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.

Purpose To date, no study has examined the synergistic effects of a nutrition and combination of aerobic and strength training (CAST) on both adiposity and metabolic parameters in overweight Latina adolescent females. The goal was to assess if a 16-wk nutrition plus CAST pilot study had stronger effects on reducing adiposity and on improving glucose/insulin indices compared with control (C), nutrition only (N), and a nutrition plus strength training (N + ST) groups. Methods In a 16-wk randomized trial, 41 overweight Latina girls (15.2 ± 1.1 yr) were randomly assigned to C (n = 7), N (n = 10), N + ST (n = 9), or N + CAST (n = 15). All intervention groups received modified carbohydrate nutrition classes (once a week), whereas the N + ST also received strength training (twice a week) and the N + CAST received a combination of strength and aerobic training (twice a week). The following were measured before and after intervention: strength by one repetition maximum, physical activity by the 7-d accelerometry and the 3-d physical activity recall, dietary intake by 3-d records, body composition by dual-energy x-ray absorptiometry (DEXA), glucose/insulin indices by oral glucose tolerance test, and intravenous glucose tolerance test with minimal modeling. Across intervention group, effects were tested using ANCOVA with post hoc pairwise comparisons. Results There were significant overall intervention effects for all adiposity measures (weight, body mass index [BMI], BMI z-scores, and DEXA total body fat), with a decrease of 3% in the N + CAST group compared with a 3% increase in the N + ST group (P ≤ 0.05). There was also an intervention effect for fasting glucose with the N group increasing by 3% and the N + CAST group decreasing by 4% (P ≤ 0.05). Conclusion The CAST was more effective than nutrition alone or nutrition plus strength training for reducing multiple adiposity outcomes and fasting glucose in overweight Latina girls. However, further research investigating and identifying intervention approaches that improve both adiposity and insulin indices, particularly in high-risk populations, are warranted.

Objective To assess the effects of a maintenance program (monthly newsletters versus monthly group classes and telephone behavioral sessions) on obesity and metabolic disease risk at one year in overweight minority adolescents. Methods After a 4-month nutrition and strength training intervention, 53 overweight Latino and African American adolescents (15.4 ±1.1 yrs) were randomized into one of two maintenance groups for 8 months: monthly newsletters (n=23) or group classes (n=30; monthly classes + individualized behavioral telephone sessions). The following outcomes were measured at months 4 (immediately following the intense intervention) and month 12: height, weight, blood pressure, body composition via BodPod™, lipids and glucose/insulin indices via frequently sampled intravenous glucose tolerance test (FSIVGTT). Results There were no significant group by time interactions for any of the health outcomes. There were significant time effects in several outcomes for both groups from month 4 to 12: bench press and leg press decreased by 5% and 14% (p=0.004 & p=0.01), fasting insulin and acute insulin response decreased by 26% and 16% (p<0.001 & p=0.046); while HDL cholesterol and insulin sensitivity improved by 5% and 14% (p=0.042 and p=0.039). Conclusions Newsletters as opposed to group classes may suffice as follow-up maintenance programs to decrease type 2 diabetes and cardiovascular risk in overweight minority adolescents.