Do alterations in muscle strength, flexibility, range of motion, and alignment predict lower extremity injury in runners: a systematic review

BACKGROUND: Injury is common in running and seen to impact up to 94% of recreational runners. Clinicians often use alterations from normal musculoskeletal clinical assessments to assess for risk of injury, but it is unclear if these assessments are associated with future injury. OBJECTIVES: To identify alterations in muscle strength, flexibility, range of motion, and alignment that may predict lower extremity injury in runners. METHODS: Articles were selected following a comprehensive search of PubMed, Embase, CINAHL, and SPORTDiscus from database inception to May 2018. Included articles were prospective cohort studies, which specifically analyzed musculoskeletal impairments associated with future running-related injury. Two authors extracted study data, assessed the methodological quality of each study using the Critical Appraisal Tool and assessed the overall quality using the GRADE approach. RESULTS: Seven articles met the inclusion criteria. There was very low quality of evidence for the 7 identified clinical assessment alteration categories. Strong hip abductors were significantly associated with running-related injury in one study. Increased hip external-to-internal rotation strength and decreased hip internal range of motion were protective for running injury, each in one study. Decreased navicular drop in females had a protective effect for running-related injury in one study. CONCLUSIONS: Due to very low quality of evidence for each assessment, confounders present within the studies, a limited number of studies, different measurement methods among studies, measurement variability within clinical assessments, inconsistent definitions of injury and runner, different statistical modeling, and study bias, caution is suggested in interpreting these results.