Author(s): LI, S., ZHANG, H., LIU, Z., HAO, W., Institution: CHINA INSTITUTE OF SPORTS SCIENCE, Country: CHINA, Abstract-ID: 661

INTRODUCTION:
Hamstring strain injury (HSI) is one of the most common and severe non-contact lower-limb injuries, frequently occurring in sports that require high-speed sprinting, such as sprinting, soccer, and rugby. In recent years, both its incidence and severity have shown an increasing trend. The study aimed to investigate the incidence of hamstring injuries among collegiate athletes and to analyze the association between knee muscle strength and the risk of HSI.
METHODS:
A total of 257 male collegiate athletes (age 21.0 ± 1.8 years; height 179.0 ± 6.0 cm; weight 75.4 ± 8.4 kg) were enrolled, primarily participating in high-speed running sports such as sprinting, soccer, and basketball. Isokinetic dynamometry was employed to assess quadriceps and hamstring strength. Concentric quadriceps strength and both concentric and eccentric hamstring strength were measured at an angular velocity of 60°/s. The functional hamstring-to-quadriceps (H: Q) ratio was calculated as the ratio of hamstring eccentric peak torque to quadriceps concentric peak torque. HSI incidence was prospectively recorded over a 12-month follow-up period. Athletes completed a monthly online questionnaire to report any occurrence of HSI. Independent-samples and paired-samples t-tests were conducted to compare athletes with and without HSI and to compare injured and uninjured limbs, respectively. Univariate Cox regression with clustering was applied to examine the relationship between muscle strength and the risk of HSI.
RESULTS:
A total of 41 athletes (42 thighs; 16.0% of the study population) sustained HSI, accounting for 34.7% of all lower-limb injuries. Five athletes experienced recurrent injuries. Athletes in the injured group exhibited a significantly lower functional H:Q ratio compared with those in the uninjured group (0.70 ± 0.14 vs. 0.76 ± 0.22, P = 0.047). No significant differences were observed between groups in hamstring concentric or eccentric strength, or quadriceps strength. Similarly, comparisons between injured and uninjured limbs showed no significant differences in muscle strength or H:Q ratios. Cox regression analysis indicated that muscle strength variables were not significantly associated with the risk of HSI.
CONCLUSION:
Injured athletes showed a lower functional H:Q ratio, whereas overall hamstring and quadriceps strength did not differ significantly between groups or between injured and uninjured limbs, indicating that functional muscle balance may better indicate HSI than strength alone. The functional H:Q ratio may therefore be useful in preventing HSI.
Consequently, preventive strategies in collegiate athletes may benefit from emphasizing dynamic muscle coordination, proper activation patterns, and functional H:Q ratio optimization rather than focusing solely on increasing hamstring or quadriceps strength.