Background Psychological well-being is closely linked to healthy aging in older women. Our study aims to elucidate inconsistencies in the literature on the relationships between physical behavior (physical activity and sedentary behavior) with optimism and positive affect using comprehensive, well-validated and objective measures in a large, diverse sample of older women.

Methods Our study of 4168 women (aged 63-99) with accelerometer-measured data from the Women’s Health Initiative (WHI) study assessed associations of physical behavior (moderate-vigorous physical activity [MVPA], light physical activity [LPA], sitting time, and mean sitting bout duration) with optimism and positive affect using multiple linear regression models. Effect modification by age, race/ethnicity, multimorbidity, and social support was examined for all study associations.

Results In unadjusted models, positive associations for physical activity and negative associations for sedentary behaviors were present for both optimism and positive affect and associations were generally linear. In adjusted models, for every increased hour of MVPA, optimism increased by 0.4 score points [95% CI 0.2, 0.6, p-value <0.001] and positive affect increased by 0.6 score points [95% CI 0.2, 0.9, p-value=0.001]. For LPA, positive affect increased by 0.2 [95% CI 0.03, 0.33, p-value=0.02] and for sedentary behavior, a negative association existed for mean sitting bout duration and positive affect (β=-0.1, 95% CI -0.10, -0.02, p-value=0.002). Although there was not strong evidence of statistically significant interaction, differential effect estimates by age showed possible effect modification; all associations were stronger in women ≥80 years old compared to those <80 years old.

Conclusions Observed associations between physical behavior with optimism and positive affect were modest but robust over the average study period of one to two years. We recommend age-appropriate, attainable interventions that encourage older women to move more than they are currently. The known benefits of increased physical activity combined with the upward spiral effects of increased physical activity and improved well-being can ultimately improve many other aspects of this population’s physical and psychosocial health.