Acute physiological effects of interval versus steady-state exercise

Abstract

This study was designed to evaluate the exercise intensity and energy expenditure of interval exercise compared to steady-state exercise on a cycle ergometer. Fourteen subjects completed a VO2max test on a cycle ergometer to determine their aerobic capacity. Subjects then completed an interval ride and a steady-state ride. The interval ride alternated one minute of high-intensity cycling at 90% of maximal power output followed by one minute of active rest for 20 minutes. The steady-state ride consisted of 20 minutes exercise at 90% of the subject's ventilatory threshold (VT). Total work was matched between conditions. Oxygen consumption (V02), heart rate (HR), lactate, and RPE values were measured. After completion of both trials, a post-exercise questionnaire was administered. No significant difference (p<.05) was found in HR between the rides (142 + 14.9 vs. 145 + 13.7). There were significant differences between the interval ride vs. steady-state ride for VO2 (31.2 + 6.05 vs. 29.9 + 5.97), lactate (4.8 + 2.19 vs. 2.1 + 1.64), and RPE (5.6 + 1.3 vs. 3.8 + .83). Interval exercise elicits 9% higher energy expenditure than steady-state exercise and may be an effective way to obtain cardiovascular benefits for individuals with limited time.