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Trajectories in Physical Activity and Inactivity among Women Veterans in the Women’s Health Initiative
Washington DL, Gray K, Katon JG, Cochrane BB, Hoerster KD, Bastian L, Weitlauf JC, Bean-Mayberry BA, Richardson CR, Tinker L. Trajectories in Physical Activity and Inactivity among Women Veterans in the Women’s Health Initiative. Paper presented at: VA HSR&D / QUERI National Meeting; 2015 Jul 8; Philadelphia, PA.
Objectives: Individuals entering the military are more physically fit than similarly aged civilians ("healthy warrior effect"). However, trajectories of physical activity after military separation have not been described or compared to non-Veterans. Understanding these trajectories is particularly important for women Veterans (WVs) given their high prevalence of cardiovascular risk factors. Our objective was to compare trajectories of physical activity and sedentary behavior between Veteran and non-Veteran women.
Methods: We included 3,240 WVs and 123,423 non-Veteran postmenopausal Women's Health Initiative participants aged 50-79 years at baseline. Self-reported physical activity, converted to MET-hours/week was assessed over 8 years in both the Clinical Trials and Observational Study participants. Self-reported sedentary behavior (hours sitting or lying down/day) was collected from Observational Study participants at baseline and years 3 and 6. We examined differences between Veterans and non-Veterans at baseline. We also assessed adjusted trajectories using a general estimating equations approach to linear regression, including an interaction term between visit and Veteran status to examine differences in trajectories.
Results: At baseline WVs had higher physical activity than non-Veterans (13.1 vs. 12.5 MET hours/week; difference 0.70; 95% confidence interval [CI] 0.24, 1.16). Physical activity declined over time in Veterans (adjusted change per visit year -0.19 MET-hours/week; 95% CI -0.12, -0.27) and non-Veterans (-0.03 MET-hours/week; 95% CI -0.005, -0.03), but the decline was greater in Veterans (p < 0.001 for interaction). At baseline WVs and non-Veterans had similar levels of sedentary behavior (15.3 vs. 15.1 sedentary hours/day; difference 0.15; 95% CI -0.02, 0.33). Trajectories of sedentary behavior differed between Veterans and non-Veterans (p = 0.01 for interaction) with sedentary behavior remaining stable among Veterans (adjusted change per visit year -0.03 hours/day; 95% CI -0.06, 0.004), but slightly declining among non-Veterans (-0.07 hours/day; 95% CI -0.07, -0.08).
Implications: WVs had healthier baseline physical activity and sedentary behavior compared to non-Veterans. However, over time WVs had more adverse trajectories than non-Veterans.
Impacts: The less favorable physical activity trajectories we found among WVs may contribute to their excess mortality later in life. Physical activity should be monitored and promoted in WVs. Research should be directed toward identifying predictors of activity trajectories and facilitators of physical activity maintenance.