The Separate Effects of Exercise Amount and Intensity on Total and Abdominal Adipose Tissue in Men and Women Who Are Abdominally Obese
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It is well established that exercise is an efficacious method for the management of abdominal obesity; however, the optimal amount and intensity of exercise that is required to combat obesity remains unclear. The purpose of this study was to determine the separate effects of exercise amount and intensity on abdominal and whole body adipose tissue in adults who are abdominally obese. One-hundred eight participants who were previously sedentary and had abdominal obesity were randomized into one of 4 groups: Control (n=21 (10 females)), low amount, low intensity (LALI) (180 kcal/session for females and 300 kcal/session for males at 50% VO2peak, n= 25 (15 females)) high amount, low intensity (HALI) (360 kcal/session for females and 600 kcal/session for males at 50% VO2peak, n=32 (21 females)), or high amount, high intensity (HAHI) (360 kcal/session for females and 600 kcal/session for males at 75% VO2peak n=30 (19 females)). Participants performed supervised exercise 5 times/wk for 24 wks. Daily dietary logs were completed throughout the intervention and unstructured physical activity was monitored using accelerometers. Change in total and abdominal adipose tissue (AT) and skeletal muscle mass was measured via magnetic resonance imaging. Exercise duration in minutes was 32 (SD, 4.8) for LALI, 58 (SD, 6.6) for HALI, and 40 (SD, 6.7) for HAHI. There was no difference in unstructured physical activity change and there was no difference in the adherence to prescribed diets between groups. Reductions in VAT was greater in LALI (-0.5 kg; SE, 0.1; p=0.001), HALI (-0.5 kg; SE, 0.1; p<0.001), and in HAHI (-0.5 kg; SE, 0.1; p<0.001) compared to control but did not differ between the exercise groups p>0.139. Reductions in total AT, SAT, total abdominal AT, abdominal SAT, weight and waist circumference was also greater in all exercise groups compared to control (p<0.002) but did not differ between groups (p>0.05). These findings indicate that there is an intensity and amount independent reduction in adipose tissue depots with exercise with a preservation of skeletal muscle mass, which highlights that there are several exercise treatment options for the management of abdominal obesity.