Concussions are associated with decreased batting performance among Major League Baseball players

Epidemiological analysis of pediatric baseball and softball concussions in United States emergency departments

PURPOSE

To evaluate the epidemiology of concussions in pediatric baseball and softball players. We hypothesized that head-to-ball injuries would be the most common cause of concussions.

METHODS

The National Electronic Injury Surveillance System (NEISS) database was used to gather data. Concussions occurring during baseball and softball participation in pediatric patients (4-17 years old) from 2012 to 2021 was gathered. Concussion mechanisms were grouped into 5 categories: head-to-player, head-to-ball, head-to-surface (ground, walls, railings), head-to-bat, and unknown. Linear regression models were used to assess changes in yearly concussion rates over the study period. Results from these models were reported using parameter estimates and the estimated Pearson correlation coefficient.

RESULTS

A weighted total of 54,978 baseball and softball related concussion injuries were analyzed. The average weighted age of our cohort at the time of injury was 13.1 years, with 54.1% (n = 29,761) of concussions occurring in males. The national estimated incidence of concussion injuries decreased non-significantly over the study period (slope estimate = -311 concussions/year, r = -0.625, p-value = 0.054). The majority of weighted national estimate concussions were due to head-to-ball injuries (n = 34,650; 63.0%), followed by head-to-player (n = 8501; 15.5%), head-to-surface (n = 5347; 9.7%), and head-to-bat (n = 5089; 9.3%). On sub-analysis, individuals were grouped into 3 age brackets: 4-8, 9-13, and 14-17 years. The most common mechanism of concussions in children of all ages was head-to-ball. The incidence of head-to-player and head-to-surface injuries increased throughout each age group, while head-to-bat decreased.

CONCLUSION

The incidence of concussions in pediatric baseball and softball athletes has been decreasing non-significantly over our 10-year study period. The most common mechanism of concussions in our study was head-to-ball injuries.

Upper-Extremity Injuries Have the Poorest Return to Play and Most Time Lost in Professional Baseball: A Systematic Review of Injuries in Major League Baseball

PURPOSE

To summarize the incidence of injuries occurring in professional baseball and compare player outcomes reported in the literature.

METHODS

We conducted a systematic review using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines across 3 databases (PubMed, MEDLINE, Embase). Inclusion criteria were studies of injury incidences and/or injury outcomes on active Major League Baseball (MLB) athletes and studies published in the English language. Exclusion criteria were non-MLB players, case series and case report studies with a cohort of ≤3 players, and/or review articles.

RESULTS

A total of 477 articles were identified from the initial search of 3 databases, with 105 studies meeting inclusion criteria. Among these articles, the most common injuries studied were elbow (38%), shoulder (14%), hip/groin (11%), hand/wrist (7%), head/face (7%), knee (7%), spine (5%), and foot/ankle (3%). Injuries with the greatest incidence included hand/wrist (150.3 per year), hamstring (7.8-73.5 per year), ulnar collateral ligament (UCL) tears (0.23-26.8 per year), gastrocnemius strains (24.2 per year), and concussions (3.6-20.5 per year). Lowest rates of return to play were seen following shoulder labral tears (40%-72.5%), rotator cuff tears (33.3%-87%), and UCL tears (51%-87.9%). The injuries leading to most time away from sport included elbow UCL tears (average 90.3 days treated nonoperatively to 622.8 days following revision reconstruction), shoulder labral tears (average 315-492 days), and anterior cruciate ligament (ACL) tears (average 156.2-417.5 days). Following ACL tears, rotator cuff tears, shoulder labral tears, and hip femoroacetabular impingement requiring arthroscopy, athletes had a significantly lower workloads compared with before injury upon return to play.

CONCLUSIONS

Most published investigations focus on elbow injuries of the UCL, with variable return to play and mixed performance following surgery. UCL tears, shoulder labral tears, and ACL tears result in the most missed time. Upper-extremity injury such as shoulder labral tears, rotator cuff tears, and UCL tears had the poorest return to play rates. Workload was most affected following ACL reconstruction, rotator cuff repair, shoulder labral repair, and hip arthroscopy for femoroacetabular impingement.

LEVEL OF EVIDENCE

IV, systematic review of level II-IV studies.

Short-Term Neurologic Manifestations of Repetitive Head Impacts Among Athletes: A Scoping Review

OBJECTIVE

To summarize the evidence linking contact sports-related repetitive head impacts (RHIs) and short-term declines in neurologic function.

METHODS

A scoping review following the guidelines in the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) and searching 3 databases (PubMed, EMBASE, and Web of Science) was performed. Peer-reviewed research articles were eligible for inclusion if they were full-length English language articles published between 1999 and 2019 examining athletes between the ages of 14 and 40 years exposed to RHIs, and reporting cognitive, vestibular, and/or oculomotor outcomes within 4 weeks of last head hit exposure.

RESULTS

Fifty-two articles met criteria for review: 14 reported oculomotor outcomes, 23 reported vestibular outcomes, and 36 reported cognitive function. Short-term RHI-related declines in neurologic function were reported in 42.9% of oculomotor studies, in 20.8% of vestibular studies, and in 33.3% of cognitive studies. Most of the 52 studies involved American football, soccer, or ice hockey athletes at the collegiate ( n = 23) or high school ( n = 14) level. Twenty-four (46%) studies involved only male athletes. Wearable sensors were used to measure RHIs in 24 studies (46%), while RHIs were not measured in 26 studies (50%). In addition, many studies failed to control for attention-deficit/hyperactivity disorder/learning disability and/or concussion history.

CONCLUSION

The results of this scoping review suggest that the evidence linking RHIs to short-term declines in neurologic function is relatively sparse and lacking in methodological rigor. Although most studies failed to find a link, those that did were more likely to use objective measures of RHIs and to control for confounders. More careful trial design may be needed to definitively establish a causal link between RHIs and short-term neurologic dysfunction.

Effects of concussion on technical performance in professional Australian Football

There is limited research on the on-field performance of previously concussed athletes. The aim of this exploratory study was to investigate athlete technical performance pre- and post-concussion in Australian Football. Using publicly available data, male athletes who sustained a concussion during the 2016-19 professional Australian Football League seasons were analysed across five games pre- and post-concussion (concussion events n=41, age 25.4 ± 3.5 years; control n=39, age 25.2 ± 3.6 years). Mean technical performance metrics (goals, time-on-ground percentage, kicks, ground ball and disposal efficiency, contested marks) over the five games pre- and post-concussion, as well as within-athlete performance variability measures (standard deviation and coefficient of variation) were analysed. Results showed no significant group-by-time interactions, nor effect of time (pre-post) for any technical performance metric. Similarly, the within-athlete standard deviation and coefficient of variation of technical performance metrics showed no group-by-time interaction, nor effect for time. This retrospective study has shown that athlete performance averaged over five games is not affected post-concussion in elite men's Australian Football. Further prospective studies controlling for contextual match factors based on opposition and environmental conditions may be required to identify potential in-game technical performance changes following return-to-play from concussion.

The Most Common Type, Severity, and Expected Frequency of Injuries Vary by Defensive Position in Professional Baseball Players

BACKGROUND

Location, frequency, and severity of in-game injuries by defensive position played have never been determined in professional baseball players.

HYPOTHESIS

Catchers would have a higher frequency of hip and knee injuries; infielders and outfielders would have a higher frequency of general lower extremity injuries; and pitchers would have a higher frequency and severity of shoulder and elbow/forearm injuries.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

The Major League Baseball Health and Injury Tracking System database was queried for all injuries in Major League Baseball and Minor League Baseball during the 2011-2019 seasons. Injuries were stratified by the following variables: athlete's level of play at the time of injury, anatomic region injured, whether the injury occurred during a game, and position played at the time of injury (infielder, outfielder, catcher, or pitcher). Number of days missed from competition immediately after an injury was used as a surrogate for injury severity: mild (0 days missed), moderate (1-5 days), and severe (>5 days). Observed versus expected injury ratios were calculated for each anatomic region based on position played, and ratios were adjusted by the number of players per position type during a standard inning of play.

RESULTS

A total of 112,405 work-related injuries were reported, with the majority of injuries (86,520; 77%) occurring in Minor League Baseball athletes. Injuries to the leg, hand, shoulder, torso, and foot were the most common for athletes in both leagues, while hip/groin injuries were the least common. Catchers sustained the most in-game defensive head/neck injuries, while infielders and outfielders had the highest number of knee injuries. Starting and relief pitchers had the greatest total proportion of in-game defensive injuries across every other body region. Infielders and outfielders sustained injuries less frequently than expected across all body regions, while pitchers experienced more injuries than expected for all body parts. Catchers experienced more injuries than expected to the head/neck, hand, hip/groin, knee, and foot, and were more likely than other position players to sustain a knee injury that was categorized as severe based on time missed.

CONCLUSION

The location, severity, and frequency of injuries vary by defensive position among professional baseball players.

Concussions in the Women's National Basketball Association: Analysis of Incidence, Return-to-Play Timing, and Player Performance From 1997 to 2020

Background:

The extent to which concussions affect Women’s National Basketball Association (WNBA) athletes has not been thoroughly examined.

Purpose:

To evaluate the incidence and impact of concussion injuries occurring in the WNBA.

Study Design:

Descriptive epidemiology study.

Methods:

Publicly available records were searched to identify all documented basketball-related concussions from WNBA seasons 1997 to 2020. Player demographics, injury details, and basketball career information were collected. Concussion incidence and return-to-play (RTP) timing were evaluated before and after the institution of the WNBA concussion protocol in 2012. Minutes per game and game score per minute were compared 5 games before and 5 games after the concussion was sustained. Player game availability and RTP performance were also compared with an age-, body mass index–, position-, and experience-matched control group of players who did not sustain any injuries during the index season.

Results:

A total of 70 concussions among 55 players were reported in the WNBA from 1997 to 2020, with a mean incidence of 2.9 ± 2.3 concussions per season. After the implementation of the WNBA concussion protocol, the incidence significantly increased from 1.7 to 5.0 concussions per season (P < .001). All players returned after a first-time concussion, missing a mean of 3.8 ± 4.7 games and 17.9 ± 20.7 days. After the adoption of the concussion protocol, the time to RTP significantly increased with games missed (P = .006) and days missed (P = .006). Minutes per game and game score per minute were not significantly affected by sustaining a concussion (P = .451 and P = .826, respectively).

Conclusion:

Since the adoption of the WNBA concussion protocol in the 2012 season, the incidence of concussions increased significantly. Athletes retained a high rate of RTP after missing a median of 4 games, and the time to RTP increased after the institution of the concussion protocol. Player game availability and performance within the same season were not significantly affected by concussion injuries after a successful RTP.

Observable player behaviours and playing performance following helmet strikes in elite cricket

OBJECTIVES

Investigate the observable player behaviours and features of both concussive (HS-C) and non-concussive (HS-NC) helmet strikes and describe their impact on playing performance.

METHODS

Elite male cricketers sustaining helmet strikes between the 2016 and 2018 seasons were identified by the England and Wales Cricket Board. Medical records identified players sustaining a concussion and those in whom concussion was excluded. Retrospective cohort analysis was performed on batting and bowling performance data available for these players in the 2 years prior to and 3 months post helmet strike. Video analysis of available incidents was conducted to describe the characteristics of the helmet strike and subsequent observable player behaviours. The HS-C and HS-NC cohorts were compared.

RESULTS

Data were available for 194 helmet strikes. 56 (29%) resulted in concussion. No significant differences were seen in playing performance in the 3 months post concussive helmet strike. However, a significant decline in batting performance was seen in this period in the HS-NC group (p<0.001).Video features signifying motor incoordination were most useful in identifying concussion post helmet strike, however, typical features suggesting transient loss of consciousness were not seen. Features such as a longer duration pause prior to the batsman resuming play and the level of concern shown by other players were also useful features.

CONCLUSION

HS-NC may be more significant for player performance than previously thought. Guidance for using video replay to identify concussion in cricket may need to be modified when compared with other field sports.

The Effects of Concussions on Batting Performance in Major League Baseball Players: A Critically Appraised Topic

Clinical Scenario: The impact of concussion in baseball athletes is far reaching although typically less studied than collision sports. The neuromotor sequelae of these injuries can have lasting effects on the high level of coordination needed in baseball skills. In professional athletes, the long-term effects of concussion combined with the high demands for performance can potentially shorten athletes' careers. Clinical Question: Do Major League Baseball players who have had a concussion compared with those with no history of concussions have decreased batting performance after they return to full participation? Summary of Key Findings: Seven articles meeting criteria for level 2 evidence were identified in this critically appraised topic. Four of 7 studies found deficits in batting performance following concussion. However, the 3 studies that did not identify differences lacked a comparative control group. Clinical Bottom Line: Evidence supports a relationship between concussion and decreased batting performance. This suggests there is a demand for screening and rehabilitation strategies aimed at improving sport-specific neuromotor and coordination skills in these individuals. Strength of Recommendation: Collectively, the body of evidence included to answer the clinical question aligns with the strength of recommendation of B.

Afferent Visual Manifestations of Traumatic Brain Injury

Traumatic brain injury (TBI) causes structural and functional damage to the central nervous system including the visual pathway. Defects in the afferent visual pathways affect visual function and in severe cases cause complete visual loss. Visual dysfunction is detectable by structural and functional ophthalmic examinations that are routine in the eye clinic, including examination of the pupillary light reflex and optical coherence tomography (OCT). Assessment of pupillary light reflex is a non-invasive assessment combining afferent and efferent visual function. While a assessment using a flashlight is relatively insensitive, automated pupillometry has 95% specificity and 78.1% sensitivity in detecting TBI-related visual and cerebral dysfunction with an area under the curve of 0.69-0.78. OCT may also serve as a noninvasive biomarker of TBI severity, demonstrating changes in the retinal ganglion cell layer and nerve fiber layer throughout the range of TBI severity even in the absence of visual symptoms. This review discusses the impact of TBI on visual structure and function.

Performance After Concussion in National Hockey League Players

CONTEXT

Concussions in ice hockey players are an interesting area of study due to the fast-paced and high-impact nature of the sport. Recently, researchers have focused on player performance after return from concussion to evaluate subclinical deficits that were previously missed.

OBJECTIVE

To examine National Hockey League (NHL) player performance from 2013 to 2019 and compare performance before a concussion with performance immediately after recovering to assess the current NHL return-to-play protocol.

DESIGN

Cross-sectional study.

SETTING

The NHL Injury Viz and sports reporting websites.

PATIENTS OR OTHER PARTICIPANTS

Players in the NHL who sustained concussions from 2013 to 2019.

MAIN OUTCOME MEASURE(S)

Goals, assists, points, plus-minus, time on ice (TOI), and hits.

RESULTS

When goals, assists, points, plus-minus, TOI, and hits were examined, only TOI was different after the players returned from injury, and this TOI difference was not substantively important.

CONCLUSIONS

After concussion, NHL player performance did not change.

Examining Batting Performance After a Sports-Related Concussion Among Major League Baseball Position Players

BACKGROUND

An ongoing challenge in sports-related concussion (SRC) is determining full recovery. This study examines performance metrics in baseball after an SRC and provides a template for assessment of return-to-performance parameters.

PURPOSE

To determine whether batting performance returns to baseline after an SRC.

STUDY DESIGN

Descriptive epidemiological study.

METHODS

Participants were all Major League Baseball (MLB) position players with confirmed SRCs that occurred during the 2011-2015 seasons. A retrospective review and assessment of performance metrics before and after injury were conducted as defined relative to the number of plate appearances (PAs) to yield reliable performance statistics. Seven batting metrics were considered as outcomes in longitudinal regressions: batting average, on-base percentage, slugging percentage, on-base plus slugging, bases on balls, strikeouts, and home runs. Metrics were calculated for each player 60, 30, and 14 days before their SRCs, as well as for the 14, 30, and 60 days after returning to play. Other variables controlled for included defensive position, player age at the time of SRC, number of days missed, mechanism of injury, whether the player completed a rehabilitation stint, and year in which the mild traumatic brain injury (MTBI) occurred (2011-2015).

RESULTS

A total of 77 MTBI case events occurred in MLB position players over 5 seasons. These injuries resulted in a mean 11.4 days lost to injury. For all performance metrics using 60 or 30 days before MTBI as baseline, no statistically significant differences were found in batting performance. In total, 63 events met PA criteria before injury. Varying the PA cutoff thresholds to be more inclusive or more restrictive yielded similar regression results. For the 48 events that met PA criteria before and after injury, most performance metrics showed no significant performance change after MTBI and, in some events, a slight though mostly nonsignificant performance improvement after MTBI.

CONCLUSIONS

MLB position players who are medically cleared to return to play after an SRC perform at the same offensive performance levels as their preinjury statistics when an adequate number of PAs is used to compare performance before and after injury.

Classification of Comprehensive Neuro-Ophthalmologic Measures of Postacute Concussion

IMPORTANCE

Symptom-based methods of concussion diagnosis in contact sports result in underdiagnosis and repeated head injury exposure, increasing the risk of long-term disability. Measures of neuro-ophthalmologic (NO) function have the potential to serve as objective aids, but their diagnostic utility is unknown.

OBJECTIVE

To identify NO measures that accurately differentiate athletes with and without concussion.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study was conducted among athletes with and without concussion who were aged 17 to 22 years between 2016 and 2017. Eye movements and cognitive function were measured a median of 19 days after injury among patients who had an injury meeting the study definition of concussion while playing a sport (retrospectively selected from a concussion clinic), then compared with a control group of participants without concussion (enrolled from 104 noncontact collegiate athlete volunteers without prior head injury). Data analysis was conducted from November 2019 through May 2020.

EXPOSURE

Concussion.

MAIN OUTCOMES AND MEASURES

Classification accuracy of clinically important discriminator eye-tracking (ET) metrics. Participants' eye movements were evaluated with a 12-minute ET procedure, yielding 42 metrics related to smooth pursuit eye movement (SPEM), saccades, dynamic visual acuity, and reaction time. Clinically important discriminator metrics were defined as those with significantly different group differences and area under the receiver operator characteristic curves (AUROCs) of at least 0.70.

RESULTS

A total of 34 participants with concussions (mean [SD] age, 19.7 [2.4] years; 20 [63%] men) and 54 participants without concussions (mean [SD] age, 20.8 [2.2] years; 31 [57%] men) completed the study. Six ET metrics (ie, simple reaction time, discriminate reaction time, discriminate visual reaction speed, choice visual reaction speed, and reaction time on 2 measures of dynamic visual acuity 2) were found to be clinically important; all were measures of reaction time, and none were related to SPEM. Combined, these 6 metrics had an AUROC of 0.90 (95% CI, 0.80-0.99), a sensitivity of 77.8%, and a specificity of 92.6%. The 6 metrics remained significant on sensitivity testing.

CONCLUSIONS AND RELEVANCE

In this study, ET measures of slowed visual reaction time had high classification accuracy for concussion. Accurate, objective measures of NO function have the potential to improve concussion recognition and reduce the disability associated with underdiagnosis.

Can Neurocognitive Function Predict Lower Extremity Injuries in Male Collegiate Athletes?

The purpose of this study is to demonstrate whether neurocognitive evaluation can confirm the association between neurocognitive level and postural control and to analyze the relationship between neurocognitive level and acute musculoskeletal injury in male non-net sports athletes. Seventy-seven male non-net sports athletes participated in this study. The Standardized Assessment of Concussion (SAC), Landing Error Scoring System (LESS), Balance Error Scoring System (BESS), and Star Excursion Balance Test (SEBT) were used for testing; we collected data related to injury history for six months after testing. Pearson's correlation analysis, logistic regression, and the independent sample t-test were used for statistical analysis. The correlation between SAC and SEBT results was weak to moderate (p < 0.05). Eleven of the seventy-seven participants experienced acute lower limb injuries. SAC, LESS, BESS, and SEBT results have no effect on the occurrence of acute lower extremity injuries (p > 0.05) and were not statistically different between the injured and non-injured groups (p > 0.05). Therefore, using the SAC score alone to determine the risk factor of lower extremity injuries, except in the use of assessment after a concussion, should be cautioned against.

Is There a Link between Stress and Cognition, and Capacity to Execute Motor Skill?

PURPOSE

This study aimed to examine the link between stress (measured via salivary cortisol and testosterone), cognition (measured via pupillometry, with greater pupil constriction and reduced pupil constriction latency associated with increased attention and improved information processing), and motor skill capacity (measured via somatosensory processing).

METHODS

Twenty-five professional rugby players participated in this study. Saliva samples were collected upon waking, before pupillometry and somatosensory processing testing, and after testing. Testing times varied for participants; however, it was always in the morning, and the order of testing was randomized.

RESULTS

Very small differences in hormone concentrations were seen across the morning (effect size = 0.01). Moderate to large differences in left eye pupil constriction for direct (left eye) versus consensual (right eye) stimulus were also seen (P < 0.01; effect size = 0.51 to 1.04). No differences for pupil constriction latency were seen for direct versus consensual stimulus. Some positive weak to moderate relationships were seen for testosterone and pupil constriction latency (r = 0.37 to 0.39, P < 0.05). Moderate to strong inverse relationships were seen for hormones with left eye pupil constriction difference between direct and consensual stimulus, and for pre- to posttest testosterone-to-cortisol ratio decline with left eye pupil constriction for direct and consensual stimulus (r = 0.41 to 0.52, P < 0.05). Weak to moderate inverse relationships for testosterone-to-cortisol ratio decline and somatosensory processing were seen (r = 0.36 to 0.47, P < 0.05).

CONCLUSION

Stress may affect ability to receive information and ability to execute motor tasks. Thus, stress may compromise ability to make appropriate objective decisions and consequently execute skill/task behavior. Strategies to help mitigate negative stress responses are noted.

Concussion Incidence and Impact on Player Performance in Major League Baseball Players Before and After a Standardized Concussion Protocol

Background:

Sports-related concussions have garnered significant attention in recent years because of the negative effects they can have on a player’s cognitive health and performance. In response to this growing concern, Major League Baseball (MLB) introduced a standardized concussion protocol during the 2011-2012 season.

Purpose/Hypothesis:

The purpose of this study was to compare the reported incidence of concussions and the subsequent performance of MLB players before and after the introduction of the standardized concussion protocol. We hypothesized that the introduction of the standardized concussion protocol would not have an impact on player performance postconcussion.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Players who suffered a concussion between 2001 and 2018 were identified from the MLB transactions page. Incidence and player performance were compared before and after the introduction of the standardized concussion protocol. Player performance was evaluated using traditional data and sabermetric data, which are advanced statistics used in conjunction with standard statistics to better compare players and teams. Player averages were calculated and compared using paired t tests for 30 days before and after concussion, 1 year before and after concussion, and career before and after concussion. Averages were also compared before and after the institution of the standardized concussion protocol using independent-measures t tests.

Results:

There were a total of 114 players who suffered 142 concussions, with 77% of those occurring after the introduction of the concussion protocol (32 before, 110 after). The average time missed because of concussion significantly decreased from 33.7 days (range, 10-122 days) to 18.9 days (range, 6-111 days) after the concussion protocol (P = .0005). There was no difference in player performance (including batting average, on-base percentage, and slugging for batters; earned run average, fielding-independent pitching, and walks plus hits per inning pitched for pitchers) after concussion at any time point (30 days, 1 year, or career) when comparing these statistics before versus after the MLB concussion protocol. However, batter performance was significantly poorer 1 year after concussion and over the remainder of the players' careers (P < .05).

Conclusion:

The number of reported concussions increased after the introduction of the MLB concussion protocol. However, players spent significantly less time on the disabled list without any adverse effect on player performance. Despite these changes, long-term batting performance was significantly poorer after concussion.

Clinical versus Functional Reaction Time: Implications for Postconcussion Management

PURPOSE

This study aimed to examine the association between clinical and functional reaction time (RT) assessments with and without simultaneous cognitive tasks among healthy individuals.

METHODS

Participants (n = 41, 49% female; 22.5 ± 2.1 yr; 172.5 ± 11.9 cm; 71.0 ± 13.7 kg) completed clinical (drop stick, Stroop) and functional (gait, jump landing, single-leg hop, anticipated cut, unanticipated cut) RT assessments in random order. All RT assessments, except Stroop and unanticipated cut, were completed under single- (movement only) and dual-task conditions (movement and subtracting by 6s or 7s). Drop stick involved catching a randomly dropped rod embedded in a weighted disk. Stroop assessed RT via computerized neurocognitive testing. An instrumented walkway measured gait RT when center-of-pressure moved after random stimulus. All other functional RT assessments involved participants jumping forward and performing a vertical jump (jump landing), balancing on one leg (single-leg hop), or a 45° cut in a known (anticipated cut) or unknown (unanticipated cut) direction. RT was determined when the sacrum moved following random visual stimulus. Pearson correlation coefficients and a 5 × 2 repeated-measures ANOVA compared RT assessments and cognitive conditions.

RESULTS

Stroop RT outcomes did not significantly correlate with functional RT assessments (r range = -0.10 to 0.24). A significant assessment by cognitive task interaction (F4,160 = 14.01; P < 0.001) revealed faster single-task RT among all assessments compared with dual-task (mean differences, -0.11 to -0.09 s; P < 0.001), except drop stick (P = 0.195). Single-leg hop (0.58 ± 0.11 s) was significantly slower compared with jump landing (0.53 ± 0.10 s), anticipated cut (0.49 ± 0.09 s), gait (0.29 ± 0.07 s), and drop stick (0.21 ± 0.03 s; P values ≤ 0.001). Dual-task assessments were significantly slower than single-task assessments (mean difference, 0.08 s; P < 0.001).

CONCLUSIONS

Clinical and functional RT assessments were not correlated with each other, suggesting that sport-like RT is not being assessed after concussion. Functional and dual-task RT assessments may add clinical value and warrant further exploration after concussion.

Concussions in the National Basketball Association: Analysis of Incidence, Return to Play, and Performance From 1999 to 2018

BACKGROUND

The effect of concussions on professional athletes has been investigated in many sports. However, few studies have evaluated concussions in National Basketball Association (NBA) players.

HYPOTHESIS

We hypothesized that concussion incidence has increased, yet the return-to-play (RTP) rate will remain high following the institution of the NBA concussion policy (NBACP). We also hypothesized that the incidence of repeat concussions will be similar to first occurrences and that player performance and game availability will not be significantly affected by sustaining a concussion.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

Publicly available records were searched to identify all concussions from NBA seasons 1999-2000 to 2017-2018. Player demographics and information regarding career history were tabulated. Incidence of concussion and RTP timing were evaluated before and after institution of the NBACP (2011). Minutes per game and game score per minute were evaluated pre- versus postconcussion. Player availability and performance were also compared with an age-, body mass index-, position-, and experience-matched control group of players who did not sustain a concussion.

RESULTS

A total of 189 concussions were reported in the NBA from 1999 to 2018, with a mean ± SD incidence of 9.7 ± 7.3 concussions per season. Following implementation of the NBACP, incidence significantly increased from 5.7 ± 2.8 to 16.7 ± 7.5 concussions per season (P = .007). All players returned to play following first-time concussion after missing 7.7 ± 8.6 days and 3.5 ± 4.1 games. RTP time was not significantly different after implementation of the NBACP (games missed, P = .24; days missed, P = .27), and there was no difference in concussion-free time interval (P = .29). Game score per minute and minutes per game were not significantly affected by sustaining a concussion (both P > .05).

CONCLUSION

Concussion incidence in NBA players is approximately 17 instances per season since the 2011 institution of a league-wide concussion policy. The number of reported concussions significantly increased following the policy, in line with trends seen in other professional sports leagues. Players have retained a high rate of RTP after 3 to 4 missed games. Player performance and availability are not affected by sustaining a concussion following successful RTP.

Evaluating Performance of National Hockey League Players After a Concussion Versus Lower Body Injury

CONTEXT

Concussions elicit changes in brain function that may extend well beyond clinical symptom recovery. Whether these changes produce meaningful deficits outside the laboratory environment is unclear. The results of player performance postconcussion within professional sports have been mixed.

OBJECTIVE

To determine whether National Hockey League (NHL) players with concussions performed worse after returning to sport than players with lower body injuries or uninjured players.

DESIGN

Cohort study.

SETTING

Publicly available Web sites that compiled injury and player statistics of NHL players.

PATIENTS OR OTHER PARTICIPANTS

Male NHL players who missed games due to a concussion (n = 22), lower body injury (n = 21), or noninjury (ie, personal reason or season break; n = 13) during the 2013-2014 and 2014-2015 regular seasons. Data on concussed athletes were used to identify similar players with lower body injury and noninjury based on (1) position, (2) time loss, (3) time on the ice, and (4) team.

MAIN OUTCOME MEASURE(S)

The primary performance metric was a modified plus-minus statistic calculated by weighting the players' plus-minus metric by their team's simple rating system to account for varying team performances. Linear mixed models assessed the relationship between injury type (concussion, lower body, or noninjury) and performance (plus-minus score).

RESULTS

We observed a quadratic effect for a time² × group interaction ( \upchi _2^2 = 8.85, P = .01). This interaction revealed that the concussion and lower body injury groups had similar patterns of an initial decrease (ie, 2 weeks after return to play), followed by an increase in performance compared with the uninjured group in weeks 5 and 6. Meanwhile, the uninjured group had an initial increase in performance. We observed no group × linear time interaction (P = .47) or overall group effect (P = .57).

CONCLUSIONS

The NHL players in the concussion and lower body injury groups displayed similar performance impairments. Both injured cohorts experienced an initial decrease in performance at weeks 1 to 2 after return to play, followed by improved performance at weeks 5 to 6 after return to play, suggesting that the performance implications of concussion may be short lived.

Concussion and National Hockey League Player Performance: An Advanced Hockey Metrics Analysis

CONTEXT

Postconcussion deficits in neurocognitive performance and postural control may persist at the time of return to sport participation. How these deficits, if present, affect athletic performance is largely unknown, with prior studies showing mixed results.

OBJECTIVE

To evaluate postconcussion National Hockey League player performance using advanced hockey metrics over short- (5 games), medium- (10 games), and long-term (remainder of the season) seasonal performance.

DESIGN

Retrospective cohort study.

PATIENTS OR OTHER PARTICIPANTS

National Hockey League players who sustained a sport-related concussion (SRC; n = 93) and returned during the same season and players (n = 51) who missed time for non-injury-related reasons.

MAIN OUTCOME MEASURE(S)

Six performance metrics were used: (1) points per 60 minutes, (2) Corsi percentage, (3) personal Fenwick shooting percentage, (4) scoring chances per 60 minutes, (5) penalty difference, and (6) PDO (not an acronym but sometimes referred to as SVSP% [save percentage shooting percentage]). Performance was compared using 2 (group) × 2 (time) repeated-measures analyses of variance for 3 time windows: (1) ±5 games, (2) ±10 games, and (3) the remainder of the season postconcussion. Alpha values were set at a conservative .01 to account for the lack of independence among dependent variables.

RESULTS

No significant interactions were present for any of the 6 dependent variables at any of the 3 time windows. Overall, none of the secondary variables differed.

CONCLUSIONS

Using advanced, sport-specific metrics, we found that National Hockey League players did not display worse seasonal performance during 3 postinjury time frames after they sustained an SRC. Whereas laboratory studies have identified lingering neurologic deficits after concussion, our results suggest that these deficits, if present, either do not translate to worse athletic performance or were not captured by these 44 metrics. Further, prospective efforts are needed to accurately quantify performance after SRC among professional hockey players.

The effect of concussion on batting performance of major league baseball players

Purpose

Previous investigations into concussions' effects on Major League Baseball (MLB) players suggested that concussion negatively impacts traditional measures of batting performance. This study examined whether post-concussion batting performance, as measured by traditional, plate discipline, and batted ball statistics, in MLB players was worse than other post-injury performance.

Subjects and methods

MLB players with concussion from 2008 to 2014 were identified. Concussion was defined by placement on the disabled list or missing games due to concussion, post-concussive syndrome, or head trauma. Injuries causing players to be put on the disabled list were matched by age, position, and injury duration to serve as controls. Mixed effects models were used to estimate concussion's influence after adjusting for potential confounders. The primary study outcome measurements were: traditional (eg, average), plate discipline (eg, swing-at-strike rate), and batted ball (eg, ground ball percentage) statistics.

Results

There were 85 concussed players and 212 controls included in the analyses. There was no significant difference in performance between concussed players and controls. However, concussed players started at a lower level of performance pre-event than the controls, striking out a 9.2% rate vs 8.2% (P=0.042) with an isolated power of 0.075 vs 0.082 (P=0.035). For concussed players, traditional batting statistics decreased before plate discipline metrics.

Conclusion

MLB players' performance was lower after return from concussion, but no more than after return from other injuries. The decreased performance prior to concussion suggests that concussion-related performance declines may not be due exclusively to concussion and perhaps point to risk factors predisposing to concussion.

Concussion rates and effects on player performance in Major League Baseball players

Background

Major League Baseball (MLB) players are throwing the ball faster and hitting harder than ever before. Although some safety measures have been implemented, by decreasing the 15 days on the disabled list (DL) to the 7 days on the DL, concussion rates remain high across positions and may impact player performance. Our hypothesis was, there would be an increase in concussion incidence following implementation of the 7 day DL, but this would not have a negative impact on player’s postconcussion performance.

Study design

This is a descriptive epidemiology study.

Methods

The concussed players from 2005 to 2016 were identified from the MLB DL and verified using established new sources. Position-specific performance metrics from before and after injuries were gathered and compared to assess effects of the injury. Postconcussion performance metrics were compared before and after the 7-day DL rule implementation.

Results

A total of 112 concussed players were placed on the DL. For all position players, the batting average (BA) and on-base percentage (OBP) showed a nonsignificant decline after injury (P=0.756). Although performance statistics for pitchers declined on average, the trend was not statistically significant. Postinjury BA and OBP did not significantly change before (0.355) and after (0.313) the 7-day DL rule change in 2011 (P=0.162).

Conclusion

The incidence of reported concussion has increased with the 7-day DL rule change. Concussion incidence was highest in catchers and pitchers compared with all other players. The most common causes identified as being hit by pitch or struck by a foul ball or foul tip. While new league rules prevent collisions with catchers at home plate, injury by a foul tip was the most common cause for concussion. The shortened time spent on the DL did not negatively impact player’s performance. Further research on protective helmets for catchers may reduce concussion incidence.

Short-Term Outcomes of Concussions in Major League Baseball: A Historical Cohort Study of Return to Play, Performance, Longevity, and Financial Impact

BACKGROUND

The short-term outcomes of concussions within Major League Baseball (MLB) warrant further consideration beyond a medical standpoint given that performance, career, and financial data remain unknown. The perception of this injury directly affects decision making from the perspective of both player and franchise.

PURPOSE

To evaluate the effect of concussion on MLB players by (1) establishing return-to-play (RTP) time after concussion; (2) comparing the career length and performance of players with concussion versus those who took nonmedical leave; and (3) analyzing player financial impact after concussion.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Contracts, transactions, injury reports, and performance statistics from 2005 to 2017 were analyzed by comparing matched players who sustained a concussion versus those who took nonmedical leave. Of the 4186 eligible MLB players, 145 sustained concussions resulting in the activation of concussion protocol and 538 took nonmedical leave. RTP time was recorded. Career length was analyzed in reference to an experience-based stratification of full seasons remaining after the concussion. Changes in player performance and salary before and after concussion were compared with the same parameters for players who took nonmedical leave.

RESULTS

The mean RTP time was 26 days (95% CI, 20-32 days) for athletes with concussion and 8 days (95% CI, 6-10 days) for those who took nonmedical leave. Athletes with concussion had a mean of 2.8 full seasons remaining, whereas athletes who took nonmedical leave had 3.1 seasons remaining (P = .493). The probability of playing in the MLB after concussion compared with the nonmedical leave pool was not significantly lower (P = .534, log-rank test; hazard ratio, 1.108). Postconcussion performance decreased significantly in position players, including a lower batting average and decreased on-base percentage in the players with concussion compared with those returning from nonmedical leave. Players who sustained a concussion lost a mean of US$654,990 annually compared with players who took nonmedical leave.

CONCLUSION

This study of the short-term outcomes after concussion in limited-contact MLB athletes demonstrates that concussions may not decrease career spans but may result in decreased performance in addition to financial loss when compared with matched controls who took nonmedical leave. In sports such as baseball that are not subject to repetitive head trauma, career spans may not decrease after a single concussive event. However, sentinel concussions have deleterious short-term effects on performance and compensation among MLB players.

Estimating Concussion Incidence Using Sports Injury Surveillance Systems: Complexities and Potential Pitfalls

Numerous sports injury surveillance systems exist with the capability of tracking concussion incidence data. It is important for the consumers of sport-related concussion data, be they researchers or the public, to have a comprehensive understanding of the strengths and limitations of sports injury surveillance systems. This article discusses issues of system design and analysis that affect the interpretation and understanding of sport-related concussion incidence data from sports injury surveillance systems. Such understanding will help inform the design of sports injury surveillance systems and research studies that aim to identify risk factors, develop prevention strategies, and evaluate prevention mechanisms.

Visual problems associated with traumatic brain injury

Traumatic brain injury (TBI) and its associated concussion are major causes of disability and death. All ages can be affected but children, young adults and the elderly are particularly susceptible. A decline in mortality has resulted in many more individuals living with a disability caused by TBI including those affecting vision. This review describes: (1) the major clinical and pathological features of TBI; (2) the visual signs and symptoms associated with the disorder; and (3) discusses the assessment of quality of life and visual rehabilitation of the patient. Defects in primary vision such as visual acuity and visual fields, eye movement including vergence, saccadic and smooth pursuit movements, and in more complex aspects of vision involving visual perception, motion vision ('akinopsia'), and visuo-spatial function have all been reported in TBI. Eye movement dysfunction may be an early sign of TBI. Hence, TBI can result in a variety of visual problems, many patients exhibiting multiple visual defects in combination with a decline in overall health. Patients with chronic dysfunction following TBI may require occupational, vestibular, cognitive and other forms of physical therapy. Such patients may also benefit from visual rehabilitation, including reading-related oculomotor training and the prescribing of spectacles with a variety of tints and prism combinations.

Systematic Review of Outcomes Reporting in Professional Baseball: A Call for Increased Validation and Consistency

BACKGROUND

Historically, treatment efficacy of professional baseball injuries has been determined by assessing the return-to-play (RTP) rate or using patient-reported functional outcomes scores; however, these methods may not be sensitive and specific enough for elite athletes. As a consequence, performance-based statistics are increasingly being reported in the medical literature.

PURPOSE

To (1) assess how treatment efficacy is currently reported in professional baseball players; (2) examine the variability in the reporting of these measures in terms of frequency, length of time followed, and units of measure; and (3) identify any attempts to validate these performance-based statistics.

STUDY DESIGN

Systematic review.

METHODS

All studies reporting treatment efficacy in professional baseball in PubMed, Embase, and Cochrane were identified. Data collected included frequency and method of reporting: RTP, functional outcomes, and performance-based statistics.

RESULTS

Fifty-four studies met all inclusion criteria. Of these, 51 (94%) reported RTP, 12 (22%) utilized functional outcomes, and 18 (33%) provided baseball-specific performance-based statistics to assess treatment efficacy. Great variability was seen in how follow-up was defined (games, seasons, months), duration of follow-up, and which performance-based statistics were utilized. None of the studies validated these performance-based statistics, determined minimal time of follow-up needed, or assessed the baseline variability in these statistics among noninjured players.

CONCLUSION

Most studies reported RTP to determine treatment efficacy, but significant variability was seen in how players were followed. Similarly, great variability was noted in the type and number of performance-based statistics utilized. Additional studies are necessary to validate these measures and determine the appropriate length of time that they should be followed.

CLINICAL RELEVANCE

This study provides a clear overview of the current methods that are used to determine treatment efficacy in professional baseball players.

Short-term Outcomes Following Concussion in the NFL: A Study of Player Longevity, Performance, and Financial Loss

BACKGROUND

A short-term protocol for evaluation of National Football League (NFL) athletes incurring concussion has yet to be fully defined and framed in the context of the short-term potential team and career longevity, financial risk, and performance.

PURPOSE

To compare the short-term career outcomes for NFL players with concussions by analyzing the effect of concussions on (1) franchise release rate, (2) career length, (3) salary, and (4) performance.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

NFL player transaction records and publicly available injury reports from August 2005 to January 2016 were analyzed. All players sustaining documented concussions were evaluated for a change to inactive or DNP ("did not participate") status. A case-control design compared franchise release rates and remaining NFL career span. Career length was analyzed via survival analysis. Salary and performance differences were analyzed with publicly available contract data and a performance-scoring algorithm based on position/player level.

RESULTS

Of the 5894 eligible NFL players over the 11-year period, 307 sustained publicly reported concussions resulting in the DNP injury protocol. Analysis of the probability of remaining in the league demonstrated a statistically significantly shorter career length for the concussion group at 3 and 5 years after concussion. The year-over-year change in contract value for the concussion group resulted in a mean overall salary reduction of $300,000 ± $1,300,000 per year (interquartile range, -$723,000 to $450,000 per year). The performance score reduction for all offensive scoring players sustaining concussions was statistically significant.

CONCLUSION

This retrospective study demonstrated that NFL players who sustain a concussion face a higher overall franchise release rate and shorter career span. Players who sustained concussions may incur significant salary reductions and perform worse after concussion. Short-term reductions in longevity, performance, and salary after concussion exist and deserve additional consideration.

Systematic Review of Traumatic Brain Injuries in Baseball and Softball: A Framework for Prevention

BACKGROUND

Traumatic brain injuries (TBIs) are an important public health challenge. The classification of baseball and softball as low contact sports and their association with extremity injuries cause individuals to overlook the risk of TBI in baseball and softball.

PURPOSE

To summarize our knowledge of the epidemiology and risk factors of TBIs associated with baseball and softball with an aim to better design and implement preventive strategies.

METHODS

A search algorithm containing keywords that were synonymous to the terms "TBI," "baseball" was applied to the following nine databases: MEDLINE, Scopus, PubMed, EMBASE, CINAHL, Healthstar, PsychINFO, AMED, Cochrane library. Cited reference lists of identified articles were also consulted yielding a total of eighty-eight articles for full review. The search was concluded on November 14, 2016. The level of evidence was evaluated according to the guidelines from Strengthening the Reporting of Observational Studies in Epidemiology statement.

RESULTS

Twenty-nine articles published between 2000 and 2016 met the criteria for analysis. Collectively, they examined the years 1982-2015 and identified 242,731 baseball-and softball-related TBIs. The most explored outcome of TBI was concussion. The average injury rate per 1,000 athletic exposures was 0.13 (range 0.03-0.46). The most common mechanism of injury was being struck by bat for younger players and being struck by ball for older athletes (adolescent and beyond). Rates of TBI were on average 4.17 times greater in games compared to practices. Females were on average 2.04 times more likely to sustain a TBI than males. Severity of TBIs varied considerably from mild and returning to the field on the same day, to immediate death. Generally, there is poor compliance with helmet use and return-to-play post-concussion guidelines. An increase TBI rates was observed over time. Multifaceted preventive strategies must be implemented to reduce the frequency and burden of these injuries.

CONCLUSION

It is difficult to compare the epidemiologic trends of TBI in baseball and softball due critical differences in the methods employed across the studies. Additional research is needed to provide a greater understanding of baseball- and softball-related TBI and to aid in the development of prevention and management modules.

Professional Athletes' Return to Play and Performance After Operative Repair of an Achilles Tendon Rupture

BACKGROUND

Most Achilles tendon ruptures are sports related. However, few studies have examined and compared the effect of surgical repair for complete ruptures on return to play (RTP), play time, and performance across multiple sports.

PURPOSE

To examine RTP and performance among professional athletes after Achilles tendon repair and compare pre- versus postoperative functional outcomes of professional athletes from different major leagues in the United States.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

National Basketball Association (NBA), National Football League (NFL), Major League Baseball (MLB), and National Hockey League (NHL) athletes who sustained a primary complete Achilles tendon rupture treated surgically between 1989 and 2013 were identified via public injury reports and press releases. Demographic information and performance-related statistics were recorded for 2 seasons before and after surgery and compared with matched controls. Statistical analyses were used to assess differences in recorded metrics.

RESULTS

Of 86 athletes screened, 62 met inclusion criteria including 25 NBA, 32 NFL, and 5 MLB players. Nineteen (30.6%) professional athletes with an isolated Achilles tendon rupture treated surgically were unable to return to play. Among athletes who successfully returned to play, game participation averaged 75.4% ( P < .001) and 81.9% ( P = .002) of the total games played the season before injury at 1 and 2 years postoperatively, respectively. Play time was significantly decreased and athletes performed significantly worse compared with preoperative levels at 1 and 2 years after injury ( P < .001). When players were compared with matched controls, an Achilles tendon rupture resulted in fewer games played ( P < .001), decreased play time ( P = .025), and worse performance statistics ( P < .001) at 1 year but not 2 years postoperatively ( P > .05). When individual sports were compared, NBA players were most significantly affected, experiencing significant decreases in games played, play time, and performance.

CONCLUSION

An Achilles tendon rupture is a devastating injury that prevents RTP for 30.6% of professional players. Athletes who do return play in fewer games, have less play time, and perform at a lower level than their preinjury status. However, these functional deficits are seen only at 1 year after surgery compared with matched controls, such that players who return to play can expect to perform at a level commensurate with uninjured controls 2 years postoperatively.

Exploration of US men's professional sport organization concussion policies

Concussion policies are increasingly being developed and adopted among professional sports organizations. We sought to compare the policies of the National Hockey League (NHL), the National Basketball Association (NBA), the National Football League (NFL), and Major League Baseball (MLB). Our objective was to summarize each policy and evaluate the extent to which each policy is organization-specific and/or consistent with medical guidelines. We visited websites for the NHL, NBA, NFL, and MLB. We searched media articles reporting concussion policy. We utilized only publically available data. We collected information on each league's approach to the definition of concussion, education provided about concussion, baseline testing requirements, minimum return to play time and return to play protocol. We found that concussion policies vary across these organizations. Most organizations utilize the Concussion in Sport Group (CISG) definition (2013) to define concussion. The NFL and NBA mandate preseason education. All organizations require some type of baseline testing. All organizations require sideline evaluation after suspected concussion. The NFL and MLB require Sport Concussion Assessment Tool (SCAT) testing for sideline evaluation of suspected concussion. MLB is the only organization to require minimum time before return to play. There is a return to play protocol in place for each organization. The NFL and MLB require independent neurologic consultation as part of their return to play protocol. There is variability in concussion policy among the professional sports organizations. The most pronounced variation from the CISG consensus statement is the variability in the minimum time to return to play. Further, the rules of the individual sports have a role in how concussion policy can be designed and implemented. Professional sports set an example for thousands of recreational sports enthusiasts so their publically available policies on concussion have a large impact.

Performance following a first professional concussion among National Basketball Association players

OBJECTIVES

Basketball is a physical game played on a hardwood floor among high-jumping athletes at risk for injury. It is currently unknown how sport-related concussion (SRC) affects player performance after injury among professional basketball players. The objective of this study was to explore the impact of SRC on basketball performance among National Basketball Association (NBA) players.

METHODS

A retrospective, archival cohort study was performed that compared NBA player performance following concussion to pre-concussive performance. A comprehensive NBA injury database, compiled from publically available sources, was queried for NBA players who suffered concussion from 2005-06 to 2014-15 (10 seasons). Intra-and inter-player analyses were performed against a matched control group of players who missed playing time for personal reasons.

RESULTS

Following application of inclusion/exclusion criteria and a matching process, 51 concussed players and 51 control players were included in analysis. There were no statistically significant decrements in baseline to post-concussion performance metrics in intra-player or player vs. controls after 5 return games.

CONCLUSIONS

Our findings suggest that at the NBA level, an athlete's performance in the initial 5 games following injury does not suffer from the after-effects of concussive injury. These results may be useful in counseling professional athletes following a concussion.

Performance and Style of Play After Returning From Concussion in the National Hockey League

BACKGROUND

Few studies have empirically examined outcomes of concussion in the National Hockey League (NHL) and whether these athletes return to games after concussion at a performance level comparable to preconcussion play.

HYPOTHESIS

NHL players would not demonstrate changes in performance or style of play after returning from a concussion when compared with a group of control athletes.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

NHL players with a reported hockey-related concussion during the 2008-2009 through 2014-2015 seasons were identified utilizing secondary media sources. Players who missed games for non-injury related causes were selected as the control group. "Performance" was operationally defined as the statistics for goals, assists, points, plus-minus, and shots, and "style of play" was operationally defined as the statistics for penalty minutes, blocked shots, hits, giveaways, and time on ice. Each gameplay statistic was recorded and totaled for the 5 games before and after each player's injury or absence. After meeting strict inclusion criteria, the 2 groups were compared across each postconcussion/absence statistic by generalized linear models while incorporating the particular preconcussion/absence statistic, position played, games missed, and concussion history as covariates to control for intraplayer and between-group differences.

RESULTS

A total of 287 players sustained a concussion; 130 missed time for non-injury related reasons and were identified as controls. After the exclusion criteria were applied, 94 concussed players were compared with 58 controls. None of the models reached statistical significance, indicating that the concussion and control groups did not differ across performance or style of play after returning from a concussion or non-injury related absence.

CONCLUSIONS

When compared with a control group, players who returned to consistent play after concussion did not demonstrate changes in performance or style of play.