Neck Strength Is Not a Protective Factor for Lower Repetitive Head Impact Exposure in Law Enforcement Cadets

Law enforcement cadets (LECs) complete occupational combat training that exposes them to head acceleration events (HAEs) at variable magnitudes and quantities. Previous sport-related HAE studies suggest that neck strength is a potential modifiable factor to reduce HAE exposure risk, but the effect differs across scenarios and populations. The purpose of this study was to examine the effect of baseline neck strength on HAE exposure for LECs during training.

This was a prospective, observational study where we measured LEC's isometric neck strength using a handheld dynamometer and recorded HAEs >5 g using instrumented mouthguards in 28 civilian LECs (9 females, 28 ± 8 years). A principal component analysis (PCA) followed by an adjusted linear regression model was used to test the hypothesis that LECs with greater neck strength and larger neck girth would sustain HAEs of lower quantity and magnitude.

Male LECs were taller, weighed more, had greater neck strength, and had larger neck girths than female LECs. PCA demonstrated no significant effect of neck characteristics on HAEs per athlete exposure, median peak linear acceleration, or median peak rotational velocity when controlling for sex. Secondary analyses confirmed measures of neck strength were not associated with HAE quantity or magnitude. Neck girth was not associated with HAE magnitude; however, greater neck girth was associated with greater HAE exposure.

Findings suggest that neck strength may not be an important target for future HAE exposure risk reduction efforts. Future work should aim to identify other risk or protective factors (e.g., prior sport participation and military history) to decrease repetitive head impact exposure, and generally promote the health and well-being of LECs during their participation in mandatory training.