Exercise changes behaviour

1. Exercise, which may be defined as bodily movement produced by the contraction of skeletal muscle and which increases energy expenditure above basal levels, is essential for fitness-related activities such as foraging, migration, and dispersal. The frequency with which individuals engage in exercise depends on a range of intrinsic and environmental factors. Exercise itself can modify behaviour by inducing endocrine changes and by a training effect that increases physiological capacities. 2. Here we test the hypothesis that exercise changes behaviour, and that there is positive feedback so that performing exercise increases the likelihood of performing exercise-related behaviours. 3. We show that there was a training effect that improved sustained swimming performance of mosquitofish (Gambusia holbrooki) exposed to chronic exercise in flowing water for four weeks compared to sedentary controls. Exercised fish also became bolder and were quicker to leave a refuge, showed an increasing t...