i s i n g and sedentary v i r g i n r a t s u n t i l the end of the l a c t a t i o n p e r i o d ( i . e . a f t e r nine weeks of t r e a d m i l l running). At t h i s time the e x e r c i s e r s had a s i g n i f i c a n t l y higher percent c a r -cass water content and a s i g n i f i c a n t l y lower percent 76 c a r c a s s f a t content than t h e i r sedentary c o n t r o l s . Mated r a t s showed a d i f f e r e n t p a t t e r n over time. At p a r t u r i t i o n , e x e r c i s i n g r a t s had s i g n i f i c a n t l y g r e a t -er percent c a r c a s s water, lower percent c a r c a s s f a t and higher percent c a r c a s s ash than t h e i r sedentary con-t r o l s . Although these d i f f e r e n c e s remained at the end of the l a c t a t i o n p e r i o d , they were no longer s i g n i f i c a n t by Schef f e ' s t e s t . Comparison of sedentary mated r a t s to t h e i r v i r g i n time c o n t r o l s at p a r t u r i t i o n , shows that the main e f f e c t of pregnancy (or mated) was to i n c r e a s e percent c a r c a s s f a t with the concomitant decrease i n percent c a r c a s s water (not d e t e c t e d by S c h e f f e ' s t e s t ) , and s i g n i f i c a n t l y decrease percent c a r c a s s ash. In con-t r a s t , a comparison of e x e r c i s i n g mated r a t s and t h e i r e x e r c i s i n g v i r g i n time c o n t r o l s shows no s i g n i f i c a n t d i f f e r e n c e i n body composition. Since e x e r c i s i n g and sedentary v i r g i n r a t s had s i m i l a r body composition at p a r t u r i t i o n , e x e r c i s i n g mated r a t s were a l s o s i m i l a r to sedentary v i r g i n animals. A f t e r two weeks of l a c t a t i o n , mated r a t s , whether e x e r c i s i n g or sedentary, had c o n s i s t e n t l y lower percent c a r c a s s f a t , h i g h e r percent c a r c a s s water, lower percent c a r c a s s ash, and lower percent c a r c a s s p r o t e i n than t h e i r r e s p e c t i v e v i r g i n c o n t r o l s , although these d i f f e r -ences were not always s i g n i f i c a n t by S c h e f f e ' s t e s t . A comparison of e x e r c i s i n g mated and sedentary mated r a t s at t h i s stage shows that e x e r c i s e c o n t i n u e d throughout 77 l a c t a t i o n r e s u l t e d i n a n o n s i g n i f i c a n t decrease i n per-cent c a r c a s s f a t , the concomitant i n c r e a s e i n percent c a r c a s s water and an increase i n percent c a r c a s s ash. The c a r c a s s composition of mated r a t s a t p a r t u r i -t i o n and a f t e r two weeks of l a c t a t i o n were compared u s i n g ANOVA fo l l o w e d by Sheffe's t e s t (p<0.05) i n order to look at the stage e f f e c t more c l o s e l y . T h i s compari-son i s not i n d i c a t e d i n Table X I I I . A f t e r two weeks of l a c t a t i o n , mated r a t s , whether e x e r c i s i n g or sedentary, had l e s s percent c a r c a s s f a t and a g r e a t e r percent c a r c a s s water than they had had at p a r t u r i t i o n . These f i n d i n g s were s i g n i f i c a n t except i n the case of the percent f a t of e x e r c i s i n g mated r a t s . N e i t h e r percent c a r c a s s ash nor percent c a r c a s s p r o t e i n changed s i g n i f i -c a n t l y from p a r t u r i t i o n to the end of the l a c t a t i o n p e r i o d i n mated r a t s . V i r g i n r a t s , on the other hand, had a s l i g h t i n c r e a s e in percent c a r c a s s f a t with the concomitant decrease i n percent c a r c a s s water over the same two week time p e r i o d . D) Carcass Energy Content E x e r c i s i n g r a t s tended to have a lower c a r c a s s energy content than sedentary r a t s , d e s p i t e t h e i r gen-e r a l l y g r e a t e r body weights. The standard d e v i a t i o n s f o r the estimated c a r c a s s energy content v a l u e s were h i g h however, and a s i g n i f i c a n t d i f f e r e n c e between groups was found only at the l a c t a t i o n stage (Table XIV). Thus at l a c t a t i o n , e x e r c i s i n g v i r g i n r a t s had a 78 s i g n i f i c a n t l y lower c a r c a s s energy content than seden-t a r y v i r g i n r a t s , while e x e r c i s i n g mated r a t s had a n o n s i g n i f i c a n t l y lower c a r c a s s energy content than sed-entary mated r a t s . Mated r a t s , whether e x e r c i s i n g or sedentary, had s i g n i f i c a n t l y lower c a r c a s s energy con-t e n t s than t h e i r r e s p e c t i v e v i r g i n c o n t r o l s at the l a c -t a t i o n stage. E) Pregnancy Outcome and L a c t a t i o n Performance Pregnancy outcome, as measured by the number of pups per l i t t e r and mean pup b i r t h w e i g h t , was not s i g n i -f i c a n t l y d i f f e r e n t between e x e r c i s i n g and sedentary dams as shown i n Tables XV and XVI. I t can a l s o be seen from these two t a b l e s that c u l l i n g of the l i t t e r s of the l a c t a t i n g dams d i d not r e s u l t i n a s i g n i f i c a n t change i n mean pup b i r t h w e i g h t f o r these l i t t e r s . L a c t a t i o n performance, as measured i n d i r e c t l y by mean pup weight gain over the two week l a c t a t i o n p e r i o d , was not s i g n i f i c a n t l y d i f f e r e n t between the e x e r c i s i n g and sedentary dams. 79 TABLE XIV Comparison of estimated c a r c a s s energy content of sedentary (S) and e x e r c i s e d ( E ) , v i r g i n (V) and mated (M) r a t s terminated a t , or c o r r e s p o n d i n g to, the time of mating ( T ) , at p a r t u r i t i o n (P) and on day 14 of l a c t a t i o n ( L ) . Mean + S.D. Estimated Carcass Energy Content ( k c a l ) Termination Time d Group T P L SV 382.6 + 42.4a 464.0 + 83.0a 567.7 + 81.1c EV 376.7 + 42.0a 466.1 + 93.9a 478.7 + 65.0b SM - 542.4 + 66.2a 422.6 + 44.9ab EM - 446.3 + 86.5a 391.6 + 28.0a a,b,c F i g u r e s i n the same column not s h a r i n g the same s u p e r s c r i p t are s i g n i f i c a n t l y d i f f e r e n t (p<0.05). d n=8 f o r a l l groups 80 TABLE XV Comparison of mean pup number per l i t t e r and mean pup bi r t h w e i g h t b e f o r e c u l l i n g , of sedentary (Sed) and e x e r c i s i n g (Ex) dams. Mean + S.D. Group P u p s / l i t t e r Pup b i r t h w e i g h t (g) Sed (SMP+SML, n=16) 12.3+3.3 5 . 9 + 0 . 4 Ex (EMP+EML, n=16) 13.2+4.7 5 . 7 + 0 . 6 ns ns ns not s i g n i f i c a n t (p>0.05) 81 TABLE XVI Comparison of mean pup birthweight a f t e r c u l l i n g and mean weight gain of pups a f t e r 14 days of l a c t a t i o n of sedentary (Sed) and e x e r c i s i n g (Ex) dams. Mean + S.D. Group Sed (SML, n=8) Ex (EML, n=8) Pup Birthweight (g) 5.9 + 0.5 5.7 + 0.4 ns Pup Weight Gain (g) 23.4 + 2.6 23.1 + 2.1 ns ns not s i g n i f i c a n t (p>0.05) 82 CHAPTER V DISCUSSION The purpose of t h i s study was to determine the e f f e c t s of strenuous a e r o b i c e x e r c i s e , d u r i n g r a t preg-nancy and l a c t a t i o n , on food i n t a k e , body weight and c o m p o s i t i o n , and on l a c t a t i o n performance. Data were o b t a i n e d from e x e r c i s e d and sedentary mated r a t s , and from non-mated e x e r c i s e d and sedentary c o n t r o l s , thus p e r m i t t i n g the e f f e c t s of e x e r c i s e d u r i n g pregnancy and l a c t a t i o n to be compared to the e f f e c t s of e x e r c i s e a l o n e . Food i n t a k e , body weight, and body composition are d i s c u s s e d i n d i v i d u a l l y i n terms of the e f f e c t s of exer-c i s e i n v i r g i n , pregnant and l a c t a t i n g r a t s . Pregnancy outcome and l a c t a t i o n performance are then d i s c u s s e d , f o l l o w e d by a c o n c l u d i n g summary. A) Food Intake As has been reported elsewhere (Mayer et a l . , 1954; Oscai et a l . , 1973; Nance et a l . , 1977; P i t t s , 1984), e x e r c i s e g e n e r a l l y r e s u l t s i n an i n c r e a s e d food intake i n v i r g i n female r a t s , and the data i n t h i s study are c o n s i s t e n t with these r e p o r t s . As was observed f o r both sedentary and e x e r c i s i n g mated r a t s i n t h i s study, food i n t a k e normally r i s e s throughout g e s t a t i o n and d u r i n g the f i r s t two weeks of 83 l a c t a t ion (Cripps and W i l l i a m s , 1975; S h i r l e y , 1984) i n order to support the growth of the f e t u s e s and a s s o c i a t e d maternal t i s s u e s , and to support the high energy demands of milk p r o d u c t i o n . As expected, the food i n t a k e of e x e r c i s i n g pregnant animals was g r e a t e r than that of sedentary c o n t r o l s . I t appears that e x e r c i s i n g pregnant r a t s compensated, at l e a s t p a r t i a l l y , f o r t h e i r i n c r e a s e d energy expenditure by i n c r e a s i n g t h e i r c a l o r i c i n t a k e . During the l a s t week of pregnancy , however, such compensation was not apparent. A sharp i n c r e a s e i n food intake d u r i n g the l a s t week of pregnancy, which c o i n c i d e s with the r a p i d f e t a l growth o c c u r r i n g at t h i s time, has been noted by o t h e r s ( S h i r l e y , 1984) and o c c u r r e d i n t h i s study (Table V ) . I t i s p o s s i b l e that d e s p i t e the e x e r c i s i n g r a t s ' i n c r e a s e d c a l o r i c requirement at t h i s time, there i s an anatomical l i m i t to the amount of food that they can i n g e s t . E x e r c i s e continued to have a p o s i t i v e though l e s s marked e f f e c t on the food intake of l a c t a t i n g r a t s . T h i s f i n d i n g i s comparable to that of Lederman et a l . (1985) who found the i n t a k e d i f f e r e n c e between e x e r c i s i n g and sedentary r a t s narrowed duri n g l a c t a t i o n as compared to d u r i n g pregnancy. T h i s suggests that there was an attempt to o f f s e t the i n c r e a s e in energy expe n d i t u r e by i n c r e a s i n g c a l o r i c i n t a k e . However, as i n the l a s t week of pregnancy, i t i s p o s s i b l e that there i s a l i m i t to the amount of food that l a c t a t i n g r a t s , 84 whether e x e r c i s i n g or not, are a b l e to consume. T h i s would be t r u e , p a r t i c u l a r l y as l a c t a t i o n progresses and the growing pups increase t h e i r demand f o r m i l k . T h i s l i m i t i s g r e a t e r during l a c t a t i o n than in pregnancy s i n c e d u r i n g l a c t a t i o n , as opposed to i n pregnancy, the a l i m e n t a r y c a n a l p r o g r e s s i v e l y i n c r e a s e s i n weight and s i z e (Cripps and W i l l i a m s , 1975) and the i n t e s t i n a l c e l l u l a r p r o l i f e r a t i o n of the g a s t r o i n t e s t i n a l t r a c t i s s t i m u l a t e d ( F e l l et a l . , 1963) i n order to accommodate an i n c r e a s e d volume of food. Thus, i n the present study, the e f f e c t of e x e r c i s e on food intake was com-parab l e i n v i r g i n , pregnant and l a c t a t i n g r a t s . B) Body Weight Previous r e p o r t s on the e f f e c t of e x e r c i s e on body weight of female nonpregnant r a t s have g e n e r a l l y shown that weight was maintained at c o n t r o l l e v e l s (Mayer, 1954; Oscai et a l . , 1973; Nance et a l . , 1977; Applegate et a l . , 1982; Barr, 1986; Mahle, 1986), although a decrease in body weight has a l s o been repo r t e d (Tokuyama et a l . , 1982). In t h i s study the body weight of e x e r c i s i n g v i r g i n r a t s was s i g n i f i c a n t l y e l e v a t e d i n comparison to that of sedentary c o n t r o l s , c o n s i s t e n t with the f i n d i n g s of Ring et a l . (1970). These discrepenci.es i n the observed e f f e c t s of e x e r c i s e on body weight in female r a t s may r e f l e c t d i f f e r e n c e s i n age, s t r a i n and e x e r c i s e p r o t o c o l s whereby the mode, i n t e n s i t y and d u r a t i o n of the e x e r c i s e bout make 85 comparisons d i f f i c u l t ( P i t t s , 1984). As was observed f o r both e x e r c i s i n g and sedentary mated r a t s i n t h i s study, body weight normally r i s e s throughout g e s t a t i o n (Naismith, 1966; C r i p p s and W i l -li a m s , 1975; S h i r l e y , 1984). In t h i s study, c o n t r a r y to the experimental h y p o t h e s i s , e x e r c i s i n g r a t s gained more weight than t h e i r sedentary c o n t r o l s d u r i n g pregnancy. These f i n d i n g s are i n c o n s i s t e n t with previous s t u d i e s which found e x e r c i s e r s to be s i g n i f i c a n t l y l i g h t e r than sedentary c o n t r o l s ( B a g n a l l et a l . , 1983; Mottola et a l . , 1983). The approximate age and the s t r a i n of these r a t s were the same as i n the present study while the e x e r c i s e p r o t o c o l d i f f e r e d o n l y i n the degree of i n c l i n e of the t r e a d m i l l (18% r a t h e r than 0%). Thus in the s t u d i e s of B a g n a l l et a l . (1983) and M o t t o l a et a l . (1983) the i n t e n s i t y of the e x e r c i s e performed was g r e a t e r . The study of female r a t s by Mayer et a l . (1954) i n d i c a t e d that c a l o r i c i n t a k e i n c r e a s e s with energy expenditure only w i t h i n a c e r t a i n zone or l e v e l of a c t i v i t y . With extreme e x e r c i s e , food intake no longer compensated f o r energy expenditure, and lower body weights were ob-served. I t i s p o s s i b l e that the animals in the present study were e x e r c i s i n g w i t h i n the range where compensa-t i o n occurs, and that animals e x e r c i s i n g more i n t e n s e l y (e.g. B a g n a l l et a l . , 1983 and Mottola et a l . , 1983) were no longer a b l e to compensate, thereby l o s i n g weight. As has been r e p o r t e d elsewhere (Spray, 1950; N a i s -86 mith, 1966; Kanto and Clawson, 1980; R o l l s et a l . , 1984), sedentary mated r a t s had a net gain i n body weight at p a r t u r i t i o n above v i r g i n c o n t r o l l e v e l s . Exer-c i s i n g r a t s , however, showed no net i n c r e a s e i n weight at p a r t u r i t i o n . T h i s f i n d i n g suggests that t h e i r i n -creased energy expenditure prevented the d e p o s i t i o n of maternal s t o r e s . Energy that would have gone i n t o maternal s t o r e s was needed to maintain t h e i r body weight at e x e r c i s i n g or sedentary v i r g i n c o n t r o l l e v e l s . By the second week of l a c t a t i o n , e x e r c i s i n g and sedentary mated r a t s were s i g n i f i c a n t l y h e a v i e r than t h e i r v i r g i n c o n t r o l s . T h i s f i n d i n g i s c o n s i s t e n t with those of Ota and Yokoyama (1967), C r i p p s and W i l l i a m s (1975), and Moore and B r a s e l (1984) in n o n - e x e r c i s i n g r a t s , but c o n t r a r y to those of Spray (1950), Kanto and Clawson (1980), T a y l o r et a l . (1986) and Sainz et a l . (1986), who found t h e i r ( n o n - e x e r c i s i n g ) r a t s l o s t weight d u r i n g the l a c t a t i o n p e r i o d and t h e i r body weights dropped below v i r g i n c o n t r o l l e v e l s . These d i s c r e p e n c i e s i n weight changes d u r i n g l a c t a t i o n may be e x p l a i n e d by d i f f e r e n c e s i n l i t t e r s i z e or, as has been suggested by Sainz et a l . (1986), by the age of the dam. Dams s u c k l i n g l a r g e r l i t t e r s would be expected to produce more milk, thereby expending more energy and having a g r e a t e r tendency to be i n negative energy balance than dams s u c k l i n g s m a l l e r l i t t e r s . However Ota and Yokoyama (1967) found no d i f f e r e n c e i n body weights of dams nursing 2, 4, 8 or 12 pups per l i t t e r . In the 87 s t u d i e s mentioned above where dams inc r e a s e d t h e i r body weight d u r i n g l a c t a t i o n , pups were c u l l e d to 8 (C r i p p s and W i l l i a m s , 1975), 2,4,8 and 12 (Ota and Yokoyama, 1967) and 6 to 10 (Moore and B r a z e l , 1984). Of those that r e p o r t e d l o s s of weight d u r i n g l a c t a t i o n , l i t t e r s were c u l l e d to 8 (Spray, 1950), 12 (Sainz et a l . , 1986; Ta y l o r et a l . , 1986) or were not repor t e d (Kanto and Clawson, 1980). Thus i t appears that l i t t e r s i z e alone does not e x p l a i n the weight d i s c r e p e n c i e s . Sainz et a l . (1986) however, noted that s t u d i e s i n which c o n t r o l dams l o s t body t i s s u e (Kanto and Clawson, 1980; T a y l o r et a l . , 1986), o l d e r r a t s were used than i n those i n which c o n t r o l s maintained or gained weight (Naismith et a l . , 1982; Moore and B r a z e l , 1984). T h i s would be ex p l a i n e d by assuming that a young growing r a t accords l a c t a t i o n a lower p r i o r i t y than a mature r a t s i n c e i t i s s t i l l growing. These assumptions, however, remain to be t e s t e d . The e f f e c t of e x e r c i s e on the body weights of l a c t a t i n g dams i n t h i s study was s i m i l a r to i t s e f f e c t observed i n v i r g i n c o n t r o l s . T h i s f i n d i n g was not ex-pected s i n c e the i n c r e a s e i n the food intake of e x e r c i -s i n g l a c t a t i n g dams was only s l i g h t l y greater than that of sedentary l a c t a t i n g dams. Thus, i n t h i s study, e x e r c i s e during pregnancy and l a c t a t i o n r e s u l t e d i n a s i g n i f i c a n t i n c rease i n body weight. T h i s e f f e c t was comparable to f i n d i n g s i n v i r g i n r a t s although the f i n d i n g s i n v i r g i n r a t s were 88 i n c o n s i s t e n t with most r e p o r t s i n the l i t e r a t u r e . C) Body Composition Fat i s s t o r e d i n a r e l a t i v e l y dehydrated form com-pared to lean body mass, t h e r e f o r e an animal with pro-p o r t i o n a t e l y more f a t w i l l c o n t a i n l e s s water as a percentage of t o t a l c a r c a s s weight. T h i s r e l a t i o n s h i p i s w e l l known (Rathbun and Pace, 1945; Flanagan, 1964) and i s the r a t i o n a l e f o r some of the body composition e s t i m a t o r s . In order to o b t a i n an independent check on the v a l i d i t y of the f a t and water assays i n t h i s e x p e r i -ment, the percent c a r c a s s f a t and water val u e s o b t a i n e d for each of the 80 r a t s was compared ( F i g u r e 8) to a r e g r e s s i o n equation d e r i v e d by Cox et a l . (1985) f o r a p r e c i s e e s t i m a t i o n of percent c a r c a s s f a t from percent c a r c a s s water: % c a r c a s s f a t = 95.96 - 1.72 * % c a r c a s s water T h i s equation was d e r i v e d by Cox et a l . from body compo-s i t i o n data compiled on 373, p r i n c i p a l l y female, r a t s and mice from nine d i f f e r e n t s t u d i e s . The percent c a r -cass f a t of the animals i n t h e i r set of data ranged from 6 to 70 percent. The spread i n percent c a r c a s s f a t f o r a given percent c a r c a s s water was approximately + 5% about the l e a s t squares f i t l i n e . The percent c a r c a s s f a t values o b t a i n e d i n t h i s study were in a more r e -s t r i c t e d range of approximately 2 to 15 p e r c e n t . Our data show a s t r o n g n e g a t i v e c o r r e l a t i o n (r = 0.96) of percent c a r c a s s f a t to percent c a r c a s s water and essen-89 FIGURE 8 Experimental data superimposed on the best fit line of Cox et al. (1985). 90 t i a l l y a l l the data f a l l w i t h i n + 5%, i n percent c a r c a s s f a t , of Cox et a l . ' s equation. C o n s i d e r i n g the d i f f e r -ences between the data from t h i s study (normal, female v i r g i n and postpartum r a t s ) and the data from s t u d i e s compiled by Cox et a l . ( r a t s and mice of both sexes with g e n e t i c or e x p e r i m e n t a l l y produced o b e s i t y , and s e v e r a l m a n i p u l a t i o n s f o r modifying the degree of o b e s i t y ) , the l e v e l of agreement obtained i s s a t i s f a c t o r y and r e p r e -sents a gross independent check on the v a l i d i t y of the f a t and water a s s a y s . 1) V i r g i n Rats As has been r e p o r t e d elsewhere ( O s c a i , l 9 7 3 ; Tokuyama et a l . , 1982; Applegate et a l . , 1982), e x e r c i s e g e n e r a l l y r e s u l t s i n a decrease i n body f a t i n female non-pregnant r a t s . The data i n t h i s study are c o n s i s -tent with these r e p o r t s . 2) Rats at P a r t u r i t i o n The tendency f o r pregnancy to cause an i n c r e a s e i n the d e p o s i t i o n of f a t i n sedentary mated r a t s i n t h i s study i s c o n s i s t e n t with p r e v i o u s r e p o r t s i n pregnant r a t s (Spray, 1950; Naismith, 1966). The data are com-pa r a b l e to that of Kanto and Clawson (1980) who looked at the i n t e r r e l a t i o n s h i p s of body components i n r a t s d u r i n g pregnancy and l a c t a t i o n . They found the percent c a r c a s s f a t of r a t s at p a r t u r i t i o n (13.5 + 0.9 S.E.) to be n o n s i g n i f i c a n t l y g r e a t e r than that of nonpregnant age c o n t r o l s (12.6 + 0.9 S.E.). T h e i r r a t s were of 91 second or l a t e r p a r i t y and t h e r e f o r e probably o l d e r than the r a t s i n the present study. T h i s f a c t may account i n part f o r t h e i r g r e a t e r percent c a r c a s s f a t s i n c e i t i s we l l known that body f a t i n c r e a s e s with age ( P a r i z k o v a , 1977). At p a r t u r i t i o n e x e r c i s i n g mated r a t s had only 60% as much f a t as t h e i r sedentary c o n t r o l s . The i n c r e a s e i n percent ash and water r e f l e c t the concomitant i n -crease i n le a n body mass. T h i s f i n d i n g suggests that e x e r c i s e d u r i n g pregnancy suppresses the f a t accumula-t i o n due. to pregnancy, and i s i n agreement with the hypothesis that r a t s e x e r c i s e d d u r i n g pregnancy have a lower percent body f a t than t h e i r sedentary c o n t r o l s . Further evidence to support e x e r c i s e ' s tendency to suppress body composition changes or f a t accumulation dur i n g pregnancy was pro v i d e d by the f i n d i n g t h at at p a r t u r i t i o n , e x e r c i s i n g mated r a t s had body compositions that d i d not d i f f e r from e i t h e r sedentary or e x e r c i s i n g v i r g i n c o n t r o l s . There are no comparable data i n the l i t e r a t u r e . However, i n a recent a b s t r a c t , Savard et a l . (1985) r e p o r t e d that the i n g u i n a l adipose t i s s u e weight, c e l l s i z e , and l i p o p r o t e i n l i p a s e a c t i v i t y of lean Zucker r a t s e x e r c i s e d i n t e n s e l y (swimming) d u r i n g pregnancy were s i g n i f i c a n t l y lower than those of seden-t a r y pregnant r a t s on day 21 of g e s t a t i o n . These f i n d -ings tend to support those of the present study. 92 3) L a c t a t i n g Rats Both sedentary and e x e r c i s i n g l a c t a t i n g r a t s i n t h i s study c a t a b o l i z e d approximately 50 percent of the body f a t present at p a r t u r i t i o n d u r i n g the two week l a c t a t i o n p e r i o d . T h i s f i n d i n g i s comparable to that of Naismith et a l . (1982) who found that 60 percent of the t o t a l c a r c a s s f a t of (non-exercising) r a t dams had been m o b i l i z e d a f t e r 14 days of l a c t a t i o n . The percent c a r -cass f a t at p a r t u r i t i o n (11.86 + 2.57) and a f t e r two weeks of l a c t a t i o n (5.72 + 1.39) i n sedentary mated r a t s in the present study are c o n s i s t e n t with those of Kanto and Clawson (13.5 + 0.9 S.E. and 6.4 + 1.2 S.E. respec-t i v e l y ) . There are no comparable data i n the l i t e r a t u r e in regard to e x e r c i s e d u r i n g l a c t a t i o n . However i t can be seen (Table XIII) that e x e r c i s e reduced the a l r e a d y d e p l e t e d f a t s t o r e s of e x e r c i s i n g r a t s at p a r t u r i t i o n to a l e v e l which was s i g n i f i c a n t l y lower than e x e r c i s i n g v i r g i n c o n t r o l s (EVL) a f t e r two weeks of l a c t a t i o n . T h i s suggests that l a c t a t i o n and e x e r c i s e were a d d i t i v e in t h e i r e f f e c t on body f a t . As expected, the changes in water content f o l l o w e d a r e c i p r o c a l p a t t e r n to the changes i n f a t c o n t e n t . While sedentary l a c t a t i n g r a t s had s i g n i f i c a n t l y l e s s percent c a r c a s s ash than t h e i r v i r g i n c o n t r o l s , e x e r c i s i n g l a c t a t i n g r a t s had a s i g n i -f i c a n t decrease i n both percent c a r c a s s ash and p r o t e i n . While these f i n d i n g s might suggest that the a d d i t i o n a l s t r e s s of e x e r c i s e d u r i n g l a c t a t i o n compromised lean body growth, an examination of the a c t u a l ash and pro-93 t e i n content of the animals at p a r t u r i t i o n and l a c t a t i o n do not support t h i s c o n c l u s i o n . The ash and p r o t e i n c o n t e n t s of e x e r c i s i n g r a t s were c o n s i s t e n t l y g r e a t e r than that of t h e i r sedentary c o n t r o l s , and represent a p o r t i o n of the i n c r e a s e i n t h e i r lean body mass (the remainder being accounted f o r by the i n c r e a s e i n c a r c a s s water). In a d d i t i o n , the ash and p r o t e i n c o n t e n t s of mated r a t s at l a c t a t i o n (SML and EML) were g r e a t e r than that of t h e i r r e s p e c t i v e mated r a t s at p a r t u r i t i o n (SMP and EMP). T h i s net i n c r e a s e i n t o t a l p r o t e i n from p a r t u r i t i o n to l a c t a t i o n was not d i f f e r e n t between sedentary and e x e r c i s i n g r a t s . Thus i t appears that lean body t i s s u e was not c a t a b o l i z e d as an energy source for l a c t a t i o n , or e x e r c i s e d u r i n g l a c t a t i o n . The lower percent c a r c a s s ash and p r o t e i n may however r e f l e c t some compromise i n the r a t e of growth of the lean body mass. D) Pregnancy Outcome and L a c t a t i o n Performance Moderately strenuous a e r o b i c e x e r c i s e d i d not ap-pear to a f f e c t pregnancy outcome. T h i s f i n d i n g i s con-s i s t e n t with p r e v i o u s r e p o r t s of pregnant r a t s t r a i n e d p r i o r to and e x e r c i s e d d u r i n g pregnancy at e i t h e r m i l d ( P a r i z k o v a , 1977; Mottola et a l . 1983) or strenuous ( B a g n a l l et a l . , 1983; M o t t o l a et a l . , 1984; M o t t o l a et a l . , 1986) l e v e l s . The l a c t a t i o n performance of r a t s doing moderately strenuous a e r o b i c e x e r c i s e d u r i n g both pregnancy and l a c t a t i o n was not compromised. While no a d d i t i o n a l 94 depot f a t was l a i d down du r i n g pregnancy, a v a i l a b l e body f a t was metabolized to at l e a s t p a r t i a l l y s u b s i d i z e the energy c o s t of l a c t a t i o n . In terms of o v e r a l l energy balance, the f i n d i n g i n t h i s study that e x e r c i s i n g r a t s g e n e r a l l y i n c r e a s e d t h e i r body weight above that of sedentary c o n t r o l s was not expected. Values c a l c u l a t e d f o r the CEC of the r a t s (Table XIV) r e v e a l that the e x e r c i s e d animals tended to have lower body energy contents d e s p i t e t h e i r i n c r e a s e d food intake and heavier weights. T h i s f i n d i n g empha-s i z e s t hat body weight alone i s not n e c e s s a r i l y a v a l i d index on which to base comparisons of energy balance i n s t u d i e s of e x e r c i s e d versus sedentary animals. The decrease in percent c a r c a s s f a t appeared to be of s u f f i -c i e n t magnitude to lower the c a r c a s s energy content, and the concomitant i n c r e a s e in percent lean body mass was r e f l e c t e d by the d e t e c t a b l e i n c r e a s e i n body weight. Previo u s s t u d i e s have demonstrated that r a t s subjected to endurance e x e r c i s e have a g r e a t e r l e a n body mass than sedentary c o n t r o l s of the same body weight (Crews et a l . , 1969), and that t h i s i s not due to hypertrophy of the muscles d i r e c t l y i n v o l v e d i n the e x e r c i s e ( H o l l o s z y , 1967). D e t a i l e d body composition a n a l y s i s on female r a t s s u b j e c t e d to a program of swimming (Oscai et a l . , 1973) found that the organs, abdominal c o n t e n t s , and the e v i s e r a t e d c a r c a s s made the major c o n t r i b u t i o n s to the i n c r e a s e d lean body mass of the swimmers. 95 In c o n c l u s i o n , the e f f e c t of moderately strenuous a e r o b i c e x e r c i s e d u r i n g pregnancy and l a c t a t i o n on food i n t a k e , body weight and body composition was comparable to the e f f e c t of e x e r c i s e i n v i r g i n r a t s . The increase i n food i n t a k e of e x e r c i s e d r a t s above sedentary l e v e l s appeared to be a response to the i n c r e a s e i n energy e x p e n d i t u r e . However near the end of pregnancy, and as l a c t a t i o n progressed, when the energy demands on the r a t dams were at or n e a r i n g t h e i r peak, t h e i r a b i l i t y to i n c r e a s e t h e i r food i n t a k e may have been p h y s i c a l l y l i m i t e d by t h e i r g a s t r o i n t e s t i n a l t r a c t ' s c a p a c i t y . The unexpected i n c r e a s e i n body weight of v i r g i n and mated e x e r c i s i n g r a t s when compared to t h e i r sedentary c o n t r o l s was accounted f o r by an i n c r e a s e i n t h e i r l e a n body mass. As expected, e x e r c i s e r e s u l t e d in a decrease in percent body f a t i n a l l r a t s which was r e f l e c t e d i n t h e i r lower c a r c a s s energy content. Exer-c i s e d u r i n g pregnancy prevented the i n c r e a s e i n the d e p o s i t i o n of body f a t normally found at t h i s time. D e s p i t e these d e p l e t e d f a t s t o r e s , e x e r c i s i n g l a c t a t i n g dams m o b i l i z e d the same percentage of f a t as sedentary c o n t r o l s . Thus e x e r c i s e and l a c t a t i o n were a d d i t i v e i n t h e i r e f f e c t on f a t s t o r e s . Since normal pup growth was not a f f e c t e d by maternal e x e r c i s e , i t was concluded that the energy s u p p l i e d by the m o b i l i z a t i o n of reduced f a t s t o r e s and the l i m i t e d i n c r e a s e i n food intake were adequate to support the energy c o s t of l a c t a t i o n . 96 BIBLIOGRAPHY Applegate, E.A., Upton, D.E., and S t e r n , J.S. Food i n t a k e , body composition and blood l i p i d s f o l l o w i n g t r e a d m i l l e x e r c i s e i n male and female r a t s . P h y s i o l . Behav. 28(5):917-920, 1982. A t k i n s o n , T., Fowler,V.R., Garton, G.A., and Lough, A.K. A r a p i d method f o r d e t e r m i n a t i o n of l i p i d i n animal t i s s u e s . A n a l y s t 97:562-568, 1972. A r t a l , R. and Gardin, S.K. Chapter 1: H i s t o r i c a l P e r s p e c t i v e s . In: E x e r c i s e i n Pregnancy. ( A r t a l , R. and Wiswell, R. edsTl pp. 1-6. W i l l i a m s and W i l k i n s , B a l t i m o r e , 1985. B a g n a l l , K.M., M o t t o l a , M.F., and McFadden, K.D. The e f f e c t s of strenuous e x e r c i s e on maternal r a t s and t h e i r d e v e l o p i n g f e t u s e s . Can. J . Appl. Sport S c i . 8(4) :254-259, 1983. B a r r , S.I. E f f e c t of i n c r e a s i n g c o n c e n t r a t i o n s of etha-nol on growth, food and water i n t a k e , and wheel-running of female Sprague-Dawley r a t s . Manuscript submitted, 1986. Bedford, T.G., T i p t o n , CM., Wilson, N.C., O p p l i g e r , R., and G i s o l f i , C.V. Maximum oxygen consumption of r a t s and i t s changes with v a r i o u s experimental procedures. J . Appl. P h y s i o l . 47(6) :1278-1283, 1979. Blackburn, M.W. and Calloway, D.H. Energy expenditure and consumption of mature pregnant and l a c t a t i n g women. J . Am. D i e t . Assoc. 69:29-37, 1976. Brooks, G.A. and White, T.P. D e t e r m i n a t i o n of metabolic and heart r a t e reponses of r a t s to t r e a d m i l l e x e r c i s e . J.Appl. P h y s i o l . 45(6) :1009-1015, 1978. Butte, N.F., Garza, C , S t u f f , J.E., O'Brian Smith, E., and N i c h o l s , B.L. E f f e c t of maternal d i e t and body composition on l a c t a t i o n a l performance. Am. J . C l i n .  Nutr. 39:296-306, 1984. Clapp, J.F. and D i c k s t e i n , S. Endurance e x e r c i s e and pregnancy outcome. Med. S c i . Sports Exerc. 16(6):556-562, 1984. C o l l i n g s , C.A., Curet, L.B. and M u l l i n , J.P. Maternal and f e t a l responses to a maternal a e r o b i c e x e r c i s e program. Am. J . Obstet. Gynecol. 145(6):702-707, 1 983. 97 Cox, J.E., Laughton, W.B. and Powley, T.L. P r e c i s e e s t i m a t i o n of c a r c a s s f a t from t o t a l body water in r a t s and mice. P h y s i o l . Behav. 35(6):905-910, 1985. Crews, E.L.,111, Fuge, K.W., O s c a i , L.B., H o l l o s z y , J.O. and Shank, R.E. Weight, food i n t a k e , and body composition: e f f e c t s of e x e r c i s e and of p r o t e i n d e f i -c i e n c y . Amer. J . P h y s i o l . 216:359, 1969. C r i p p s , A.W., and W i l l i a m s , V . J . The e f f e c t of pregnancy and l a c t a t i o n on food i n t a k e , g a s t r o i n t e s t -i n a l anatomy and the a b s o r p t i v e c a p a c i t y of the small i n t e s t i n e in the a l b i n o r a t . Br. J . Nutr. 33:17-32, 1 975. Csapo, A.I., P u l k k i n e n , M.O., Ruttner, B., Sauvage, J.P. and Wiest, W.G. The s i g n i f i c a n c e of the human corpus luteum i n pregnancy maintenance. I: P r e l i m i n a r y s t u -d i e s . Am. J . O b s t e t . Gynecol. 112:1061-1067, 1972. Dale, E., M u l l i n a x , K.M. and Bryan, D.H. E x e r c i s e d u r i n g pregnancy: e f f e c t s on the f e t u s . Can. J .  Appl. Sport S c i . 7(2):98-l03, 1982.. Dempsey, J.A. A n t h r o p o m e t r i c a l o b s e r v a t i o n s on obese and nonobese young men undergoing a program of v i g o r -ous p h y s i c a l e x e r c i s e . Res. Quart. 35:275-287, 1964. D i b b l e e , L. and Graham, T. 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 compostion, and energy intake i n p r i m i g r a v i d p a t i e n t s . Am. J .  Obstet. Gynecol. 147(8):908-914, 1983. Drinkwater, B.L. Women and E x e r c i s e : P h y s i o l o g i c a l Aspects. In: E x e r c i s e and Sports Science Reviews, ACSM s e r i e s , pp. 21-51, V o l . 12, 1984. F e l l , B.F., Smith, K.A. and Campbell, R.M. Hypertropic and h y p e r p l a s t i c changes i n the a l i m e n t a r y canal of the l a c t a t i n g r a t . J . P a t h o l . B a c t e r i o l . 85:179-188, 1 963. Field-Zimmer, K.L. and M i l e s , J.E. D i e t a r y intakes of pregnant women. J . Cdn. D i e t . Assoc. 41(4):300-308, 1 980. Flanagan, B. The r e l a t i o n of t o t a l body water to lean body mass d u r i n g pregnancy i n the r a t . C l i n . S c i . 27:335-340, 1964. Forbes, G.B. Some i n f l u e n c e s on lean body mass: exer-c i s e , androgens, pregnancy and food. In: D i e t and  E x e r c i s e : Synergism i n H e a l t h Maintenance. (White, P.L. and Mondeika, T., eds.) pp.75-79. Am. Med. Assoc., 1 982. 98 Forbes, G.B. Body composition as a f f e c t e d by p h y s i c a l a c t i v i t y and n u t r i t i o n . Fed. Proc. 44(2):343-347, 1985. Forbes, G.B. and Welle, S. Lean body mass in o b e s i t y . I n t . J . Obesity 7: 99-107, 1983. Fukomoto, H., and Chang, G.W. Manual s a l i c y l a t e -h y p o c h l o r i t e procedure f o r d e t e r m i n a t i o n of ammonia in K j e l d a h l d i g e s t s . J . Assoc. O f f . A n a l . Chem. 65(5):1076-1079, 1982. G e t c h e l l , L.H. and Moore J.C. P h y s i c a l t r a i n i n g : c o m paritive responses of middle-aged a d u l t s . Arch.  Phys. Med. R e h a b i l . 56:250-254, 1975. G i r a n d o l a , R.N. Body compo s i t i o n changes in women: e f f e c t s of high and low e x e r c i s e i n t e n s i t y . Arch.  Phys. Med. R e h a b i l . 57:297-300, 1976. Hartsook, E.W. and Hershberger, T.V. A s i m p l i f i e d method for sampling s m a l l animal c a r c a s s e s f o r a n a l y s e s . Soc. Exp. B i o l . Med. 113:973-977, 1963. H e a l t h and Welfare Canada. Recommended N u t r i e n t Intakes  f o r Canadians. (Bureau of N u t r i t i o n a l Sciences Food D i r e c t o r a t e , H e a l t h P r o t e c t i o n Branch, Dept. of N a t l . Health and W e l f a r e ) . Ottawa: Information Canada, 1 983. H o l l o s z y , J.O. B i o c h e m i c a l a d a p t a t i o n s i n muscle. E f f e c t s of e x e r c i s e on m i t o c h o n d r i a l oxygen uptake and r e s p i r a t o r y enzyme a c t i v i t y i n s k e l e t a l muscle. J . B i o l . Chem. 242: 2278, 1967. Hug, C C . and Murphy, M.R. T i s s u e r e d i s t r i b u t i o n of f e n t a n y l and d e t e r m i n a t i o n of i t s e f f e c t s i n r a t s . A n e s t h e s i o l o g y 55: 369-375, 1981. Hytten, F.E. and L e i t c h , I. The Physiology of Human Pregnancy. 2nd. ed. pp. 333-369. B l a c k w e l l S c i e n t i f i c P u b l i c a t i o n s , Oxford, 1971. J a r r e t t , J.C. and S p e l l a c y , W.N. Jogging d u r i n g pregnancy: an improved outcome? Obstet. Gynecol. 61(6) : 705-709, 1983. Kanto, U. and Clawson, A.J. E f f e c t of energy i n t a k e d u r i n g pregnancy and l a c t a t i o n on body composition i n r a t s . J . Nutr. 110:1829-1839, 1980. Karasawa, K., Suwa, J . , and Kimura, S. V o l u n t a r y e x e r c i s e during pregnancy and l a c t a t i o n and i t s e f f e c t on l a c t a t i o n a l performance in mice. J . Nutr.  S c i . V i t a m i n o l . 27: 333-339, 1981. 99 Karvonen, M.J., Pekkarinen, M. , Metsala, P., and Rautanen, Y. D i e t and serum c h o l e s t e r o l of lumberjacks. B r i t . J . Nutr. 15: 157-164, 1961. Kaufman, D.A. and H a l l , D.C. E f f e c t s of p h y s i c a l c o n d i t i o n i n g on h e a l t h of pregnant women and t h e i r o f f s p r i n g . Med. S c i . Sports Exer. 17(2): 215, 1985. ( a b s t r a c t ) Klopper, A. and B i l l e w i c z , W. U r i n a r y e x c r e t i o n of o e s t r i o l and pr e g n a n e d i o l d u r i n g normal pregnancy. J . Obstet. Gynaecol. Br. Cwlth. 70: 1024-1033, 1963. Knopp, R.H., Saudek, CD., Arky, R.A., and O ' S u l l i v a n , J.B. Two phases of adipose t i s s u e metabolism i n pregnancy: maternal a d a p t a t i o n s f o r f e t a l growth. Endo. 92: 984-988, 1973. Kulpa, P., White, B., V i s s c h e r , R., DeWeese, M. , Hiemenga, J . , T a y l o r , S. and Zeh, M. P r o s p e c t i v e data on moderate e x e r c i s e d u r i n g pregnancy - f e t a l outcome, maternal weight and course of l a b o r . Med.  S c i . Sports Exer. 18(2): 546, 1986. ( a b s t r a c t ) Lederman, S.A., Cat o r , P. and Treadway, J.L. The e f f e c t s of e x e r c i s e t r a i n i n g d u r i n g pregnancy on maternal body composition and o f f s p r i n g growth i n we l l fed and food r e s t r i c t e d r a t s . Fed. Proc. 44(4): 1280, 1985. ( a b s t r a c t ) L o t g e r i n g , F.K. G i l b e r t , R.D., and Longo, L.D. Maternal and f e t a l responses to e x e r c i s e during pregnancy. P h y s i o l . Rev. 65(1) : 1-36, 1985. Mahle, CD., Tejwani, G.A., H a n i s s i a n , S.H., G i r t e n , B., Dernbach, A., and Merola, A.J. The e f f e c t of long term a e r o b i c e x e r c i s e on weight g a i n , food and water i n t a k e , heart r a t e and blood pressure i n Zucker r a t s . Fed. Proc. 45(3): 616, 1986. ( a b s t r a c t ) Manning-Dalton, C , and A l l e n , L.H. The e f f e c t s of l a c t a t i o n on energy and p r o t e i n consumption, postpartum weight change and body composition of w e l l nourished North American women. Nutr. Res. 3(3): 293-308, 1983. Mayer, J . , M a r s h a l l , N.B., V i t a l e , J . J . , C h r i s t e n s e n , J.H., Mashayekhi, M.B., and St a r e , F.J. E x e r c i s e , food intake and body weight i n normal r a t s and g e n e t i c a l l y obese a d u l t mice. Am. J . P h y s i o l . 177: 544-548, 1954. 1 00 Mayer, J . , Roy, P., and M i t r a , K.P. R e l a t i o n between c a l o r i c i n t a k e , body weight, and p h y s i c a l work: s t u d i e s i n an i n d u s t r i a l male p o p u l a t i o n i n West Bengal. Am. J . C l i n . Nutr. 4 ( 2 ) : 169-175, 1956. Moore, B.J. and B r a s e l , J . One c y c l e of r e p r o d u c t i o n c o n s i s t i n g of pregnancy, l a c t a t i o n or no l a c t a t i o n , and recovery: e f f e c t s on f a t pad c e l l u l a r i t y i n ad-l i b i t u m fed and f o o d - r e s t r i c t e d r a t s . J . Nutr. 114 (9): 1560-1565, 1984. Mot t o l a , M.F., B a g n a l l , K.M., and Barker, P.A. E f f e c t s of strenuous maternal e x e r c i s e on the f e t o p l a c e n t a l u n i t on day 20 i n r a t s . Med. S c i . Sp o r t s Exer. 18(2): 551, 1986. ( a b s t r a c t ! M o t t o l a , M., B a g n a l l , K.M., and McFadden, K.D. The e f f e c t s of maternal e x e r c i s e on d e v e l o p i n g r a t f e t u s e s . B r i t . J . Sports Med. 17(2): 117-121, 1983. Mot t o l a , M.F., F o s t e r , J . , B a g n a l l , K.M. and McFadden, K.D. E f f e c t s of strenuous maternal a e r o b i c e x e r c i s e on f e t a l organ weights. Med. S c i . Sp o r t s Exer. 16(2): 157, 1984. ( a b s t r a c t ! Nagy, L.E. and King, J.C. Energy expenditure of pregnant women at r e s t or walking s e l f - p a c e d . Am. J .  C l i n . Nutr. 38: 369-376, 1983. Naismith, D.J. The requirement f o r p r o t e i n , and the u t i l i z a t i o n of p r o t e i n and c a l c i u m d u r i n g pregnancy. Metab. 15(7): 582-595, 1966. Naismith, D.S. Endocrine f a c t o r s in the c o n t r o l of n u t r i e n t u t i l i z a t i o n i n pregnancy. In: Maternal  N u t r i t i o n d u r i n g Pregnancy and L a c t a t i o n " (Aebi, H. and Whitehead, R. eds.) pp. 16-26. Hans Huber P u b l i s h e r s , Bern, 1979. Naismith, D.J., Richardson, D.P., and P r i t c h a r d , A.E. The u t i l i z a t i o n of p r o t e i n and energy d u r i n g l a c t a t i o n i n the r a t , with p a r t i c u l a r r e g ard to the use of f a t accumulated i n pregnancy. Br. J . Nutr. 48: 433-441, 1982. Nance, D.M., Bromley, B., Barnard, R.J., and G o r s k i , R.A. S e x u a l l y dimorphic e f f e c t s of f o r c e d e x e r c i s e on food i n t a k e and body weight i n the r a t . P h y s i o l . Behav. 19(1): 155-158, 1977. Nelson, P.S., G i l b e r t , R.D. and Longo, L.D. F e t a l growth and 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 i n guinea p i g s f o l l o w i n g long-term maternal e x e r c i s e . J . Dev.  P h y s i o l . 5(1): 1-10, 1983. 101 Nie, N.H. SPSSx User's Guide, McGraw-Hill Book Company, New York, 1983. Oliva-Rasbach, J . , Casey, C.E., N e v i l l e , M.N., Hambidge, K.M., and L u t e s , V.S. Energy intake and weight change d u r i n g the f i r s t year of l a c t a t i o n : a l o n g i t u d i n a l study. Fed. Proc. 44(5): 1675, 1985. ( a b s t r a c t ) Ota, K. and Yokoyama, A. Body weight and food con-sumption of l a c t a t i n g r a t s n u r s i n g v a r i o u s s i z e s of l i t t e r s . J . Endocr. 38: 263-268, 1967. O s c a i , L.B. The r o l e of e x e r c i s e i n weight c o n t r o l . In: E x e r c i s e and Sport Sciences Reviews, V o l . 1 (Wilmore, J.H., e d . ) , pp 103-123, Academic Press Inc., New York, 1973. O s c a i , L.B., Mole, P.A., Krusack, L.M. and H o l l o s z y , J.O. D e t a i l e d body composition a n a l y s i s on female r a t s s u b j e c t e d to a program of swimming. J . Nutr. 103:412-418, 1973. P a r i z k o v a , J . Body f a t and p h y s i c a l f i t n e s s , pp. 24-51 Martinus N i j h o f f B. V., The Hague, 1977. P a r i z k o v a , J . and Petrasek, R. The impact of d a i l y work load d u r i n g pregnancy on l i p i d metabolism i n the l i v e r of the o f f s p r i n g . Eur. J . Appl. P h y s i o l . 39: 81-87, 1978. P i t t s , G.C. Body composition i n the r a t : i n t e r a c t i o n s of e x e r c i s e , age, sex, and d i e t . Am. J . P h y s i o l . 246(4): R495-R501, 1984. Rathbun, E.N. and Pace, N. S t u d i e s i n body comp o s i t i o n . I. The d e t e r m i n a t i o n of t o t a l body f a t by means of the body s p e c i f i c g r a v i t y . J . B i o l . Chem. 158:667, 1 945. Ring, G.C, Bosch, M. , and Lo, C. E f f e c t s of e x e r c i s e on growth, r e s t i n g metabolism, and body composition of F i s c h e r r a t s . Soc. Exp. B i o l . Med. 133:1162-65, 1970. R o l l s , B.S., van Duijvenvoorde, P.M. and Rowe, E.A. E f f e c t s of d i e t and o b e s i t y on body weight r e g u l a t i o n d u r i n g pregnancy and l a c t a t i o n i n the r a t . P h y s i o l .  Behav. 32(2):161 - 168 , 1984. Sainz, R.D., C a l v e r t , C C and Baldwin, R.L. R e l a t i o n -s h i p s among d i e t a r y p r o t e i n , feed intake and changes in body and t i s s u e composition of l a c t a t i n g r a t s . J . Nutr. 116: 1529-1539, 1986. 1 02 Savard, R., Palmer, J.E., Raley, S., and Greenwood, M.R.C. The e f f e c t s of endurance e x e r c i s e t r a i n i n g on a d i p o s i t y and f e t a l development i n lean pregnant r a t s . Fed. Proc. 44(4): 1280, 1985. ( a b s t r a c t ) Shepherd, R.E. and G o l l n i c k , P.D. Oxygen Uptake of r a t s at d i f f e r e n t work i n t e n s i t i e s . P f l u q e r s A r c h . 362:219-222, 1976. S h i r l e y , B. The food intake of r a t s d u r i n g pregnancy and l a c t a t i o n . Lab. A n i . S c i . 34(2): 169-172, 1984. Smith, D.P. and Stransky, F.W. The e f f e c t of t r a i n i n g and d e t r a i n i n g on the body composition and c a r d i o v a s c u l a r response of young women to e x e r c i s e . J . Sports Med., 16: 112-120, 1976. Spray, C M . A study of some aspects of r e p r o d u c t i o n by means of chemic a l a n a l y s i s . Br. J . Nutr. 4: 354-360, 1950. Taggart, N.R., H o l l i d a y , R.M., B i l l e w i c z , W.Z., Hytten, F.E. and Thomson, A.M. Changes i n s k i n f o l d s d u r i n g pregnancy. B r i t . J . Nutr. 21: 439-451, 1967. Ta y l o r , J.B., C a l v e r t , C.C>, Baldwin, R.L. and Sainz, R.D. E f f e c t s of d i e t a r y p r o t e i n , f a t and r e s t r i c t i o n on body composition and energy balance i n l a c t a t i n g r a t s . J . Nutr. 116: 1519-1528, 1986. 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 b efore 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. T e r a t o l o g y 10: 141-144, 1974. Tokuyama, K., S a i t o , M. , and Okuda, H. E f f e c t s of wheel running on food intake and weight g a i n of male and female r a t s . P h y s i o l . Behav. 28(5): 899-903, 1982. Treadway, J.L. and Lederman, S.A. The e f f e c t s of e x e r c i s e t r a i n i n g on milk composition i n r a t s . Fed.  Proc. 44(5): 1'675, 1985. ( a b s t r a c t ) Tremblay, A., Despres, J . , and Bouchard, C. The e f f e c t s of e x e r c i s e - t r a i n i n g on energy balance and adipose t i s s u e morphology and metabolism. Sp o r t s Med. 2(3): 223-233, 1985. Wilmore, J.H. Body composition i n sp o r t and e x e r c i s e : d i r e c t i o n s f o r f u t u r e r e s e a r c h . Med. S c i . Sports  Exer. 15(1): 21-31 , 1983. 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 pregnancy. J . A p p l i e d P h y s i o l . 4: 34-40, 1980. 1 03 Wong, S.C. and McKenzie, D.C. F i t n e s s and pregnancy. Med. S c i . Sports Exer. 17(2):208, 1985. ( a b s t r a c t ) Woo, R., Garrow, J.S. and Pi-Sunyer, F.X. V o l u n t a r y food i n t a k e d u r i n g prolonged e x e r c i s e i n obese women. Am. J . C l i n . Nutr. 36: 478-484, 1982. Woo, R. and Pi-Sunyer, F.X. E f f e c t of i n c r e a s e d p h y s i c a l a c t i v i t y on v o l u n t a r y intake i n lea n women. Metabolism 34(9): 836-841, 1985. Worthington-Roberts, B.S., Vermeersch, J . , and W i l l i a m s , S.R. N u t r i t i o n i n pregnancy and l a c t a t i o n . 3rd ed., pp. 140~! Times Mirror/Mosby C o l l e g e P u b l i s h i n g , St L o u i s , 1985. 1 04 

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
https://iiif.library.ubc.ca/presentation/dsp.831.1-0096869/manifest

Comment

Related Items