Date of Graduation

5-2019

Document Type

Thesis

Degree Name

Bachelor of Science

Degree Level

Undergraduate

Department

Health, Human Performance and Recreation

Advisor/Mentor

Howie, Erin K.

Committee Member/Reader

Ganio, Matthew

Committee Member/Second Reader

Washington, Tryone

Abstract

Background: Adolescent obesity has been on the rise with studies showing obesity tracks into adulthood. Obesity is an independent risk factor for cardiovascular disease (CVD); CVD is the leading cause of adult death in the U.S. Previous research shows a strong positive relationship between physical activity (PA) and cardiovascular (CV) health even in an obese adult population. Thus, the relationship between adolescent physical fitness and lifetime risk for CVD and all-cause mortality should be investigated. Purpose: The purpose of this study is to determine associations between PA and adiposity with cardiovascular health in obese and non-obese weight adolescents, with the hypothesis that physical activity will be positively associated with cardiovascular health independent of adiposity. Methodology: A convenience sample of 30 adolescents (ages 12-18) from the community completed assessments of height, weight, a dual x-ray absorptiometry (DXA) scan, resting blood pressure, and a flow-mediated dilation ultrasound (FMD) as a measure of endothelial function and cardiac health. Participants wore an accelerometer for one week to track PA. Participants were assigned to non-obese and obese categories from DXA, the gold standard, measure of body fat. Activity level was also grouped by minutes of moderate-to-vigorous PA (MVPA) per day based on a median split of 15 minutes per day. FMD value was calculated as (maximum diameter – baseline diameter)/ baseline diameter x 100. Comparisons in FMD (dependent variable) between body fat and MVPA groups (independent variables) were made using t-tests and associations between body fat and MVPA were tested using linear regression adjusted for sex. Results: FMD data was only available for 10 participants: average age=14.6 (SD 1.8), 50% female, BMI=20.9 (2.6), FMD%=11.9 (8.5). There were no differences (p=.943) in FMD between the obese (mean FMD% = 12.2, SE 4.1) and non-obese (11.8, SE 3.4) groups. Similarly, when percent body fat was examined as a continuous variable, percent body fat was not associated with FMD (coefficient =0.16 (SE 0.31), p=.612). Those with greater than 15 minutes of MVPA per day had a higher FMD (15.0, SE 3.3) compared to those with less than 15 minutes of MVPA per day (8.9, SE 3.3, p=.024). When MVPA was examined as a continuous variable, MVPA was positively associated with MVPA (coefficient =.32 (SE 15), p=.067, however, not statistically significant. Discussion: Despite the small sample size, there does appear to be a positive association between FMD and MVPA in adolescents but not an association between FMD and percent body fat. These results suggest an important correlation between PA and cardiac health and may also support the notion that PA may be more important in overall CV health when compared to body composition. Clinicians should emphasize promoting physical activity among adolescents, and not just focus solely on body fat.

Keywords

physical activity, cardiovascular health, body composition, adolescents

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