Postural control deficits identify lingering post-concussion neurological deficits

Objective Clinical Measurement Tools for Functional Evaluation of the Surgical Patient

Following knee surgery, clinicians have traditionally used visually rated or time-based assessments of lower extremity movement quality to measure surgical outcomes, plan rehabilitation interventions, and measure success. These methods of assessment are prone to error and do not fully capture a patient's inefficient movement patterns post surgery. Further, currently available systems which objectively measure kinematics during these tasks are expensive and unidimensional. For these reasons, recent research has called for the development of objective and low-cost precision rehabilitation tools to improve clinical measurement of movement tasks. The purpose of this article is to highlight two such tools and their applications to knee surgery. The systems highlighted within this article are the Mizzou Point-of-Care Assessment System (MPASS) and the Mizzou Knee Arthrometer Testing System (MKATS). MPASS has demonstrated high levels of agreement with the gold-standard Vicon system in measuring kinematics during sit-to-stand (R > 0.71), lateral step-down (intraclass correlation coefficient [ICC] > 0.55, apart from ankle flexion), and drop vertical jump tasks (ICC > 0.62), as well as gait (R > 0.87). MKATS has been used to quantify differences in tibiofemoral motion between groups during lateral step-down, step-up-and-over, and step-up/step-down tasks. Objective measurement of clinical tasks using portable and inexpensive instruments, such as the MPASS and MKATS, can help clinicians identify inefficient movement patterns and asymmetries which may damage and wear down supporting structures within the knee and throughout the kinetic chain causing pain and discomfort. Identifying these issues can help clinicians to plan interventions and measure their progress at a lower cost than currently available systems. The MPASS and MKATS are useful tools which have many applications to knee surgery.

Relationship between severity of concussion's symptoms and functional performance in children

INTRODUCTION

Concussion is a common brain injury that has significant effects on multiple functional domains in children. However, limited research exists on the relationship between concussion severity and functional performance in this population. This study aimed to examine the relationship between the severity of concussion symptoms and children's balance and functional performance.

METHODS

This cross-sectional study recruited 23 children (9 males and 14 females; mean age 13.9 ± 2.2 years) with clinically diagnosed concussions from a tertiary balance center in 2016. Participants underwent clinical and functional evaluations by specialized physical therapists. Symptom severity was assessed using the Post-Concussion Symptom Scale (PCSS), while functional performance was measured using the Functional Gait Assessment (FGA).

RESULTS

There was a trend suggesting a negative correlation between symptom severity (PCSS) and functional performance (FGA), indicating potentially better performance in individuals with milder symptoms. However, this trend was not significant (rs (21) = -.072, p = 0.744). Furthermore, no significant correlation was found between FGA scores and the severity of individual symptoms.

CONCLUSION

The findings suggest that concussion symptom severity may not be directly related to functional performance in children. Therefore, it is crucial to incorporate functional performance measures alongside symptom assessment for comprehensive concussion management.

Neural Mechanisms Associated With Postural Control in Collegiate Soccer and Non-Soccer Athletes

BACKGROUND AND PURPOSE

Sport-specific training may improve postural control, while repetitive head acceleration events (RHAEs) may compromise it. Understanding the neural mechanisms underlying postural control may contextualize changes due to training and RHAE. The goal of this study was to determine whether postural sway during the Balance Error Scoring System (BESS) is related to white matter organization (WMO) in collegiate athletes.

METHODS

Collegiate soccer (N = 33) and non-soccer athletes (N = 44) completed BESS and diffusion tensor imaging. Postural sway during each BESS stance, fractional anisotropy (FA), and mean diffusivity (MD) were extracted for each participant. Partial least squares analyses determined group differences in postural sway and WMO and the relationship between postural sway and WMO in soccer and non-soccer athletes separately.

RESULTS

Soccer athletes displayed better performance during BESS 6, with lower FA and higher MD in the medial lemniscus (ML) and inferior cerebellar peduncle (ICP), compared to non-soccer athletes. In soccer athletes, lower sway during BESS 2, 5, and 6 was associated with higher FA and lower MD in the corticospinal tract, ML, and ICP. In non-soccer athletes, lower sway during BESS 2 and 4 was associated with higher FA and lower MD in the ML and ICP. BESS 1 was associated with higher FA, and BESS 3 was associated with lower MD in the same tracts in non-soccer athletes.

DISCUSSION AND CONCLUSIONS

Soccer and non-soccer athletes showed unique relationships between sway and WMO, suggesting that sport-specific exposures are partly responsible for changes in neurological structure and accompanying postural control performance and should be considered when evaluating postural control after injury.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content, available at: http://links.lww.com/JNPT/A472).

Collegiate student-athletes concussion knowledge and attitudes: what a difference a decade Makes

OBJECTIVE

The purpose of this study was to assess changes in concussion knowledge and attitudes amongst incoming intercollegiate student-athletes over the course of a decade (2010-2012 vs 2021-2023).

METHODS

There were 592 student-athletes from 2 cohorts (2010-2012, 2021-2023) who completed the Rosenbaum Concussion Knowledge and Attitudes Survey (ROCKaS) questionnaire which is comprised of a concussion knowledge index (CKI, 0-24) and attitude index (CAI, 15-75) with higher scores reflecting better performance. A three factor ANOVA (Group, Sex, Concussion History) compared performance on the CKI and CAI. Individual questions were compared between groups with a Chi-Square analysis.

RESULTS

For the CKI, there was a significant main effect for Group (2010-2012: 18.5 ± 2.6, 2021-2023: 19.4 ± 2.5, p < 0.001, η 2 = 0.032 ) . For the CAI, there was also a significant main effect for group (2010-2012: 52.9 ± 6.0, 2021-2023: 62.2 ± 6.5, p < 0.001, η 2 = 0.359 ) .

CONCLUSIONS

The results of this study show a modest increase in concussion knowledge; however, large improvements in concussion attitudes were observed between groups. These results suggest a continued improvement in student-athlete concussion awareness and provide specific areas to continue addressing persistent misconceptions.

Wearable Loop Sensor for Bilateral Knee Flexion Monitoring

We have previously reported wearable loop sensors that can accurately monitor knee flexion with unique merits over the state of the art. However, validation to date has been limited to single-leg configurations, discrete flexion angles, and in vitro (phantom-based) experiments. In this work, we take a major step forward to explore the bilateral monitoring of knee flexion angles, in a continuous manner, in vivo. The manuscript provides the theoretical framework of bilateral sensor operation and reports a detailed error analysis that has not been previously reported for wearable loop sensors. This includes the flatness of calibration curves that limits resolution at small angles (such as during walking) as well as the presence of motional electromotive force (EMF) noise at high angular velocities (such as during running). A novel fabrication method for flexible and mechanically robust loops is also introduced. Electromagnetic simulations and phantom-based experimental studies optimize the setup and evaluate feasibility. Proof-of-concept in vivo validation is then conducted for a human subject performing three activities (walking, brisk walking, and running), each lasting 30 s and repeated three times. The results demonstrate a promising root mean square error (RMSE) of less than 3° in most cases.

National Collegiate Athletic Association athletic trainers' response to the Arrington settlement: management, compliance, and practice patterns

The primary purpose of this study was to assess Athletic Trainers' (ATs) report of NCAA member institution compliance with the Arrington settlement, the concussion lawsuit vs. the NCAA, and to elucidate compliance predictors. A secondary purpose was to provide a contemporary concussion management clinical practice pattern description among NCAA collegiate athletic trainers. Head Athletic Trainers from NCAA Division I, II, and III completed an electronic questionnaire in August 2020 regarding their institution's response to the Arrington Settlement and their current concussion management clinical practice patterns. The 37-item questionnaire included AT and institution demographics, current concussion management policies, and response to the Arrington settlement with a specific focus on the five settlement requirements. An overall compliance score on the five requirements, compliance on the individual requirements, and concussion management practices are reported with descriptives. Regression was used to identify specific predictors of both overall and individual settlement requirements. An ANOVA compared compliance by NCAA division level. Being pressured to be non-compliant was assessed between sexes by a chi-square. There were 223 respondents (21.8%), and overall compliance was high (4.1 ± 0.7) with the five required Arrington Settlement components. Settlement requirement 1, pre-season baseline testing, and requirement 5, presence of trained personnel at all contact sport practices, had the lowest compliance rates at 44.8% and 73.3%, respectively. The number of sports the institution offered was the only significant predictor of each requirement. There was no difference in compliance between NCAA divisions. Although the overall rate of being non-compliant pressure was low (13.8%), females were 3.28x more likely report being pressured than males. NCAA institutions are generally compliant with the Arrington settlement; however, lack of clarity in the requirements, particularly requirement 1, raises potential concerns. Concussion management practices continue to incorporate multifaceted approaches and are largely consistent with current best practices.

Principal components analysis of postural sway in persons with unilateral lower limb amputation: A wearable sensor approach

Standing sway assessments can detect sensory imbalances which compromise postural control. Persons with lower limb amputation (LLA) often demonstrate impaired postural control, increasing fall risk. Here, principal features of postural sway were identified in persons with unilateral LLA using a single, commercially available wearable sensor. Sixty-one persons with LLA (n = 44 transtibial; n = 17 transfemoral) stood on a firm surface with eyes open/closed while wearing a single accelerometer mounted over the sacrum. Common parameters quantified spatiotemporal and spectral features of sway in anterior-posterior (AP) and mediolateral (ML) directions. Principal component (PC) dimensionality reduction was applied and loadings inspected to identify a reduced, non-redundant set among 14 original variables capturing 90 % variance. Six PCs described ≥ 90 % variance, with the first 3 explaining 75 %. With eyes open and closed, PC1 was loaded by variables characterizing trajectory planar size: area, jerk (i.e., sway smoothness), AP/ML RMS path distance, and AP/ML path range. With eyes open, PC2 was loaded by variables characterizing direction and spectral features: ellipse rotation, AP centroidal frequency, and ML jerk. With eyes closed, PC2 spectral loadings increased: ML centroidal frequency, ML frequency dispersion, and AP centroidal frequency. With eyes open, PC3 was loaded by ellipse rotation, jerk, ML velocity, ML centroidal frequency. With eyes closed, PC3 was loaded by ellipse rotation, ML centroidal frequency, ML frequency dispersion, and AP path velocity, characterizing off-axis error/corrections. RMS of path distance, ellipse rotation, centroidal frequency, frequency dispersion, path velocity, and jerk are a concise parameter set, derived from an accelerometer, to capture principal sway features in persons with LLA during standing balance with visual perturbations.

Validity and Reliability of Methods to Assess Movement Deficiencies Following Concussion: A COSMIN Systematic Review

BACKGROUND

There is an increased risk of subsequent concussion and musculoskeletal injury upon return to play following a sports-related concussion. Whilst there are numerous assessments available for clinicians for diagnosis and during return to play following concussion, many may lack the ability to detect these subclinical changes in function. Currently, there is no consensus or collated sources on the reliability, validity and feasibility of these assessments, which makes it difficult for clinicians and practitioners to select the most appropriate assessment for their needs.

OBJECTIVES

This systematic review aims to (1) consolidate the reliability and validity of motor function assessments across the time course of concussion management and (2) summarise their feasibility for clinicians and other end-users.

METHODS

A systematic search of five databases was conducted. Eligible studies were: (1) original research; (2) full-text English language; (3) peer-reviewed with level III evidence or higher; (4) assessed the validity of lower-limb motor assessments used to diagnose or determine readiness for athletes or military personnel who had sustained a concussion or; (5) assessed the test-retest reliability of lower-limb motor assessments used for concussion management amongst healthy athletes. Acceptable lower-limb motor assessments were dichotomised into instrumented and non-instrumented and then classified into static (stable around a fixed point), dynamic (movement around a fixed point), gait, and other categories. Each study was assessed using the COSMIN checklist to establish methodological and measurement quality.

RESULTS

A total of 1270 records were identified, with 637 duplicates removed. Titles and abstracts of 633 records were analysed, with 158 being retained for full-text review. A total of 67 records were included in this review; 37 records assessed reliability, and 35 records assessed the validity of lower-limb motor assessments. There were 42 different assessments included in the review, with 43% being non-instrumented, subjective assessments. Consistent evidence supported the use of instrumented assessments over non-instrumented, with gait-based assessments demonstrating sufficient reliability and validity compared to static or dynamic assessments.

CONCLUSION

These findings suggest that instrumented, gait-based assessments should be prioritised over static or dynamic balance assessments. The use of laboratory equipment (i.e. 3D motion capture, pressure sensitive walkways) on average exhibited sufficient reliability and validity, yet demonstrate poor feasibility. Further high-quality studies evaluating the reliability and validity of more readily available devices (i.e. inertial measurement units) are needed to fill the gap in current concussion management protocols. Practitioners can use this resource to understand the accuracy and precision of the assessments they have at their disposal to make informed decisions regarding the management of concussion.

TRAIL REGISTRATION

This systematic review was registered on PROSPERO (reg no. CRD42021256298).

Risk of Upper Extremity Musculoskeletal Injury Within the First Year After a Concussion

Background

Emerging evidence suggests that athletes and military personnel are at increased risk for lower extremity musculoskeletal injury after a concussion; however, the association between concussion and subsequent upper extremity (UE) musculoskeletal injury is unknown.

Purpose

To prospectively examine the association between concussion and UE musculoskeletal injury risk within the first year after returning to unrestricted activity.

Study Design

Cohort study; Level of evidence, 3.

Methods

A total of 316 cases of concussion 42% (132/316 women) were observed among 5660 Concussion Assessment, Research and Education Consortium participants at the United States Military Academy from May 2015 to June 2018. Active injury surveillance within the cohort was conducted for 12 months after unrestricted return to activity to identify any incident cases of acute UE musculoskeletal injury. Injury surveillance during the follow-up period was also conducted for nonconcussed controls who were matched by sex and competitive sport level. Univariate and multivariable Cox proportional hazards regression models were used to estimate hazard ratios between concussed cases and nonconcussed controls for time to UE musculoskeletal injury.

Results

During the surveillance period, 19.3% of concussed cases and 9.2% of nonconcussed controls sustained a UE injury. In the univariate model, concussed cases were 2.25 times (95% CI, 1.45-3.51) more likely to sustain a UE injury during the 12-month follow-up period when compared with the nonconcussed controls. In the multivariable model, adjusted for history of concussion, sport level, somatization, and history of UE injury, concussed cases were 1.84 times (95% CI, 1.10-3.07) more likely to sustain a UE injury during the surveillance period compared with nonconcussed controls. Sport level remained an independent risk factor for UE musculoskeletal injury; however, concussion history, somatization, and history of UE injury were not independent risk factors.

Conclusion

Concussed cases were more than twice as likely to sustain an acute UE musculoskeletal injury within the first 12 months after unrestricted return to activity when compared with nonconcussed controls. The higher hazard of injury remained in the concussed group after adjusting for other potential risk factors.

Sleep Problems After Concussion Are Associated With Poor Balance and Persistent Postconcussion Symptoms

We examined the association of self-reported sleep problems with clinical measures of postural stability, memory performance, symptom burden, and symptom duration following youth concussion. Patients 6-18 years of age presenting ≤21 days postconcussion underwent a clinical evaluation including modified Balance Error Scoring System, single- and dual-task tandem gait, immediate and delayed recall, and symptom severity. We calculated time from injury until symptom resolution and determined the proportion of patients who developed persistent postconcussion symptoms, defined as a symptom duration >28 days postconcussion. We grouped patients based on whether they reported sleep problems at their postconcussion clinical evaluation and compared symptom-based and functional outcomes between groups. Of the 207 patients included, n = 97 (14.3 ± 2.9 years; 49% female; initial visit 10.2 ± 5.8 days postconcussion) reported sleep problems postconcussion and n = 110 (14.3 ± 2.4 years; 46% female; initial visit 9.3 ± 5.4 days postinjury) did not. Those reporting sleep problems postconcussion had significantly more modified Balance Error Scoring System errors than those without (8.4 ± 5.5 vs 6.7 ± 4.7; P = .01), but similar tandem gait and memory performance. A significantly greater proportion of those who reported sleep problems postconcussion experienced persistent postconcussion symptoms than those who did not (53% vs 31%; P = .004). After adjusting for time from concussion to clinical visit and preconcussion sleep problems, postconcussion sleep problems were associated with a 2 times greater odds of developing persistent postconcussion symptoms (adjusted odds ratio = 2.02, 95% CI = 1.01, 4.06; P = .049). Identifying sleep problems early following concussion may allow clinicians to implement targeted treatment recommendations to improve sleep and provide an optimal recovery environment.

Concussion history is associated with increased lower-extremity injury incidence in Reserve Officers' Training Corps cadets

INTRODUCTION

Concussions have been associated with an increased risk of lower-extremity musculoskeletal injury (LE-MSI) in athletes and US Army soldiers, creating an added economic, physical and social burden. Yet, there is a paucity of evidence on this relationship among Reserve Officers' Training Corps (ROTC) cadets, a group which engages in activities with high-injury risk and will subsequently commission as active duty officers. This study aimed to examine the association between concussions and LE-MSI in ROTC cadets.

METHODS

125 (83 were male) Army and Air Force ROTC cadets (19.8±2.0 years) from two large state universities' Army and Air Force ROTC programmes participated in this study. Cadets completed a reliable injury history questionnaire to ascertain the following variables of interest: (1) any concussion history, (2) reported concussions, (3) undiagnosed concussions, and (4) potentially unrecognised concussion history and LE-MSI history (eg, ankle sprain, knee sprain or muscle strain). Data were analysed using a χ² test for association and binary logistic regression to determine ORs.

RESULTS

Cadets with any concussion history (n=42) had a significantly (p=0.035) higher association with LE-MSI (OR 2.47, 95% CI 1.05 to 5.83) than those without. Cadets who had a reported concussion (n=33) had a significantly (p=0.026) higher association with LE-MSI (OR 2.95, 95% CI 1.11 to 7.84) compared to cadets without.

CONCLUSIONS

ROTC cadets with a history of diagnosed concussion were more likely to have suffered an LE-MSI than cadets without a concussion history. ROTC cadre should be aware of this relationship and incorporate injury prevention protocols.

Dual task cost in adults with persistent concussion symptoms

BACKGROUND

Persistent concussion symptoms (PCS) negatively affects common activities of daily living including deficits in both single and dual-task (DT) gait. DT gait deficits are present post-concussion; however, task prioritization and the effects of differing cognitive challenge remain unexplored in the PCS population.

RESEARCH QUESTION

The purpose of this study was to investigate single and dual-task gait performance in individuals with persistent concussion symptoms and to identify task priorization strategies during DT trials.

METHODS

Fifteen adults with PCS (age: 43.9+11.7 y.o.) and 23 healthy control participants (age: 42.1+10.3 y.o.) completed five trials of single task gait followed by fifteen trials of dual task gait along a 10-m walkway. The cognitive challenges consisted of five trials each of visual stroop, verbal fluency, and working memory cognitive challenges. Groups were compared on DT cost stepping characteristics with independent samples t-test or Mann-Whitney U tests.

RESULTS

There were significant overall gait Dual Task Cost (DTC)difference between groups for gait speed (p = 0.009, d=0.92) and step length (p = 0.023, d=0.76). Specific to each DT challenge, PCS participants were slower during Verbal Fluency (0.98 + 0.15 m/s and 1.12 + 0.12 m/s, p = 0.008; d=1.03), Visual Stroop (1.06 + 0.19 m/s and 1.20 + 0.12 m/s, p = 0.012, d=0.88), and Working Memory (1.02 + 0.15 m/s and 1.16 + 0.14 m/s, p = 0.006, d=0.96). There were significant cognitive DTC differences between groups for WM accuracy (p = 0.008, d=0.96), but not for VS accuracy (p = 0.841, d=0.061) or VF total words (p = 0.112, d=0.56).

SIGNIFICANCE

The PCS participants displayed a posture-second strategy whereby gait performance generally decreased in the absence of cognitive changes. However, during the Working Memory DT, PCS participants had a mutual interference response whereby both motor and cognitive performance decreased suggesting the cognitive task plays a key role in the DT gait performance of PCS patients.

Cognitive and Behavioral Outcomes in Male and Female NCAA Soccer Athletes across Multiple Years: A CARE Consortium Study

PURPOSE

The purpose of this study was to determine changes in neurocognitive, psychosocial, and balance functioning in collegiate male and female soccer players across three consecutive years of baseline testing compared with a control group of noncontact athletes.

METHODS

Generalized estimating equations were used to compare changes in annual, preseason baseline measures of neurocognitive function, neurobehavioral and psychological symptoms, and postural stability between collegiate soccer players ( n = 75; 51 [68%] female soccer players) and noncontact athletes ( n = 210; 133 [63%] female noncontact athletes) across three consecutive years.

RESULTS

Among all participants, the group-time interaction was not significant for any outcome measures. Overall, soccer players reported lower (better) Brief Symptom Inventory 18 Depression ( P = 0.004, Exp(B) = 0.36, 95% confidence interval [CI] = 0.18-0.73), Global Severity Index ( P = 0.006, Exp(B) = 0.53, 95% CI = 0.33-0.84), and Post-Concussion Symptom Scale Symptom Severity ( P < 0.001, Exp(B) = 0.45, 95% CI = 0.22-0.95) scores than noncontact athletes. No other outcome measures were different between soccer players and noncontact athletes.

CONCLUSIONS

Among collegiate athletes, soccer players report similar or better psychosocial functioning and symptom scores than noncontact athletes. Importantly, neurocognitive functioning, neurobehavioral and psychological symptoms, and postural stability do not worsen over time in collegiate soccer players relative to their noncontact counterparts. Our findings suggest that despite possible exposure to repetitive head impacts, collegiate soccer players do not exhibit changes in observable function and symptoms across multiple seasons.

Lower Extremity Musculoskeletal Injuries After Concussion in Collegiate Student-Athletes

BACKGROUND

An association has been identified between concussion and lower extremity musculoskeletal injury (LEMSKI) after return to sports participation. However, the collegiate student-athlete studies have relied on relatively small single-institution studies, which limits generalizability.

PURPOSE

To assess odds of, and time to, LEMSKI after concussion in US collegiate athletes, using the National Collegiate Athletic Association (NCAA) Injury Surveillance Program (ISP).

STUDY DESIGN

Descriptive epidemiology study.

METHODS

Data from the NCAA ISP during the 2010-2011 through 2019-2020 athletic seasons were considered for analysis. Frequency distributions were examined for details related to the initial and subsequent injuries (injuries to bone, bursa, joint, ligament, muscle, or tendon). Multivariable logistic regression models and random-effects Poisson regression models examined odds of time loss (TL) and non-time loss (NTL) LEMSKI after concussion, as well as the time interval between initial concussion and subsequent LEMSKI in a single athletic season, or initial musculoskeletal injury (MSKI) and subsequent LEMSKI in a single athletic season. Analyses were performed separately for football and other sports.

RESULTS

A total of 31,556 initial injuries were recorded (football: 11,900; other sports: 19,656), which were followed by 0 or 1 injury in the same season. Overall, first injury type was not a significant predictor of subsequent LEMSKI, although certain contrasts yielded significant estimates. In football, the odds of NTL LEMSKI were higher after concussion than after upper extremity MSKI (UEMSKI; adjusted odds ratio [OR_Adj], 1.56; 95% CI, 1.06-2.31). In football, the odds of TL LEMSKI were lower after concussion than after UEMSKI (OR_Adj, 0.71; 95% CI, 0.51-0.99). No other significant effect estimates were observed for football or other sports.

CONCLUSION

First injury type, either concussion or upper extremity, was not associated with an elevated risk of LEMSKI. Specifically, the results of this study did not identify an elevated odds of LEMSKI after a concussion. However, the authors observed greater odds of NTL LEMSKI and lower odds of TL LEMSKI in football.

STUDY ON THE CHARACTERISTICS OF LOWER LIMB MUSCLE MOTOR ORGANIZATION AMONG ATHLETES WITH TRAUMATIC KNEE INJURIES

ABSTRACT Introduction Traumatic injury to the knee joints and their adjacent muscles is common among athletes, and their organizational characteristics require thorough analysis. Objective Investigate the motor organization of muscles in the lower limbs of athletes with traumatic knee injuries. Methods A systematic survey of the peculiarities of motor organization in the muscles of physically healthy athletes was preceded by an analytical survey of the peculiarities of this organization among athletes with traumatic knee injuries interested in medical treatment to restore the functional condition of the knee joints and perform active sports activities. Results The characteristics of muscle motor organization in traumatic injuries and their recovery methods were determined, as well as the formation of a sequential understanding of the recovery process of knee joint injuries for athletes representing various sports. Conclusion The results of this scientific study and the conclusions formulated based on them are of great importance for athletes concerned with restoring functional status after knee joint injuries sustained during the competition and in the training process. Evidence level II; Therapeutic studies - outcomes research.

Lower-Extremity Neuromuscular Function Following Concussion: A Preliminary Examination

CONTEXT

Neuromuscular function is altered acutely following concussion and theoretically linked to the subsequent postconcussion musculoskeletal injury risk. Existing research has only examined voluntary muscle activation, limiting mechanistic understanding. Therefore, our study aimed to examine voluntary and involuntary muscle activation between college-aged, concussed individuals when symptom-free and healthy matched controls.

DESIGN

Prospective, cross-sectional cohort laboratory study.

METHODS

Concussed and healthy participants (n = 24; 58% male, age: 19.3 [1.1] y, mass: 70.3 [16.4] kg, height: 177.3 [12.7] cm) completed the superimposed burst (SB) neuromuscular assessment on their dominant limb within 72 hours after self-reporting asymptomatic (22.4 [20.2] d postinjury). Unnormalized and bodyweight-normalized quadriceps maximal voluntary isometric contraction torque (in newton meters), unnormalized and bodyweight-normalized electrically stimulated SB torque, pain (numeric 1-10) during SB, and the central activation ratio (in percentage) were assessed via the SB. Parametric and nonparametric analyses, 95% confidence intervals (95% CIs), and Hedges g (parametric) and Spearman ρ (nonparametric) effect sizes were used to examine group differences (α = .05).

RESULTS

The maximal voluntary isometric contraction torque (concussed: 635.60 N·m [300.93] vs control: 556.27 N·m [182.46]; 95% CI, -131.36 to 290.02; P = .443; d = 0.33), SB torque (concussed: 203.22 N·m [97.17], control: 262.85 N·m [159.07]; 95% CI, -171.22 to 51.97; P = .280; d = -0.47), and central activation ratio (concussed: 72.16% [17.16], control: 70.09% [12.63]; 95% CI, -10.68 to 14.83; P = .740; d = 0.14) did not differ between the concussed and control groups regardless of bodyweight normalization (P ≥ .344). Pain during the SB was significantly higher with a medium effect for participants with a concussion versus healthy controls (concussed: median = 7, control: median = 5; P = .046; ρ = -0.42).

DISCUSSION

These findings suggest concussed participants do not have statistically altered voluntary or involuntary quadricep neuromuscular function once asymptomatic compared with controls. Therefore, the elevated postconcussion musculoskeletal injury risk may not be attributed to lower-extremity muscle activation. Concussed participants displayed greater pain perception during the SB, which suggests somatosensory or perception changes requiring further examination.

Neuromotor changes in participants with a concussion history can be detected with a custom smartphone app

Neuromotor dysfunction after a concussion is common, but balance tests used to assess neuromotor dysfunction are typically subjective. Current objective balance tests are either cost- or space-prohibitive, or utilize a static balance protocol, which may mask neuromotor dysfunction due to the simplicity of the task. To address this gap, our team developed an Android-based smartphone app (portable and cost-effective) that uses the sensors in the device (objective) to record movement profiles during a stepping-in-place task (dynamic movement). The purpose of this study was to examine the extent to which our custom smartphone app and protocol could discriminate neuromotor behavior between concussed and non-concussed participants. Data were collected at two university laboratories and two military sites. Participants included civilians and Service Members (N = 216) with and without a clinically diagnosed concussion. Kinematic and variability metrics were derived from a thigh angle time series while the participants completed a series of stepping-in-place tasks in three conditions: eyes open, eyes closed, and head shake. We observed that the standard deviation of the mean maximum angular velocity of the thigh was higher in the participants with a concussion history in the eyes closed and head shake conditions of the stepping-in-place task. Consistent with the optimal movement variability hypothesis, we showed that increased movement variability occurs in participants with a concussion history, for which our smartphone app and protocol were sensitive enough to capture.

Age of First Concussion and Cognitive, Psychological, and Physical Outcomes in NCAA Collegiate Student Athletes

OBJECTIVE

Concussions are common among youth athletes and could disrupt critical neurodevelopment. This study examined the association between age of first concussion (AFC) and neurocognitive performance, psychological distress, postural stability, and symptoms commonly associated with concussion in healthy collegiate men and women student athletes.

METHODS

Participants included 4267 collegiate athletes from various contact, limited-contact, and non-contact sports (1818 women and 2449 men) who completed baseline assessments as part of the Concussion Assessment, Research and Education (CARE) Consortium. Psychological distress was assessed with the Brief Symptom Inventory 18; neurocognitive performance was assessed with the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT); symptoms commonly associated with concussion were assessed with the ImPACT Post-Concussion Symptom Scale; postural stability was assessed with the Balance Error Scoring System. Generalized linear models were used to examine the effects of AFC on clinical outcomes separately in men and women.

RESULTS

Later AFC was associated with lower global (Exp(B) = 0.96, P = 0.001) and somatic (Exp(B) = 0.96, P = 0.002) psychological distress on the Brief Symptom Inventory 18 and faster ImPACT reaction time (B =  - 0.003, P = 0.001) in women. AFC was not associated with any clinical outcomes in men.

CONCLUSION

Younger AFC was associated with some differences in psychological distress and reaction time among women but not men; however, these results are likely not clinically meaningful. Sociodemographic disparities, pre-existing conditions, and sport type may impact clinical and cognitive outcomes in collegiate athletes more than concussion history. Future work should examine the relationship between AFC and lifespan-related outcomes.

Reactive Balance Responses After Mild Traumatic Brain Injury: A Scoping Review

OBJECTIVE

Balance testing after concussion or mild traumatic brain injury (mTBI) can be useful in determining acute and chronic neuromuscular deficits that are unapparent from symptom scores or cognitive testing alone. Current assessments of balance do not comprehensively evaluate all 3 classes of balance: maintaining a posture; voluntary movement; and reactive postural response. Despite the utility of reactive postural responses in predicting fall risk in other balance-impaired populations, the effect of mTBI on reactive postural responses remains unclear. This review sought to (1) examine the extent and range of available research on reactive postural responses in people post-mTBI and (2) determine whether reactive postural responses (balance recovery) are affected by mTBI.

DESIGN

Scoping review.

METHODS

Studies were identified using MEDLINE, EMBASE, CINAHL, Cochrane Library, Dissertations and Theses Global, PsycINFO, SportDiscus, and Web of Science. Inclusion criteria were injury classified as mTBI with no confounding central or peripheral nervous system dysfunction beyond those stemming from the mTBI, quantitative measure of reactive postural response, and a discrete, externally driven perturbation was used to test reactive postural response.

RESULTS

A total of 4747 publications were identified, and a total of 3 studies (5 publications) were included in the review.

CONCLUSION

The limited number of studies available on this topic highlights the lack of investigation on reactive postural responses after mTBI. This review provides a new direction for balance assessments after mTBI and recommends incorporating all 3 classes of postural control in future research.

The Toronto Concussion Study: Reference Data for Balance and Gait Measures in Community-Dwelling Adults With Concussion

OBJECTIVE

Concussion can cause deficits in balance and gait. Much of what is known about how concussion affects balance and gait has been derived from studies involving youth, high school, and university athletes. However, investigation into the effects of concussion on balance and gait in community-dwelling young, middle-age, and older aged adults is limited. This study aimed to present descriptive reference values for common balance and gait measures in community-dwelling adults between the ages of 20 and 69 years with concussion.

METHODS

In this observational study, 318 participants were enrolled from a concussion care clinic at a rehabilitation hospital in an urban center and were assessed within 7 days of injury. Balance measures included the Balance Error Scoring System (BESS), modified BESS, and center-of-pressure root mean square during quiet standing. Gait measures included velocity (absolute and height adjusted), cadence, and step length during self-paced gait. Data were binned by decade-long age range.

RESULTS

Mean (SD) per-decade scores for the BESS ranged from 14.8 (5.1) to 21.8 (5.6) errors and 4.0 (3.0) to 9.4 (4.6) errors for the modified BESS. Mean values for center-of-pressure root mean square in the anteroposterior direction ranged from 0.42 (0.18) to 0.52 (0.26) with the eyes open, and from 0.49 (0.19) to 0.62 (0.39) with eyes closed. Mean absolute gait velocity ranged from 98.5 (9.1) to 119.3 (21.3) cm/s. The range of step length values was 58.2 (6.8) to 66.3 (7.3) cm and cadence ranged from 102.1 (9.8) to 108.6 (10.8) steps/min across age groups.

CONCLUSION

These data provide insight into the impact of concussion on balance and mobility in community-dwelling adults across the lifespan.

IMPACT

Community-dwelling adults can experience concussion across the lifespan. Availability of reference values for commonly used balance and gait measures can help to inform clinical strategies and progression of recovery of balance and mobility after injury.

Dizziness, Psychosocial Function, and Postural Stability Following Sport-Related Concussion

OBJECTIVE

To examine if self-reported dizziness is associated with concussion symptoms, depression and/or anxiety symptoms, or gait performance within 2 weeks of postconcussion.

DESIGN

Cross-sectional study.

SETTING

Research laboratory.

PARTICIPANTS

Participants were diagnosed with a concussion within 14 days of initial testing (N = 40). Participants were divided into 2 groups based on their Dizziness Handicap Inventory (DHI) score: 36 to 100 = moderate/severe dizziness and 0 to 35 = mild/no dizziness.

INTERVENTIONS

Participants were tested on a single occasion and completed the DHI, hospital anxiety and depression scale (HADS), Patient Health Questionnaire-9 (PHQ-9), and Post-Concussion Symptom Inventory (PCSI). Three different postural control tests were use: modified Balance Error Scoring System, single-/dual-task tandem gait, and a single-/dual-task instrumented steady-state gait analysis.

MAIN OUTCOME MEASURES

Comparison of patient-reported outcomes and postural control outcomes between moderate/severe (DHI ≥ 36) and mild/no (DHI < 36) dizziness groups.

RESULTS

Participants with moderate/severe dizziness (n = 19; age = 17.1 ± 2.4 years; 63% female) reported significantly higher symptom burden (PSCI: 43.0 ± 20.6 vs 22.8 ± 15.7; P = 0.001) and had higher median HADS anxiety (6 vs 2; P < 0.001) and depression (6 vs 1; P = 0.001) symptom severity than those with no/minimal dizziness (n = 21; age = 16.5 ± 1.9; 38% female). During steady-state gait, moderate/severe dizziness group walked with significantly slower single-task cadence (mean difference = 4.8 steps/minute; 95% confidence interval = 0.8, 8.8; P = 0.02) and dual-task cadence (mean difference = 7.4 steps/minute; 95% confidence interval = 0.7, 14.0; P = 0.04) than no/mild dizziness group.

CONCLUSION

Participants who reported moderate/severe dizziness reported higher concussion symptom burden, higher anxiety scores, and higher depression scores than those with no/mild dizziness. Cadence during gait was also associated with the level of dizziness reported.

Association Between Collision Sport Career Duration and Gait Performance in Male Collegiate Student-Athletes

BACKGROUND

Investigations of estimated age of first exposure to repetitive head impacts from collision and contact sports have shown no associations with neurocognitive or neurobehavioral function at the collegiate level, but the effect of career duration may be a more comprehensive factor. Understanding whether longer career duration influences gait performance would provide insights into potential neurological impairment.

PURPOSE

To examine the relationship between career duration of collision sports and single/dual-task gait performance in collegiate student-athletes.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

We recruited 168 male student-athletes from collision sports: football, lacrosse, ice hockey, and wrestling (mean ± SD age, 19.2 ± 1.3 years; height, 184.5 ± 7.2 cm; mass, 94.3 ± 15.9 kg; estimated age of first exposure, 8.6 ± 3.1 years; career duration, 10.6 ± 3.0 years). All participants completed a baseline single- and dual-task gait assessment before the start of their athletic season. Inertial measurement units were used to measure gait speed and stride length. During the dual task, participants were asked to perform working memory cognitive tasks while walking. The dependent variables were single/dual-task gait speed and stride length, cognitive accuracy, and dual-task cost. The relationship between career duration, analyzed as a continuous variable, and the dependent variables was analyzed using a linear regression.

RESULTS

There were no significant associations between career duration and single-task gait speed (1.16 ± 0.16 m/s; β = -0.004; P = .35; 95% CI = -0.012 to 0.004; η² = 0.005) or dual-task gait speed (1.02 ± 0.17 m/s; β = -0.003; P = .57; 95% CI = -0.011 to 0.006; η² = 0.002). There were also no significant associations between career duration and single/dual-task stride length, cognitive accuracy, or dual-task cost.

CONCLUSION

Career duration among collegiate collision sport athletes was not associated with single- or dual-task gait performance, suggesting that a greater exposure to repetitive head impacts is not detrimental to dynamic postural control at the college level. However, the effects of diminished gait performance over the lifetime remain to be elucidated.

Towards defining biomarkers to evaluate concussions using virtual reality and a moving platform (BioVRSea)

Current diagnosis of concussion relies on self-reported symptoms and medical records rather than objective biomarkers. This work uses a novel measurement setup called BioVRSea to quantify concussion status. The paradigm is based on brain and muscle signals (EEG, EMG), heart rate and center of pressure (CoP) measurements during a postural control task triggered by a moving platform and a virtual reality environment. Measurements were performed on 54 professional athletes who self-reported their history of concussion or non-concussion. Both groups completed a concussion symptom scale (SCAT5) before the measurement. We analyzed biosignals and CoP parameters before and after the platform movements, to compare the net response of individual postural control. The results showed that BioVRSea discriminated between the concussion and non-concussion groups. Particularly, EEG power spectral density in delta and theta bands showed significant changes in the concussion group and right soleus median frequency from the EMG signal differentiated concussed individuals with balance problems from the other groups. Anterior–posterior CoP frequency-based parameters discriminated concussed individuals with balance problems. Finally, we used machine learning to classify concussion and non-concussion, demonstrating that combining SCAT5 and BioVRSea parameters gives an accuracy up to 95.5%. This study is a step towards quantitative assessment of concussion.

Concussion is not associated with elevated rates of lower-extremity musculoskeletal injuries in National Football League Players

OBJECTIVE

Emerging evidence has identified an ~2x elevated risk of musculoskeletal (MSK) injury in the year following a concussion. Most of these studies have examined a single college/university athletic department and may lack generalizability to professional sports. Therefore, the purpose of this study was to assess the odds of post-concussion MSK injury utilizing publicly available National Football League (NFL) injury reports.

METHODS

Concussions were identified through a review of published NFL injury reports during the 2015, 2016, and 2017 regular seasons. Concussed players were matched by team and position, and injuries were tracked for both groups for the remainder of the season. A chi-square analysis compared the frequency of MSK injury in both groups and a Cox Proportional Hazard model calculated the risk of sustaining a subsequent MSK injury.

RESULTS

There were 322 concussed NFL players who met inclusion criteria and were successfully matched. From the time of concussion through the remainder of the season, 21.4% of the concussed players were injured and 26.4% of control participants were injured. There was no difference in MSK injury rates (p = 0.166), and the relative risk ratio was 0.90 for subsequent injury in the concussion group. There was no difference in the time to event for subsequent MSK between the two groups (p = 0.123).

CONCLUSION

The primary finding of this study was no elevated risk of post-concussion MSK in NFL football players.

Acute Physical and Mental Activity Influence on Concussion Recovery

INTRODUCTION

Physical activity (PA) and mental activity (MA) postconcussion has received renewed attention to improve concussion management; however, most protocols start after several days and do not assess the acute window. Therefore, the purpose of this study was to assess PA and MA in the first 48 h postconcussion on the time to symptom-free status and return to play.

METHODS

We recruited 78 NCAA Division I athletes (male, 51.3%; age, 19.6 ± 1.4 yr; height, 173.7 ± 11.5 cm; weight, 80.1 ± 23.2 kg) who were diagnosed with a sports-related concussion. Participants completed a 0-5 PA and MA scale daily until fully cleared for return to participation (mean, 15.1 ± 6.9 d). A quadratic model regression assessed PA and MA over the first 2 d (acute) postconcussion on to time to symptom-free status and return to play.

RESULTS

The overall model was significant for both time to symptom free (r2 = 0.27, P = 0.004) and return to play (r2 = 0.23, P = 0.019). Reported PA was the only significant predictor for time to symptom-free (P = 0.002) and return-to-participation (P = 0.006) day. Reported MA was not associated either outcome.

CONCLUSIONS

The primary finding of this study was that mild to moderate PA acutely postconcussion was associated with reduced time to symptom free and return to participation as opposed to either lower or higher levels of PA. Conversely, acute MA was not associated with recovery outcomes. These results further elucidate the role of postconcussion PA.

Longitudinal Assessment of Acute Concussion Outcomes Through SMS Text (ConText Study)

OBJECTIVE

Mild traumatic brain injury (mTBI), or concussion, is a common health problem that has seen a recent increase in US adolescents. This study uses SMS text messaging (a mobile health [mHealth] tool) to report patient symptoms. We aim to better characterize mTBI recovery and hypothesize that this mHealth tool will have high retention rates and correlate with a conventional means of assessing symptoms, the Post-Concussion Symptom Inventory (PCSI).

METHODS

A prospective observational cohort pilot study. Thirty-one pediatric patients with acute mTBI were recruited to characterize their injury and report their symptoms via text messaging. Patients reported symptoms once every 3 days for the first 21 days, then once a week for 6 weeks.

RESULTS

There was a strong and positive correlation between the PCSI and the mHealth tool (rs = 0.875, P < 0.000, n = 22). Retention was 74% until symptom resolution and 42% until study completion. Patients with balance deficits had a significantly higher somatization score than those with normal balance (6.53 ± 3.25 vs 2.56 ± 2.30, t(22) = 3.211, P < 0.01).

CONCLUSIONS

This pilot study demonstrates that this tool is a valid and easy-to-use method of reporting pediatric mTBI symptoms-it replicates and identifies novel findings. Our results suggest that there may be a relationship between balance and the manifestation of somatic symptoms. Retention rates were lower than predicted, indicating that text messaging may not be the ideal format in this population. Text messaging may still have other applications for short-term communication/symptom measurement.

Thirty-Second Single-Leg Stance Identifies Impaired Postural Control in Children After Concussion: A Preliminary Report

CONTEXT

Objective and expedient assessments of standing postural control incorporating static and dynamic tasks are necessary for identifying subtle motor deficits and clearing children to return to high-risk activities after concussion. The Revised Physical and Neurological Examination for Subtle Signs (PANESS) gaits and stations tasks evaluate both static and dynamic aspects of postural control. While the PANESS gaits and stations subscale is sensitive to concussion in youth, the benefit of each specific task for this purpose is unknown.

PURPOSE

This study evaluated whether specific PANESS tasks identify postural impairments after youth concussion.

DESIGN

Cross-sectional study.

SETTING

Academicallyaffiliated research laboratory.

PARTICIPANTS

Sixty youth, ages 10-17 years, comprised 3 groups: (1) youth symptomatic from concussion (4-14 d postinjury [n = 18]), (2) clinically-recovered youth (27-122 d postinjury [n = 15]), and (3) age- and gender-matched never-concussed controls (n = 27).

MAIN OUTCOME MEASURE

PANESS gaits and stations tasks (6 dynamic and 3 static) at the time of the initial research visit.

RESULTS

Kruskal-Wallis statistic identified a significant main effect of group on standing on one foot (a 30-s task). Both symptomatic and clinically-recovered youth showed deficits on standing on one foot relative to controls.

CONCLUSIONS

Single-leg tasks of longer duration may maximize the ability to detect residual postural deficits after concussion and can be readily incorporated in targeted sport rehabilitation protocols.

Single-Task and Dual-Task Tandem Gait Performance Across Clinical Concussion Milestones in Collegiate Student-Athletes

OBJECTIVE

To determine the length of time after concussion that impaired tandem gait performance is observed.

DESIGN

Clinical measurement, prospective longitudinal.

SETTING

NCAA collegiate athletic facility.

PARTICIPANTS

Eighty-eight concussed NCAA Division I student-athletes and 30 healthy controls.

INDEPENDENT VARIABLES

Group (concussion/control) and time (Baseline, Acute, Asymptomatic, and RTP).

MAIN OUTCOME MEASURES

Participants completed 4 single-task and dual-task tandem gait trials. The concussion group completed tests at the following time points: preseason (Baseline), within 48 hours after concussion (Acute), on the day symptoms were no longer reported (Asymptomatic), and when cleared to return to sports (RTP). Controls completed the same protocol at similar intervals. The dual-task trials involved minimental style cognitive questions answered simultaneously during tandem gait. We analyzed the best time of the 4 trials, comparing groups with a linear mixed model.

RESULTS

Acutely after concussion, the concussion group performed single-task tandem gait slower (worse) than controls (concussion: 11.36 ± 2.43 seconds, controls: 9.07 ± 1.78 seconds, P < 0.001). The concussion group remained significantly slower than controls (9.95 ± 2.21 vs 8.89 ± 1.65 seconds, P = 0.03) at Asymptomatic day but not RTP. There were significant group (P < 0.001) and time (P < 0.001) effects for dual-task tandem gait. The groups were not significantly different at baseline for single-task (P = 0.95) or dual-task (P = 0.22) tandem gait.

CONCLUSIONS

Our results indicate that tandem gait performance is significantly impaired acutely after concussion, compared with both preseason measures and controls. Postural control impairments were not present when the student-athletes were cleared for RTP. This information can assist clinicians when assessing postural control and determining recovery after a concussive injury.

The Functional Assessment of Balance in Concussion (FAB-C) Battery

Background

There is no clinical tool that assesses multiple components of postural control potentially impacted by sport-related concussion (SRC).

Objective

To develop and assess the feasibility and construct validity of the Functional Assessment of Balance in Concussion (FAB-C) battery.

Study Design

Cross-sectional study.

Methods

Tests for inclusion in the FAB-C battery were identified through a search of the literature. The feasibility and construct validity of the battery was assessed with a convenience sample of active individuals (13-24 years) with and without a SRC. Feasibility outcomes included battery completion (yes/no), number of adverse events, time to administer (minutes) and cost of the battery (Canadian Dollars). Construct validity was assessed by examining correlations between tests included in the battery, and describing differences [mean (standard deviation), median (range) or proportion] in outcomes between uninjured participants and participants with SRC.

Results

Seven tests were included in the FAB-C battery. All 40 uninjured participants [12 female; median age 17 years] completed the FAB-C assessment compared to 86% of seven participants with SRC [1 female; median age 17]. No participants demonstrated adverse effects. The median administration time of the battery was 49 minutes (range 44-60). The cost of the battery was low (~$100 Canadian Dollars). Limited correlations (r<0.7) between tests in the battery were observed. A greater percentage of uninjured participants (52% to 82%) passed individual tests in the battery compared to participants with SRC (17% to 66%).

Conclusion

Although promising, the FAB-C battery requires further evaluation before adoption for widespread clinical use.

Level of Evidence

Level 3b.

Potential Mechanisms of Acute Standing Balance Deficits After Concussions and Subconcussive Head Impacts: A Review

Standing balance deficits are prevalent after concussions and have also been reported after subconcussive head impacts. However, the mechanisms underlying such deficits are not fully understood. The objective of this review is to consolidate evidence linking head impact biomechanics to standing balance deficits. Mechanical energy transferred to the head during impacts may deform neural and sensory components involved in the control of standing balance. From our review of acute balance-related changes, concussions frequently resulted in increased magnitude but reduced complexity of postural sway, while subconcussive studies showed inconsistent outcomes. Although vestibular and visual symptoms are common, potential injury to these sensors and their neural pathways are often neglected in biomechanics analyses. While current evidence implies a link between tissue deformations in deep brain regions including the brainstem and common post-concussion balance-related deficits, this link has not been adequately investigated. Key limitations in current studies include inadequate balance sampling duration, varying test time points, and lack of head impact biomechanics measurements. Future investigations should also employ targeted quantitative methods to probe the sensorimotor and neural components underlying balance control. A deeper understanding of the specific injury mechanisms will inform diagnosis and management of balance deficits after concussions and subconcussive head impact exposure.

Postural Control Deficits After Repetitive Soccer Heading

OBJECTIVE

To determine the acute effects of repetitive soccer heading on postural control.

DESIGN

Prospective study; participants were divided into 2 groups: a soccer heading group and a control group.

SETTING

Biomechanics laboratory.

PARTICIPANTS

One hundred sixty participants, including youth (age = 13.0 ± 0.8 years), high school (age = 17.2 ± 1.0 years), and collegiate (age = 20.2 ± 1.3 years) male and female soccer players, participated in this study.

INTERVENTIONS

Participants in the soccer heading group performed 12 soccer headers (initial velocity = 11.2 m/s). Postural control testing was performed both before (PRE) and immediately after (POST) the purposeful soccer headers. Control participants performed postural control testing PRE and POST a 15-minute wait period. During postural control testing, participants were asked to stand on the MobileMat (Tekscan Inc, Boston, Massachusetts) for two 2-minute intervals with their hands on their hips and their feet together with one eyes-open and one eyes-closed trial.

MAIN OUTCOME MEASURES

Using the center-of-pressure data, 95% area, sway velocity, and ApEn were calculated. Multilevel linear models were used to analyze the effects of age, sex, group, condition, and concussion history simultaneously.

RESULTS

Participants in the soccer heading group had significantly higher sway velocity POST than participants in the control group after controlling for age, sex, concussion history, condition, and PRE (t = -3.002; P = 0.003; 95% confidence interval, -0.482 to -0.100). There were no significant differences from PRE to POST for 95% area, M/L ApEn, and A/P ApEn.

CONCLUSIONS

Repetitive soccer heading does not affect most postural control measures, even among youth athletes. However, sway velocity increased after heading relative to control participants independent of age, sex, and concussion history.

Gait Performance Is Associated with Subsequent Lower Extremity Injury following Concussion

PURPOSE

The purpose was to examine gait characteristics between collegiate athletes who did and did not sustain a lower-extremity musculoskeletal (LEMSK) injury in the year after concussion.

METHODS

Thirty-four NCAA collegiate athletes with diagnosed concussions were divided into two groups based on if they did (n = 16) or did not (n = 18) sustain a LEMSK in the year after concussion. Participants completed baseline testing before the start of the season and again at return to play postconcussion. Injuries were tracked using an electronic medical database. Participants were instrumented with three APDM Opal triaxial accelerometers and performed five single-task (ST) and five dual-task (DT) gait trials. Participants traversed a 10-meter walkway, turned around a specified endpoint, and returned to the original line. During DT, participants simultaneously walked and answered mini-mental style questions. A linear mixed-effects model assessed interactions and/or main effects between groups for gait speed, double support time, cadence, stride length, and cognitive accuracy.

RESULTS

The LEMSK group walked slower (ST, 1.15 ± 0.10 m·s; DT, 1.01 ± 0.10 m·s) than the uninjured group (ST, 1.23 ± 0.11 m·s; DT, 1.10 ± 0.11 m·s) during both ST (P = 0.04) and DT (P = 0.03). The injury group spent longer in double support (ST, 20.19% ± 2.34%; DT, 21.92% ± 2.13%) than the uninjured group (ST, 18.16% ± 2.60%; DT, 20.00% ± 2.32%) during both ST (P = 0.02) and DT (P = 0.02). The injury group had a significantly lower cognitive accuracy (89.56% ± 6.48%) than the uninjured group (95.40% ± 7.08%) across time points (P = 0.02).

CONCLUSIONS

There were significant differences in gait characteristics and cognitive accuracy between those who did and did not sustain a LEMSK injury after concussion. The LEMSK group demonstrated a conservative gait strategy both before and after their concussive injury.

Persistent Visual and Vestibular Impairments for Postural Control Following Concussion: A Cross-Sectional Study in University Students

OBJECTIVE

To examine how concussion may impair sensory processing for control of upright stance.

METHODS

Participants were recruited from a single university into 3 groups: 13 participants (8 women, 21 ± 3 years) between 2 weeks and 6 months post-injury who initiated a return-to-play progression (under physician management) by the time of testing (recent concussion group), 12 participants (7 women, 21 ± 1 years) with a history of concussion (concussion history group, > 1 year post-injury), and 26 participants (8 women, 22 ± 3 years) with no concussion history (control group). We assessed sensory reweighting by simultaneously perturbing participants' visual, vestibular, and proprioceptive systems and computed center of mass gain relative to each modality. The visual stimulus was a sinusoidal translation of the visual scene at 0.2 Hz, the vestibular stimulus was ± 1 mA binaural monopolar galvanic vestibular stimulation (GVS) at 0.36 Hz, the proprioceptive stimulus was Achilles' tendon vibration at 0.28 Hz.

RESULTS

The recent concussion (95% confidence interval 0.078-0.115, p = 0.001) and the concussion history (95% confidence interval 0.056-0.094, p = 0.038) groups had higher gains to the vestibular stimulus than the control group (95% confidence interval 0.040-0.066). The recent concussion (95% confidence interval 0.795-1.159, p = 0.002) and the concussion history (95% confidence interval 0.633-1.012, p = 0.018) groups had higher gains to the visual stimulus than the control group (95% confidence interval 0.494-0.752). There were no group differences in gains to the proprioceptive stimulus or in sensory reweighting.

CONCLUSION

Following concussion, participants responded more strongly to visual and vestibular stimuli during upright stance, suggesting they may have abnormal dependence on visual and vestibular feedback. These findings may indicate an area for targeted rehabilitation interventions.

The diagnostic and prognostic utility of the dual-task tandem gait test for pediatric concussion

BACKGROUND

The tandem gait test has gained interest recently for assessment of concussion recovery. The purpose of our study was to determine the prognostic and diagnostic use of the single- and dual-task tandem gait test, alongside other clinical measures, within 10 days of pediatric concussion.

METHODS

We assessed 126 patients post-concussion (6.3 ± 2.3 days post-injury, mean ± SD) at a pediatric sports medicine clinic and compared them to 58 healthy controls (age: 15.6 ± 1.3 years; 43% female). We also compared the 31 patients with concussion who developed persistent post-concussion symptoms (PPCS) (age = 14.9 ± 2.0 years; 48% female) to the 81 patients with concussion who did not develop PPCS following the initial assessment (age: 14.1 ± 3.0 years; 41% female). All subjects completed a test battery, and concussion patients were monitored until they experienced concussion-symptom resolution. The test battery included tandem gait (single-task, dual-task (performing tandem gait while concurrently completing a cognitive test) conditions), modified Balance Error Scoring System (mBESS), and concussion symptom assessment (Health and Behavior Inventory). We defined PPCS as symptom resolution time > 28 days post-concussion for the concussion group. Measurement outcomes included tandem gait time (single- and dual-task), dual-task cognitive accuracy, mBESS errors (single/double/tandem stances), and symptom severity.

RESULTS

The concussion group completed the single-task (mean difference = 9.1 s, 95% confidential interval (95%CI): 6.1-12.1) and dual-task (mean difference = 12.7 s, 95%CI: 8.7-16.8) tandem gait test more slowly than the control group. Compared to those who recovered within 28 days of concussion, the PPCS group had slower dual-task tandem gait test times (mean difference = 7.9 s, 95%CI: 2.0-13.9), made more tandem-stance mBESS errors (mean difference = 1.3 errors, 95%CI: 0.2-2.3), and reported more severe symptoms (mean difference = 26.6 Health and Behavior Inventory rating, 95%CI: 21.1-32.6).

CONCLUSION

Worse dual-task tandem gait test time and mBESS tandem stance performance predicted PPCS in pediatric patients evaluated within 10 days of concussion. Tandem gait assessments may provide valuable information augmenting common clinical practices for concussion management.

Impaired eye tracking is associated with symptom severity but not dynamic postural control in adolescents following concussion

PURPOSE

The purpose of the study was to (1) examine the relationship between self-reported symptoms and concussion-related eye tracking impairments, and (2) compare gait performance between (a) adolescents with a concussion who have normal eye tracking, (b) adolescents with a concussion who have abnormal eye tracking, and (c) healthy controls.

METHODS

A total of 30 concussed participants (age: 14.4 ± 2.2 years, mean ± SD, 50% female) and 30 controls (age: 14.2 ± 2.2 years, 47% female) completed eye tracking and gait assessments. The BOX score is a metric of pupillary disconjugacy, with scores <10 classified as normal and ≥10 abnormal. Symptoms were collected using the Post-Concussion Symptom Scale (PCSS), and gait speed was measured with triaxial inertial measurement units. We conducted a linear regression to examine the relationship between PCSS and BOX scores and a two-way mixed effects analysis of variance to examine the effect of group (abnormal BOX, normal BOX, and healthy control) on single- and dual-task gait speed.

RESULTS

There was a significant association between total PCSS score and BOX score in the concussion group (β = 0.16, p = 0.004, 95% confidence interval (95%CI): 0.06‒0.27), but not in the control group (β = 0.21, p = 0.08, 95%CI: -0.03 to 0.45). There were no significant associations between PCSS symptom profiles and BOX scores in the concussion or control groups. There were also no significant differences in single-task (Abnormal: 1.00 ± 0.14 m/s; Normal: 1.11 ± 0.21 m/s; Healthy: 1.14 ± 0.18 m/s; p = 0.08) or dual-task (Abnormal: 0.77 ± 0.15 m/s; Normal: 0.84 ± 0.21 m/s; Healthy: 0.90 ± 0.18 m/s; p = 0.16) gait speed.

CONCLUSION

The concussed group with impaired eye tracking reported higher total symptom severity, as well as worse symptom severity across the 5 PCSS symptom domain profiles. However, eye tracking deficits did not appear to be driven by any particular symptom domain. While not statistically significant, the slower gait speeds in those with abnormal BOX scores may still be clinically relevant since gait-related impairments may persist beyond clinical recovery.

Estimated Age of First Exposure to Contact Sports and Neurocognitive, Psychological, and Physical Outcomes in Healthy NCAA Collegiate Athletes: A Cohort Study

BACKGROUND

Collegiate football players who started playing tackle football before age 12 years did not show worse neuropsychological test performance than those who started playing tackle football after age 12 years. It is unknown if beginning other contact sports, such as lacrosse, at a younger age is associated with worse neurocognitive performance, greater psychological distress, or worse postural stability in collegiate student athletes.

OBJECTIVE

The purpose of this study was to examine the association between estimated age of first exposure (eAFE) to repetitive head impacts (RHI) and these outcome measures in collegiate student athletes.

METHODS

1891 female and 4448 male collision/contact (i.e., football, ice hockey, lacrosse, wrestling, soccer) and non-contact (i.e., golf, rifle, rowing/crew, swimming, tennis) sport athletes completed baseline testing, including the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT), Brief Symptom Inventory 18 (BSI-18), and Balance Error Scoring System (BESS).

RESULTS

For women, the eAFE-by-sport interaction was associated with ImPACT Verbal Memory and Visual Memory, whereby earlier eAFE to contact sports was associated with higher composite scores (B = - 0.397, B = - 0.485, respectively). For men, the eAFE-by-sport interaction was associated with BSI-18 Depression and Global Severity Index and symptom severity scores, whereby earlier eAFE to football was associated with lower psychological distress and symptom severity [Depression, Exp(B) = 1.057; Global Severity Index, Exp(B) = 1.047; Symptom Severity, Exp(B) = 1.046]. Parameter estimates were small suggesting these results may have minimal practical relevance.

CONCLUSION

Findings suggest that RHI during early adolescence is unrelated to brain health as measured by these specific outcome measures in collegiate student athletes.

MOVEMENT PATTERNS DIFFER BETWEEN ATHLETES AFTER SPORT-RELATED CONCUSSION COMPARED TO HEALTHY CONTROLS DURING JUMP LANDING TASK

CONTEXT

A relationship between a positive history of sport-related concussion (SRC) and lower extremity (LE) injury has been well established in the literature.

OBJECTIVE

The purpose of this study was to determine if biomechanical differences exist during a double limb jump landing (DLJ) between athletes who had been released for return to play after SRC and healthy matched controls (Healthy).

DESIGN

Cross-Sectional Study Setting: Health system-based Outpatient Sports Medicine Center Participants: 21 participants (16.33±12.7 days out from being released to return to sport after SRC) (age: 15.38±1.77; height: 169.23±8.59; mass: 63.43±7.39) were compared to 21 age, sex, activity-matched healthy controls (age: 15.36±1.73; height: 169.92±11.1; mass: 65.62±12.08). No significant differences existed between groups for descriptive data.

MAIN OUTCOME MEASURE(S)

Biomechanical performance during DLJ was assessed using Motion Capture System and force plates. The average of five consecutive trials was used to calculate lower extremity joint kinetic and kinematics. Variables of interest included internal knee extension moment, internal varus moment, and total sagittal plane knee displacement for both the dominant and non-dominant limbs. Independent t-tests were performed to examine the differences between SRC and Healthy groups for variables of interest.

RESULTS

The SRC group demonstrated greater internal knee extension moments on their dominant (KEDomDiff=-.028±.009; p=.003) and non-dominant (KENonDomDiff=-.018±.007, p=.019) limbs. The SRC group also demonstrated greater internal varus moments on their dominant (VDomDiff=.012±.004, p=.005) and non-dominant (VNonDomDiff=.010±.003, p=.005) limbs. For sagittal plane knee displacement, the SRC group demonstrated less knee flexion displacement on their dominant (DispDomDiff=-12.56±4.67, p=.011) but not their non-dominant limb (DispNonDomDiff=-8.30±4.91, p=.099).

CONCLUSIONS

Athletes who have been released for return to sport after SRC land in greater knee valgus compared to healthy matched controls.

The Influence of Cognitive Dual Tasks on Concussion Balance Test Performance

OBJECTIVE

To determine the influence of a cognitive dual task on postural sway and balance errors during the Concussion Balance Test (COBALT).

METHODS

Twenty healthy adults (12 females, eight males; aged 21.95 ± 3.77 years; height = 169.95 ± 9.95 cm; weight = 69.58 ± 15.03 kg) partook in this study and completed single- and dual-task versions of a reduced COBALT.

RESULTS

Sway velocity decreased during dual-task head rotations on foam condition (p = .021, ES = -0.57). A greater number of movement errors occurred during dual-task head rotations on firm surface (p = .005, ES = 0.71), visual field flow on firm surface (p = .008, ES = 0.68), and head rotations on foam surface (p < .001, ES = 1.61) compared with single-task conditions. Cognitive performance was preserved throughout different sensory conditions of the COBALT (p = .985).

DISCUSSION

Cognitive dual tasks influenced postural control and destabilized movements during conditions requiring advanced sensory integration and reweighting demands. Dual-task versions of the COBALT should be explored as a clinical tool to identify residual deficits past the acute stages of concussion recovery.

Changes in postural strategy of the lower limb under mechanical knee constraint on an unsteady stance surface

Joint constraint could limit the available degrees of freedom in a kinematic chain for maintaining postural stability. This study investigated adaptive changes in postural synergy due to bracing of bilateral knee joints, usually thought to have a trifling impact on upright stance. Twenty-four young adults were requested to maintain balance on a stabilometer plate as steadily as possible while wearing a pair of knee orthoses, either unlocked (the non-constraint (NC) condition) or locked to restrict knee motion (the knee constraint (KC) condition). Knee constraint led to a significant increase in the regularity of the stabilometer angular velocity. More than 95% of the variance properties of the joint angular velocities in the lower limb were explained by the first and second principal components (PC1 and PC2), which represented the ankle strategy and the combined knee and hip strategy, respectively. In addition to the increase trend in PC1 regularity, knee constraint enhanced the mutual information of the stabilometer angular velocity and PC1 (MI_STBV-PC1) but reduced the mutual information of the stabilometer angular velocity and PC2 (MI_STBV-PC2). The MI_STBV-PC1 was also positively correlated to stance steadiness on the stabilometer in the KC condition. In summary, in the knee constraint condition, postural synergy on the stabilometer was reorganized to increase reliance on ankle strategies to maintain equilibrium. In particular, a stable stabilometer stance under knee constraint is associated with a high level of coherent ankle–stabilometer interaction.

Using functional movement tests to investigate the presence of sensorimotor impairment in amateur athletes following sport-related concussion: A prospective, longitudinal study

OBJECTIVE

To longitudinally investigate the presence of sensorimotor impairments in amateur athletes following sport-related concussion using two functional movement tests.

DESIGN

Prospective, longitudinal study.

SETTING

Human movement analysis laboratory.

PARTICIPANTS

Athletes who presented to a hospital emergency department and were diagnosed with sport-related concussion, and sex-, age-, and activity-matched non-concussed, control athletes. Concussed participants were assessed within one-week following sport-related concussion, upon clearance to return-to-sporting activity (RTA), and two weeks after RTA. Control participants were assessed at an initial time-point and approximately two and four weeks following their initial study assessment.

MAIN OUTCOMES MEASURES

At each laboratory assessment, participants completed two functional movement tests: the Star Excursion Balance Test to evaluate anterior reach distance (normalised for leg length) and fractal dimension (centre of pressure path complexity), and the Multiple Hop Test to evaluate corrective postural strategies and time-to-stabilisation.

RESULTS

Fifty concussed athletes and 50 control athletes completed the study. There were no significant differences at any study assessment between the concussion and control group on the Star Excursion Balance Test anterior reach distance or fractal dimension (centre of pressure path complexity). During the Multiple Hop Test, the concussion group used a significantly greater number of corrective postural strategies than the control group one-week following sport-related concussion and upon clearance to RTA, but not two weeks following RTA.

CONCLUSION

Recently concussed athletes made a greater number of corrective postural strategies than control participants during the Multiple Hop Test upon clearance to RTA but not two weeks after RTA. The Multiple Hop Test may offer a clinically useful tool for practitioners to examine the recovery of subtle sensorimotor impairments and related RTA readiness.

Head stabilization during standing in people with persisting symptoms after mild traumatic brain injury

Increased postural sway is often observed in people with mild traumatic brain injury (mTBI), but our understanding of how individuals with mTBI control their head during stance is limited. The purpose of this study was to determine if people with mTBI exhibit increased sway at the head compared with healthy controls. People with persisting symptoms after mTBI (n = 59, 41 women) and control participants (n = 63, 38 women) stood quietly for one minute in four conditions: eyes open on a firm surface (EO-firm), eyes closed on a firm surface (EC-firm), eyes open on a foam pad (EO-foam), and eyes closed on foam (EC-foam). Inertial sensors at the head, sternum, and lumbar region collected tri-axial accelerations. Root-mean-square (RMS) accelerations in anteroposterior (AP) and mediolateral (ML) directions and sway ratios between the head and sternum, head and lumbar, and sternum and lumbar region were compared between groups. Temporal coupling of anti-phase motion between the upper and lower body angular accelerations was assessed with magnitude squared coherence and cross-spectral phase angles. People with mTBI demonstrated greater sway than controls across conditions and directions. During foam-surface conditions, the control group, but not the mTBI group, reduced ML sway at their head and trunk relative to their lumbar by increasing the expression of an anti-phase hip strategy within the frontal plane. These results are consistent with suggestions of inflexible or inappropriate postural control in people with mTBI.

No Clinical Predictors of Postconcussion Musculoskeletal Injury in College Athletes

PURPOSE

This study aimed to identify clinical predictors of postconcussion subsequent musculoskeletal (MSK) injuries.

METHODS

We recruited 66 National Collegiate Athletic Association intercollegiate student-athletes with a diagnosed concussion as well as 36 National Collegiate Athletic Association student-athletes without a concussion. All participants completed a multifaceted concussion baseline consisting of 1) 22-item 0-6 self-reported symptom checklist with outcomes including both the number of symptoms endorsed (0-22) and 2) total symptom score (0-132), 3) Standard Assessment of Concussion, 4) Balance Error Scoring System, 5) Immediate Post-Concussion Assessment and Cognitive Testing, 6) clinical reaction time, and 7) the King-Devick as well as demographic and injury characteristics. The concussion participants completed the same examination acutely postconcussion, and binary logistic regression was used to identify predictors of subsequent MSK from the change scores (acute minus baseline). From the 66 concussed student-athletes, a subset 36, matched with the healthy athletes, compared the risk of subsequent MSK in the year before and year after their concussion.

RESULTS

The concussion participants were 1.78 times (95% confidence interval, 1.12-2.84; P = 0.015) more likely to suffer a lower extremity MSK in the year after their concussion than the control participants. The participant demographics and injury characteristics (P = 0.318) and concussion clinical outcomes (P = 0.461) did not predict subsequent MSK.

CONCLUSION

The concussion participants were 1.78 times more likely to sustain a subsequent MSK; however, no demographic, injury characteristic, or concussion assessments predicted the MSK. Thus, clinicians are not able to utilize common neurological measures or participant demographics to identify those at risk for subsequent lower extremity MSK. Injury prevention strategies should be considered for collegiate student-athletes upon premature return to participation after a concussion to reduce the subsequent MSK.

Estimated age of first exposure to American football and outcome from concussion

OBJECTIVE

To examine the association between estimated age at first exposure (eAFE) to American football and clinical measures throughout recovery following concussion.

METHODS

Participants were recruited across 30 colleges and universities as part of the National Collegiate Athletic Association (NCAA)-Department of Defense Concussion Assessment, Research and Education Consortium. There were 294 NCAA American football players (age 19 ± 1 years) evaluated 24-48 hours following concussion with valid baseline data and 327 (age 19 ± 1 years) evaluated at the time they were asymptomatic with valid baseline data. Participants sustained a medically diagnosed concussion between baseline testing and postconcussion assessments. Outcome measures included the number of days until asymptomatic, Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) composite scores, Balance Error Scoring System (BESS) total score, and Brief Symptom Inventory 18 (BSI-18) subscores. The eAFE was defined as participant's age at the time of assessment minus self-reported number of years playing football.

RESULTS

In unadjusted regression models, younger eAFE was associated with lower (worse) ImPACT Visual Motor Speed (R ² = 0.031, p = 0.012) at 24-48 hours following injury and lower (better) BSI-18 Somatization subscores (R ² = 0.014, p = 0.038) when the athletes were asymptomatic. The effect sizes were very small. The eAFE was not associated with the number of days until asymptomatic, other ImPACT composite scores, BESS total score, or other BSI-18 subscores.

CONCLUSION

Earlier eAFE to American football was not associated with longer symptom recovery, worse balance, worse cognitive performance, or greater psychological distress following concussion. In these NCAA football players, longer duration of exposure to football during childhood and adolescence appears to be unrelated to clinical recovery following concussion.

Impairments in Dynamic Postural Control across Concussion Clinical Milestones

The aim of this study was to assess gait initiation (GI) performance longitudinally across clinical concussion recovery milestones through return to participation (RTP). We recruited 54 collegiate student-athletes, 27 with concussions and 27 matched controls (15 female and 12 male per group). Participants performed five trials of GI at baseline and again at five post-concussion clinical milestones: 1) Acute, the day clinical tests achieved baseline values on the 2) Balance Error Scoring System (BESS), 3) Immediate Post-Concussion Assessment and Cognitive Test ImPACT, 4) Asymptomatic, and 5) RTP Day. GI performance on six outcome measures (anterior/posterior and medial/lateral center of pressure displacements and velocities during the anticipatory postural adjustment [APA] phase and initial step length and velocity) with repeated-measures mixed model and pair-wise post hoc. A reliable change index (RCI) was calculated, and post-concussion participant's performance was compared to the RCI at milestones. There were significant interactions for APA posterior and lateral displacement, APA posterior velocity, step length, and step velocity. The post-hoc tests identified significant deficits across clinical milestones and at RTP for APA posterior and lateral displacement, step length, and step velocity. There were no post-hoc differences for any outcome measure in the control group. At RTP, 85.2-88.9% of concussion participants had at least one outcome measure which exceeded the 80% or 95% RCI. The primary finding of this study was persistent impairments in dynamic postural control, suggesting ongoing neurophysiological impairment despite clinical recovery. These results suggest that collegiate student-athletes may be RTP before neurophysiological recovery and potentially exposing themselves to elevated risk of recurrent concussion or subsequent musculoskeletal injury.

Impact of Extremity Manipulation on Postural Sway Characteristics: A Preliminary, Randomized Crossover Study

OBJECTIVE

Evaluate multisegmental postural sway after upper- vs lower-extremity manipulation.

METHODS

Participants were healthy volunteers (aged 21-40 years). Upper- or lower-extremity manipulations were delivered in a randomized crossover design. Postural assessments were made pre-post manipulation, in floor and rocker board conditions. Analysis included traditional balance measures of pathlength and range and sample entropy (SampEn) to examine the temporal structure of sway of the head, trunk, and surface.

RESULTS

No statistical changes in pathlength or sway range on the ground surface condition were observed. No increases in the amount of sway occurred in any condition. Chiropractic manipulation of either upper or lower extremities led to reductions in traditional measures of postural control on the rocker board. In the anteroposterior direction (sagittal plane), lower-extremity manipulation led to increased trunk SampEn while on the ground, and conversely a decreased SampEn while on the rocker board. In the mediolateral rocker board condition (frontal plane), manipulation elicited a change in SampEn that differed according to site of manipulation; upper-extremity manipulation increased SampEn, whereas lower-extremity manipulation reduced SampEn.

CONCLUSION

Both upper- and lower-extremity manipulation influenced several measures of postural sway on both the ground and the rocker board. Lower-extremity manipulation improved the organization of sway at the trunk (anteroposterior direction) and the board (mediolateral direction). Given the reduction and reorganization of sway metrics seen in this study, we propose extending this line of research to the elderly who are at greatest risk of increased sway and falls.

Sensory Reweighting for Upright Stance in Soccer Players: A Comparison of High and Low Exposure to Soccer Heading

The purpose of this study was to compare sensory reweighting for upright stance between soccer players who report higher soccer heading exposure to those who report lower soccer heading exposure. Thirty participants completed a self-reported questionnaire to estimate the number of soccer headers experienced over the previous year and were divided into "low exposure" and "high exposure" groups based on their responses. Sensory reweighting for upright stance was assessed by simultaneously perturbing visual, vestibular, and proprioceptive systems. The visual stimulus was a sinusoidal translation of the visual scene at 0.2 Hz, the vestibular stimulus was ±1mA binaural monopolar galvanic vestibular stimulation (GVS) at 0.36 Hz, and the proprioceptive stimulus was Achilles tendon vibration at 0.28 Hz. The visual stimulus was presented at two amplitudes (0.2 m, 0.8 m). Center of mass (COM) gain/phase to each modality, total power, 95% area and velocity were compared between low exposure (N = 15, six males, 21.5 ± 1.9 years, 27.7 ± 31.6 headers) and high exposure groups (N = 15, 10 males, 22.1 ± 3.5years, 734.9 ± 877.7 headers). Without vibration, COM 95% area (F = 5.861, p = 0.022*, partial η² = 0.173), velocity (F = 14.198, p = 0.001, partial η² = 0.336), and total power (F = 13.491, p = 0.001, partial η² = 0.325) for the "high exposure" group were higher than for the "low exposure" group, and postural sway lagged the vestibular stimulus in the "high exposure" group rather than leading it as in the "low exposure" group (F = 4.765, p = 0.038, partial η² = 0.145). There were no differences in sensory reweighting and no differences in COM gain/phase between groups. These findings lend empirical evidence to a detrimental effect of soccer heading exposure on balance control during upright stance.