Healthy Eating, Aerobic and Resistance Training in Youth (HEARTY): study rationale, design and methods.
ABSTRACT The objective of the Healthy Eating Aerobic and Resistance Training in Youth (HEARTY) trial (ClinicalTrials.Gov # NCT00195858) was to examine the effects of resistance training, with and without aerobic training, on percent body fat in sedentary, post-pubertal overweight or obese adolescents aged 14-18 years. This paper describes the HEARTY study rationale, design and methods.
After a 4-week supervised low-intensity exercise run-in period, 304 overweight or obese adolescents with a body mass index≥85th percentile for age and sex were randomized to 4 groups for 22 weeks (5 months): diet+aerobic exercise, diet+resistance exercise, diet+combined aerobic and resistance exercise, or a diet only waiting-list control. All participants received dietary counseling designed to promote healthy eating with a maximum daily energy deficit of -250 kcal.
The primary outcome is percent body fat measured by Magnetic Resonance Imaging. Secondary outcomes include changes in anthropometry, regional body composition, resting energy expenditure, cardiorespiratory fitness, musculoskeletal fitness, cardiometabolic risk markers, and psychological health.
To our knowledge, HEARTY is the largest clinical trial examining effects of aerobic training, resistance training, and combined aerobic and resistance training on changes in adiposity and cardiometabolic risk markers in overweight and obese adolescents. The findings will have important clinical implications regarding the role that resistance training should play in the management of adolescent obesity and its co-morbidities.
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ABSTRACT: Background Sedentary behavior has been associated with deleterious cardiometabolic health indicators in adults, but very little research has examined this relationship in youth. Purpose To examine the association between the duration and type of sedentary screen behavior with diabetes risk factors (fasting glucose, insulin, homeostasis model-insulin resistance [HOMA-IR], 2-hour postload glucose, hemoglobin A1c) in a sample of overweight and obese adolescents. Methods A cross-sectional study of 307 overweight or obese adolescents aged 14–18 years (90 boys, 217 girls) assessed at baseline of a lifestyle intervention for weight control conducted from 2005 to 2010. Sedentary screen behaviors, defined as hours per day spent watching TV, playing seated video games, recreational computer use, and total screen time were measured by self-report. Data were analyzed using linear regression analyses in 2012. Results TV viewing was the only type of sedentary screen behavior associated with elevated diabetes risk factors before and after adjustment for confounders. Specifically, TV viewing remained positively associated with fasting insulin (adjusted r=0.11, β=0.10, p=0.048) and HOMA-IR (adjusted r=0.11, β=0.10, p=0.05) after adjustment for age, gender, waist-to-hip ratio, caloric intake, percentage of intake in carbohydrates, physical activity duration, and physical activity intensity. Conclusions TV watching may be independently associated with an increase in diabetes risk factors in a high-risk sample of overweight and obese adolescents. These findings provide support for interventions designed to reduce time spent watching TV as a possible means to attenuating diabetes risk factors in this high-risk population. Trial registration This study is registered at clinicaltrials.govNCT00195858.American Journal of Preventive Medicine 04/2013; 44(4):S364–S370. DOI:10.1016/j.amepre.2012.11.040 · 4.28 Impact Factor
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ABSTRACT: Importance Little evidence exists on which exercise modality is optimal for obese adolescents.Objective To determine the effects of aerobic training, resistance training, and combined training on percentage body fat in overweight and obese adolescents.Design, Setting, and Participants Randomized, parallel-group clinical trial at community-based exercise facilities in Ottawa (Ontario) and Gatineau (Quebec), Canada, among previously inactive postpubertal adolescents aged 14 to 18 years (Tanner stage IV or V) with body mass index at or above the 95th percentile for age and sex or at or above the 85th percentile plus an additional diabetes mellitus or cardiovascular risk factor.Interventions After a 4-week run-in period, 304 participants were randomized to the following 4 groups for 22 weeks: aerobic training (n = 75), resistance training (n = 78), combined aerobic and resistance training (n = 75), or nonexercising control (n = 76). All participants received dietary counseling, with a daily energy deficit of 250 kcal.Main Outcomes and Measures The primary outcome was percentage body fat measured by magnetic resonance imaging at baseline and 6 months. We hypothesized that aerobic training and resistance training would each yield greater decreases than the control and that combined training would cause greater decreases than aerobic or resistance training alone.Results Decreases in percentage body fat were −0.3 (95% CI, −0.9 to 0.3) in the control group, −1.1 (95% CI, −1.7 to −0.5) in the aerobic training group (P = .06 vs controls), and −1.6 (95% CI, −2.2 to −1.0) in the resistance training group (P = .002 vs controls). The −1.4 (95% CI, −2.0 to −0.8) decrease in the combined training group did not differ significantly from that in the aerobic or resistance training group. Waist circumference changes were −0.2 (95% CI, −1.7 to 1.2) cm in the control group, −3.0 (95% CI, −4.4 to −1.6) cm in the aerobic group (P = .006 vs controls), −2.2 (95% CI −3.7 to −0.8) cm in the resistance training group (P = .048 vs controls), and −4.1 (95% CI, −5.5 to −2.7) cm in the combined training group. In per-protocol analyses (≥70% adherence), the combined training group had greater changes in percentage body fat (−2.4, 95% CI, −3.2 to −1.6) vs the aerobic group (−1.2; 95% CI, −2.0 to −0.5; P = .04 vs the combined group) but not the resistance group (−1.6; 95% CI, −2.5 to −0.8).Conclusions and Relevance Aerobic, resistance, and combined training reduced total body fat and waist circumference in obese adolescents. In more adherent participants, combined training may cause greater decreases than aerobic or resistance training alone.Trial Registration clinicaltrials.gov Identifier: NCT00195858JAMA Pediatrics 09/2014; 168(11). DOI:10.1001/jamapediatrics.2014.1392 · 4.25 Impact Factor
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ABSTRACT: Excessive screen time and diminished health-related quality of life (HRQoL) are greater problems for obese than non-obese adolescents, but no research has examined the relationship between these two variables. This study examined the association between screen time and HRQoL in overweight and obese adolescents. A sample of 358 overweight and obese adolescents aged 14-18 years were assessed at baseline between 2005 and 2010 as part of the Canadian Healthy Eating, Aerobic and Resistance Training in Youth (HEARTY) trial. We used the Pediatric Quality of Life (PEDS-QL) and other self-report measures to assess HRQoL and screen time, defined as how long the 261 females and 97 males spent viewing TV, using the computer and playing video games. After adjusting for socio-demographic variables, adiposity, physical activity and diet, screen time duration was associated with reduced overall HRQoL (adjusted r = -0.16, ß = -0.16, p=0.009) and psychosocial HRQoL (adjusted r =-0.16, ß = -0.18, p=0.004), but not physical HRQoL. No differences were found between males and females. Screen time was associated with reduced overall and psychosocial HRQoL in overweight and obese adolescents. Future research should determine if reducing screen time improves overall and psychosocial HRQoL in obese adolescents. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.Acta Paediatrica 06/2015; DOI:10.1111/apa.13073 · 1.84 Impact Factor