One of the more common injuries in field sports involving high intensity sprinting are hamstring strains. Apart from the competitive season, a common time of year that hamstring injuries occur is during pre-season training camps. In fact, most coaches can probably attest to witnessing athletes “blowing a wheel” during performance testing (e.g., 40 yard dash) before any of the practices even take place. Generally, these injuries take place due to inadequate training throughout the off-season period. It’s important for coaches to understand that strength training alone may not sufficiently prepare the hamstrings for the high velocity contractions that take place during a sprint. Not only is there a tremendous amount of force that must be produced to propel the body, this must also take place at extremely high rates for appreciable running speed. In addition, focusing only on concentric force production in training may not prepare the muscles for the high eccentric stress occurring during the late swing phase of high speed running. As performance coaches, we need to prepare our athletes as best as possible to limit injury potential and maximize speed.
In a recently published study from Medicine and Science in Sports and Exercise, Opar et al. (2014) sought to determine the effect of eccentric hamstring strength, or imbalances of eccentric hamstring strength between legs, on the risk of injury in Australian footballers. A total of 210 athletes from 5 different teams participated in this study. Eccentric hamstring strength was assessed with the Nordic Hamstring Curl exercise before and after the preseason and competitive season. Injury history information was gathered and reports were collected regarding all hamstring injuries throughout the study. A total of 28 hamstring injuries occurred. Analysis revealed that eccentric hamstring strength below 256N at the start of preseason and 279N at the end of preseason was a major risk factor for future hamstring strain. Interestingly, a greater than 10% imbalance in eccentric strength between legs did not increase risk of future hamstring injury. Lastly, it was found that the odds of hamstring strain occurrence in high risk athletes (e.g., older athletes or individuals with previous hamstring injuries) were reduced if they had high levels of eccentric hamstring strength.
Given the high association with eccentric hamstring strength and reduced injury potential, coaches should emphasize and monitor this in their athletes. Performing Nordic hamstring curls with emphasis on the eccentric portion would obviously be a great exercise. Other options include the numerous variation of supine bodyweight hamstring curls that can be done from the floor, with a Swiss ball, or on a bench. These can also be performed bilaterally or unilaterally and even with a suspension trainer. In addition to emphasizing eccentric strength, it’s important for athletes to sprint! Not spring for extended periods of time may also put athletes into a higher risk category. If athletes have not been sprinting, they most definitely should be eased back into it with extensive warm-ups and shorter distances. Hamstring strains can keep our athletes side lined for quite a while, we must be proactive in limiting injury through smart training and proper progression.
Reference:
Opar, D. A., Williams, M. D., Timmins, R. G., Hickey, J., Duhig, S. J., Shield, A. J., & Innovation, B. (2014). Eccentric Hamstring Strength and Hamstring Injury Risk in Australian Footballers. Medicine & Science in Sports & Exercise.
