Gender differences in head-neck segment dynamic stabilization during head acceleration.

PURPOSE Recent epidemiological research has revealed that gender differences exist in concussion incidence but no study has investigated why females may be at greater risk of concussion. Our purpose was to determine whether gender differences existed in head-neck segment kinematic and neuromuscular control variables responses to an external force application with and without neck muscle preactivation. METHODS Forty (20 females and 20 males) physically active volunteers participated in the study. The independent variables were gender, force application (known vs unknown), and force direction (forced flexion vs forced extension). The dependent variables were kinematic and EMG variables, head-neck segment stiffness, and head-neck segment flexor and extensor isometric strength. Statistical analyses consisted of multiple multivariate and univariate analyses of variance, follow-up univariate analyses of variance, and t-tests (P < or = 0.05). RESULTS Gender differences existed in head-neck segment dynamic stabilization during head angular acceleration. Females exhibited significantly greater head-neck segment peak angular acceleration (50%) and displacement (39%) than males despite initiating muscle activity significantly earlier (SCM only) and using a greater percentage of their maximum head-neck segment muscle activity (79% peak activity and 117% muscle activity area). The head-neck segment angular acceleration differences may be because females exhibited significantly less isometric strength (49%), neck girth (30%), and head mass (43%), resulting in lower levels of head-neck segment stiffness (29%). CONCLUSION For our subject demographic, the results revealed gender differences in head-neck segment dynamic stabilization during head acceleration in response to an external force application. Females exhibited significantly greater head-neck segment peak angular acceleration and displacement than males despite initiating muscle activity earlier (SCM only) and using a greater percentage of their maximum head-neck segment muscle activity.

[1]  J. Powell,et al.  Traumatic brain injury in high school athletes. , 1999, JAMA.

[2]  Philip Schatz,et al.  Current Issues in the Identification, Assessment, and Management of Concussions in Sports-Related Injuries , 2003, Applied neuropsychology.

[3]  D. Medina,et al.  Normative database of isometric cervical strength in a healthy population. , 2002, Medicine and science in sports and exercise.

[4]  R. Zernicke,et al.  Computer Simulation of Head Impact: Estimation of Head-Injury Risk during Soccer Heading , 1988 .

[5]  P. Borsa,et al.  Glenohumeral Stiffness Response Between Men and Women for Anterior, Posterior, and Inferior Translation. , 2002, Journal of athletic training.

[6]  Roland Örtengren,et al.  Analysis and comparison of reflex times and electromyogram of cervical muscles under impact loading using surface and fine-wire electrodes , 2001, IEEE Transactions on Biomedical Engineering.

[7]  C. Oatis,et al.  The use of a mechanical model to describe the stiffness and damping characteristics of the knee joint in healthy adults. , 1993, Physical therapy.

[8]  Donna K. Broshek,et al.  Acceleration-Deceleration Sport-Related Concussion: The Gravity of It All. , 2001, Journal of athletic training.

[9]  J. B. Wheeler,et al.  Cervical muscle response during whiplash: evidence of a lengthening muscle contraction. , 2000, Clinical biomechanics.

[10]  G Raviv,et al.  Neck muscle resistance to head impact. , 1981, Aviation, space, and environmental medicine.

[11]  J. Giesey,et al.  The relationship between elbow flexor volume and angular stiffness at the elbow. , 1997, Clinical biomechanics.

[12]  D. Hewson,et al.  Stiffness and passive peak force changes at the ankle joint: the effect of different joint angular velocities. , 2002, Clinical biomechanics.

[13]  M. Alexander,et al.  Principles of Neural Science , 1981 .

[14]  F. G. Evans,et al.  Anatomical Data for Analyzing Human Motion , 1983 .

[15]  P. Schantz,et al.  Muscle fibre type distribution, muscle cross-sectional area and maximal voluntary strength in humans. , 1983, Acta physiologica Scandinavica.

[16]  Allan J Ryan,et al.  American Orthopedic Society for Sports Medicine. , 1982, The Physician and sportsmedicine.

[17]  E. M. Winter,et al.  Electromechanical response times and muscle elasticity in men and women , 2004, European Journal of Applied Physiology and Occupational Physiology.

[18]  L. Cohen.  Role of eye and neck proprioceptive mechanisms in body orientation and motor coordination. , 1961, Journal of neurophysiology.

[19]  C. Hass,et al.  Impact forces and neck muscle activity in heading by collegiate female soccer players , 2001, Journal of sports sciences.

[20]  Scott M. Lephart,et al.  Reestablishing Proprioception and Neuromuscular Control in the ACL-Injured Athlete , 1997 .

[21]  P J McNair,et al.  Stiffness of the hamstring muscles and its relationship to function in anterior cruciate ligament deficient individuals. , 1992, Clinical biomechanics.

[22]  Tracey Covassin,et al.  Epidemiological Considerations of Concussions Among Intercollegiate Athletes , 2003, Applied neuropsychology.

[23]  Stefano Corna,et al.  The functional effectiveness of neck muscle reflexes for head-righting in response to sudden fall , 1997, Experimental Brain Research.

[24]  D Brunt,et al.  Analysis of EMG activity and temporal components of gait during recovery from perturbation. , 1990, Archives of physical medicine and rehabilitation.

[25]  C. Swanik,et al.  Effects of Football Collars on Cervical Hyperextension and Lateral Flexion. , 2003, Journal of athletic training.

[26]  S. Delp,et al.  Influence of Muscle Morphometry and Moment Arms on the Moment‐Generating Capacity of Human Neck Muscles , 1998, Spine.

[27]  A. Wittek,et al.  Finite Element Model for Simulation of Muscle Effects on Kinematic Responses of Cervical Spine in Low-Speed Rear-End Impacts , 2000 .

[28]  D H Perrin,et al.  Alternative approaches to the assessment of mild head injury in athletes. , 1997, Medicine and science in sports and exercise.

[29]  S. Kumar,et al.  Role of awareness in head-neck acceleration in low velocity rear-end impacts. , 2000, Accident; analysis and prevention.