Healthy Eating Aerobic and Resistance Training in Youth (HEARTY) Trial
Condition: Obesity
Study type: Interventional
Phase: Phase 2/Phase 3

Summary: 
      The purpose of this study is to evaluate the effects of resistance training, aerobic
      training, and combined aerobic and resistance training on percent body fat, measured using
      Magnetic Resonance Imaging (MRI), in sedentary post-pubertal overweight or obese youth aged
      14-18 years.
    

Detailed description: 
      Background: Obesity and inactivity independently increase risks of chronic disease in
      adolescence and all-cause mortality in adulthood. In clinical trials, changes in exercise and
      diet can reduce adiposity and risk of diabetes and other chronic diseases in obese adults and
      youth. In many school systems, physical education is mandatory in elementary school but not
      high school, and physical activity often declines during adolescence. Because physical
      activity habits track from adolescence to adulthood, adolescence may represent a critical
      period for establishing a physically active lifestyle to prevent diseases associated with
      inactivity in adulthood. Obesity can make adherence to aerobic activity challenging, but
      would present less of an obstacle to resistance training. Resistance exercise has shown
      favorable effects on lean body mass, metabolic rate, insulin resistance, and quality of life
      in adults, but almost no research has examined effects of resistance training in obese
      adolescents. Our own survey in a sample of obese, primarily sedentary youth found greater
      overall interest in resistance exercise than aerobic exercise.

      Objectives: The primary objective of this study is to evaluate the effects of resistance
      training, aerobic training, and combined aerobic and resistance training on percent body fat
      measured using Magnetic Resonance Imaging (MRI) in sedentary post-pubertal overweight or
      obese youth aged 14-18 years.

      Study Design: Randomized controlled trial conducted at a single site. After a 4-week
      supervised low-intensity exercise run-in period to test compliance, 292 adolescents with BMI
      ≥ 85th percentile for age and gender will be randomized in equal numbers to one of 4 arms:
      Diet + aerobic exercise, diet + resistance exercise, diet + combined aerobic and resistance
      exercise, or diet-only control. The intervention will last 22 weeks, with a follow-up
      assessment at 6-months post-treatment (11-months post-randomization).

      Hypotheses: Reduction in percent body fat will be larger in diet + aerobic exercise and diet
      + resistance exercise than diet-only controls at post-treatment, and the combined aerobic and
      resistance training will be superior to either aerobic or resistance training alone in
      reducing percent body fat at post-treatment. The combined resistance and aerobic group will
      show greater improvements in percent body fat, body composition, and physiological and
      psychosocial function at post-treatment and 12-months follow-up. Groups that include
      resistance training will produce greater psychosocial changes and better adherence than
      aerobic training alone at post-treatment and follow-up.

      Significance: The global burden of obesity in youth is increasing, and more effective
      intervention is needed. This study may identify that resistance training is an important
      component in the treatment of overweight adolescents. As such, findings may influence
      clinical decision making in the management of juvenile obesity, as well as inform public
      health exercise guidelines and school-based physical education curricula in attempt to reduce
      the economic, medical, and psychosocial burden of obesity in youth.
    

Intervention name(s): aerobic and resistance exercise
Intervention type(s): Behavioral
Intervention description(s): aerobic and resistance exercise
Other intervention name(s): non applicable
Allocation: Randomized
Intervention model: Factorial Assignment
Masking: Single (Participant)
Primary purpose: Treatment
Keywords: Youth; Exercise; Physical Activity; Aerobic; Resistance; Overweight; obese; Canada; Sigal