Purpose: To determine the relation of self-reported strength training, accounting for moderate-vigorous aerobic activity, to 7-year trajectories of objectively measured and self-reported physical function.
Significance: Quantifying longitudinal patterns of physical function associated with strength training participation may facilitate our understanding of the broader impacts of this exercise mode and better inform tailored exercise prescription for adults with knee OA.
Methods: Participants were included from the Multicenter Osteoarthritis (MOST) study. MOST is a NIH-funded, longitudinal cohort study of individuals with or at risk of developing knee OA. Participants completed the Physical Activity Scale for the Elderly questionnaire at baseline from which level of strength training participation was obtained. The 20-meter walk test, repeated chair-stand test, and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) function subscale were used to assess physical function at baseline, 30-, 60-, and 84-months. Trajectories of physical function were identified using group-based trajectory modeling. Logistic regression was used to determine the association between strength training participation status at baseline and trajectories of changes in physical function. Analyses were adjusted for age, sex, BMI, radiographic knee OA, self-reported moderate-vigorous aerobic activity (never versus any), and knee pain severity. Odds ratios with 95% confidence intervals were determined for each analysis.
Conclusion: Participants who engage in strength training exercise are more likely to have and maintain higher levels of physical function over 7 years independent of self-reported level of moderate-vigorous aerobic activity.