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Completed

NCT Number: NCT00755547

A Study of the Effects of Exercise Intensity on Insulin Sensitivity in Overweight Youth

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.

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Key information

Conditions

Type 2 Diabetes Mellitus Adolescent Obesity Body Weight Diabetes Mellitus Diabetes Mellitus, Type 2 Digestive System Diseases Endocrine System Diseases Fatty Liver Glucose Metabolism Disorders Hyperinsulinism Insulin Resistance Liver Diseases Metabolic Diseases Nutrition Disorders Nutritional and Metabolic Diseases Obesity Overnutrition Overweight Pathological Conditions, Signs and Symptoms Pediatric Obesity Signs and Symptoms

Age range

13 year–19 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 4

Primary location

Manitoba Institute of Child Health

Winnipeg, Manitoba, R3E3P4, Canada

About this study

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.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Ethnic minority considered at risk for T2DM
  • In utero exposure to hyperglycemia (i.e. mother with gestational or frank diabetes during pregnancy) and/or evidence of hepatic steatosis (serum ALT > 60U/L, ultrasound or MRI-based evidence of steatosis).

Exclusion criteria

  • The investigators will exclude any patients that may have altered insulin sensitivity or tissue lipid content that would confound (mask) the effects of the intervention.
  • These include overweight adolescents who:
  • are diagnosed with impaired glucose tolerance or type 2 diabetes
  • are currently being treated with corticosteroids or atypical antipsychotics, as these agents significantly influence carbohydrate metabolism
  • are undergoing puberty (Tanner Stage 2-4) at the time of the investigation, as it is associated with transient changes in insulin sensitivity
  • have an orthopaedic injury that would prevent them from performing the intervention
  • have experienced weight loss or enrolled in weight loss program in the six months prior to the study
  • have a history of alcoholism or drug abuse.

Treatment and study plan

Aerobic exercise training

Other

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.

Primary outcomes

  1. Insulin sensitivity measured from Bergman's frequently sampled intravenous glucose tolerance test

    Time frame: 6 months

Secondary outcomes

  1. 1H-Magnetic resonance spectroscopy-derived measure of lipid content in liver and muscle tissue

    Time frame: 6 months

Sponsors and collaborators

Lead sponsor

University of Manitoba

Other

Collaborators

  • Manitoba Institute of Child Health

Registry information

Official study title

Physical Activity for Overweight Youth at Risk for Type 2 Diabetes Mellitus (POWER) Trial

Acronym: POWER

Important dates

Study start
2008
Primary completion
2013
Study completion
2013
First posted
Sep 19, 2008
Registry last updated
Mar 29, 2013

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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