Lower-limb work during low- and high-impact tasks in hip-related pain: Associations with sex and symptoms

      Background: Hip-related pain (HRP) is a movement-related condition; however, previous biomechanics research into HRP have concentrated on male-dominated cohorts and focused on people undergoing surgical intervention. As a result, little is known about the biomechanical impairments of women with HRP and those not seeking surgery. Therefore, the aims of this study were threefold: (i) to evaluate the differences in lower-limb joint work between football players with and without HRP, (ii) to explore the relationship between lower-limb work and a person’s burden of HRP, and (iii) to determine whether any potential differences/relationships were sex-dependent.
      Methods: Football players aged 18-50 years were eligible to participate. For the HRP group, participants were eligible if they presented with a 6-month history of HRP; whereas control players were eligible if they presented with no lower-limb or lower-back pain/injury over the previous six months. A total of 88 players with HRP (23 women) and 30 asymptomatic controls (13 women) participated. Biomechanical data were collected during walking and single-leg drop jumps (SLDJ). HRP burden was quantified using the International Hip Outcome Tool (iHOT33). Between-group differences and relationships between lower-limb work done and a person’s burden of HRP were assessed using linear regressions incorporating sex-based interactions.
      Results: Walking: No joint work variables were different between footballers with and without HRP independent of sex, nor were any relationships with a person’s burden of HRP evident. SLDJ: A sex-specific interaction was present for the knee’s relative contribution to total lower-limb negative work done, with women with HRP demonstrating a lower contribution compared to their asymptomatic female peers (37.7% vs 42.4%, P=0.04). The iHOT33 was significantly associated with positive (P=0.03 to <0.01) and negative (P=0.02 to <0.01) work done by the hip as well as negative work done by the ankle (P=0.03 to 0.01), independent of sex
      Discussion: Overall, few differences were observed between players with and without HRP. Only one significant between-group difference was revealed, involving the knee in women only, providing further insight that the relationship between hip pain and biomechanics may be modified by sex. In addition, players with a greater self-reported burden of HRP tended to display lower hip joint work during the SLDJ. Rehabilitation programs for people with HRP should target these impairments and normalize lower-limb work done during high impact tasks.
      COI statement: Funding was supplied by the NHMRC (GNT:1088683).