Alterations to the gut microbiome after sport-related concussion and subconcussive impacts in a collegiate football players cohort.

Concussions, both single and repetitive, during contact sports cause brain and body alterations in athletes. The role of the brain-gut connection and changes in the microbiota have not been well established after a head injury or concussion-related health consequences. We recruited 33 Division I Collegiate football players and collected blood, stool, and saliva samples throughout the athletic season. Analysis of the gut microbiome reveals a decrease in abundance for two bacterial species, Eubacterium rectale and Anaerostipes hadrus, after a diagnosed concussion. No significant differences were found regarding the salivary microbiome. Serum biomarker analysis shows an increase in GFAP blood levels in athletes during athletic activity. Additionally, S100β and SAA blood levels were positively correlated with the abundance of Eubacterium rectale species among athletes exposed to subconcussive impacts. These novel findings provide evidence that detecting changes in the gut microbiome may pave the way for improved concussion diagnosis following head injury.

Effect of Head Accelerations on Dynamic Balance in Collegiate Women’s Rugby

The effect of subconcussive impacts on balance are not well known. The purpose of this study is to determine the effect of subconcussive impacts on dynamic balance over the course of a rugby season. Significant negative linear correlations were found between total peak linear acceleration and dominant leg (r = −.585, p = .046) and bilateral score (r = −.615, p = .033); also between total impacts over 10g and dominant leg (r = −.653, p = .021), nondominant leg (r = −.687, p = .014), and the combined total (r = −.731, p = .007). Results indicate subconcussive impacts may affect dynamic balance over the course of a competitive season of women’s collegiate rugby.

Characterization of the Biomechanical and Situational Aspects of High Magnitude Subconcussive Impacts in Collegiate Football

ObjectiveThe objective of this study was to characterize high magnitude subconcussive impacts in football to identify injurious relationships between player/game-based characteristics and impact magnitude and frequency.BackgroundSubconcussive impacts are asymptomatic head impacts thought to induce alterations in the brain after repetitive exposure. Understanding factors that lead to higher magnitude or frequency of head impacts in football is crucial to develop harm reduction and prevention strategies.Design/MethodsEighty-one male university level football players were equipped with helmet accelerometers to capture linear acceleration (LA), impact frequency and helmet impact location. Impacts with LA = 60 g were included in the analysis. Video footage from 15 games over three seasons was analyzed to characterize aspects of play including play type, position, closing distance, player technique, tackling versus blocking and impact type (helmet-to-helmet/body/ground).ResultsA total of 570 impacts were included in the analysis with a mean LA of 83.44 g ± 23.60. Impacts with a closing distance of = 10 yards resulted in higher LA compared to <10 yards and occurred most frequently in run plays. Wide receivers and defensive backs were most often involved in impacts with a larger closing distance and experienced the highest average LA behind quarterbacks. Helmet-to-body impacts generated significantly higher LA compared to helmet-to-helmet, though helmet-to-helmet occurred more often. Players involved in a tackle sustained significantly higher LAs than those involved in a block. Impacts in which players exhibited poor technique lead to higher LA and occurred more frequently in tackling versus blocking impacts.ConclusionsThe results of this work suggest that rules regarding offensive backfield running starts could be adjusted to decrease risk of impact after a larger closing distance. Behavioral modifications and coaching approaches aimed at improving tackling technique could decrease exposure to threshold impacts at the level of the individual player.

Correlation of Head Impact Exposures With Vestibulo-Ocular Assessments

Context: Managing a concussion injury should involve the incorporation of a multifaceted approach, including a vision assessment. The frontoparietal circuits and subcortical nuclei are susceptible to trauma from a concussion injury, leading to dysfunction of the vestibulo-ocular system. Research investigating the effect of cumulative subconcussive impacts on neurological function is still in its infancy, but repetitive head impacts may result in vestibular system dysfunction. This dysfunction could create visual deficits, predisposing the individual to further head trauma. Objective: The purpose of this study was to investigate the cumulative effect of subconcussive impacts on minimum perception time, static visual acuity, gaze stability, and dynamic visual acuity scores. Design: Prospective cohort. Setting: Division I university. Patients: Thirty-three Division I men’s lacrosse players (age = 19.52 [1.20] y). Intervention: Competitive lacrosse season. Main Outcome Measures: At the beginning and end of the season, the players completed a vestibulo-ocular reflex assessment, using the InVision™ system by Neurocom® to assess perception, static acuity, gaze stability, and dynamic visual acuity. Score differentials were correlated with the head impact exposure data collected via instrumented helmets. Results: A significant correlation was found between change in perception scores and total number of head impacts (r = .54), and between changes in dynamic visual acuity loss scores on the rightside and maximum rotational acceleration (r = .36). No statistical differences were found between preseason and postseason vestibulo-ocular reflex variables. Conclusions: Cumulative subconcussive impacts may negatively affect vestibulo-ocular reflex scores, resulting in decreased visual performance. This decrease in vestibulo-ocular function may place the athlete at risk of sustaining additional head impacts or other injuries.

Exploring the association between recent concussion, subconcussive impacts and depressive symptoms in male Australian Football players

ObjectivesTo explore the association between depressive symptoms and recent head-related trauma (diagnosed concussion, subconcussive impacts) in semiprofessional male Australian Football (AF) players.MethodsSixty-nine semiprofessional male players from a West Australian Football League (WAFL) club participated in the study (Mage=21.81, SD=2.91 years). Depressive symptoms were measured using the Centre for Epidemiological Studies Depression Scale. Injuries and potential confounding variables (eg, pre-existing mental health condition; alcohol or drug hangovers; experiencing a stressful event) were self-reported anonymously using the WAFL Injury Report Survey. Both tools were administered every 2-weeks over the first 22-weeks of the WAFL season. Controlling for potential confounding variables and other injuries, a repeated measures generalised estimating equations model assessed the risk of clinically relevant depressive symptoms occurring, when diagnosed concussion or subconcussive impacts were experienced.ResultsA total of 10 concussions and 183 subconcussive impacts were reported. Players who experienced a concussion were almost nine times more likely to experience clinically relevant depressive symptoms (OR 8.88, 95% CI 2.65 to 29.77, p<0.001). Although elevated, depressive symptoms following subconcussive impacts were not statistically significant (OR 1.13, 95% CI 0.67 to 1.92, p=0.641).ConclusionThese findings indicate that semiprofessional AF athletes may be at risk of experiencing depressive symptoms after concussion. Severity (concussion vs subconcussive impacts) and dose (number of impacts) appear to have an important relationship with depressive symptom outcomes in this cohort and should be considered for further research and management of player welfare.

Effect of subconcussive impacts on functional outcomes over a single collegiate football season

Context In collision sports, particularly American football, athletes can accumulate thousands of subconcussive impacts, or head acceleration events (HAEs), across a single season; however, the short-term consequences of these impacts are not well understood. Objective To investigate the effects of the accumulation of impacts during practices on cognitive functions over a single football season. Design Prospective observational study. Setting Athletic training room and University laboratory. Participants Twenty-three NCAA Football Bowl Subdivision players. Main outcome measures Helmet accelerometers during practices and virtual reality testing (VR; balance, reaction time, spatial memory) before and after the season. Results Preseason had the majority of ≥80 G impacts while during the season had the majority of ≥25 G to <80 G impacts and positional differences showed that linemen had the majority of both types. Virtual reality analysis revealed that scores significantly decreased after the season for spatial navigation ( p < 0.05) but not for balance or reaction time. Significant correlations ( p < 0.05) were found between cognitive measures and player demographic variables. Conclusions Even in the absence of clinical symptoms and concussion diagnosis, repetitive impacts may cause cognitive alterations. Documenting the distribution of impact quantity and intensity as a function of time and position may be considered by coaches and clinicians to reduce the accumulation of impacts in athletes exposed in contact sports.

Clinical Changes in Cervical Neuromuscular Control Following Subconcussive Impacts

Context: Increased injury rates following concussive injury have been attributed to decreased neuromuscular coordination frequently documented following a concussion. However, altered integration between the vestibular system and oculomotor pathways following impacts at subconcussive thresholds implicate all sports-related impacts not just those at a concussive threshold in future musculoskeletal injury. While, several studies have explored the utility of vestibular and oculomotor clinical testing to detect altered neuromuscular control and then correlated those alterations to future injury risk, no research has explored the use of cervical clinical tests in the same capacity. Outcome Measures: Cervical joint position error test, Neck Disability Index and head acceleration. Interventions: Soccer headers, fatigue protocol, soccer headers + fatigue. Objective: To explore the clinical utility of a novel clinical approach to measuring changes in cervical neuromuscular control following subconcussive impacts in a controlled lab environment. Participants: 40 current female colligate club soccer athletes were recruited. Inclusion criteria included between the age of 18 and 25 and a minimum of 4-year soccer heading experience. Setting: Laboratory. Design: A repeated-measures design with 4 groups was utilized to test the hypothesis. Results: A 65%, 54%, and 49% increased error was observed following the soccer heading, fatigue only, and soccer heading + fatigue interventions, respectively. Meanwhile, the controls saw a 6% decrease in neck position error. Concussion: While, cervical joint position error testing was sensitive to decreased neuromuscular coordination following soccer heading, it was not specific enough to rule out an exercise effect in the absence of subconcussive impacts. Further research is warranted to explore the clinical utility and specificity of cervical joint position error testing to measured alterations in supraspinal processing following subconcussive impacts, and how these alterations may lead to decreased coordination and movement of the body during sports-related task.