The preventative effect of the Nordic hamstring exercise on hamstring injuries in amateur soccer players: a randomized controlled trial
Van der Horst N, Smits DW, Petersen J, Goedhart EA, & Backx FJG. The American Journal of Sports Medicine. Online ahead of print, March 20, 2015.
Take Home Message: A program focused on eccentric hamstring strengthening may prevent hamstring injuries.
Hamstring strains are common, especially in soccer, and can result in significant recovery times. Eccentric hamstring strengthening may be a modifiable risk factor of hamstring strains but it remains unknown if eccentric strengthening will prevent hamstring injuries. Therefore, Van der Horst and colleagues conducted a randomized controlled trial to evaluate the effectiveness of an eccentric hamstring strengthening program (Nordic Hamstring Exercise [NHE]) in comparison to no intervention on hamstring injury incidence rates, severity, and time loss among a male amateur soccer population. A total of 579 male soccer players from 32 teams completed the study. The authors randomized teams to the NHE or control group for the 13 week intervention program. The NHE group completed 25 sessions of NHE exercises at the end of practices during the 13 weeks, and adjustments to the protocol were made for injury. The training sessions were supervised by the coach or medical staff. For one year, the medical staff for each team reported any hamstring injury that required medical attention or time loss from soccer. Thirty-six hamstring injuries occurred with an incidence rate of 0.7 per 1000 exposure hours, with a greater occurrence in matches when compared with practices. There were no group differences for hamstring injury incidence during the 13 week intervention; however, the chance of a hamstring injury was 72% lower in the NHE group during the remainder of the year. There were no differences in injury severity between the NHE and control groups.
Eccentric hamstring strengthening exercises, such as NHE, may have a positive effect in preventing hamstring injuries for up to 39 weeks after the program. The authors of this study noted that a few teams withdrew or did not have full compliance due to the soreness affiliated with the NHE protocol. It would be interesting to investigate the effectiveness of an NHE program prior to the soccer season. This would prevent soreness from impeding sport-specific training and lead to the effects of the training program to peak as the athletes are starting their competitive season. The overall hamstring incidence rates seem relatively low within this current study. Future research could work on replicating this study to determine if it has a similar effect in other levels of soccer athletes (e.g., college, high school) as well as to determine its treatment benefit among athletes with previous hamstring injuries. Further objective measures of pre- and post-season hamstring strength would also add value to the effects of this training program as well as possibly identifying “at risk” athletes who have suffered repetitive hamstring strains and prescribing this type of program to them. Despite the need for more evidence, sports medicine clinicians may want to consider advocating for off-season and pre-season eccentric hamstring exercises as a possible strategy to reduce the number of hamstring injuries on their team(s). After all, these exercises can be easily done on the field at practice with minimal chance of harm and the potential to improve strength and reduce the rate of hamstring strains.
Questions for Discussion: Will you use eccentric hamstring exercises to prevent hamstring injuries with any of your athletes/patients? Will eccentric hamstring exercises decrease the risk of injury in other groups of athletes?
Written by: Nicole Cattano
Reviewed by: Jeffrey Driban