Purpose: To determine whether various intensities of aerobic training differentially affect aerobic capacity as well as resting HR and resting blood pressure (BP).
Methods: Sixty-one health young adult subjects were matched for sex and V˙O2max and were randomly assigned to a moderate- (50% V˙O2 reserve (V˙O2R), vigorous (75% V˙O2R), near-maximal-intensity (95% V˙O2R), or a nonexercising control group. Intensity during exercise was controlled by having the subjects maintain target HR based on HR reserve. Exercise volume (and thus energy expenditure) was controlled across the three training groups by varying duration and frequency. Fifty-five subjects completed a 6-wk training protocol on a stationary bicycle ergometer and pre- and posttesting. During the final 4 wk, the moderate-intensity group exercised for 60 min, 4 d·wk-1 the vigorous-intensity group exercised for 40 min, 4 d·wk-1 and the near-maximal-intensity group exercised 3 d·wk-1 performing 5 min at 75% V˙O2R followed by five intervals of 5 min at 95% V˙O2R and 5 min at 50% V˙O2R.
Results: V˙O2max significantly increased in all exercising groups by 7.2, 4.8, and 3.4 mL·min-1·kg-1 in the near-maximal-, the vigorous-, and the moderate-intensity groups, respectively. Percent increases in the near-maximal- (20.6%), the vigorous- (14.3%), and the moderate-intensity (10.0%) groups were all significantly different from each other (P < 0.05). There were no significant changes in resting HR and BP in any group.
Conclusion: When volume of exercise is controlled, higher intensities of exercise are more effective for improving V˙O2max than lower intensities of exercise in healthy, young adults.