AJP - Regulatory, Integrative and Comparative Physiology, Vol 256, Issue 4 886-R891, Copyright © 1989 by American Physiological Society
Effects of exercise-rest cycles on energy balance in rats
D. Richard, P. Lachance and Y. Deshaies
Department de Physiologie, Faculte de Medecine, Universite Laval, Quebec City, Canada.
The present study investigated the nutritional energetics of rats exercised
either intermittently or continually. Male rats were divided into three
groups: a sedentary group, an intermittently trained group, and a
continually trained group. Continually trained rats were exercised every
day for a period of 8 wk. Over the same period, intermittently trained rats
were exercised for 4 wk, each week being followed by a week of rest. Rats
were trained on a rodent treadmill at a moderate intensity. Carcasses were
analyzed for energy, fat, and protein contents. Brown adipose tissue (BAT)
thermogenesis was assessed by measuring mitochondrial guanosine
5'-diphosphate binding. Energy intake was lower in both intermittently and
continually trained rats than in sedentary animals. The weight, fat, and
protein gains were, in continually trained rats, significantly lower than
in sedentary animals. Similarly, intermittently trained rats had lower
gains than sedentary animals, although the difference between the two
groups was not as marked as the difference between sedentary and
continually trained animals. Energy expenditure, which represents the
difference between energy intake and energy gain, was less than sedentary
controls in both intermittently and continually trained rats. The low
expenditure in trained groups did not, however, relate to changes in
facultative BAT thermogenesis.A low energy expenditure on components such
as basal metabolic rate and obligatory diet-induced thermogenesis would
most likely account for the difference in expenditure between sedentary and
trained rats.(ABSTRACT TRUNCATED AT 250 WORDS)
