Differences in the Mechanism of Head Impacts Measured Between Men's and Women's Intercollegiate Lacrosse Athletes.

Background: Lacrosse is a rapidly growing sport in the United States. Comparing the magnitude and frequency of head impact mechanisms between sexes will provide data for injury prevention techniques and risk reduction of head injuries.

Purpose: To compare sex-specific differences in the magnitude and frequency of head impact mechanisms in National Collegiate Athletic Association (NCAA) Division III intercollegiate lacrosse athletes.

Study Design: Cohort study; Level of evidence, 2.

Methods: A total of 31 NCAA Division III intercollegiate lacrosse athletes (16 men [mean age, 21 ± 1 years; mean height, 179.70 ± 5.82 cm; mean weight, 80.71 ± 6.33 kg] and 15 women [mean age, 20 ± 1 years; mean height, 165.43 ± 5.25 cm; mean weight, 64.08 ± 7.59 kg]) voluntarily participated in this study. Participants wore xPatch sensors at every event during the 2015 spring season. Sensors recorded the magnitude, frequency, and location of head impacts over 10 g . Linear ( g ) and rotational (deg/s2 ) acceleration determined impact magnitudes. We calculated incidence rates (IRs; per 1000 athlete-exposures [AEs]) and incidence rate ratios (IRRs) with 95% CIs to determine frequency differences. Film footage from each event was synchronized with the time of each head impact for verification and mechanism coding. Sex and impact mechanism served as the independent variables.

Results: A significant interaction was found between impact mechanism and sex ( P < .001) and main effects for impact mechanism ( P < .001) and sex ( P < . 001). The most common mechanism in men's lacrosse was head to body (IR, 970.55/1000 AEs [95% CI, 266.14-331.98]), and in women's lacrosse, stick to head (IR, 289.87/1000 AEs [95% CI, 124.32-184.55]) was most common. Only 9 of 419 impermissible head impacts in men's lacrosse games were classed as penalties (2%); 7 of 25 impermissible head impacts in women's lacrosse games were called as penalties (28%).

Conclusion: The impact mechanisms of head to body in men's lacrosse and stick to head in women's lacrosse are penalties but occur frequently, suggesting that a focus on stressing rule enforcement is warranted. Because mechanism and sex affect the magnitude of head impacts, proper offensive and defensive techniques against opponents should be encouraged to reduce head impacts.