HEALTH NEWS

Study Title:

Aerobic Versus Resistance Training on Visceral and Liver Fat Stores

Study Abstract

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.

From CBS News:

Want to burn belly fat? Maybe ditch the weights and lace up those running shoes.

A new study showed aerobic exercise burns nearly 70 percent more calories than resistance weight training.

"Resistance training is great for improving strength and increasing lean body mass," study author Dr. Cris Slentz, an exercise physiologist at Duke University, said in a written statement. "But if you are overweight, which two thirds of the population is, and you want to lose belly fat, aerobic exercise is the better choice because it burns more calories,"

For the eight-month study - published in the August 25 issue of the American Journal of Physiology -196 overweight and sedentary adults, ages 18 to 70, did aerobic training, resistance training, or a combination of the two. Study participants weren't allowed to slack - aerobic exercisers had to jog 12 miles per week at 80 percent of their maximum heart rate, and resistance trainers had to lift weights for 8-12 reps, three times a week.

What happened? By study's end, the joggers had improved insulin resistance and levels of liver enzymes and triglycerides, which are tied to a lower risk for diabetes and heart disease. They also sported less belly fat.

Belly fat doesn't just look bad. Also known as visceral fat, belly fat fills the spaces between organs, and too much of it is associated with heart disease, diabetes, and cancer.

"When it comes to increased health risks, where fat is deposited in the body is more important than how much fat you have," Slentz said.

Don't feel up to running 12 miles a week?

Slentz said what really counts is whatever it takes to lose calories, adding, "If you choose to work at a lower aerobic intensity, it will simply take longer to burn the same amount of unhealthy fat."

Study Information

Slentz CA, Bateman LA, Willis LH, Shields AT, Tanner CJ, Piner LW, Hawk VH, Muehlbauer MJ, Samsa GP, Nelson RC, Huffman KM, Bales C, Houmard JA, Kraus WE.
The Effects of Aerobic versus Resistance Training on Visceral and Liver Fat Stores, Liver Enzymes and HOMA from STRRIDE AT/RT: A Randomized Trial.
Am J Physiol Endocrinol Metab.
2011 August
Duke University Medical Center.