Can tests of physical fitness predict traumatic knee injury in youth female athletes? A prospective cohort study

Objectives: To compile a battery of test including various aspects of physical fitness that could be used on the field and to assess whether any of these tests are associated with future traumatic knee injuries in youth female team sports athletes. Design: Prospective cohort. Setting: Sport setting. Participants: Female athletes (n = 117, age 15-19 years), from Swedish sport high schools, active in soccer, handball, or floorball. Main outcome measures: Differences in pre-injury tests values of 11 physical fitness tests in injured versus non- injured athletes, assessed as number of traumatic knee injuries over one season. Results: 28 athletes sustained 34 traumatic knee injuries. Athletes who sustained an injury had a shorter distance on the Yo-Yo IR1 test at baseline than those without an injury (mean difference-193 m, CI-293--65 m). None of the other tests, assessed for muscular strength, endurance, power, flexibility and dynamic knee valgus, differed between injured and non-injured athletes. Conclusions: Youth female athletes with lower intermittent endurance capacity, assessed with the Yo-Yo IR1, seemed to be at greater risk of traumatic knee injury. Neither hop performance, flexibility, dynamic knee valgus nor isolated strength tests at baseline could distinguish between injured and non-injured youth female athletes at follow-up.