Cervical Muscle Strength and Kinematics during an Unanticipated Perturbation in University Aged Male and Female Rugby Athletes

Introduction: Female athletes participating in contact sports demonstrate a concussion injury risk factor that is two times greater than their age-matched male counterparts. Recent literature has outlined the importance of neck muscle strength and neuromuscular characteristics in the mitigation of excessive head kinematics. Rugby is a contact sport in which tackles comprise the mechanism for concussion, which is caused by inertial impacts. Females exhibit higher measurements of acceleration and investigating potential gender differences in dynamic stabilization of the head is warranted in rugby. Methods: Twenty-three (15 female, 8 male) university-aged rugby athletes participated in kinematic analysis; and a series of clinical tests of the cervical musculature. Neck strength was measured using handheld dynamometry. Electromyography and accelerometers were used to analyze activity of the sternocleidomastoid, upper trapezius, external and internal oblique muscles; as well as to quantify head, neck, and trunk change in velocity during a simulated unexpected dynamic task. One-way MANOVAs were used to determine gender differences in anthropometrics, muscle activation, and head kinematics. Independent t-tests were used to compare neck muscle endurance. Results: Males demonstrated greater neck girth (p=0.000) 95% CI females [33.45, 35.91] males [40.03, 43.40], head girth (p= 0.008) 95% CI females [55.08, 57.04] males [57.38, 60.09], and head-neck segment mass (p=0.002) 95% CI females [5.88, 6.83] males [7.09, 8.39]. Isometric strength was significantly different with males demonstrating 40-60% greater strength. Males demonstrated 43% greater muscle endurance than females. Males had a statistically significant greater change in velocity of the head in the sagittal plane. Discussion: In agreement with current literature, males and females demonstrate differences in their ability to stabilize the head in dynamic situations. This data suggests even female competitive rugby players demonstrate significant clinical factors that increase the risk of concussion. Determining injury risk predictors between male and female rugby athletes can help to design specific injury prevention interventions. Keywords rugby; neck muscles; neck kinematics; athletic injury, sport related concussio