Persisting changes in the 24-hour profile of locomotor activity by daily activity restriction in rats

Male Wistar rats were acclimated to cages with running wheels. Then, the running time of rats were limited to the last 3 (WR3) or 6 (WR6) h of the dark phase. After a 2-week activity restriction, the rats were again allowed access to the wheel freely. In the WR3 or WR6, wheel revolutions for the last 3 or 6 h of the dark phase was significantly greater after the activity restriction than before. The results suggest that, in rats, voluntary running limited to a fixed time daily alters the distributions of locomotor activity in a day, i.e., running activity increases during the period when the rats had been previously allowed to exercise.