Effects of training and age on VO2max in laboratory rats.

To study the effects of training and aging on aerobic capacity, 8-wk-old female Wistar rats were assigned to training and sedentary, free-eating control groups (N = 10, each). Training involved 5 wk of daily progressive treadmill running reaching an intensity of 26.8 m . min-1 on 15% grade for 1 h. Training was maintained at this intensity for an additional 11 wk. The VO2max of trained and sedentary control rats was assessed every 2 wk. Peak VO2max (25.4 +/- 3.2 ml . min-1; X +/- SEM) was observed in the trained group at 20 wk of age and represented a 15% increase over the untrained group. When expressed on a relative basis, the peak VO2max in trained rats at 20 wk of age was 86.6 +/- 8.6 ml . kg-1 . min-1, or an 8% improvement compared to controls. In control animals VO2max was also greatest at 20 wk of age (22.0 +/- 1.9 ml . min-1; 79.9 +/- 6.4 ml . kg-1 . min-1). After 20 wk of age, VO2max declined in sedentary controls, but was maintained in trained animals were approximately 6% heavier than sedentary free-eating controls. Endurance training may stimulate anabolic processes as well as improve and maintain aerobic capacity in the female rat.