Age and sex differences in prospective effects of health goals and motivations on daily leisure-time physical activity

Objective: To examine relationships between health goals, types of motivation for those goals, and daily leisure-time physical activity (LTPA), and whether these relationships differ by age or sex. Methods: From 2005 to 2008, 710 participants in and around Berlin, Germany provided life goals and motivational attributes of those goals at baseline, then reported LTPA daily for 25. days. Results: Having (vs. not having) a goal of physical health predicted higher odds of engaging in LTPA for younger but not older participants (under age 30; OR= 1.26, p= 0.048), and was not related to duration of LTPA episodes. Effect of intrinsic motivation for the health goal differed by sex: for females, higher intrinsic motivation predicted higher odds of LTPA (OR= 1.19, p= 0.001), but was not related to duration. For males, higher intrinsic motivation predicted lower LTPA odds marginally (OR= 0.70, p= 0.054) but predicted longer duration (estimate = 18.27. min, p< 0.001). More approach motivation for the health goal predicted longer duration of LTPA episodes (0.67. min, p= 0.022). Conclusions: One size does not fit all in LTPA intervention design. Future research should identify the mechanisms by which health goals and motivations affect health behavior.