Indirect association of kinesiophobia with physical activity through pain self-efficacy in older women with primary osteoporosis.

BACKGROUND: Physical activity is a core component of osteoporosis management, yet many older women with primary osteoporosis remain insufficiently active. Kinesiophobia, pain self-efficacy, and physical activity are theoretically linked, but their cross-sectional inter-relationships in this population remain unclear. METHODS: This multi-center cross-sectional study recruited older women with primary osteoporosis and chronic musculoskeletal pain from outpatient clinics at three tertiary hospitals in China between March and July 2025. The primary exposure was kinesiophobia, assessed with the Tampa Scale for Kinesiophobia (TSK). The proposed statistical intermediary was pain self-efficacy, assessed with the Chronic Pain Self-Efficacy Scale (CPSS). The outcome was physical activity, assessed with the Physical Activity Scale for the Elderly (PASE). Covariate-adjusted regression and observed-variable structural equation models were used to estimate theory-informed indirect associations. RESULTS: A total of 448 participants were included in the primary analysis. The mean age was 69.9 years, and 79.0% had TSK scores > 37. Higher kinesiophobia was associated with lower pain self-efficacy and lower physical activity, while higher pain self-efficacy was associated with higher physical activity (all p < 0.001). In the primary cross-sectional indirect-association model, the standardized indirect association of TSK with PASE through CPSS was -0.159 (bootstrap 95% CI -0.216 to -0.101), accounting for 46.5% of the total statistical association. Findings were similar in a parsimonious covariate model. CONCLUSION: In this cross-sectional sample of older women with primary osteoporosis, pain self-efficacy statistically accounted for part of the association between kinesiophobia and physical activity. These findings should be interpreted as indirect associations rather than evidence of a causal or temporally ordered pathway, and they require confirmation in longitudinal and experimental studies.