Separate Effects of Exercise Amount and Intensity on Adipose Tissue and Skeletal Muscle Mass in Adults with Abdominal Obesity

Abstract

To determine the effects of exercise amount (kilocalories per session) and intensity (percent of maximal oxygen consumption [% VO2 peak]) on adipose tissue (AT) and skeletal muscle (SM) in adults with abdominal obesity. Participants (n = 103; 52.7 ± 7.6 years) were randomized to the following groups: control; low-amount, low-intensity exercise (180 kcal/session [women] and 300 kcal/session [men] at 50% VO2 peak); high-amount, low-intensity exercise (HALI; 360 kcal/session [women] and 600 kcal/session [men] at 50% VO2 peak); or high-amount, high-intensity exercise (HAHI; 360 kcal/session [women] and 600 kcal/session [men] at 75% VO2 peak) for 24 weeks. Activities of daily living were measured by accelerometry. Magnetic resonance imaging was used to measure tissue mass. Reduction in all AT depots was greater in the exercise groups compared with control (P < 0.002); however, there were no differences between exercise groups (P > 0.05). Visceral and abdominal subcutaneous AT reduction was uniform across the abdomen. Total SM mass did not change with exercise compared with control (P = 0.32). However, while lower-body SM mass was maintained (P = 0.32), upper-body SM mass in the high-amount, high-intensity and the high-amount, low-intensity groups was reduced compared with controls (P < 0.008). In adults with abdominal obesity, substantial reductions in total, abdominal subcutaneous, and visceral AT with a preservation of total SM mass were observed independent of exercise amount or intensity.