Sex Comparison of Hamstring Electromechanical Delay and the Influence of Musculotendinous Stiffness (2008)

Undergraduate: Lauren Engstrom

Faculty Advisor: Troy Blackburn
Department: Exercise & Sport Science

---

Females display a higher incidence of anterior cruciate ligament (ACL) injury than males. The hamstring muscles potentially protect the ACL, and hamstring electromechanical delay (EMD) and musculotendinous stiffness (MTS) are neuromechanical properties suggested as contributors to dynamic knee joint stability. Sex differences in these characteristics may contribute to the sex discrepancy in ACL injury rate. We hypothesized that females would demonstrate longer EMD and lesser MTS than males, and that EMD and MTS would be negatively correlated. Although MTS differed significantly across sex, EMD was similar in males and females, and the relationship between EMD and MTS was non-significant. These non-significant findings are likely attributable to our definition of EMD relative to onset of the smallest detectable level of force production. Future research is necessary to evaluate the relationship between MTS and EMD at physiologically relevant levels of force production and the effects of MTS on dynamic knee joint stability.