Objective: To identify risk factors for hamstring injury in community-level Australian football players.
Design: Cohort study.
Setting: The preseason and 2000 season of 4 adult Victorian Amateur Football Association clubs.
Participants: All players in the clubs who were training at the time of the baseline assessment were invited to participate (n = 148). Players who were injured and unable to participate in the baseline assessment were excluded (22 players; 15%).
Assessment of risk factors: During 3 weeks before preseason practice, each player had a series of musculoskeletal tests and completed a questionnaire. The musculoskeletal screening included flexibility tests of the hamstrings, lower extremities, quadriceps, and iliopsoas; range of motion assessments of the lumbar spine and hip rotation; and the active slump test of neural mobility. Testing was done after a brief warm up by 4 trained screeners. A questionnaire with pre-established validity and reliability included information on playing experience, injury history, and training habits.
Main outcome measures: The main outcome measure was a first hamstring injury that resulted in missed participation time and/or treatment from a health professional in relation to predictive factors. Criteria defining a hamstring injury were sudden onset of posterior thigh pain, and tenderness on palpation with or without pain on stretching or contracting the hamstring muscle group. Through the season, the clubs' coaching staff collected information on exposure (hours of match and training participation).
Main results: A total of 26 hamstring injuries occurred (incidence, 4 injuries per 1000 player hours). More injuries were sustained during competition (77%) than training. Rapid acceleration during running or sprinting was the primary mechanism of injury (81%), with the remainder occurring as the player kicked the ball. After adjustment for exposure, younger age was associated with a lower relative risk (RR) of injury (RR for age > or =23 years, 3.8; 95% CI, 1.1-14.0), as were quadriceps flexibility (RR for >51 degree knee flexion, 0.3; CI, 0.1-0.8) and active knee extension range of motion (RR for >27 degree knee flexion, 2.8; CI, 0.9-8.5; not significant). Frequency of off-season running, body height, and neural mobility were not significantly associated with hamstring injury.
Conclusions: Hamstring injuries in amateur Australian football players most commonly occurred with sprinting and were more frequent in players older than 23 years or with lesser quadriceps flexibility.