Effect Of High Intensity Interval Training On Body Composition In Overweight And Obese Sedentary Adults

Only ~20% of adults adhere to physical activity guidelines. Thus, exercise programs that require less time, such as high intensity interval training (HIIT), need to be investigated. Recent studies suggest HIIT incorporating body weight exercises result in increased exercise capacity (VO2peak) and leg muscle endurance in healthy adults. PURPOSE: It is unclear if HIIT incorporating body weight exercises influences body composition and exercise capacity in overweight/obese, sedentary adults. We hypothesized that HIIT will 1) increase lean mass and decrease body fat and 2) increase VO2peak to a greater extent than moderate intensity continuous training (MICT) in sedentary, overweight/obese adults. METHODS: : Eleven participants (10 women) were randomized and have completed all study components (6 HIIT vs. 5 MICT; Age: HIIT 39±7 vs. MICT 42±12 yrs; BMI: HIIT: 30±1 vs. 32±3 kg/m2) (both, p>0.05). Exercise capacity (VO2peak -cardiopulmonary exercise testing) and body composition (via dual energy X-ray absorptiometry) were measured at baseline and after 12 weeks of training. The HIIT group performed 5 body weight exercises (squats, pushups, lunges, mountain climbers, and plank) 3 days/week for 12 weeks at an intensity equal to a rating of perceive exertion (RPE) >17. The MICT group performed 150 min of MICT/week for 12 weeks at a RPE between 12-14. RESULTS: Percent (%) lean mass increased from baseline following HIIT (p<0.05), but not MICT (HIIT: 54.4±3.4 vs. 55.5±4.0 %; MICT: 52.5±3.9 vs. 51.7±4.3 %). Body fat % significantly decreased from baseline following HIIT (p<0.05), but not MICT (HIIT: 43.9±3.5 vs. 42.7±4.1 %; MICT: 45.9±4.1vs. 46.7±4.7 %). BMI was not different from baseline following HIIT or MICT (HIIT: 32 ±3 vs. 31±3 kg/m2; MICT: 30±1 vs. 30±3 Kg/m2;both, p>0.05). VO2peak significantly increased from baseline following HIIT (p<0.05), but not MICT (HIIT: 23.7 ±0.9 vs. 25.0±0.9 mL/kg/min; MICT: 22.2±6.1 vs. 23.1±6.1 mL/kg/min). CONCLUSIONS: These preliminary data support the hypotheses that non-traditional aerobic HIIT (e.g., HIIT incorporating body weight exercises) leads to more advantageous changes in body composition and exercise capacity compared to MICT alone.