Effect of exercise intensity on cardiac and vascular function, and intra-abdominal fat in obese children and adolescents.
Professor Jeff Coombes
60 participants
Feb 3, 2014
Interventional
Conditions
Summary
Childhood obesity is associated with reduced levels of fitness, damage to blood vessels, impaired hormone regulation and decreased heart function. These can lead to poor quality of life, increased risk of heart disease as an adult and premature death. Exercise is beneficial for obese individuals, however the most effective exercise prescription for obese children and adolescents is not yet known. In many adult populations, high intensity interval training has been shown to be superior to traditional continuous moderate-intensity exercise modes. The objective of the study is to investigate the effects of high intensity exercise intensity on myocardial and arterial function, intra-abdominal fat and cardiovascular disease risk factors in obese children and adolescents over one year. The hypothesis is that high intensity aerobic interval training will be significantly better at improving myocardial and vascular function and decreasing intra-abdominal fat compared to moderate intensity exercise and diet intervention only (control) in children and adolescents.
Eligibility
Inclusion Criteria8
- Gender: Males and females are eligible. The study will endeavour to recruit approximately equal numbers of males and females.
- Body mass index: Obese individuals, with a body mass index greater than or equal to an equivalent of 30kg/m2 in adults are eligible. Eligibility of obese individuals with a BMI greater than 99th percentile (CDC Growth Charts) will be assessed on an individual basis.
- Age: Individuals aged 7-16 years old (inclusive) are eligible.
- Ethnicity: All ethnic groups are eligible for the study. There is likely to be incidental recruitment of participants of Aboriginal or Torres Strait Islander ethnicity.
- Blood pressure: Individuals with blood pressure less than the 95th percentile for systolic or diastolic values measured upon three or more occasions will be eligible
- Lipid control: Individuals with fasting total cholesterol less than 5.5mmol/L and low-density lipoprotein cholesterol less than 3.0mmol/L are eligible.
- Willingness to participate: Participants must be willing to be randomised to either High Intensity Aerobic Interval Training, Moderate Intensity Exercise or Control groups and to follow the protocol that they have been assigned.
- Successful completion of self-monitoring: Successful seven accelerometer compliance and diet diary completion will be an indication of willingness to participate and will be required for eligibility
Exclusion Criteria15
- Unwilling to participate or participation in another study
- Coronary heart disease
- Congenital cardiac abnormalities (i.e. anomalous coronary artery origins)
- Family history of hypertrophic obstructive cardiomyopathy
- Any abnormality during the resting or exercise stress echo that indicates it would be unsafe to participate in the intervention
- Self reported kidney failure
- Any major organ transplant
- Considerable pulmonary disease including severe or poorly controlled asthma or exercise induced asthma
- Smoking
- Diabetes
- Epilepsy or history of seizures
- Orthopaedic and/or neurological limitations to exercise
- Diagnosed Attention Deficit Hypersensitivity Disorder (ADHD)
- Medications such as steroids
- Conditions not specifically mentioned above may serve as criteria for exclusion at discretion of the clinical site
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Interventions
Eligible participants are randomized to the three arms of the study: a high intensity interval training group, a moderate intensity exercise group and a control group. Participants in all three interventions and their general practitioners are given results from study examinations after each testing session (at baseline, 3 months and 12 months). The exercise intervention arms combine dietary advice with an exercise training intervention over 12 months. Participants assigned to these arms will receive dietary education sessions that will parallel sessions provided to those assigned to the control group. They will attend a 30 minutes session every second week for three months, followed by one session every two months for the next nine months. Participants in the exercise groups will be asked to train three times a week for twelve months. In the first three months, they will perform two supervised sessions in the gymnasium in the School of Human Movement Studies, UQ St Lucia. The remaining one session will be performed at home. During the following nine months, all exercising training will be performed at home. The exercise training in both groups will be by walking or running on a treadmill, or on a bike for the older children. The younger children will have an exercise activity adjusted to age, gender and climate (to be discussed with clinical investigators). Each session, participants will be given the choice of using a treadmill or stationary bike. All participants will perform a 10-minute warm up at 60% of maximal heart rate (HRmax). Participants randomised to the high intensity interval training (HIIT) group will either walk, run or cycle at 85-95% of their maximal heart rate at intervals of 4 x 4 minutes, with 3 minute active breaks (~60% of HRmax) between intervals. Total exercise time in this group will be 40 minutes. Participants randomised to the moderate intensity exercise (MICT) group will walk, run or cycle continuously at 70% HRmax for approximately 44 minutes to equalize the energy expenditure performed by the HIIT. Total exercise time in this group will be 50 minutes. All participants will perform a 5-minute cool down period. Participants will be encouraged to maintain the required HR through a reward system. For example, the younger children (7-12) will get stars/stickers on a public board, giving them feedback on their progress compared to others in the study. Participants will be required to fill out a training diary to record the one unsupervised session every week that they do. An compliance of 80% to training sessions will be required.
Locations(1)
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ACTRN12613001037796