Women and Men Use Different Strategies to Stabilize the Head in Response to Impulsive Loads: Implications for Concussion Injury Risk.

BACKGROUND: Cervical musculoskeletal and neuromuscular attributes, which may vary between men and women, influence an individual's capacity to stabilize the head.
OBJECTIVES: To examine sex differences in cervical musculoskeletal and neuromuscular attributes and their impact on head stability. The secondary objective was to examine the effects of anticipation and preload on head kinematics.
METHODS: Thirty-four (20 men, 14 women) recreationally active adult athletes completed a perturbation protocol with anticipation and preloading conditions in this descriptive cross-sectional study. We assessed the neuromuscular response of the sternocleidomastoid to perturbation and head kinematics. We measured neck girth, sternocleidomastoid physiological cross-sectional area, and isometric strength.
RESULTS: Women had smaller neck girth, smaller sternocleidomastoid physiological cross-sectional area, and lower isometric strength than men. Women had greater baseline electromyography (EMG) amplitude and greater peak EMG response than men. There were no sex differences in sternocleidomastoid onset latency or head kinematics. Women had a greater increase in baseline EMG amplitude after preloading and anticipated conditions. Preloading attenuated sex differences in muscle onset latency. Across the sexes, there was a significant main effect of anticipation on head kinematics.
CONCLUSION: Men and women used different strategies to stabilize the head, and responded differently to the preloading and anticipation conditions. J Orthop Sports Phys Ther 2019;49(11):779-786. Epub 15 May 2019. doi:10.2519/jospt.2019.8760.