The Effects Of High Intensity Interval Training Versus Moderate Intensity Continuous Training On Energy Compensation

Abstract

To determine the effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on energy compensation in response to 12-weeks of supervised aerobic exercise. After a 4 wk lead in period of 3x/wk of MICT, subjects (N = 24) were randomly assigned into: HIIT or MICT, for an additional 8 wks. HIIT included a 10x1 min protocol 3x/wk and MICT included 30 min of exercise 5x/wk. Subjects completed both stationary cycling and inclined treadmill exercise. 13 participants (1 M, 12 F) were randomized into the HIIT group (28.0 ± 9.7 yr; BMI = 23.9 ± 3.9 kg/m2; VO2max = 29.0 ± 6.0 ml/kg/min). 11 participants (2 M, 9 F) were randomized into the MICT group (26.0 ± 6.9 yr; BMI = 27.4 ± 8.7 kg/m2; VO2max = 26.2 ± 7.3 ml/kg/min). Resting metabolic rate (RMR), body composition, and maximal oxygen uptake (VO2max) were measured at baseline and after 4 and 12 wks. Physical activity and dietary intake were measured for 7-day periods pre-intervention and during wks 5 and 12. Compensation was calculated through caloric equivalents of fat and lean mass compared to cumulative total exercise energy expenditure. 5 of 11 in MICT and 6 of 13 in HIIT were categorized as compensators. Change in fat mass (kg) (MICT: -0.59 ± 1.89, HIIT: -0.03 ± 1.72, p=0.45), change in weight (kg) (MICT: +0.66 ± 2.11, HIIT: -0.54 ± 1.45, p=0.12), and overall compensation (kcal) (MICT: 3111 ± 17220, HIIT: 3870 ± 15911, p=0.91) were similar between exercise groups. The difference between actual and predicted weight loss was greater for MICT (-1.61 ± 2.15 kg) than HIIT (-0.07 ± 1.45 kg, p=0.049). Potential compensatory variables including changes in RMR, VO2max, daily steps, and sedentary time were not different between the compensator and non-compensator groups (P > 0.05). Mean energy and macronutrient intake did not differ among all participants, by exercise intervention group, or by compensation status (P > 0.05). Both HIIT and MICT led to a similar percentage (~45%) of participants compensating for the exercise intervention. Despite the large difference in cumulative exercise training time (480 vs 1200 min, HIIT vs MICT), body fat and weight changes were similar between groups. Finally, our data suggests that HIIT may elicit weight loss that is closer to that predicted by exercise energy expenditure when compared to MICT.