The effect of aging on submaximal exercise performance and recovery.

The upward drift of gas exchange variables during 70% maximal exercise and recovery half-times in aged and young subjects of equivalent age-predicted aerobic capacity was measured. In the aged subjects, upward drift of VE, VO2, and HR was reduced compared with the young group. The recovery of VE, VCO2, and VO2 was slowed in the aged. However, at 10 minutes post-exercise, VCO2, VO2, and HR had returned to similar relative values for both groups; in the young subjects VE remained elevated at the end of recovery. The reduced upward drift of gas exchange variables and HR during exercise in aged subjects is consistent with an attenuated response of glycogenolysis and lactate production to adrenergic stimulation and/or to selective loss of type II skeletal muscle fibers. The slowed recovery of VE, VCO2, and VO2 in elderly persons is consistent with age-related reduced CO2 chemosensitivity, delaying elimination of the exercise-induced CO2 load.