Effects of a Single-session Hip-strengthening Exercise on Gluteus Medius Muscle Thickness and Dynamic Balance in Adults with Knee Pain

This study investigated the immediate effects of a single session of hip-strengthening exercises on gluteus medius muscle thickness, dynamic balance, and knee pain in adults with nonspecific knee pain. Nonspecific knee pain, which lacks clear structural abnormalities, is often associated with hip muscle weakness and altered lower-extremity biomechanics. Forty-eight adult males with activity-related anterior knee pain were randomly assigned to either a side-bridge or a clamshell exercise group. Both interventions were performed once under supervision. Gluteus medius thickness was measured using ultrasound imaging, dynamic balance was assessed with the Y-Balance Test, and pain intensity was evaluated using a visual analog scale. Within-group pre–post changes were analyzed using paired t-tests, and between-group comparisons of change scores (Δ) were performed using independent t-tests. Pearson correlation analysis was conducted to examine relationships among changes in muscle thickness, balance performance, and pain. Both groups showed significant improvements in muscle thickness, balance, and pain after exercise (p < .05), with the side-bridge group demonstrating significantly greater gains in gluteus medius thickness and Y-Balance Test scores compared with the clamshell group (p < .05). Although pain decreased in both groups, the intergroup difference was not significant. Increases in muscle thickness were positively correlated with balance improvement and negatively correlated with pain reduction. These findings suggest that even a single bout of side-bridge exercise can induce short-term neuromuscular and functional changes, and may support its use as an early intervention option for nonspecific knee pain.