Determining the range of aerobic exercise on a treadmill for male Wistar rats at different ages: A pilot study

The purpose of this study was to investigate the range of aerobic exercise on a treadmill for male Wistar rats at different ages. Twelve male Wistar rats were divided to three groups of immature, adult, and old (n= four in each). In the first session, the rats began to run at a rate of 2 m/min to perform the fatigue test, and the treadmill speed increased by 2 m/min every 2 minutes. The process of acceleration continued until the rats were no longer able to continue moving on the treadmill and were exhausted. Then, the blood lactate of each subject was measured immediately and their maximum speed was recorded. After 48 hours of recovery, the subjects performed maximum recorded speed on a treadmill in three 10-minute steps of 25%, 50% and 75%, respectively. Immediately after each step, the blood lactate was measured and recorded. Immature rats at an average speed of 18 m/min reached to their maximum speed with an average lactate concentration of 8±1.8 mmol/l, the adult rats at an average speed of 36 m/min reached to their maximum speed with an average lactate concentration of 6.8±0.4 mmol/l while the old rats reached to their maximum velocity with an average of 30 m/min and an average lactate concentration of 6.95±0.9 mmol/l. Therefore, it is recommended that aerobic exercise start at low speed for untrained rats, i.e. 25% of their maximum speed, which is lower than the lactate threshold, and gradually increase up to 50% of their maximum speed.