(34) THE INFLUENCE OF BMI ON THE RELATIONSHIP BETWEEN AEROBIC CAPACITY AND TESTOSTERONE IN CAREER FIREFIGHTERS

Purpose: The purpose of this study was to understand the confounding effect that BMI may have on the association between testosterone and VO_2PEAK in career firefighters. Methods: Annual health data were retrospectively analyzed from 1151 career firefighters (age = 39 ± 9 years, BMI: 30.0 ± 4.7). Data included demographics, anthropometrics (BMI), cardiopulmonary exercise testing using a maximal-effort, cycle-based graded exercise testing protocol to directly quantify VO_2PEAK, and serum testosterone acquired via venipuncture. Testosterone levels were categorized as: low (< 264 ng/dL), borderline (264-399 ng/dL), reference range (400 – 916 ng/dL) and above reference ( >916 ng/dL). Linear mixed effect models were employed to use VO_2PEAK as the dependent variable, with BMI and testosterone category as independent variables. Random effects included random intercepts for subjects nested within fire department locations. Results: After adjusting for BMI, outcomes indicated that VO_2PEAK was higher for individuals in the reference range (B = 2.30 ml/kg/min; t = 4.01; p < 0.001) and above reference range (B = 2.63; t = 3.88; p < 0.001) testosterone categories. Conclusions: The study suggests that firefighters in the low or borderline testosterone categories may present with lower VO_2PEAK values than those within at least reference testosterone categories or higher. Practical Applications: Tactical Strength and Conditioning Facilitators who work with the fire service should monitor testosterone levels in order to encourage a higher aerobic capacity. Acknowledgements: none