The Effects of Aerobic versus Resistance Training on Fat Stores
While the benefits of being physically active are clear, there are many unresolved issues surrounding the optimal exercise prescription for these benefits. Many organizations recommend both aerobic training (AT) and resistance training (RT) for all adults. However, these recommendations are mainly based on the evaluation of each modality separately, as few studies have investigated the effects of combined AT and RT regimens compared to each modality individually. Further, adherence to exercise recommendations of physicians are notoriously poor and many patients provide lack of time as a reason for noncompliance.
Understanding the effects of AT and RT is of critical importance if we are to apply evidence based approaches to exercise recommendations to a wide population. Visceral fat and liver fat are associated with type 2 diabetes, metabolic syndrome and metabolic abnormalities. Both are also independent risk factors for all-cause mortality. Elevated concentrations of circulating liver enzymes are also associated with type 2 diabetes, fatty liver, metabolic syndrome and mortality. In fact, alanine aminotransferase (ALT) is considered to be a marker of fatty liver infiltration. Elevated liver enzymes, even at concentrations considered to be within normal levels, are independent predictors of incident diabetes and nonalcoholic fatty liver disease.
The importance of insulin resistance (HOMA) is well established, and aerobic exercise consistently improves insulin sensitivity. While the benefits of aerobic exercise on visceral adiposity and insulin sensitivity are well established, few studies have compared the effects of AT, RT and a combination on these outcomes, and to our knowledge none have examined the effect of RT on liver fat or concentrations of circulating liver enzymes.
The present study, STRRIDE-AT/RT (Studies Targeting Risk Reduction Interventions through Defined Exercise – Aerobic Training and/or Resistance Training), was designed to address three major questions relating to exercise recommendations for overweight, sedentary adults.
First, what are the specific benefits of resistance training (RT) in this population?
Second, how do these benefits compare with those that accrue when a similar amount of time is spent in aerobic training (AT)?
Third, what are the additive, synergistic or possibly antagonistic effects that occur when both are combined (AT/RT)?
These findings should improve the ability of clinicians, exercise professionals and the lay public to more accurately understand the benefits of different exercise regimens, target exercise recommendations to specific outcomes, and more efficiently utilize precious exercise time. This report summarizes the effects of AT, RT and AT/RT on visceral fat and fatty liver infiltration, as represented by liver density and the circulating liver-derived enzyme, ALT, as well as fasting insulin resistance as presented by HOMA.
While resistance training reliably improves strength and increases lean body mass, its effects on central ectopic fat depots are less clear. The major finding in this study was that in sedentary, overweight and obese adults, aerobic training was consistently more effective than resistance training at improving visceral fat, total abdominal fat, liver fat, and the liver derived enzyme alanine aminotransferase. When RT was added to AT, there was no additional beneficial effect on these variables. These data show that for overweight and obese individuals who want to reduce body weight and measures of visceral fat and fatty liver infiltration and also improve fasting insulin resistance and liver enzymes, a moderate amount of aerobic exercise is the most time efficient and effective exercise mode.
Slentz CA, Bateman LA, Willis LH, et al. 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. The Effects of Aerobic versus Resistance Training on Visceral and Liver Fat Stores, Liver Enzymes and HOMA from STRRIDE AT/RT: A Randomized Trial
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.
While the benefits of being physically active are clear, there are many unresolved issues surrounding the optimal exercise prescription for these benefits. Many organizations recommend both aerobic training (AT) and resistance training (RT) for all adults. However, these recommendations are mainly based on the evaluation of each modality separately, as few studies have investigated the effects of combined AT and RT regimens compared to each modality individually. Further, adherence to exercise recommendations of physicians are notoriously poor and many patients provide lack of time as a reason for noncompliance.
Understanding the effects of AT and RT is of critical importance if we are to apply evidence based approaches to exercise recommendations to a wide population. Visceral fat and liver fat are associated with type 2 diabetes, metabolic syndrome and metabolic abnormalities. Both are also independent risk factors for all-cause mortality. Elevated concentrations of circulating liver enzymes are also associated with type 2 diabetes, fatty liver, metabolic syndrome and mortality. In fact, alanine aminotransferase (ALT) is considered to be a marker of fatty liver infiltration. Elevated liver enzymes, even at concentrations considered to be within normal levels, are independent predictors of incident diabetes and nonalcoholic fatty liver disease.
The importance of insulin resistance (HOMA) is well established, and aerobic exercise consistently improves insulin sensitivity. While the benefits of aerobic exercise on visceral adiposity and insulin sensitivity are well established, few studies have compared the effects of AT, RT and a combination on these outcomes, and to our knowledge none have examined the effect of RT on liver fat or concentrations of circulating liver enzymes.
The present study, STRRIDE-AT/RT (Studies Targeting Risk Reduction Interventions through Defined Exercise – Aerobic Training and/or Resistance Training), was designed to address three major questions relating to exercise recommendations for overweight, sedentary adults.
First, what are the specific benefits of resistance training (RT) in this population?
Second, how do these benefits compare with those that accrue when a similar amount of time is spent in aerobic training (AT)?
Third, what are the additive, synergistic or possibly antagonistic effects that occur when both are combined (AT/RT)?
These findings should improve the ability of clinicians, exercise professionals and the lay public to more accurately understand the benefits of different exercise regimens, target exercise recommendations to specific outcomes, and more efficiently utilize precious exercise time. This report summarizes the effects of AT, RT and AT/RT on visceral fat and fatty liver infiltration, as represented by liver density and the circulating liver-derived enzyme, ALT, as well as fasting insulin resistance as presented by HOMA.
While resistance training reliably improves strength and increases lean body mass, its effects on central ectopic fat depots are less clear. The major finding in this study was that in sedentary, overweight and obese adults, aerobic training was consistently more effective than resistance training at improving visceral fat, total abdominal fat, liver fat, and the liver derived enzyme alanine aminotransferase. When RT was added to AT, there was no additional beneficial effect on these variables. These data show that for overweight and obese individuals who want to reduce body weight and measures of visceral fat and fatty liver infiltration and also improve fasting insulin resistance and liver enzymes, a moderate amount of aerobic exercise is the most time efficient and effective exercise mode.
Slentz CA, Bateman LA, Willis LH, et al. 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. The Effects of Aerobic versus Resistance Training on Visceral and Liver Fat Stores, Liver Enzymes and HOMA from STRRIDE AT/RT: A Randomized Trial
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.
