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

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.

Conditions

• Type 2 Diabetes Mellitus
• Adolescent Obesity

Interventions

OTHER

Aerobic Exercise Training

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.

Sponsors & Collaborators

• Manitoba Institute of Child Health

  collaborator INDUSTRY

• University of Manitoba

  lead OTHER

Principal Investigators

• Jonathan M McGavock, PhD · University of Manitoba

Study Design

Allocation

RANDOMIZED

Purpose

PREVENTION

Masking

NONE

Model

PARALLEL

Eligibility

Min Age

13 Years

Max Age

19 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2008-04-30

Primary Completion

2013-01-31

Completion

2013-01-31

Countries

• Canada

Study Locations