The purpose of this study is to examine the effects of high intensity interval exercise (HIIE) on inflammation and endothelial dysfunction found in children with obesity. Our working hypothesis is that, compared with obese children prescribed moderate exercise, obese children prescribed HIIE will demonstrate greater improvements in endothelial function and inflammatory markers following a 6-week exercise intervention.

Obesity, even in children, is generally accompanied by a state of chronic inflammation. To combat childhood obesity, clinicians and scientists recommend lifestyle interventions that include increased physical activity and exercise in an attempt to promote weight loss and, consequently, decrease comorbidities associated with excess adiposity. More importantly, it appears that the influence of regular exercise may offer children with obesity a multitude of health benefits, independent of weight loss. However, the intensity of exercise required to elicit significant health benefits is still unclear. Therefore, the aim of the present project is to study the influence of high intensity interval exercise (HIIE) on the existing inflammatory state found in obesity. Specifically, the proposed project will examine endothelial function and markers of inflammation, such as TNFa, IL-6, hsCRP, and adiponectin, in children with obesity before and after an exercise intervention. The data will then be used to determine if changes in these values differ in magnitude based on the intensity of exercise. Children with obesity will be randomized into either moderate exercise or HIIE groups, and attend sessions 3 times per week for 6 weeks. The moderate group will cycle continuously for 30 minutes at 65%-70% of maximal heart rate and the HIIE group will perform ten, 2-minute bouts at 90%-95% of maximal heart rate. Outcome measures of body composition, aerobic capacity, blood lipids, glucose metabolism, endothelial function, and inflammation will be measured pre- and post-intervention. Results may help in establishing exercise protocols not only for children with obesity, but also other inflammatory diseases such as diabetes, cancer, and arthritis.

Inclusion Criteria:

• 13-17 years old
• obesity (defined as as BMI≥ 95th percentile for age and sex as defined by the Centers for Disease Control

Exclusion Criteria:

• active participation in ≥30 minutes of vigorous exercise more than 2 days per week
• participation in an organized combined diet/exercise weight loss intervention
• acute inflammatory disease or febrile illness
• recent trauma or injury
• asthma requiring steroid use or that has resulted in hospitalization within 3 months prior to enrollment
• chronic disease known to affect inflammation (e.g. lupus)
• any renal, heart, or liver disease