Emotionality changes in rats following chronic exercise.

The effect of chronic endurance exercise on the emotionality of male albino rats was studied in five experimental groups: Controls, Runners, Walkers, Swimmers and Waders. Runners and Swimmers were trained for 8 weeks using programs which produced significant bradycardia and cardiac hypertrophy. Walkers and Waders received comparable handling and exposure to the psychological aspects of the treadmill running and swimming routines but were not physically trained. The Control group was allowed only home cage activity. After 8 weeks all animals were tested for their level of emotionality using the tunnel emergence test and the open field test. The emergence test was judged to be too stressful for the Sasco rat strain used in this study since many rats failed to emerge in one hour. Three measurements in the open field: urination, defecation and central squares also lacked power to discriminate emotionality because of their very low level of occurrence. The Control rats had significantly longer latency times, which indicates that the additional handling received by the other groups reduced their emotionality. The significantly larger number of total squares entered by the Runners and Swimmers supports the hypothesis that chronic physical exercise does function to lower emotionality in the rat.