The effect of exercise training on energy balance in the laboratory rat
The effect of training by moderate intensity treadmill running and spontaneous wheel exercise on metabolizable energy intake, resting oxygen consumption, thermic effect of food and energy expenditure excluding the cost of exercise (the latter calculated from energy balance determinations) was investigated. The two training regimes had different effects on energy intake The spontaneous wheel exercise training regime resulted in an increase in metaholizab1e energy intake following correction for metabolic body size compared to sedentary controls. However, no increase in metabolizable energy intake relative to sedentary controls was noted in treadmill trained rats, possibly reflecting the differing degrees of stress associated with the two training regimes. Both training regimes resulted in a decrease in energy expenditure excluding the cost of exercise compared with sedentary controls. This reduction in energy expenditure was not found to be a long term adaptation and was not thought to be due to a decrease in resting oxygen consumption. A reduction in interscapular brown adipose tissue cytochrome oxidase activity in the spontaneous wheel exercise - trained rats suggested that brown adipose tissue regulatory thermogenesis may have been depressed. Down regulation of brown adipose tissue -adrenoreceptors was not observed in the spontaneous wheel exercise-trained rats, suggesting that -adrenergic stimulation of brown adipose tissue was not of the magnitude previously reported in cold exposed rats.
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