Comparison Of Interval Exercise And Continuous Exercise On Excess Post-exercise Oxygen Consumption: Matched For Duration

Abstract

PURPOSE: Compare the excess post-exercise oxygen consumption (EPOC) after duration-matched bouts of high-intensity (HIIT) and sprint interval (SIT) exercise to moderate-intensity continuous (MCT) exercise. METHODS: Recreationally active men (n=7; 22±3 yrs; 180.4±4.7 cm; 77.8±9.3; 13.4±3.4 %BF; 44.7±2.6 ml·kg-1·min-1) completed a maximal graded exercise test (VO2max) and three exercise trials (HIIT, SIT, and MCT) in a randomized, counterbalanced fashion on a cycle ergometer. HIIT consisted of 15 × 90-sec bouts at 85% VO2max and 90-sec active recovery periods. SIT consisted of 15 × 20-sec bouts at 130% maximum wattage and 160-sec active recovery periods. MCT was continuous bout at 65% VO2max. Each trial lasted 53 min, including a 5-min warm-up and a 3-min cool-down. Oxygen consumption (VO2; ml·kg-1·min-1) was measured after bouts 1 (B1), 5 (B5), 10 (B10), 15 (B15), and cool-down (CD) which corresponded with min 0-3, 12-15, 27-30, and 42-45 of MCT, respectively. VO2 was also measured for 30 min prior to exercise (PRE) and during 1 h of recovery. EPOC (L of O2) was measured by the area under the curve with respect to increase (AUCi) from PRE VO2 during the first 20 min of recovery. Trial effects were assed via one-way analyses of variance. RESULTS: VO2 was lower in SIT compared to MCT after B1 (p = 0.002; 17.6 ± 4.6 ml·kg-1·min-1; 24.2 ± 1.8 ml·kg-1·min-1, respectively), B5 (p = 0.007; 21.8 ± 4.8 ml·kg-1·min-1, 29.1 ± 3.4 ml·kg-1·min-1, respectively), B10 (p < 0.001; 21.8 ± 2.6 ml·kg-1·min-1, 30.0 ± 2.5 ml·kg-1·min-1, respectively) and B15 (p < 0.001; 21.8 ± 2.6 ml·kg-1·min-1, 29.3 ± 3.3 ml·kg-1·min-1, respectively). SIT was also lower than HIIT at B5 (27.5 ± 3.4 ml·kg-1·min-1; p = 0.021), B10 (28.2 ± 2.9 ml·kg-1·min-1; p < 0.001) and B15 (28.8 ± 3.7 ml·kg-1·min-1; p = 0.001), while MCT was higher than HIIT at B10. After CD, VO2 was higher in MCT (19.0 ± 2.9 ml·kg-1·min-1) compared to SIT (16.4 ± 2.6 ml·kg-1·min-1; p = 0.015) and HIIT (15.5 ± 2.0 ml·kg-1·min-1; p = 0.007). EPOC was lower following SIT (5.5 ± 1.1 L) compared to MCT (7.4 ± 1.6 L; p = 0.005) and HIIT (6.7 ± 0.8 L; p = 0.006). CONCLUSION: EPOC was similar following both HIIT and MCT, but not SIT, when matched for duration. Of note, despite identical duration, the MCT protocol involved more total work when compared to both HIIT and SIT.