Neither high- nor low-intensity exercise promotes whole-body conservation of protein during severe dietary restrictions.
The effects of 11 weeks of severe dietary restriction alone or in combination with either high- or low-intensity exercise on conservation of protein were studied in 32 male Sprague-Dawley rats. The rats were assigned to one of four groups: sedentary control (C), diet restriction alone (DO) or diet restriction in combination with either high-intensity (HI) or low-intensity (LO) exercise. The groups trained at either 75 percent (HI) or 37.5 percent (LO) of maximal running speed for up to 45 or 90 min/day, 5 days/week, respectively. Total (g) proteins, fat, water and ash content did not differ between the DO, HI and LO groups and were all reduced significantly in comparison to C. Similarly, heart, gastrocnemius muscle and epididymal fat pad masses were significantly reduced for the DO, HI and LO groups in comparison to C. However, the absolute decrease in heart mass was reduced for the HI group (heart mass = 0.31 percent of body mass) in comparison to the DO group (heart mass = 0.28 percent of body mass). Thus, in lean rats undergoing severe dietary restrictions, neither high- nor low-intensity exercise appears to affect total protein conservation in comparison to diet alone. However, high-intensity exercise training appears to attenuate cardiac but not skeletal muscle mass loss in the face of severe dietary restriction.
Ballor
D L
DL
Physical Education and Dance, University of Wisconsin-Madison 53706.
Smith
D B
DB
Tommerup
L J
LJ
Thomas
D P
DP
D000818:Animals; D001823:Body Composition / Q000502:physiology*; D004038:Diet, Reducing / Q000009:adverse effects*; D008297:Male; D024510:Muscle Development; D010805:Physical Conditioning, Animal; D011506:Proteins / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains
D011506:Proteins