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

OBJECTIVE: 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.

METHODS: 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.

RESULTS: 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).

CONCLUSIONS: 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.