Association Between Quadriceps Strength and Self-Reported Physical Activity in Individuals with Knee Osteoarthritis

Limited quadriceps strength is common with knee osteoarthritis (KOA) and may lead to activity avoidance and low physical activity (PA) levels. The purpose of the current study was to investigate the association between quadriceps strength and self-reported PA in individuals with KOA. Secondary analyses evaluated the association between a change (Δ) in quadriceps strength and ΔPA following a therapeutic intervention. Ninety individuals with KOA were enrolled (57% female; Age: 62.1 ± 7.4 years). At baseline, immediately post intervention, and 4 weeks after intervention completion, participants completed the Physical Activity Scale for the Elderly (PASE) and a quadriceps maximal voluntary isometric contraction normalized to body mass (nMVIC). After accounting for covariates (age, sex, OA severity, pain) there was no association between nMVIC and PASE (ΔR 2 = 0.007, P = 0.418) at baseline and no association between the ΔnMVIC and ΔPASE following the intervention (ΔR 2 = 0.028, P = 0.145), or 4 weeks post intervention (ΔR 2 = 0.004, P = 0.623). Quadriceps strength was not associated with self-reported PA. Increased strength following a therapeutic intervention did not lead to a subsequent increase in self-reported PA in this sample of individuals with KOA.