The hamstring exercise (the Nordic curl) involves the player using hamstrings to resist forward falling of the trunk from a kneeling position. Players completed 2–3 sets of

5–12 repetitions of the exercise for 1–3 sessions per week. Outcome measures: The primary outcome was the number of overall, new, and recurrent acute hamstring injuries during one full soccer season. A hamstring injury was defined as any acute physical complaint in the region of the posterior thigh sustained during a soccer AUY922 match or training. Recurrence of an injury already reported in the trial period was not included to avoid recording the same injury more than once. Results: 50 teams with 942 players completed the study. At the end of the season, there had been 15 hamstring injuries (12 new, 3 recurrent) in the eccentric hamstring exercise group and 52 injuries (32 new, 20 recurrent) in the control group. The number needed to treat (NNT) to prevent 1 hamstring injury (new or recurrent) was 13 (95% CI 9 to 23). The NNT to prevent 1 new injury was 25 (95% CI 15 to 72) and the NNT for recurrent injury was 3 (95%

CI 2 to 6). Apart from short term muscle soreness no adverse VE-821 events were reported in the exercise group. Conclusion: An eccentric strengthening exercise program for the hamstring muscles that can be performed during training can help prevent hamstring injuries in soccer players. It is well documented that acute hamstring muscle strain is the most common injury in many sports that involve repeated bouts of sprinting, including soccer (Ekstrand et al 2011) and Australian Rules football (Orchard and Seward 2011). Prevention of primary and recurrent injury is therefore paramount, but unfortunately little evidence currently exists to support the efficacy of preventive interventions (Goldman and Jones 2011). This rigorous large-scale trial is extremely relevant for physiotherapists who treat sports people

with acute hamstring muscle strains, found as it provides the strongest evidence yet that eccentric strength training can significantly reduce the incidence rate of both primary and especially recurrent injury. The intervention was not complicated nor did it rely upon expensive gym-based equipment: repeated sessions of the Nordic hamstring exercise were performed over a 10-week period, and the dosage prescribed produced a preventive effect for at least 12 months. While the Nordic hamstring exercise might be considered an intense load, particularly for people who are unaccustomed to eccentric strength training, it is important to note that no injuries were actually experienced during the conduct of the exercise program. Thus, even though the intervention likely evoked considerable muscle soreness, it was safe.