HIGH-INTENSITY INTERVAL EXERCISE PRODUCES SIGNIFICANT FAT LOSS

Hahn, D., Angadi, S., & Gaesser, G. A. (2011). Effects of moderate-intensity continuous and high-intensity interval exercise on post-exercise oxygen uptake. Medicine and Science in Sports and Exercise, 43(5). Supplement abstract 1833.

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"Sprint-interval training has been shown to result in greater fat loss when compared to traditional moderate-intensity exercise training, despite a significantly lower energy cost during training sessions. Whether post-exercise oxygen uptake is significantly elevated following sprint-interval exercise in comparison to moderate-intensity exercise remains unknown."

This study compared post-exercise oxygen uptake following moderate-intensity continuous exercise, aerobic-interval exercise, and sprint-interval exercise. Healthy Ss (M = 10; F = 1) underwent one control and three exercise conditions in a randomized order: 1) continuous moderate-intensity (30 minutes at 80% HRmax), 2) aerobic-interval exercise (four x 4-minute bouts at 95/HRmax with three minutes of active recovery), and 3) sprint-interval exercise (six "all-out" 30-second sprint Wingate tests separated by four minutes of active recovery). Ventilation and gas exchange were continuously measured before, during, and for 180 minutes after the exercise bouts.

Post-exercise oxygen consumption was significantly greater following sprint-interval exercise when compared to the other exercise conditions. All exercise conditions were greater than the control condition. Both interval-exercise protocols resulted in significantly lower respiratory exchange ratios during the third hour post-exercise, reflecting greater post-exercise fat oxidation. However, oxygen consumption during exercise sessions was greater for moderate-intensity exercise than for both aerobic-interval and sprint-interval conditions. Total oxygen consumed (exercise + post-exercise) and estimated energy expenditure were highest for moderate-intensity exercise and lowest for sprint-interval exercise.

Implication. Sprint-interval exercise results in significantly greater three-hour post-exercise oxygen uptake than does aerobic-interval and moderate-intensity exercise. The post-exercise metabolic stimulation was more than offset by significantly lower oxygen consumption during the sprint-interval exercise session. The greater fat loss reported after high-intensity interval exercise training is likely due to effects that extend well beyond the acute exercise period.

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