Decreased Average Power of the Hip External Muscles as a Predictive Parameter for Lower Extremity Injury in Women: A Prospective Study

Objective: To prospectively identify hip strength associated risk factors contributing to the development of lower extremity (LE) injury. Design: Data were prospectively collected on healthy female physical education students. Setting: This study was conducted in the institution of the University of Ghent. Participants: Eighty-nine female physical education students aged 19.53 6 1.07 years. Assessment of Risk Factors: Testing included isokinetic hip strength measurements of abductors, adductors, internal rotators, and external rotators (ERs). Main Outcome Measures: Follow-up of the participants was assessed using a weekly online questionnaire and a 3-month retrospective control questionnaire. Lower extremity injury was diagnosed by an experienced medical doctor. Cox regression was used to identify the potential risk factors for the development of an LE injury. Results: Thirty-four participants were diagnosed with an LE injury during follow-up. This study identified that decreased average power (AP) (P 5 0.031) on concentric ER strength was found to be a significant risk factor for LE injury. No other hip strength parameters were found to be significant contributors to the development of LE injury. Conclusions: Decreased AP of the hip ER muscles was identified as a significant predictor for LE injury, whereas no hip abduction weakness or peak torque parameters were found to be predictive. Because controlling LE extremity movements is an important function of the hip muscles, they might be more challenged in a dynamic measure such as AP than in a point measure such as peak torque. Concentric AP of hip ER muscles can therefore be seen as an interesting factor to include in LE injury screening protocols.