Physiological adjustments to higher- or lower-intensity exercise in elders

A program of physical activity for people over 60 yr of age was developed to determine whether exercising at lower intensities (LI) is a significant conditioning stimulus. In addition, differences in aerobic capacities (VO2max) elicited by training at LI, as opposed to training at higher intensities (HI), were evaluated. Thirty-two volunteers over 60 yr of age (mean = 67.8 yr) participated in a 9-wk exercise program. After initial testing of VO2max on a cycle ergometer, subjects were assigned randomly to the HI, LI, or control group. Endurance training of the two exercise groups on cycle ergometers was maintained at 30-45% (N = 14) or 60-75% (N = 14) of the range (HRR) between the subject's resting and maximum heart rate for 25 min during each exercise session. These training intensities represented 57 and 70% of the VO2max of the LI and HI groups, respectively. Participants averaged three exercise sessions per week. Non-exercising volunteers served as control subjects. A one-way ANOVA with repeated measures was utilized for comparisons of retest, groups, and interaction. As a result of the exercise program, significant changes (P less than 0.005) in absolute (VO2max, 1 X min-1) and relative (VO2max, ml X min-1 X kg-1) aerobic capacities were realized within each training group while initial and post-training VO2max were not significantly different between the two groups. Similar changes were documented by a reduction in heart rate at submaximal exercise intensities and during recovery. It was concluded that exercising at LI (30-45% HRR) is an adequate training stimulus in older individuals and produces changes in VO2max that are comparable to those elicited by HI (60-75% HRR) training.