Epidemiology of Hamstring Strains in 25 NCAA Sports in the 2009-2010 to 2013-2014 Academic Years

Background: The epidemiology of hamstring strains among student-athletes has been extensively researched. However, there is a paucity of recent data describing patterns of hamstring strains. Purpose: To describe the epidemiology of hamstring strains in 25 National Collegiate Athletic Association (NCAA) championship sports. Study Design: Descriptive epidemiology study. Methods: Hamstring strains data were analyzed from the NCAA Injury Surveillance Program during the 2009-2010 to 2013-2014 academic years. Hamstring strain injury rates, rate ratios (RRs), and injury proportion ratios were reported with 95% CIs. Results: During the study period, 1142 hamstring strains were reported, leading to an injury rate of 3.05 per 10,000 athlete-exposures (AEs). Most hamstring strains occurred during practices (68.2%). However, the competition rate (5.24 per 10,000 AEs) was larger than the practice rate (2.56 per 10,000 AEs; RR = 2.05; 95% CI, 1.81-2.32). A slight majority occurred during the regular season (52.9%). However, the preseason rate (5.00 per 10,000 AEs) was larger than the regular season/postseason rate (2.34 per 10,000 AEs; RR = 2.14; 95% CI, 1.90-2.40). Men's football, men's soccer, and women's soccer contributed the greatest proportion of hamstring strains (35.3%, 9.9%, and 8.3%, respectively). Most hamstring strains were due to noncontact (72.3%). Of all hamstring strains, 12.6% were recurrent, 37.7% resulted in a time loss of <24 hours, and 6.3% resulted in a time loss >3 weeks. Variations in hamstring strain patterns existed by sport. The hamstring strain rate was larger in men than in women in soccer (RR = 1.60; 95% CI, 1.22-2.11), baseball/softball (RR = 1.66; 95% CI, 1.07-2.59), and indoor track (RR = 1.88; 95% CI, 1.26-2.78). In addition, proportions of hamstring strains that were recurrent were higher among men in most sex-comparable sports, but this difference was not significant. Conclusion: Hamstring strain rates were higher in the preseason and in competition. Student-athletes should be acclimatized to the rigors of preseason participation. Meanwhile, further surveillance should investigate the effectiveness of prospective prevention programs in an effort to reduce the prevalence of initial and recurrent hamstring strain injuries.