Effects of Exercise Intensity in Obese Children and Adolescents

A Multi-centre Randomized Controlled Trial Examining the Effects of High Intensity Interval Training on Cardio-metabolic Outcomes in Obese Children and Adolescents

The prevalence of paediatric obesity has increased over the last two decades and with it, an increased diagnosis of lifestyle-related diseases in children and adolescents. High intensity interval training has recently been explored as an alternate to traditional aerobic exercise in adults with chronic disease and has potential to induce rapid reversal of subclinical disease markers in obese children and adolescents.

High intensity interval training has recently been explored as an alternate to traditional aerobic exercise in adults with chronic disease and has potential to induce rapid reversal of subclinical disease markers in obese children and adolescents.

Goal: The primary aim of this randomised controlled trial is to evaluate the effectiveness of a high intensity interval training intervention on myocardial function, vascular function and visceral adipose tissue in obese children and adolescents at baseline, three and twelve months.

Method: Multi-centre randomised controlled trial of 100 obese children and adolescents in the cities of Trondheim (Norway) and Brisbane (Australia). Participants will be randomised to (1) high intensity interval training, (2) moderate intensity continuous training or (3) nutrition advise. Participants will partake in supervised exercise training and/or nutrition consultations for 3 months. Measurements for all study endpoints will occur at baseline, 3 months (post intervention) and 12 months (follow up).

Scientific Significance : This randomised controlled trial will general substantial information regarding the effects of exercise intensity on paediatric obesity, specifically the cardio-metabolic health of this at-risk population. It is expected that communication of results will allow for more robust and realistic guidelines regarding exercise prescription in this population to be formed while outlining the benefits of high intensity interval training on subclinical markers of disease.

Worldwide, childhood overweight and obesity rates are approximately 10%, this high incidence attributed to a physically inactive lifestyle and inappropriate nutrition. Early cohort studies illustrated that fifty per cent of obese children became obese adults and consequently had an higher risk for metabolic syndrome than obese adults who were not obese as children. Both female and male overweight children and adolescents had a 30% increase in all cause mortality. The increases in risk of death were independent of adult body mass index.

Systematic reviews suggest that lifestyle and exercise interventions in obese children and adolescents can lead to improvements in anthropometric and cardio-metabolic outcomes, but these are not inclusive of several important outcomes such as myocardial and vascular function or visceral adipose tissue.

Inclusion Criteria:

- Obese (BMI ≥ 95th percentile - age and sex specific criteria)

Exclusion Criteria:

• Elevated blood pressure (≥ 95th percentile for systolic or diastolic values)
• Congenital heart disease
• Coronary artery disease
• Family history of hypertropic obstructive cardiomyopathy
• Any abnormality during rest or stress echocardiography which indicates it would be unsafe to participate
• Self reported kidney failure
• Any major organ transplant
• Considerable pulmonary disease including severe or poorly controlled asthma
• Smoking
• Diabetes
• Epilepsy or a history of seizures
• Orthopaedic or neurological limitations to exercise
• Diagnosed attention deficit hypersensitivity disorder
• Steroid medications
• Participation in another research study