While the benefits of exercise are clear, there are many unresolved issues surrounding the optimal exercise prescription. Many organizations recommend aerobic training (AT) and resistance training (RT), yet few studies have compared their effects alone or in combination . The purpose of this study was to compare the effects of AT, RT and the full combination (AT/RT) on central ectopic fat, liver enzymes and fasting insulin resistance (HOMA). In a randomized trial, 249 subjects, 18 to 70 years old, overweight, sedentary, and with moderate dyslipidemia (LDL cholesterol 130-190 mg/dL; or HDL cholesterol ≤40 mg/dL for men or ≤45 mg/dL for women), performed an initial four-month run-in period. Of these, 196 finished the run-in and were randomized into one of the following eight-month exercise training groups: 1) RT: 3 d/wk, 8 exercises, 3 sets/exercise, 8-12 repetitions/set, 2) AT: equivalent to ~19.2 km/wk (12 miles/wk) at 75% peakVO2, 3) full Aerobic Training plus full Resistance Training (AT/RT), with 155 subjects completing the intervention. The primary outcome variables were: visceral and liver fat via computed tomography, plasma liver enzymes, and HOMA. AT led to significant reductions in liver fat, visceral fat, alanine aminotransferase (ALT), HOMA and both total and subcutaneous abdominal fat (all P<0.05). RT resulted in a decrease in subcutaneous abdominal fat (P<0.05), but did not significantly improve the other variables. AT was more effective than RT at improving visceral fat, liver to spleen ratio, total abdominal fat (all P<0.05) and trended towards a greater reduction in liver fat score (P<0.10). The effects of AT/RT were statistically indistinguishable from AT. These data show that for overweight and obese individuals who want to reduce measures of visceral fat and fatty liver infiltration and improve HOMA and ALT, a moderate amount of aerobic exercise is the most time efficient and effective exercise mode.
- resistance training
- weight lifting
- aerobic training
- liver fat
- Copyright © 2011, American Journal of Physiology - Endocrinology and Metabolism