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Background: Gait impairments have been well-studied in concussed athletes. However, the sex-specific effect of cumulative head impacts on gait is not well understood. When a cognitive task is added to a walking task, dual-task gait assessments can help amplify deficits in gait and are representative of tasks in everyday life. Dual-task cost is the difference in performance from walking (single-task) to walking with a cognitive load (dual-task). Purpose: The objectives of this study were to explore the differences between sexes in 1) dual-task gait metrics, 2) gait metric changes from pre-season to post-concussion and post-season, and 3) the dual-task costs associated with gait metrics. Study Design: Cross-sectional study Methods: Over two seasons, 77 female athlete-seasons and 64 male athlete-seasons from collegiate club rugby teams participated in this study. Subjects wore inertial sensors and completed walking trials with and without a cognitive test at pre-season, post-season, and post-concussion (if applicable). Results: Females athletes showed improvement in cadence (mean = 2.7 step/min increase), double support time (mean = -0.8% gait cycle time decrease), gait speed (mean = 0.1 m/s increase), and stride length (mean = 0.2 m increase) in both task conditions over the course of the season (p < 0.030). Male athletes showed no differences in gait metrics over the course of the season, except for faster gait speeds and longer stride lengths in the dual-task condition (p < 0.034). In all four gait characteristics, at baseline and post-season, females had higher dual-task costs (mean difference = 4.4, p < 0.003) than the males. Conclusions: This results of this study showed little evidence suggesting a relationship between repetitive head impact exposure and gait deficits. However, there are sex-specific differences that should be considered during the diagnosis and management of sports-related concussion.

This document details the protocol used by the Virginia Tech Helmet Ratings to rate snow sport helmets based on concussion risk.

Head impact sensors allow researchers to learn more about human tolerance to head impact exposure and concussion. Previous on-field data collection has worked to quantify concussion biomechanics, based primarily on helmeted male athletes. Data from unhelmeted and female athletes still need to be collected and quantified to understand how concussion tolerance varies by sex and loading environment. The primary goal of this study was to instrument collegiate rugby players with head impact sensors embedded in mouthguards and to report head impact and concussion biomechanics. Over four seasons of data collection, four males and 15 females sustained concussions. To reduce underreporting, we collected weekly graded symptom surveys from all players. Kinematics were only collected for two male concussions and three female concussions due to different challenges with the instrumentation. The secondary goal of this study was to discuss head impact sensors that are used on-field and explore their practicality and limitations. We present our experience using two instrumented mouthguards, the Wake Forest Instrumented Retainer and the Prevent Biometrics Intelligent Instrumented Mouthguard, to measure head impacts in athletes. Not enough injury data were collected to quantify unhelmeted concussion tolerance. Still, the following reports may provide foundational and reference cases for future research, in addition to discussion of data quality, sex-specific athlete compliance, general usability, and provide recommendations for future head impact sensor use.

Symptom inventories are generally only collected after a suspected concussion, but regular in-season monitoring may allude to clinical symptoms associated with repetitive subconcussive impacts and potential undiagnosed concussions. Despite sex-specific differences in symptom presentation and outcome of concussion, no return-to-play protocol takes sex into account. The objective of this study was to monitor a cohort of contact-sport athletes and compare the frequency and severity of in-season concussion-like symptom reporting between sexes. Graded symptom checklists from 144 female and 104 male athlete-seasons were administered weekly to quantify the effect of subconcussive impacts on frequency and severity of in-season symptom reporting. In-season, mean symptom severity score (SSS) (p = 0.026, mean difference of 1.8), mean number of symptoms (p = 0.044, mean difference of 0.9), max SSS (p < 0.001, mean difference of 19.2), and max number of symptoms (p < 0.001, mean difference of 6.8) were higher in the females. The females' survey results showed differences between elevated and concussed SSS (p < 0.005, mean difference of 28.1) and number of symptoms reported (p = 0.001, mean difference of 6.6). The males did not have a difference in SSS (p = 0.97, mean difference of 1.12) nor in number of symptoms (p = 0.35, mean difference of 1.96) from elevated to concussed athletes. Rugby players report concussion-like symptoms in the absence of a diagnosed concussion in-season. Female athletes reported elevated symptom frequencies with greater severities than the males, but both sexes reported considerable levels throughout the season.