Hamstring injuries have been reported as one of the most common sporting injuries across a variety of sports that involve repetitive kicking and high speed running,  such as soccer, track and field, football, and rugby. Re-injury rates are also an issue affecting many athletes long term, with roughly 30% of athletes suffering a re-injury to the hamstring within the first year. As such, risk factors, injury mechanisms and prevention strategies are essential for coaches and athletes participating in these high-risk sports.

Injury Background

The hamstrings are a group of 3 muscles whose main purpose is to bring the hip back and bend the knee. They play a major role in many daily activities involving walking, running, and jumping. The majority of injuries to the hamstrings are grade 1-2 strains that occur during sprinting, especially as the muscles contract eccentrically to decelerate the leg. Injuries that occur during running usually take an average of 16 weeks to return to pre-injury level. Injury can also occur during activities like dancing and kicking where the muscle is overly stretched. Research has shown that an injury due to over stretching of the muscle will take much longer to heal, with an average of 50 wks to return to pre-injury level (Heiderscheit et al., 2010).

Due to the high prevalence of hamstring injuries, combined with a devastatingly long recovery and high probability of re-injury, research has focused greatly on risk factors and rehabilitation strategies to help prevent hamstring injuries altogether.

Risk Factors:

Age

Unfortunately, the older you get, the higher your chance for hamstring injury. The age when the risk starts to significantly increase is 25 years old, with research suggesting a 30% increase in risk annually thereafter.

Decreased Flexibility

Although a lot of prevention programs focus on only stretching the hamstrings, research has shown that tight hamstrings are not a significant risk factor for injury, interestingly, tight hip flexors and/or quads have been associated with increased hamstring injury.

Demographics

Although research is conflicting, there are some studies showing that an increased BMI (Body Mass Index) is a risk factor for hamstring injury. Furthermore, research consistently shows that race plays a role, with an increased incidence of hamstring injuries in aboriginal, African and Caribbe