Running Mechanics After Repeated Sprints in Femoroacetabular Impingement Syndrome, Cam Morphology, and Controls

Background: People with femoroacetabular with femoroacetabular impingement syndrome (FAIS) often report pain during sports involving repeated sprinting. It remains unclear how sports participation influences running biomechanics in individuals with FAIS. Hypothesis: Changes in running biomechanics and/or isometric hip strength after repeated sprint exercise would be greatest in individuals with FAIS compared with asymptomatic individuals with (CAM) and without cam morphology (Control). Study Design: Controlled laboratory study. Methods: Three-dimensional hip biomechanics during maximal running (10 m) and hip strength were measured in 49 recreationally active individuals (FAIS = 15; CAM = 16; Control = 18) before and after repeated sprint exercise performed on a nonmotorized treadmill (8-16 x 30 m). Effects of group and time were assessed for biomechanics and strength variables with repeated-measures analyses of variance. Relationships between hip pain (Copenhagen Hip and Groin Outcome Score) and changes in hip moments and strength after repeated sprint exercise were determined using Spearman's correlation coefficients (rho). Results: Running speed, hip flexion angles, hip flexion and extension moments, and hip strength in all muscle groups were significantly reduced from pre to post. No significant between-group differences were observed before or after repeated sprint exercise. No significant relationships (rho = 0.04-0.30) were observed between hip pain and changes in hip moments or strength in the FAIS group. Conclusion: Changes in running biomechanics and strength after repeated sprint exercise did not differ between participants with FAIS and asymptomatic participants with and without cam morphology. Self-reported pain did not appear to influence biomechanics during running or strength after repeated sprint exercise in participants with FAIS.