Startup Circuit Training Program Reduces Metabolic Risk in Latino Adolescents

Abstract

Purpose This study aimed to test the effects of a circuit training (CT; aerobic + strength training) program, with and without motivational interviewing (MI) behavioral therapy, on reducing adiposity and type 2 diabetes risk factors in Latina teenagers. Methods Thirty-eight Latina adolescents (15.8 ± 1.1 yr) who are overweight/obese were randomly assigned to control (C; n = 12), CT (n = 14), or CT + MI (n = 12). The CT classes were held twice a week (60–90 min) for 16 wk. The CT + MI group also received individual or group MI sessions every other week. The following were measured before and after intervention: strength by one-repetition maximum; cardiorespiratory fitness (V̇O2max) by submaximal treadmill test; physical activity by accelerometry; dietary intake by records; height, weight, waist circumference; total body composition by dual-energy x-ray absorptiometry; visceral adipose tissue, subcutaneous adipose tissue, and hepatic fat fraction by magnetic resonance imaging; and glucose/insulin indices by fasting blood draw. Across-intervention group effects were tested using repeated-measures ANOVA with post hoc pairwise comparisons. Results CT and CT + MI participants, compared with controls, significantly increased fitness (+16% and +15% vs −6%, P = 0.03) and leg press (+40% vs +20%, P = 0.007). Compared with controls, CT participants also decreased waist circumference (−3% vs +3%; P < 0.001), subcutaneous adipose tissue (−10% vs 8%, P = 0.04), visceral adipose tissue (−10% vs +6%, P = 0.05), fasting insulin (−24% vs +6%, P = 0.03), and insulin resistance (−21% vs −4%, P = 0.05). Conclusions CT may be an effective starter program to reduce fat depots and improve insulin resistance in Latino youth who are overweight/obese, whereas the additional MI therapy showed no additive effect on these health outcomes.

Does Diet-Induced Weight Loss Lead to Bone Loss in Overweight or Obese Adults? A Systematic Review and Meta-Analysis of Clinical Trials

“…(93,95) Therefore the validity of lumbar spine BMD results can be questionable, highlighting the greater reliance on total hip BMD measures for the estimation of fracture risk. (58,60,64,82,96) The majority of studies identified in this systematic review and meta-analysis investigated total body BMD, which was significantly reduced by 6-month (but not by 3-month or 12-month) weight-loss interventions. However, measures of total body BMD are not clinically relevant because they do not identify specific areas that are affected by loss of bone mass.…”

“…Although we were able to categorize interventions according to the levels of prescribed energy intake, this did not take into account differences in macronutrient composition of the diets. A further limitation of this metaanalysis was that only 25% of the included studies involved comparison with a control group, (22,25,36,40,(45)(46)(47)73,74,80,82) as mentioned in the second paragraph of this Discussion.…”

Exercise and Insulin Resistance in Youth: A Meta-Analysis

“…For example, a circuit training approach allowed sedentary overweight and obese adolescents to train at 70% to 85% of their maximum heart rate for 60 to 90 minutes by dividing their exercise training into 2-minute bouts followed by 1 minute of recovery between activities. 36 Davis et al 50 suggest training programs involving a combination of aerobic and resistance training can incorporate short aerobic intervals into circuit training and allow overweight and obese adolescents with low aerobic fitness to accumulate the required duration of aerobic exercise and improve adherence by incorporating smaller, more manageable exercise bouts.…”

“…29 IR was calculated by using fasting levels of insulin and glucose by using the homeostasis model assessment (HOMA) technique in each study included in this analysis. 22,25,31,32,[34][35][36][37][38][39][40][41] A decrease in fasting insulin levels or IR among participants in exercise interventions resulted in a positive ES. Two authors (M.V.F.…”

“…For example, a circuit training approach allowed sedentary overweight and obese adolescents to train at 70% to 85% of their maximum heart rate for 60 to 90 minutes by dividing their exercise training into 2-minute bouts followed by 1 minute of recovery between activities. 36 Davis et al 50 suggest training programs involving a combination of aerobic and resistance training can incorporate short aerobic intervals into circuit training and allow overweight and obese adolescents with low aerobic fitness to accumulate the required duration of aerobic exercise and improve adherence by incorporating smaller, more manageable exercise bouts.Study duration of the exercise intervention was not a significant moderator of the effect of exercise on fasting insulin secretion, despite a previous hypothesis by other researchers that short and long interventions could influence fasting insulin secretion differently. 38 Improvement in fasting insulin and IR can occur after exercise training in the absence of improvements in weight or body composition.…”