Impacts to the head are common in collision sports such as football. Emerging research has begun to elucidate concussion tolerance levels, but sub-concussive impacts that do not result in clinical signs or symptoms of concussion are much more common, and are speculated to lead to alterations in cerebral structure and function later in life. We investigated the cumulative number of head impacts and their associated acceleration burden in 95 high school football players across four seasons of play using the Head Impact Telemetry System (HITS). The 4-year investigation resulted in 101,994 impacts collected across 190 practice sessions and 50 games. The number of impacts per 14-week season varied by playing position and starting status, with the average player sustaining 652 impacts. Linemen sustained the highest number of impacts per season (868); followed by tight ends, running backs, and linebackers (619); then quarterbacks (467); and receivers, cornerbacks, and safeties (372). Post-impact accelerations of the head also varied by playing position and starting status, with a seasonal linear acceleration burden of 16,746.1g, while the rotational acceleration and HIT severity profile burdens were 1,090,697.7 rad/sec 2 and 10,021, respectively. The adolescent athletes in this study clearly sustained a large number of impacts to the head, with an impressive associated acceleration burden as a direct result of football participation. These findings raise concern about the relationship between sub-concussive head impacts incurred during football participation and late-life cerebral pathogenesis, and justify consideration of ways to best minimize impacts and mitigate cognitive declines.

Forty-six limbs in 28 patients were surgically treated for exertional compartment syndrome. One group of 16 patients (26 limbs) underwent a fasciotomy for exertional anterior compartment syndrome (Group 1). A second group of 12 patients (20 limbs) underwent a fasciotomy for exertional deep posterior compartment syndrome (Group 2). Patients in Group 2 experienced symptoms for a significantly longer time than those in Group 1:16 versus 6.8 months (P < 0.01). All three of the pressure measurements used in this study (resting pressure, 1 minute after exercise, and 5 minutes after exercise) were significantly higher in both groups than in normal controls (P < 0.01). The 1 minute after exercise values were significantly higher in Group 1 (mean, 36.5) than in Group 2 (mean, 29.1) (P < 0.01). In Group 1, 25 of 26 limbs (96%) had excellent results. In Group 2, 13 of 20 limbs (65%) had satisfactory results (5 excellent and 8 good) and 7 (35%) had unsatisfactory results (4 fair and 3 poor). Those patients who had an unsatisfactory outcome did so within 6 months. Patients in Group 1 had a significantly higher rate of satisfactory results than those in Group 2 (P < 0.05).

Concussion has a well-defined, acute effect on motor control with alterations in gait documented up to thirty days post injury. There is a dearth of research examining the chronic effects of concussion on gait. The purpose of this investigation was to examine the effects of concussion in the gait patterns of young adults with and without a history of concussion during single and dual task paradigms. Individuals with (n=28, mean 6.32 years post injury) and without (n=40) a concussion history completed a battery of gait conditions during single and dual-task conditions.Normalized velocity, step length, stride width, number correct from cognitive task, time in single leg stance, and time in double leg stance were the variables of interest. Gait was analyzed using a GAITRite Electronic Walkway system and the Brooks visuospatial cognitive task was used to index cognition. Data analysis was assessed with multiple two-way, repeated measures ANOVAs and correlation analyses. The current investigation found that individuals with a history of concussion spent significantly greater time in double leg stance, significantly decreased time in single leg stance and had slower gait velocity. There was also a significant negative correlation between number of concussions and time in single leg stance and a positive correlation between number of concussions and time in double leg stance double stance percent.These findings suggest that individuals with a history of concussion adopt a more conservative gait strategy, perhaps to reduce the risk of further injury.