Jul 19, 2018Hamstrung by Hamstrings
Throughout any sports season, athletic trainers witness and treat many injuries. According to an article for the British Journal of Sports Medicine by Adam Johnson, First Team Performance Physiotherapist at Brighton and Hove Albion Football Club in England, one of the most common is the hamstring injury. Athletic trainers can help decrease the frequency of hamstring injury by understanding the risk factors involved and how they can be addressed.
What is one of the biggest risk factors? Having a previous hamstring injury. Fortunately, the best test for this is simply asking athletes whether they have ever suffered this injury before. Of course, there is always the chance they may not remember. To remedy this, Johnson suggests following up a negative answer by probing the athlete again and asking, “So you have definitely never had a hamstring injury in the past?”
If an athlete has previously suffered from a hamstring injury, research shows that he or she will likely have decreased eccentric knee flexor strength compared to an athlete who has not. This decreased strength is also a risk factor for future hamstring injury, as the same study shows that athletes with low levels of eccentric knee flexor strength in preseason testing were 3.3 times more likely to experience another injury during the season. Johnson also cited a 2016 study that said athletes displaying eccentric knee flexor strength below 337N are at a greater risk for hamstring injury.
Beyond eccentric knee flexor strength, another risk factor for hamstring injury is decreased biceps femoris fascicle length. According to a 2016 investigation, athletes with a fascicle length of less than 10.56 centimeters have a higher risk of hamstring injury. Johnson explains that while the athletes in this study showed an increase in fascicle length during the first two months of the season, these numbers declined over the course of the entire season.
It may seem close to impossible to work against such intertwining risk factors. However, Johnson says the best approach for athletic trainers is to incorporate eccentric training into their programs — specifically the Nordic Hamstring Exercise. Multiple studies have found this exercise to have a positive effect on eccentric knee flexor strength, as well as fascicle length.