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ObjectiveTo longitudinally assess brain microstructure and function in female varsity athletes participating in contact and noncontact sports.MethodsConcussion-free female rugby players (n = 73) were compared to age-matched (ages 18–23) female swimmers and rowers (n = 31) during the in- and off-season. Diffusion and resting-state fMRI (rs-fMRI) measures were the primary outcomes. The Sports Concussion Assessment Tool and head impact accelerometers were used to monitor symptoms and impacts, respectively.ResultsWe found cross-sectional (contact vs noncontact) and longitudinal (in- vs off-season) changes in white matter diffusion measures and rs-fMRI network connectivity in concussion-free contact athletes relative to noncontact athletes. In particular, mean, axial, and radial diffusivities were increased with decreased fractional anisotropy in multiple white matter tracts of contact athletes accompanied with default mode and visual network hyperconnectivity (p < 0.001). Longitudinal diffusion changes in the brainstem between the in- and off-season were observed for concussion-free contact athletes only, with progressive changes observed in a subset of athletes over multiple seasons. Axial diffusivity was significantly lower in the genu and splenium of the corpus callosum in those contact athletes with a history of concussion.ConclusionsTogether, these findings demonstrate longitudinal changes in the microstructure and function of the brain in otherwise healthy, asymptomatic athletes participating in contact sport. Further research to understand the long-term brain health and biological implications of these changes is required, in particular to what extent these changes reflect compensatory, reparative, or degenerative processes.

The purpose of this study was to examine the correlations between the torque of four extremity muscle groups and the bone mineral density (BMD) of the lumbar spine and hip in postmenopausal women. Fifty-six postmenopausal women (means age = 55.4 years, s = 7.1; means height = 162.6 cm, s = 6.4; means weight = 65.9 kg, s = 9.3) served as subjects. Bone mineral density was measured from the L2-L4 vertebral bodies, greater trochanter, femoral neck, and Ward's triangle using dual-photon absorptiometry. Hip abduction, knee extension, hip flexion, and grip force were assessed using the Spark Muscle Examination and Exercise Dosimeter (MEED) 3000 system. The Pearson product-moment correlations between muscle torque and BMD ranged from .07 to .42. The significant (p less than .05) correlations between torque and BMD (r = .27-.42) occurred in functionally and anatomically related areas. Results of this study demonstrate a statistically significant relationship between torque and BMD in anatomically related areas in postmenopausal women. This relationship, however, is not sufficiently strong to allow for prediction of BMD from the four muscle groups tested in this study. The relationship does suggest that strength may be a factor in the determination of BMD. Maintenance of strength in those muscle groups with anatomical or functional relationships to the hip and lumbar spine may play a role in the prevention and cessation of the osteoporotic changes that occur.

Laboratory-based retroreflective and magnetic scleral search-coil technologies are the current standards for collecting saccadometric data, but such equipment is costly and cumbersome. We have validated a novel, portable, high-speed video camera-based system (Exilim EX-FH20, Casio, Tokyo, Japan) for measuring saccade reaction time (RT) and error rate in a well-lit environment. This system would enable measurements of pro-and antisaccades in athletes, which is important because antisaccade metrics provide a valid tool for concussion diagnosis and determining an athlete's safe return to play. A total of 529 trials collected from 15 participants were used to compare saccade RT and error rate measurements of the high-speed camera system to a retroreflective video-based eye tracker (Eye-Trac 6: Applied Sciences Laboratories, Bedford, MA). Bland-Altman analysis revealed that the RT measurements made by the highspeed video system were 11 ms slower than those made by the retroreflective system. Error rate measurements were identical between the two systems. An excellent degree of reliability was found between the system measurements and in the ratings of independent researchers examining the video data. A strong association (r = .97) between the RTs determined via the retroreflective and high-speed camera systems was observed across all trials. Our high-speed camera system is portable and easily set up, does not require extensive equipment calibration, and can be used in a well-lit environment. Accordingly, the camera-based capture of saccadometric data may provide a valuable tool for neurological assessment following a concussive event and for the continued monitoring of recovery.

Appropriate performance tests are critical for documenting training, fatigue and injury-related changes. Functional performance testing can provide quantitative information on specialized sport movements. The single-leg, medial countermovement jump is an objective measure of frontal plane force, velocity and power, and is particularly applicable for ice hockey players given that ice skating involves applying lateral forces. This study assessed the short-term reliability (10 days) of the single-leg, medial countermovement jump performed by ten competitive male youth ice hockey players. Each participant performed three right and three left maximal single-leg, medial countermovement jumps from force plates. Measured variables included lateral and vertical takeoff velocity, lateral and vertical maximal force, maximal force above bodyweight, lateral and vertical peak concentric power, average concentric power, and average concentric power during the last 100 ms of push-off. Relative reliability was quantified by intraclass correlations. Absolute reliability and the smallest real difference were also calculated. The single-leg, medial countermovement jump had moderate-to-excellent test–retest reliability (ICC: 0.50–0.98) for all twelve variables of interest. These results suggest that the single-leg, medial countermovement jump is a reliable test for assessing frontal plane force, velocity and power in ice hockey players, and is a valid functional performance test for this population given the similarity to ice skating.

This study quantified head impact exposures for Canadian university football players over their varsity career. Participants included 63 players from one team that participated in a minimum of 3 seasons between 2013 and 2018. A total of 127,192 head impacts were recorded from 258 practices and 65 games. The mean (SD) number of career impacts across all positions was 2023.1 (1296.4), with an average of 37.1 (20.3) impacts per game and 7.4 (4.4) impacts per practice. The number of head impacts that players experienced during their careers increased proportionally to the number of athletic exposures (P < .001, r = .57). Linebackers and defensive and offensive linemen experienced significantly more head impacts than defensive backs, quarterbacks, and wide receivers (P ≤ .014). Seniority did not significantly affect the number of head impacts a player experienced. Mean linear acceleration increased with years of seniority within defensive backs and offensive linemen (P ≤ .01). Rotational velocity increased with years of seniority within defensive backs, defensive and offensive linemen, running backs, and wide receivers (P < .05). These data characterize career metrics of head impact exposure for Canadian university football players and provide insights to reduce head impacts through rule modifications and contact regulations.

This study sought to evaluate head accelerations in both players involved in a football collision. Players on two opposing Canadian university teams were equipped with helmet mounted sensors during one game per season, for two consecutive seasons. A total of 276 collisions between 58 instrumented players were identified via video and cross-referenced with sensor timestamps. Player involvement (striking and struck), impact type (block or tackle), head impact location (front, back, left and right), and play type were recorded from video footage. While struck players did not experience significantly different linear or rotational accelerations between any play types, striking players had the highest linear and rotational head accelerations during kickoff plays (p ≤ .03). Striking players also experienced greater linear and rotational head accelerations than struck players during kickoff plays (p = .001). However, struck players experienced greater linear and rotational accelerations than striking players during kick return plays (p ≤ .008). Other studies have established that the more severe the head impact, the greater risk for injury to the brain. This paper’s results highlight that kickoff play rule changes, as implemented in American college football, would decrease head impact exposure of Canadian university football athletes and make the game safer.

Head impacts in soccer have been associated with both short-and long-term neurological consequences. Youth players' brains are especially vulnerable given that their brains are still developing, and females are at an increased risk of traumatic brain injury (TBI) compared to males. Approximately 90% of head impacts in soccer occur from purposeful heading. Accordingly, this study assessed the relationship between kinematic variables and brain strain during purposeful headers in female youth soccer players. A convenience sample of 36 youth female soccer players (13.4 [0.9] years of age) from three elite youth soccer teams wore wireless sensors to quantify head impact magnitudes during games. Purposeful heading events were categorized by game scenario (e.g., throw-in, goal kick) for 60 regular season games (20 games per team). A total of 434 purposeful headers were identified. Finite element model simulations were performed to calculate average peak maximum principal strain (APMPS) in the corpus callosum, thalamus, and brainstem on a subset of 110 representative head impacts. Rotational velocity was strongly associated with APMPS in these three regions of the brain (r = 0.83-0.87). Linear acceleration was weakly associated with APMPS (r = 0.13-0.31). Game scenario did not predict APMPS during soccer games ( p > 0.05). Results demonstrated considerable APMPS in the corpus callosum (mean = 0.102) and thalamus (mean = 0.083). In addition, the results support the notion that rotational velocity is a better predictor of brain strain than linear acceleration and may be a potential indicator of changes to the brain.