Sex differences in mechanisms of head impacts in collegiate soccer athletes

BACKGROUND

There has been growing interest in head impacts related to sports participation due to potential long- and short-term consequences of head injuries. Our purpose was to compare head impact magnitude and frequency between men's and women's intercollegiate soccer players based on head impact mechanism.

METHODS

28 collegiate soccer players (16 women: age = 19.94 (1.06) years, height = 163.75 (5.15) cm, mass = 61.21 (5.09) kg; 12 men: age = 20.25 (1.14) years, height = 180.34 (6.03) cm, mass = 74.09 (9.32) kg) wore xPatch (X2 Biosystems, Seattle, WA) head impact sensors. Each practice and game was video recorded in order to confirm head impacts. The independent variable was impact mechanism (head to head, head to body (other than head), head to ground, ball to head, goal to head, and combination). Sensors collected linear and rotational accelerations and frequency of head impacts per 1000 athlete exposures.

FINDINGS

Men were more likely to sustain head impacts than women (IRR = 1.74, CI₉₅ = 1.59-1.92). The highest head impact incidence rate for men was head to body (IR = 611.68, CI₉₅ = 553.11-670.25) while the highest impact incidence rate for women was ball to head (IR = 302.29, CI₉₅ = 270.93-333.64). The interaction between sex and mechanism was significant for rotational accelerations (F_{4, 1720} = 3.757, P = .005, ω² = 0.013) but not for linear accelerations (F_4,1720 = 0.680, P = .606, ω² < 0.001, 1 - β = 0.223).

INTERPRETATION

To reduce the frequency of head impacts in men, perhaps rules governing player to player contact should be more strictly enforced as these data confirm frequent player-to-head contact during soccer practices and games. Prevention efforts for women should be focused on limiting the amount of purposeful heading (planned contact between the head and ball) occurring during play especially since these impacts had higher magnitudes compared to men.

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 10g. 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.