Objectives: Regular vigorous physical activity (PA) and high levels of physical fitness (PF) confer health benefits. Conversely, sedentary time is a risk factor for chronic illness, independent of PA. We evaluated associations between self-reported PA, sedentary time, and objective PF measures in military Service members. Design: Cross-sectional study including 10,105 Air Force Millennium Cohort participants with a valid physical fitness assessment (PFA). Methods: Linear regression assessed associations between self-report PA, screen time, and usual activity and abdominal circumference (AC) and VO2 max; logistic regression was used for PFA failure. We stratified by age and sex. Results: Men who self-reported high versus low levels of PA had greater AC (19–29 years: β = 0.23 in., 95% CI 0.07, 0.39; 30–39 years: β = 0.45 in., 95% CI 0.17, 0.72). High versus low self-reported PA was also associated with greater VO2Max (β =: 0.81–1.41 mL/kg/min). Self-reported strength training for ≥2 days/week was associated with greater VO2Max in 19–29 year old men (β = 0.84 mL/kg/min, 95% CI 0.09, 0.60) and 30–39 year old women (β = 0.74 mL/kg/min, 95% CI 0.02, 1.46). For younger men and women,<2 h of screen time/day was associated with greater VO2Max (Males 19–29 years: β = 0.23 mL/kg/min, 95% CI 0.44, 1.26; Females 19–29 years: β = 0.83 mL/kg/min, 95% CI 0.25, 1.42). PA was not associated with PFA failure, while screen time was (Males OR: 0.32–0.65, 95% CI 0.17–0.92, p < 0.001–0.016). Conclusions: Self-reported PA and screen time were associated with some objective PF measures, including VO2Max and AC. However, screen time alone was associated with PFA failure.
de la Motte, S. J., Welsh, M. M., Castle, V., Burnett, D., Gackstetter, G. D., Littman, A. J., … Hooper, T. I. (2019). Comparing self-reported physical activity and sedentary time to objective fitness measures in a military cohort. Journal of Science and Medicine in Sport, 22(1), 59–64. https://doi.org/10.1016/j.jsams.2018.05.023