Effects of Aerobic Versus Resistance Exercise Without Caloric Restriction on Abdominal Fat, Intrahepatic Lipid, and Insulin Sensitivity in Obese Adolescent Boys

Abstract

The optimal exercise modality for reductions of abdominal obesity and risk factors for type 2 diabetes in youth is unknown. We examined the effects of aerobic exercise (AE) versus resistance exercise (RE) without caloric restriction on abdominal adiposity, ectopic fat, and insulin sensitivity and secretion in youth. Forty-five obese adolescent boys were randomly assigned to one of three 3-month interventions: AE, RE, or a nonexercising control. Abdominal fat was assessed by magnetic resonance imaging, and intrahepatic lipid and intramyocellular lipid were assessed by proton magnetic resonance spectroscopy. Insulin sensitivity and secretion were evaluated by a 3-h hyperinsulinemic-euglycemic clamp and a 2-h hyperglycemic clamp. Both AE and RE prevented the significant weight gain that was observed in controls. Compared with controls, significant reductions in total and visceral fat and intrahepatic lipid were observed in both exercise groups. Compared with controls, a significant improvement in insulin sensitivity (27%) was observed in the RE group. Collapsed across groups, changes in visceral fat were associated with changes in intrahepatic lipid (r = 0.72) and insulin sensitivity (r = −0.47). Both AE and RE alone are effective for reducing abdominal fat and intrahepatic lipid in obese adolescent boys. RE but not AE is also associated with significant improvements in insulin sensitivity.

4. Prevention or Delay of Type 2 Diabetes

“…The DPP included 150 min/week of moderate-intensity exercise and showed beneficial effect on glycemia in those with prediabetes (1). Both resistance training and endurance exercise appear to have beneficial effects on waist circumference, insulin sensitivity, and thus diabetes risk (24,25). The preventative effects of exercise appear to extend to the prevention of gestational diabetes mellitus (GDM) as well (26).…”

Exercise and Insulin Resistance in Youth: A Meta-Analysis

“…23,25,28,40,51,53,57,58 Sensitivity analysis removing these 9 effects decreased the mean effect of exercise on fasting insulin in children and adolescents from .001) for the remaining 24 effects. When examining IR, 3 effects from 2 studies outside of the 95% CI were identified by using the forest plot to identify potential outliers.…”

The benefits of exercise for patients with non-alcoholic fatty liver disease

“…Moreover, despite performing double the training load of the aerobic alone or PRT alone groups, aerobic exercise combined with PRT led to a non-significant reduction in liver fat. A superior hepatic benefit of aerobic exercise training was also demonstrated in obese adolescent girls [12]; however, comparable reductions between aerobic and resistance training have been observed in NAFLD patients with type 2 diabetes [5] and in obese adolescent boys [13].…”

“…To date, there is sparse evidence for the efficacy of PRT as per these guidelines for liver fat reduction. Of the nine studies employing PRT in isolation, five observed a significant reduction in liver fat [5,13,[17][18][19], three of which conformed with the abovementioned guidelines [5,13,18], while four showed no benefit [12,[20][21][22] with discrepancies in outcomes likely due to the large heterogeneity in study design. These differences include the use of circuit-based training (which has a concurrent 'aerobic' exercise stimulus) [19,22], the use of home-based prescription [17], and variation in training intensities and study populations, all of which combined limit the ability to generalize findings and draw practical conclusions.…”

“…With respect to aerobic exercise, these guidelines promote moderate-intensity cardiorespiratory exercise training for ‡30 min on at least 5 days per week, or vigorous cardiorespiratory exercise training for ‡20 min on 3 days per week, or a combination of both and align with global recommendations for health, fitness and disease prevention [10]. Exercise interventions meeting these guidelines consistently demonstrate reduction in liver fat of 10-43% in patients with NAFLD [5,6,[11][12][13][14][15][16].…”