Consensus Head Acceleration Measurement Practices (CHAMP): Origins, methods, transparency and disclosure

The use of head kinematic measurement devices has recently proliferated owing to technology advances that make such measurement more feasible. In parallel, demand to understand the biomechanics of head impacts and injury in sports and the military has increased as the burden of such loading on the brain has received focused attention. As a result, the field has matured to the point of needing methodological guidelines to improve the rigor and consistency of research and reduce the risk of scientific bias. To this end, a diverse group of scientists undertook a comprehensive effort to define current best practices in head kinematic measurement, culminating in a series of manuscripts outlining consensus methodologies and companion summary statements. Summary statements were discussed, revised, and voted upon at the Consensus Head Acceleration Measurement Practices (CHAMP) Conference in March 2022. This manuscript summarizes the motivation and methods of the consensus process and introduces recommended reporting checklists to be used to increase transparency and rigor of future experimental design and publication of work in this field. The checklists provide an accessible means for researchers to apply the best practices summarized in the companion manuscripts when reporting studies utilizing head kinematic measurement in sport and military settings

Detailed description of Division I ice hockey concussions: Findings from the NCAA and Department of Defense CARE Consortium

Objective: Since concussion is the most common injury in ice hockey, the objective of the current study was to elucidate risk factors, specific mechanisms, and clinical presentations of concussion in men's and women's ice hockey. Methods: Ice hockey players from 5 institutions participating in the Concussion Assessment, Research, and Education Consortium were eligible for the current study. Participants who sustained a concussion outside of this sport were excluded. There were 332 (250 males, 82 females) athletes who participated in ice hockey, and 47 (36 males, 11 females) who sustained a concussion. Results: Previous concussion (odds ratio (OR) = 2.00; 95% confidence interval (95% CI): 1.02‒3.91) was associated with increased incident concussion odds, while wearing a mouthguard was protective against incident concussion (OR = 0.43; 95%CI: 0.22‒0.85). Overall, concussion mechanisms did not significantly differ between sexes. There were specific differences in how concussions presented clinically across male and female ice hockey players, however. Females (9.09%) were less likely than males (41.67%) to have a delayed symptom onset (p = 0.045). Additionally, females took significantly longer to reach asymptomatic (p = 0.015) and return-to-play clearance (p = 0.005). Within the first 2 weeks post-concussion, 86.11% of males reached asymptomatic, while only 45.50% of females reached the same phase of recovery. Most males (91.67%) were cleared for return to play within 3 weeks of their concussion, compared to less than half (45.50%) of females. Conclusion: The current study proposes possible risk factors, mechanisms, and clinical profiles to be validated in future concussions studies with larger female sample sizes. Understanding specific risk factors, concussion mechanisms, and clinical profiles of concussion in collegiate ice hockey may generate ideas for future concussion prevention or intervention studies

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

Postural control deficits identify lingering post-concussion neurological deficits

Concussion, or mild traumatic brain injury, incidence rates have reached epidemic levels and impaired postural control is a cardinal symptom. The purpose of this review is to provide an overview of the linear and non-linear assessments of post-concussion postural control. The current acute evaluation for concussion utilizes the subjective balance error scoring system (BESS) to assess postural control. While the sensitivity of the overall test battery is high, the sensitivity of the BESS is unacceptably low and, with repeat administration, is unable to accurately identify recovery. Sophisticated measures of postural control, utilizing traditional linear assessments, have identified impairments in postural control well beyond BESS recovery. Both assessments of quiet stance and gait have identified lingering impairments for at least 1 month post-concussion. Recently, the application of non-linear metrics to concussion recovery have begun to receive limited attention with the most commonly utilized metric being approximate entropy (ApEn). ApEn, most commonly in the medial-lateral plane, has successfully identified impaired postural control in the acute post-concussion timeframe even when linear assessments of instrumented measures are equivalent to healthy pre-injury values; unfortunately these studies have not gone beyond the acute phase of recovery. One study has identified lingering deficits in postural control, utilizing Shannon and Renyi entropy metrics, which persist at least through clinical recovery and return to participation. Finally, limited evidence from two studies suggest that individuals with a previous history of a single concussion, even months or years prior, may display altered ApEn metrics. Overall, non-linear metrics provide a fertile area for future study to further the understanding of postural control impairments acutely post-concussion and address the current challenge of sensitive identification of recovery

Does baseline concussion testing aid in identifying future concussion risk?

The purpose was to determine differences in pre-season baseline performance between student-athletes who suffered a future sport-related concussion (fSRC) and those who did not. Collegiate student-athletes (82 fSRC, 82 matched control, age = 18.4 ± 0.8years, height = 172.7 ± 10.3 cm, mass = 80.1 ± 20.9 kg) completed baseline Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT), Balance Error Scoring System (BESS), and Standardized Assessment of Concussion (SAC). Results of the independent t-tests suggested there were no differences between the fSRC and the control groups for ImPACT composite scores (95% confidence intervals, Visual Memory: fSRC 70.4–75.9, Control 73.4–78.5, p = 0.134; Verbal Memory: fSRC 83.8–87.7, Control 85.7–89.9, p = 0.155; Reaction Time: fSRC 0.562–0.591, Control 0.580–0.614, p = 0.071; Visual Motor Speed: fSRC 38.5–41.1, Control 38.2–40.9, p = 0.757), BESS total errors (fSRC 11.3–13.7, Control 11.8–14.4, p = 0.483), or SAC (fSRC 26.6–27.4, Control 26.9–27.6, p = 0.394). Receiver operating characteristic (ROC) areas-under-the-curve were 0.417–0.515. Our findings suggest that baseline concussion assessments cannot be used to predict individuals who may sustain a fSRC

Estimated Age of First Exposure to American Football and Neurocognitive Performance Amongst NCAA Male Student-Athletes: A Cohort Study

Repetitive head impacts in young athletes are potentially detrimental to later life (e.g., age 50 + years) neurological function; however, it is unknown what the short-term effects (e.g., age 20 years) are in collegiate student-athletes. The purpose of this study was to determine the effect of the estimated age of first exposure to American tackle football participation on neurocognitive performance and symptom severity scores in collegiate student-athletes. We used a cohort study in which neurocognitive performance was assessed using the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) test in 4376 male athletes (age 19.3 ± 1.5 years, mass 96.3 ± 20.3 kg, height 185.0 ± 7.4 cm). Athletes were grouped by sport participation [American football (n = 3462) or non-contact (n = 914)] and estimated age of first exposure [< 12 years (n = 3022) or ≥ 12 years (n = 1354)]. The outcome measures were the four primary cognitive scores and the symptom severity score from ImPACT. We assessed primary outcomes across groups, controlling for age, learning accommodations, and concussion history. Neurocognitive performance was not associated with the estimated age of first exposure-by-group interaction. Our findings indicate that participation in American tackle football before age 12 years does not result in neurocognitive deficits in college. Therefore, we suggest the following: the consequences of early exposure to repetitive head impacts do not manifest by college, the ImPACT test was not sensitive enough to identify the effects of an earlier estimated age of first exposure, or there is no association between an earlier estimated age of first exposure and neurocognitive functioning. Future longitudinal studies are warranted

Clinical Reaction-Time Performance Factors in Healthy Collegiate Athletes

Context: In the absence of baseline testing, normative data may be used to interpret postconcussion scores on the clinical reaction-time test (RTclin). However, to provide normative data, we must understand the performance factors associated with baseline testing. Objective: To explore performance factors associated with baseline RTclin from among candidate variables representing demographics, medical and concussion history, self-reported symptoms, sleep, and sport-related features. Design: Cross-sectional study. Setting: Clinical setting (eg, athletic training room). Patients or other participants: A total of 2584 National Collegiate Athletic Association student-athletes (n = 1206 females [47%], 1377 males [53%], and 1 unreported (<0.1%); mass = 76.7 ± 18.7 kg; height = 176.7 ± 11.3 cm; age = 19.0 ± 1.3 years) from 3 institutions participated in this study as part of the Concussion Assessment, Research and Education Consortium. Main outcome measure(s): Potential performance factors were sex; race; ethnicity; dominant hand; sport type; number of prior concussions; presence of anxiety, learning disability, attention-deficit disorder or attention-deficit/hyperactivity disorder, depression, or migraine headache; self-reported sleep the night before the test; mass; height; age; total number of symptoms; and total symptom burden at baseline. The primary study outcome measure was mean baseline RTclin. Results: The overall RTclin was 202.0 ± 25.0 milliseconds. Female sex (parameter estimate [B] = 8.6 milliseconds, P < .001, Cohen d = 0.54 relative to male sex), black or African American race (B = 5.3 milliseconds, P = .001, Cohen d = 0.08 relative to white race), and limited-contact (B = 4.2 milliseconds, P < .001, Cohen d = 0.30 relative to contact) or noncontact (B = 5.9 milliseconds, P < .001, Cohen d = 0.38 relative to contact) sport participation were associated with slower RTclin. Being taller was associated with a faster RTclin, although this association was weak (B = -0.7 milliseconds, P < .001). No other predictors were significant. When adjustments are made for sex and sport type, the following normative data may be considered (mean ± standard deviation): female, noncontact (211.5 ± 25.8 milliseconds), limited contact (212.1 ± 24.3 milliseconds), contact (203.7 ± 21.5 milliseconds); male, noncontact (199.4 ± 26.7 milliseconds), limited contact (196.3 ± 23.9 milliseconds), contact (195.0 ± 23.8 milliseconds). Conclusions: Potentially clinically relevant differences existed in RTclin for sex and sport type. These results provide normative data adjusting for these performance factors

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

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