Effect of Intensity of Aerobic Training on VO2max

In order to achieve cardiovascular benefits, exercise must at least be performed at a moderate intensity. There are limited data on the potentially greater effects of vigorous intensity, and of interval training at near-maximal intensity, for increasing aerobic capacity. PURPOSE: To determine whether or not various intensities of aerobic training differentially affect aerobic capacity. METHODS: Sixty-one healthy subjects were matched for age, gender, and VO2max and randomly assigned to a moderate-intensity (50% VO2 Reserve), vigorous-intensity (75% VO2R), maximal-intensity (95% VO2R) or a non-exercising control group. Intensity during exercise was controlled by having the subjects maintain target heart rates based on heart rate reserve. The weekly duration of training varied in opposition to the intensity to ensure there was equivalent energy expenditure across the three training groups. Subjects completed a six-week training protocol on a stationary bicycle ergometer. During the final four weeks, the moderate group exercised 60 min, 4 d.wk−1, the vigorous group exercised 40 min, 4 d.wk−1, and the maximal group exercised 3 d.wk−1 performing 5 min at 75% VO2R followed by five intervals of 5 min at 95% VO2R and 5 min at 50% VO2R. RESULTS: VO2max significantly increased across all exercising groups (p < 0.05). The maximal-intensity group had the greatest increase of 7.2 ml·min1·kg−1, followed by an increase of 4.8 ml·min1·kg−1 in the vigorous-intensity group and an increase of 3.4 ml·min1·kg−1 in the moderate-intensity group. Percent increases in the maximal (20.6%), vigorous (14.3%) and moderate-intensity (10.0%) groups were all significantly different from each other (p < 0.001). CONCLUSIONS: The results indicate that when energy expenditure is controlled, higher intensities of exercise are more effective for improving VO2max than lower intensities of exercise in healthy, young, college-aged students.