Abstract Knee osteoarthritis (KOA) is a chronic disease that often leads to persistent pain, functional limitations, and diminished quality of life. Physical activity can be an effective countermeasure but its adherence typically relies on behavioral determinants. Currently, there is limited work investigating how clinical symptoms among patients with KOA affect behavioral determinants, and there is a need for further insight into why females engage in less physical activity. The purpose of this study was to investigate these questions in a sample of patients with KOA. Patients (n = 736; mean age 56.4 years) with symptomatic KOA (Kellgren–Lawrence grades 0–4) were evaluated at a tertiary sports medicine clinic and completed validated measures of physical activity behavior and behavioral determinants (attitudes, exercise self-efficacy, social support, barriers), in addition to pain and symptoms. Physical activity score was inversely associated with pain intensity (VAS; β = −0.037, p= .004), pain catastrophizing (PCS; β = −0.124, p = .004), and functional limitation (WOMAC; β = −0.364, p < .001). Greater social support was associated with lower WOMAC (β = -.30, p < .001), lower VAS (β = -.14, p =.021), and lower PCS scores (β = -.18, p = .002). Higher exercise self-efficacy was independently associated with reduced pain catastrophizing (PCS; β = −.061, p = .017) and functional limitation (WOMAC; β = −.267, p < .001). Worsening functional status (WOMAC) was significantly associated with more negative affective attitudes (β = .19, p = .001), lower exercise self-efficacy (β = .34, p < .001), and greater perceived barriers (β = .16, p = .002). Exercise intention was a significant predictor of physical activity (β = .36, p <.001), and was itself predicted by affective attitude, social support, self-efficacy, and perceived barriers. Sex comparisons revealed that males scored significantly higher than females in physical activity (p = .015), exercise intention (p = .031), exercise self-efficacy (p = .007), and social support (p = .038), with no significant differences in affective attitude or perceived barriers. Males also reported lower symptom severity than females across VAS (p = .006), PCS (p = .007), and WOMAC (p < .001); however, sex differences in VAS were no longer significant after covariate adjustment. Conclusions. Higher physical activity levels were associated with lower pain and improved functionality in patients with KOA. Sex-based discrepancies in exercise self-efficacy, social support, and exercise intention could help explain why females with KOA participate in less physical activity compared with their male counterparts.
Jahn et al. (Sat,) studied this question.