Strength Training And Physical Function: Role of Self-Efficacy

Abstract

Background: The occurrence of knee osteoarthritis (OA) poses a significant problem for individuals' physical function. Strength training impacts physical function through improvements at the muscular level, where activities of daily living may feel easier to accomplish and may also positively impact perceptions of ability and physical symptoms. Therefore, this study aims to explore whether a strength training intervention leads to changes in self-efficacy and whether changes in self-efficacy mediate the effects of strength training on physical function. Methods: The Strength Training for Arthritis Trial (START) included 377 community- dwelling adults (≥ 50 years) with a body mass index ranging from 20 to 45, knee pain, and radiographic knee OA, who self-reported disability due to knee OA. Measures of Adherence Self-Efficacy, 6-minute Walk Distance, Western Ontario and McMaster Universities OA Index for physical function, and the SF-36 Physical Component Score were collected before randomization and again at an 18-month follow-up in adults who were assigned to 1 of 3 treatment conditions: high-intensity strength training, low-intensity strength training, or attention control. Results: Among 377 randomized participants (mean age, 65 years; 151 women [40%]), 320 (85%) completed the trial. The intervention had a significant positive effect on self-efficacy across all outcomes (ꞵ = 0.24-0.26, p < 0.001). Self-efficacy significantly mediated treatment effects on strength training and physical function across all measures (SF-36 PCS, WOMAC Function, and 6MWD; p < .05). Conclusions: Results supported that a strength training intervention led to improvements in self-efficacy and that self-efficacy mediated the relationship between strength training and physical function. Strength training programs designed to influence aspects of physical function should consider methods to improve self-efficacy and assist individuals with managing physical symptoms. This study was supported by grants 1R01AR059105-01 from the National Institute of Arthritis and Musculoskeletal and Skin Diseases and P30 AG21332 from the National Institute on Aging.