A Study of the Effects of Exercise Intensity on Insulin Sensitivity in Overweight Youth
Condition: Type 2 Diabetes Mellitus; Adolescent Obesity
MeSH terms: Diabetes Mellitus; Diabetes Mellitus, Type 2; Overweight; Pediatric Obesity
Study type: Interventional
Phase: Phase 4

Summary: 
      Background:

      The investigators know that exercise helps children develop strong bones and muscles and
      generally stay healthy. What is unclear however, is how much exercise a child needs to lower
      their risk of developing type 2 diabetes.

      Objective:

      The investigators will try to find out whether high-intensity exercise for a short-period of
      time is better than moderately intense exercise for improving the diabetes risk profile in
      teens who are at risk for type 2 diabetes.

      The working hypothesis is that exercise-mediated improvements in insulin sensitivity (a risk
      factor for diabetes) will be greater following vigorous intermittent physical activity than
      following low intensity physical activity in overweight adolescents 13-18 yrs at risk for
      T2DM.

      Brief Description of Research Project: Teenagers between the ages of 13 and 18 yrs, who are
      at risk for type 2 diabetes (either by their family history or an abnormal response to sugar)
      will be randomly assigned to one of two activity groups or a control group. The activity
      groups will have supervised exercise sessions 3 to 5 days per week for 6 months. One group
      will do high-intensity exercise, and the other will do lower-intensity exercise. We will
      measure how sensitive their body is to insulin and the amount of fat in their muscle and
      liver tissue at the beginning and end of the exercise intervention.
    

Detailed description: 
      The Physical activity for OverWEight youth at Risk for type 2 diabetes (POWER) Trial is a
      randomized controlled clinical trial designed to study the effects of aerobic exercise
      training regimens differing in intensity (relative to peak fitness) on insulin sensitivity in
      overweight youth. Additionally, this trial will explore the biologic mechanisms through which
      chronic physical activity alters lipid metabolism to result in improvements in insulin
      sensitivity.

      We will recruit 90 eligible adolescents and randomly assign them to one of two six-month
      intervention arms that differ by intensity but elicit similar amounts of energy expenditure:
      (1) a low intensity continuous activity arm (40-55% of peak oxygen uptake for 60 min); (2)
      vigorous intensity intermittent activity arm (70-85% of peak oxygen uptake for 30 min) or a
      sedentary control group. The primary outcome measure of this trial will be insulin
      sensitivity, measured directly from Bergman's frequently sampled intravenous glucose
      tolerance test.
    

Intervention name(s): Aerobic Exercise Training
Intervention type(s): Other
Intervention description(s): All sessions will be designed to elicit a certain degree of energy expenditure that will progressively increase throughout the trial. Adolescents randomized to the vigorous activity group will perform interval sessions that ensure an average heart rate between 70 and 85% of maximal heart rate reserve while those randomized will perform aerobic activity between 40 and 50% of heart rate reserve. The goal for the trial will be to expend a minimum of 350 kcal. The type of exercise will depend on the preference of each participant however, during the supervised sessions walking/jogging on a treadmill or outdoors will be used to elicit exercise intensities. The three activity sessions held at the YMCA-YWCA facilities in Winnipeg and be supervised by a trained kinesiologist who will record heart rate and perceived exertion for each session.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Prevention
Keywords: Childhood; insulin sensitivity; steatosis, spectroscopy