A 12-week exercise program for patients with hip osteoarthritis has no influence on gait parameters: A secondary analysis of a randomized controlled trial

•RCT on the effectiveness of a 12-week exercise program for hip OA on gait.•Strength-improving exercises have no effect on hip and knee joint angles.•Strength-improving exercises have no effect on spatio-temporal variables.•To improve walking, gait related tasks should be incorporated in exercise. Hip osteoarthritis is a major musculoskeletal disorder in the elderly. Evidence is given for the efficacy of exercise interventions in terms of self-reported physical functioning and pain. However, it has not yet been fully examined whether exercises influence gait. The purpose of this RCT therefore was to evaluate effects of a 12-week exercise program on kinematic gait variables in subjects with hip osteoarthritis. 210 participants were randomly assigned to exercise, non-treated control, or placebo ultrasound groups. The 12-week exercise intervention combined a weekly group session with home-based exercises (2/week), which entailed exercises for motor learning, flexibility, strengthening, and balance. Placebo ultrasound was given once a week. A 6-camera motion capture system was used for data collection. Data were derived from shod walking at self-selected speeds. Spatio-temporal and hip and knee joint angles of the stance phase were calculated. Data were averaged across five trials. Measurements were taken prior to and immediately after the intervention period. ANOVA/Kruskall-Wallis-Tests were used to analyze between-group effects for differences between test days. Pairwise comparisons were subsequently conducted in case of significant model effects. Data were analyzed per protocol (n = 185). No statistically significant differences were detected for any of the outcome measures. Although hip muscle strength and gait quality are related, strength training of the hip-surrounding musculature without specific gait training elements cannot improve spatio-temporal gait characteristics or hip and knee joint angles in subjects with mild to moderate hip osteoarthritis. If gait should explicitly be improved through exercise, interventions must incorporate a relevant portion of gait-related tasks.