Nine-year risk of depression diagnosis increases with increasing self-reported concussions in retired professional football players

BACKGROUND

Concussions may accelerate the progression to long-term mental health outcomes such as depression in athletes.

PURPOSE

To prospectively determine the effects of recurrent concussions on the clinical diagnosis of depression in a group of retired football players.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Members of the National Football League Retired Players Association responded to a baseline General Health Survey (GHS) in 2001. They also completed a follow-up survey in 2010. Both surveys asked about demographic information, number of concussions sustained during their professional football career, physical/mental health, and prevalence of diagnosed medical conditions. A physical component summary (Short Form 36 Measurement Model for Functional Assessment of Health and Well-Being [SF-36 PCS]) was calculated from responses for physical health. The main exposure, the history of concussions during the professional playing career (self-report recalled in 2010), was stratified into 5 categories: 0 (referent), 1 to 2, 3 to 4, 5 to 9, and 10+ concussions. The main outcome was a clinical diagnosis of depression between the baseline and follow-up GHS. Classic tabular methods computed crude risk ratios. Binomial regression with a Poisson residual and robust variance estimation to stabilize the fitting algorithm estimated adjusted risk ratios. χ(2) analyses identified associations and trends between concussion history and the 9-year risk of a depression diagnosis.

RESULTS

Of the 1044 respondents with complete data from the baseline and follow-up GHS, 106 (10.2%) reported being clinically diagnosed as depressed between the baseline and follow-up GHS. Approximately 65% of all respondents self-reported sustaining at least 1 concussion during their professional careers. The 9-year risk of a depression diagnosis increased with an increasing number of self-reported concussions, ranging from 3.0% in the "no concussions" group to 26.8% in the "10+" group (linear trend: P < .001). A strong dose-response relationship was observed even after controlling for confounders (years retired from professional football and 2001 SF-36 PCS). Retired athletes with a depression diagnosis also had a lower SF-36 PCS before diagnosis. The association between concussions and depression was independent of the relationship between decreased physical health and depression.

CONCLUSION

Professional football players self-reporting concussions are at greater risk for having depressive episodes later in life compared with those retired players self-reporting no concussions.

Concussion in sports: the sideline assessment

CONTEXT

The vast differences between individual athletes makes identifying and evaluating sports-related concussion one of the most complex and perplexing injuries faced by medical personnel.

EVIDENCE ACQUISITION

This review summarizes the existing literature supporting the use of a multifaceted approach to concussion evaluation on the sideline of the athletic field. Information was drawn from a PubMed search (MEDLINE) for the terms sport concussion for the most recent and relevant literature.

CONCLUSIONS

By using a standardized clinical examination that is supported by objective measures of concussion-related symptoms, mental status, and postural control, the medical professional becomes well equipped to make an informed diagnosis.

Association between Previous Concussion History and Symptom Endorsement during Preseason Baseline Testing in High School and Collegiate Athletes

Background:

A graded symptom checklist is a commonly used concussion evaluation measure. Little is known about preseason baseline symptomatology of high school and college athletes with and without a previous concussion history.

Hypothesis:

The primary hypothesis investigated was that those individuals with a concussion history would report more symptoms at baseline testing. The effects of sex and age on symptoms were also examined.

Study Design:

Cross-sectional study.

Methods:

Subjects included 8930 high school and collegiate athletes (height, 177.79 ± 9.97 cm; mass, 75.20 ± 19.21 kg; age, 16.60 ± 1.64 years). Subjects completed a self-report graded symptom checklist and concussion history questionnaire during a preseason clinical testing session. Symptoms reported (yes or no) on the 18-item graded symptom checklist served as the dependent variables.

Results:

A significant association was observed between symptoms on the graded symptom checklist and previous concussion history (P ≤ .001). No differences were observed between high school and college athletes regarding symptom endorsement (t₈₉₂₈ = 0.620; P = .535). A statistical but not clinically meaningful difference was observed between the means for males and females symptom endorsement (t₈₉₂₈ = −3.03; P = .002): men endorsed 1.88 ± 2.81 symptoms, and women endorsed 2.09 ± 2.90 symptoms. Headache, sleeping more than usual, difficulty concentrating, drowsiness, difficulty remembering, fatigue, difficulty sleeping, and irritability were reported by more than 10% of athletes.

Conclusion:

High school and college athletes with a history of multiple concussions may be at risk for experiencing concussion-linked symptoms well beyond the acute stage of injury. Clinicians should be mindful of previous concussion history in athletes with increased presence of base-rate symptoms as they may be predisposed to future injury.

Systematic review of the balance error scoring system

Context:

The Balance Error Scoring System (BESS) is commonly used by researchers and clinicians to evaluate balance.A growing number of studies are using the BESS as an outcome measure beyond the scope of its original purpose.

Objective:

To provide an objective systematic review of the reliability and validity of the BESS.

Data Sources:

PubMed and CINHAL were searched using Balance Error Scoring System from January 1999 through December 2010.

Study Selection:

Selection was based on establishment of the reliability and validity of the BESS. Research articles were selected if they established reliability or validity (criterion related or construct) of the BESS, were written in English, and used the BESS as an outcome measure. Abstracts were not considered.

Results:

Reliability of the total BESS score and individual stances ranged from poor to moderate to good, depending on the type of reliability assessed. The BESS has criterion-related validity with force plate measures; more difficult stances have higher agreement than do easier ones. The BESS is valid to detect balance deficits where large differences exist (concussion or fatigue). It may not be valid when differences are more subtle.

Conclusions:

Overall, the BESS has moderate to good reliability to assess static balance. Low levels of reliability have been reported by some authors. The BESS correlates with other measures of balance using testing devices. The BESS can detect balance deficits in participants with concussion and fatigue. BESS scores increase with age and with ankle instability and external ankle bracing. BESS scores improve after training.

A dynamic warm-up model increases quadriceps strength and hamstring flexibility

Research suggests that static stretching can negatively influence muscle strength and power and may result in decreased functional performance. The dynamic warm-up (DWU) is a common alternative to static stretching before physical activity, but there is limited research investigating the effects of a DWU. The purpose of this study was to compare the acute effects of a DWU and static stretching warm-up (SWU) on muscle flexibility, strength, and vertical jump using a randomized controlled trial design. Forty-five volunteers were randomly assigned into a control (CON), SWU, or DWU group. All participants rode a stationary bicycle for 5 minutes and completed a 10-minute warm-up protocol. During this protocol, the DWU group performed dynamic stretching and running, the SWU group performed static stretching, and the CON group rested. Dependent variables were measured immediately before and after the warm-up protocol. A digital inclinometer measured flexibility (degrees) for the hamstrings, quadriceps, and hip flexor muscles. An isokinetic dynamometer measured concentric and eccentric peak torque (N·m/kg) for the hamstrings and quadriceps. A force plate was used to measure vertical jump height (meters) and power (watts). In the DWU group, there was a significant increase in hamstring flexibility (pretest: 26.4 ± 13.5°, posttest: 16.9 ± 9.4°; p < .0001) and eccentric quadriceps peak torque (pretest: 2.49 ± 0.83 N·m/kg, posttest: 2.78 ± 0.69 N·m/kg; p = 0.04). The CON and SWU did not significantly affect any flexibility, strength, or vertical jump measures (p > 0.05). The DWU significantly improved eccentric quadriceps strength and hamstrings flexibility, whereas the SWU did not facilitate any positive or negative changes in muscle flexibility, strength, power, or vertical jump. Therefore, the DWU may be a better preactivity warm-up choice than an SWU.

Reliability of concussion history in former professional football players

PURPOSE

The reliability of athletes to recall and self-report a concussion history has never been quantified. This study examined the reliability of the self-report concussion history measure and explored determinants of recall in the number of self-reported concussions in a group of retired professional football players.

METHODS

In 2001, a short questionnaire was administered to a cohort of former professional football players to ascertain the number of self-reported concussions they sustained during their professional playing careers. In 2010, the same instrument was readministered to a subset (n = 899) of the original cohort to assess reliability.

RESULTS

Overall reliability was moderate (weighted Cohen κ = 0.48). The majority (62.1%) reported the same number of concussions in both administrations (2001 and 2010); 31.4% reported more concussions in the second administration. Compared with the "same number reported" group, the "greater number reported" group had more deficits in the second administration in their Short Form 36 physical health (composite score combining physical functioning, role physical, bodily pain, general health) and mental health (e.g., composite score combining vitality, social functioning, role emotional) scales.

CONCLUSIONS

The self-reported concussion history had moderate reliability in former professional football players, on the basis of two administrations of the same instrument, 9 yr apart. However, changes in health status may be differentially associated with recall of concussions.

Age-related differences and reliability on computerized and paper-and-pencil neurocognitive assessment batteries

CONTEXT

Neurocognitive testing is a recommended component in a concussion assessment. Clinicians should be aware of age and practice effects on these measures to ensure appropriate understanding of results.

OBJECTIVE

To assess age and practice effects on computerized and paper-and-pencil neurocognitive testing batteries in collegiate and high school athletes.

DESIGN

Cohort study.

SETTING

Classroom and laboratory.

PATIENTS OR OTHER PARTICIPANTS

Participants consisted of 20 collegiate student-athletes (age = 20.00 ± 0.79 years) and 20 high school student-athletes (age = 16.00 ± 0.86 years).

MAIN OUTCOME MEASURE(S)

Hopkins Verbal Learning Test scores, Brief Visual-Spatial Memory Test scores, Trail Making Test B total time, Symbol Digit Modalities Test score, Stroop Test total score, and 5 composite scores from the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) served as outcome measures. Mixed-model analyses of variance were used to examine each measure.

RESULTS

Collegiate student-athletes performed better than high school student-athletes on ImPACT processing speed composite score (F(1,38) = 5.03, P = .031) at all time points. No other age effects were observed. The Trail Making Test B total time (F(2,66) = 73.432, P < .001), Stroop Test total score (F(2,76) = 96.85, P = < .001) and ImPACT processing speed composite score (F(2,76) = 5.81, P = .005) improved in test sessions 2 and 3 compared with test session 1. Intraclass correlation coefficient calculations demonstrated values ranging from 0.12 to 0.72.

CONCLUSIONS

An athlete's neurocognitive performance may vary across sessions. It is important for clinicians to know the reliability and precision of these tests in order to properly interpret test scores.

Postconcussive impairment differences across a multifaceted concussion assessment protocol

OBJECTIVE

To examine the proportion of athletes with concussion and with impairment disagreements across various clinical concussion assessment measures.

DESIGN

Quasi-experimental repeated measures design.

SETTING

Clinical research laboratory.

PARTICIPANTS

A sample of 100 collegiate-aged athletes participated in the study (mean [SD] age, 18.5 ± 1.1 years; mean [SD] height, 180.6 ± 9.9 cm; mean [SD] weight, 84.1 ± 20.6 kg). METHODS OR INTERVENTIONS: Participants completed preseason baseline and postconcussive injury assessments on a clinical assessment battery, including a 17-item graded symptom checklist, a computerized neurocognitive assessment, and a balance performance assessment.

MAIN OUTCOME MEASUREMENTS

Symptom severity total score, 8 cognitive domain scores from the Automated Neuropsychological Assessment Metrics, and the composite balance score obtained from the Sensory Organization Test served as outcome measures for the study. McNemar tests of paired proportions were then used to analyze impairment disagreements (where one measure identified impairments not identified by the other) between the study outcome measures. The α level was set to .05 a priori.

RESULTS

We observed significant disagreements between symptom severity total scores, and all other measures used in the study in which symptom severity total scores identified more impairments than all other measures. In addition, we observed significant disagreements for half of the clinical measures used in the study, with disagreement proportions that ranged from 22%-52%.

CONCLUSIONS

Our study underscores the importance of using a multifaceted approach for management of concussion that includes assessment of symptom severity, cognitive function, and balance. Use of this multifaceted approach also can aid clinicians in understanding other comorbidities that may complicate the management of concussion.

National athletic trainers' association position statement: preventing sudden death in sports

OBJECTIVE

To present recommendations for the prevention and screening, recognition, and treatment of the most common conditions resulting in sudden death in organized sports.

BACKGROUND

Cardiac conditions, head injuries, neck injuries, exertional heat stroke, exertional sickling, asthma, and other factors (eg, lightning, diabetes) are the most common causes of death in athletes.

RECOMMENDATIONS

These guidelines are intended to provide relevant information on preventing sudden death in sports and to give specific recommendations for certified athletic trainers and others participating in athletic health care.

Pediatric sports-related concussion

This article aims to examine pediatric concussion literature with respect to epidemiology, etiology, return to play, and recurrent concussions, and to provide recommendations for future research. We conducted a review of pediatric concussion literature regarding incidence, etiology, return to play, and recurrent concussive injury by using MEDLINE, CINAHL, Sport-Discus, and PsychInfo databases from 1995-2010. A review of reference lists in the aforementioned articles was also performed. We discovered that the research on sports-related concussion specific to children and adolescents is rather limited. Results of existing studies of concussion incidence in this population indicate that concussion is relatively rare compared with most musculoskeletal injuries; however, the potential consequences of mismanagement and of subsequent injury warrant significant attention regarding injury recognition and recovery, and the challenge of determining readiness to return to play. Evidence exists that children and adolescents take longer to recover than adults after a concussion, which underscores the need for a more conservative approach to management and return to physical and cognitive activities. Concussion in the young athlete is of specific concern because of the continuing cognitive maturation, therefore, the recovery may be more difficult to track when using the standard assessment tools currently available. Until future studies can better delineate the mechanisms of, response to, and recovery from concussion in the young athlete, it is prudent to act in a conservative manner when dealing with pediatric athletes with concussion.

The effect of play type and collision closing distance on head impact biomechanics

Football accounts for 55% of concussions to collegiate athletes. In the National Football League, players are at a greater risk for concussion during kickoffs and punts compared to rushing and passing plays. The two primary purposes of this study were to determine if game-related special teams head impacts were greater in magnitude than head impacts sustained during offensive and defensive plays, and to better understand the effect closing distance between players (short vs. long) had on head impact magnitude. Collegiate football players were enrolled in a prospective cohort study assessing head impact biomechanics during special teams, offensive, and defensive collisions; long closing distance (≥ 10 yards) and short closing distance (<10 yards) impacts were also studied. Data were analyzed using random intercepts general linear mixed models. Long closing distance collisions generated more severe head impacts than short closing distances. Collisions occurring on special teams plays over long closing distances were most severe while collisions occurring on special teams and defensive plays over short closing distances resulted in the least severe impacts. Decreasing the impact severity of collisions in collegiate football may be accomplished by reducing the closing distance prior to impact.

The relationship between subconcussive impacts and concussion history on clinical measures of neurologic function in collegiate football players

Concussions sustained during college and professional football careers have been associated with both acute and chronic neurologic impairment. The contribution of subconcussive impacts to this impairment has not been adequately studied. Therefore, we investigated the relationship between subconcussive impacts and concussion history on clinical measures of neurologic function. Forty-six collegiate football players completed five clinical measures of neurologic function commonly employed in the evaluation of concussion before and after a single season. These tests included the Automated Neuropsychological Assessment Metrics, Sensory Organization Test, Standardized Assessment of Concussion, Balance Error Scoring System, and Graded Symptom Checklist. The Head Impact Telemetry (HIT) System recorded head impact data including the frequency, magnitude, and location of impacts. College football players sustain approximately 1,000 subconcussive impacts to the head over the course of a season, but for the most part, do not demonstrate any clinically meaningful changes from preseason to postseason on measures of neurologic function. Changes in performance were mostly independent of prior concussion history, and the total number, magnitude and location of sustained impacts over one season as observed R(2) values ranged between 0.30 and 0.35. Repetitive subconcussive head impacts over a single season do not appear to result in short-term neurologic impairment, but these relationships should be further investigated for a potential dose-response over a player's career.

Effects of an age-specific anterior cruciate ligament injury prevention program on lower extremity biomechanics in children

BACKGROUND

Implementing an anterior cruciate ligament injury prevention program to athletes before the age at which the greatest injury risk occurs (15-17 years) is important from a prevention standpoint. However, it is unknown whether standard programs can modify lower extremity biomechanics in pediatric populations or if specialized training is required.

HYPOTHESIS/PURPOSE

To compare the effects of traditional and age-specific pediatric anterior cruciate ligament injury prevention programs on lower extremity biomechanics during a cutting task in youth athletes. The authors hypothesized that the age-specific pediatric program would result in greater sagittal plane motion (ie, hip and knee flexion) and less motion in the transverse and frontal plane (ie, knee valgus, knee and hip rotation) as compared with the traditional program.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

Sixty-five youth soccer athletes (38 boys, 27 girls) volunteered to participate. The mean age of participants was 10 ± 1 years. Teams (n, 7) were cluster randomized to a pediatric injury prevention program, a traditional injury prevention program, or a control group. The pediatric program was modified from the traditional program to include more feedback, progressions, and variety. Teams performed their programs as part of their normal warm-up routine. Three-dimensional lower extremity biomechanics were assessed during a sidestep cutting task before and after completion of the 9-week intervention period.

RESULTS

The pediatric program reduced the amount of knee external rotation at initial ground contact during the cutting task, F ((2,62)) = 3.79, P = .03 (change: pediatric, 7.73° ± 10.71°; control, -0.35° ± 7.76°), as compared with the control group after the intervention period. No other changes were observed.

CONCLUSION

The injury prevention program designed for a pediatric population modified only knee rotation during the cutting task, whereas the traditional program did not result in any changes in cutting biomechanics. These findings suggest limited effectiveness of both programs for athletes younger than 12 years of age in terms of biomechanics during a cutting task.

Contributions of neuroimaging, balance testing, electrophysiology and blood markers to the assessment of sport-related concussion

OBJECTIVE

To review the diagnostic tests and investigations used in the management of sports concussion, in the adult and paediatric populations, to (a) monitor the severity of symptoms and deficits, (b) track recovery and (c) advance knowledge relating to the natural history and neurobiology of the injury.

DESIGN

Qualitative literature review of the neuroimaging, balance testing, electrophysiology, blood marker and concussion literature.

INTERVENTION

PubMed and Medline databases were reviewed for investigations used in the management of adult and paediatric concussion, including structural imaging (computerised tomography, magnetic resonance imaging, diffusion tensor imaging), functional imaging (single photon emission computerised tomography, positron emission tomography, functional magnetic resonance imaging), spectroscopy (magnetic resonance spectroscopy, near infrared spectroscopy), balance testing (Balance Error Scoring System, Sensory Organization Test, gait testing, virtual reality), electrophysiological tests (electroencephalography, evoked potentials, event related potentials, magnetoencephalography, heart rate variability), genetics (apolipoprotein E4, channelopathies) and blood markers (S100, neuron-specific enolase, cleaved Tau protein, glutamate).

RESULTS

For the adult and paediatric populations, each test has been classified as being: (1) clinically useful, (2) a research tool only or (3) not useful in sports-related concussion.

CONCLUSIONS

The current status of the diagnostic tests and investigations is analysed, and potential directions for future research are provided. Currently, all tests and investigations, with the exception of clinical balance testing, remain experimental. There is accumulating research, however, that shows promise for the future clinical application of functional magnetic resonance imaging in sport concussion assessment and management.

Collision type and player anticipation affect head impact severity among youth ice hockey players

OBJECTIVE

The objective was to determine how body collision type and player anticipation affected the severity of head impacts sustained by young athletes. For anticipated collisions, we sought to evaluate different body position descriptors during delivery and receipt of body collisions and their effects on head impact severity. We hypothesized that head impact biomechanical features would be more severe in unanticipated collisions and open-ice collisions, compared with anticipated collisions and collisions along the playing boards, respectively.

METHODS

Sixteen ice hockey players (age: 14.0 + or - 0.5 years) wore instrumented helmets from which biomechanical measures (ie, linear acceleration, rotational acceleration, and severity profile) associated with head impacts were computed. Body collisions observed in video footage captured over a 54-game season were evaluated for collision type (open ice versus along the playing boards), level of anticipation (anticipated versus unanticipated), and relative body positioning by using a new tool developed for this purpose.

RESULTS

Open-ice collisions resulted in greater head linear (P = .036) and rotational (P = .003) accelerations, compared with collisions along the playing boards. Anticipated collisions tended to result in less-severe head impacts than unanticipated collisions, especially for medium-intensity impacts (50th to 75th percentiles of severity scores).

CONCLUSION

Our data underscore the need to provide players with the necessary technical skills to heighten their awareness of imminent collisions and to mitigate the severity of head impacts in this sport.

Integrated injury prevention program improves balance and vertical jump height in children

Implementing an injury prevention program to athletes under age 12 years may reduce injury rates. There is limited knowledge regarding whether these young athletes will be able to modify balance and performance measures after completing a traditional program that has been effective with older athletes or whether they require a specialized program for their age. The purpose of this study was to compare the effects of a pediatric program, which was designed specifically for young athletes, and a traditional program with no program in the ability to change balance and performance measures in youth athletes. We used a cluster-randomized controlled trial to evaluate the effects of the programs before and after a 9-week intervention period. Sixty-five youth soccer athletes (males: n = 37 mass = 34.16 +/- 5.36 kg, height = 143.07 +/- 6.27 cm, age = 10 +/- 1 yr; females: n = 28 mass = 33.82 +/- 5.37 kg, height = 141.02 +/- 6.59 cm) volunteered to participate and attended 2 testing sessions in a research laboratory. Teams were cluster-randomized to either a pediatric or traditional injury prevention program or a control group. Change scores for anterior-posterior and medial-lateral time-to-stabilization measures and maximum vertical jump height and power were calculated from pretest and post-test sessions. Contrary with our original hypotheses, the traditional program resulted in positive changes, whereas the pediatric program did not result in any improvements. Anterior-posterior time-to-stabilization decreased after the traditional program (mean change +/- SD = -0.92 +/- 0.49 s) compared with the control group (-0.49 +/- 0.59 s) (p = 0.003). The traditional program also increased vertical jump height (1.70 +/- 2.80 cm) compared with the control group (0.20 +/- 0.20 cm) (p = 0.04). There were no significant differences between control and pediatric programs. Youth athletes can improve balance ability and vertical jump height after completing an injury prevention program. Training specificity appears to affect improvements and should be considered with future program design.

Variability of motion in individuals with mechanical or functional ankle instability during a stop jump maneuver

BACKGROUND

Movement variability may influence episodes of instability following lateral ankle sprain.

METHODS

Sixty-three recreational athletes with a history of moderate-severe ankle sprain were recruited. Mechanically and functionally unstable ankle groups had 2 episodes of instability in the last year. Mechanically unstable had clinically lax lateral ankle ligaments; functionally unstable and copers did not. Copers had a history of sprain but no residual instability. Lower extremity 3-dimensional kinematics and ground reaction forces were measured during a 2-legged stop jump. Average ensemble curves of eight trials normalized to 100% of stance phase were created. The coefficient of variation and average standard deviation of the ensemble curves of each variable were identified. A log(e) (ln) transformation was performed on the data. One-way ANOVAs with Tukey post hoc testing were utilized with alpha=0.05.

FINDINGS

The functionally unstable group demonstrated greater mean (standard deviation) ln coefficient of variation ankle inversion/eversion 3.56 (1.19) than the mechanically unstable 2.77 (0.95) and copers 2.74 (1.05) (P=0.05 and P=0.04; eta(p)(2)=0.12), and greater ln standard deviation ankle inversion/eversion 1.07 (0.78) than copers 0.61 (0.31) (eta(p)(2)=0.13). The mechanically unstable group demonstrated greater ln coefficient of variation anterior-posterior ground reaction force 3.69 (0.27) than functionally unstable 3.43 (0.25) (P=0.02; eta(p)(2)=0.13).

INTERPRETATION

Functionally unstable individuals demonstrated greater ankle frontal plane movement variability during a stop jump, which may increase risk of instability. Mechanically unstable participants demonstrated greater anterior-posterior ground reaction force variability, which may indicate difficulty mitigating landing forces with lax ligaments. Movement variability may influence episodes of ankle instability.

The effects of feedback with and without strength training on lower extremity biomechanics

BACKGROUND

Feedback instruction is a proven modality for the alteration of motion patterns. There are no existing data on the contribution of strength training, when combined with feedback instruction, to the altering of lower extremity biomechanics.

HYPOTHESIS

Lower extremity muscle strength training provides an increased capacity to alter knee and hip biomechanics during a stop-jump task in response to a feedback protocol.

STUDY DESIGN

Controlled laboratory study.

METHODS

Knee and hip 3-dimensional kinematic and kinetic data were collected for 58 female recreational athletes while performing 3 stop-jump tasks after completing a 9-week strength training program (ST-FB; n = 29) or a 9-week period of no strength training (FB; n = 29). Data were then collected for both groups after completing a jump-landing feedback instruction protocol. Knee and hip joint angles, as well as resultant forces and moments, were calculated.

RESULTS

Across all participants, there were decreased peak vertical ground-reaction forces (P < .001) and increased knee flexion (P = .050), hip flexion (P < .001), and hip abduction (P = .032) angles, subsequent to the feedback protocol. Hip abduction angle (P < .001) increased in the ST-FB group but not the FB group, and peak knee anterior shear force (P = .015) decreased in the ST-FB group but increased in the FB group (P = .009).

CONCLUSION

The results indicate that strength training, when used in conjunction with video-assisted feedback, may provide an increased capacity for the alteration of knee and hip biomechanics.

CLINICAL RELEVANCE

Programs that include both strength training and movement education through feedback may be necessary to increase the effectiveness of anterior cruciate ligament prevention programs. Strength training may provide an increased capacity for athletes to respond to other intervention modalities used in anterior cruciate ligament injury prevention programs.

Balance measures for discriminating between functionally unstable and stable ankles

PURPOSE

To identify force plate measures that discriminate between ankles with functional instability and stable ankles and to determine the most accurate force plate measure for enabling this distinction.

METHODS

Twenty-two subjects (177 +/- 10 cm, 77 +/- 16 kg, 21 +/- 2 yr) without a history of ankle injury and 22 subjects (177 +/- 10 cm, 77 +/- 16 kg, 20 +/- 2 yr) with functional ankle instability (FAI) performed a single-leg static balance test and a single-leg jump-landing dynamic balance test. Static force plate measures analyzed in both anterior/posterior (A/P) and medial/lateral (M/L) directions included the following: ground reaction force (GRF) SD; center-of-pressure (COP) SD; mean, maximum, and total COP excursion; and mean and maximum COP velocity. COP area was also analyzed for static balance. A/P and M/L time to stabilization quantified dynamic balance. Greater values of force plate measures indicated impaired balance. A stepwise discriminant function analysis examined group differences, group classification, and accuracy of force plate measures for discriminating between ankle groups.

RESULTS

The FAI group had greater values than the stable ankle group for A/P GRF SD (P = 0.027), M/L GRF SD (P = 0.006), M/L COP SD (P = 0.046), A/P mean COP velocity (P = 0.015), M/L mean COP velocity (P = 0.016), A/P maximum COP velocity (P = 0.037), M/L mean COP excursion (P = 0.014), M/L total COP excursion (P = 0.016), A/P time to stabilization (P = 0.011), and M/L time to stabilization (P = 0.040). M/L GRF SD and A/P time to stabilization had the greatest accuracy scores of 0.73 and 0.72, respectively.

CONCLUSION

Although 10 measures identified group differences, M/L GRF SD and A/P time to stabilization were the most accurate in discriminating between ankle groups. These results provide evidence for choosing these GRF measures for evaluating static and dynamic balance deficits associated with FAI.

Concussion symptom inventory: an empirically derived scale for monitoring resolution of symptoms following sport-related concussion

Self-report post-concussion symptom scales have been a key method for monitoring recovery from sport-related concussion, to assist in medical management, and return-to-play decision-making. To date, however, item selection and scaling metrics for these instruments have been based solely upon clinical judgment, and no one scale has been identified as the "gold standard". We analyzed a large set of data from existing scales obtained from three separate case-control studies in order to derive a sensitive and efficient scale for this application by eliminating items that were found to be insensitive to concussion. Baseline data from symptom checklists including a total of 27 symptom variables were collected from a total of 16,350 high school and college athletes. Follow-up data were obtained from 641 athletes who subsequently incurred a concussion. Symptom checklists were administered at baseline (preseason), immediately post-concussion, post-game, and at 1, 3, and 5 days post-injury. Effect-size analyses resulted in the retention of only 12 of the 27 variables. Receiver-operating characteristic analyses were used to confirm that the reduction in items did not reduce sensitivity or specificity. The newly derived Concussion Symptom Inventory is presented and recommended as a research and clinical tool for monitoring recovery from sport-related concussion.

Application of reliable change indices to computerized neuropsychological measures of concussion

Serial assessments of neurocognitive functioning in athletes with concussion are commonly used for return to play decisions. This study provides reliable change indices (RCIs) for computerized tests from 40 NCAA Division I collegiate athletes that suffered a sports-related concussion. The normative data that resulted from the RCIs and subsequent analyses of differences between improved and not improved athletes may aid both clinicians and researchers to assess whether observed change on neuropsychological measures is reliable change or change due simply to practice effects. Hence, the RCIs presented herein provide information that may be used judiciously by a clinician for assessing meaningful change.

Return of postural control to baseline after anaerobic and aerobic exercise protocols

CONTEXT

With regard to sideline concussion testing, the effect of fatigue associated with different types of exercise on postural control is unknown.

OBJECTIVE

To evaluate the effects of fatigue on postural control in healthy college-aged athletes performing anaerobic and aerobic exercise protocols and to establish an immediate recovery time course from each exercise protocol for postural control measures to return to baseline status.

DESIGN

Counterbalanced, repeated measures.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Thirty-six collegiate athletes (18 males, 18 females; age = 19.00 +/- 1.01 years, height = 172.44 +/- 10.47 cm, mass = 69.72 +/- 12.84 kg).

INTERVENTION(S)

Participants completed 2 counterbalanced sessions within 7 days. Each session consisted of 1 exercise protocol followed by postexercise measures of postural control taken at 3-, 8-, 13-, and 18-minute time intervals. Baseline measures were established during the first session, before the specified exertion protocol was performed.

MAIN OUTCOME MEASURE(S)

Balance Error Scoring System (BESS) results, sway velocity, and elliptical sway area.

RESULTS

We found a decrease in postural control after each exercise protocol for all dependent measures. An interaction was noted between exercise protocol and time for total BESS score (P = .002). For both exercise protocols, all measures of postural control returned to baseline within 13 minutes.

CONCLUSIONS

Postural control was negatively affected after anaerobic and aerobic exercise protocols as measured by total BESS score, elliptical sway area, and sway velocity. The effect of exertion lasted up to 13 minutes after each exercise was completed. Certified athletic trainers and clinicians should be aware of these effects and their recovery time course when determining an appropriate time to administer sideline assessments of postural control after a suspected mild traumatic brain injury.

Lower extremity kinematics and ground reaction forces after prophylactic lace-up ankle bracing

CONTEXT

Long-term effects of ankle bracing on lower extremity kinematics and kinetics are unknown. Ankle motion restriction may negatively affect the body's ability to attenuate ground reaction forces (GRFs).

OBJECTIVE

To evaluate the immediate and long-term effects of ankle bracing on lower extremity kinematics and GRFs during a jump landing.

DESIGN

Experimental mixed model (2 [group] x 2 [brace] x 2 [time]) with repeated measures.

SETTING

Sports medicine research laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 37 healthy subjects were assigned randomly to either the intervention (n = 11 men, 8 women; age = 19.63 +/- 0.72 years, height = 176.05 +/- 10.58 cm, mass = 71.50 +/- 13.15 kg) or control group (n = 11 men, 7 women; age = 19.94 +/- 1.44 years, height = 179.15 +/- 8.81 cm, mass = 74.10 +/- 10.33 kg).

INTERVENTION(S)

The intervention group wore braces on both ankles and the control group did not wear braces during all recreational activities for an 8-week period.

MAIN OUTCOME MEASURE(S)

Initial ground contact angles, maximum joint angles, time to reach maximum joint angles, and joint range of motion for sagittal-plane knee and ankle motion were measured during a jump-landing task. Peak vertical GRF and the time to reach peak vertical GRF were assessed also.

RESULTS

While participants were wearing the brace, ankle plantar flexion at initial ground contact (brace = 35 degrees +/- 13 degrees , no brace = 38 degrees +/- 15 degrees , P = .024), maximum dorsiflexion (brace = 21 degrees +/- 7 degrees , no brace = 22 degrees +/- 6 degrees , P = .04), dorsiflexion range of motion (brace = 56 degrees +/- 14 degrees , no brace = 59 degrees +/- 16 degrees , P = .001), and knee flexion range of motion (brace = 79 degrees +/- 16 degrees , no brace = 82 degrees +/- 16 degrees , P = .036) decreased, whereas knee flexion at initial ground contact increased (brace = 12 degrees +/- 9 degrees , no brace = 9 degrees +/- 9 degrees , P = .0001). Wearing the brace for 8 weeks did not affect any of the outcome measures, and the brace caused no changes in vertical GRFs (P > .05).

CONCLUSIONS

Although ankle sagittal-plane motion was restricted with the brace, knee flexion upon landing increased and peak vertical GRF did not change. The type of lace-up brace used in this study appeared to restrict ankle motion without increasing knee extension or vertical GRFs and without changing kinematics or kinetics over time.

The effects of menstrual cycle phase on clinical measures of concussion in healthy college-aged females

The management of concussion and mild traumatic brain injury is an area of clinical uncertainty for many sports medicine professionals. While recent studies suggest sex differences in neurocognitive function may exist, our understanding of the effects of menstrual cycle phase and oral contraceptive pill (OCP) use in healthy females is limited. The purpose of this study was to investigate whether there were changes in neurocognitive function, postural stability and self-reported symptoms between the early and late stages of the menstrual cycle, and also to identify whether performance across menstrual cycle would differ between females using OCP and eumenorrheic females not using OCP. Healthy college-aged females completed a standard concussion test battery including computerised assessment of neurocognitive function, postural stability and symptom status. Participants completed the counterbalanced testing design during the early and late phases of their menstrual cycle. No significant main effects or interactions for any neurocognitive function or postural stability outcome measure were observed. Eumenorrheic females endorsed a higher number of symptoms and reported an increased symptom severity score compared to females using OCP. Menstrual cycle phase had no effect on the total severity or the number of symptoms endorsed. These results suggest preseason neurocognitive and postural stability baseline tests are stable across the menstrual cycle, regardless of OCP use. Therefore, decreased performance on these measures following a suspected concussion is likely not attributable to menstrual cycle phase or use of OCP.

Effect of ice hockey helmet fit on cervical spine motion during an emergency log roll procedure

OBJECTIVE

To investigate cervical spine motion during a log roll technique in ice hockey players under different helmet fit conditions.

DESIGN

Prospective counterbalanced design.

SETTING

University research laboratory.

PARTICIPANTS

Eighteen club ice hockey players were recruited to participate in this study.

ASSESSMENT OF RISK FACTORS

A standard emergency log roll was performed 3 times under each of 3 different helmet fit conditions: properly fit, improperly (competition) fit, and helmet-removed.

MAIN OUTCOME MEASUREMENTS

Frontal, sagittal, and transverse plane cervical spine motion were used as outcome measures.

RESULTS

Significantly less sagittal and transverse plane motion occurred during the helmet-removed condition. No differences in frontal plane motion among the 3 conditions were observed.

CONCLUSIONS

Presence of helmet (whether properly fit or not) resulted in increased of sagittal and transverse plane movement. This suggests that when an ice hockey helmet is stabilized, the head within it is not. We recommend the helmet and face shield be removed before performing an emergency prone log roll.

Muscle stiffness and spinal stretch reflex sensitivity in the triceps surae

CONTEXT

Greater musculotendinous stiffness may enhance spinal stretch reflex sensitivity by improving mechanical coupling of the muscle spindle and the stretch stimulus. This heightened sensitivity would correspond with a shorter latency and higher-amplitude reflex response, potentially enhancing joint stability.

OBJECTIVE

To compare spinal stretch reflex latency and amplitude across groups that differed in musculotendinous stiffness.

DESIGN

Static group comparisons.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Forty physically active individuals (20 men, 20 women).

INTERVENTION(S)

We verified a sex difference in musculotendinous stiffness and compared spinal stretch reflex latency and amplitude in high-stiffness (men) and low-stiffness (women) groups. We also evaluated relationships between musculotendinous stiffness and spinal stretch reflex latency and amplitude, respectively.

MAIN OUTCOME MEASURE(S)

Triceps surae musculotendinous stiffness and soleus spinal stretch reflex latency and amplitude were assessed at 30% of a maximal voluntary isometric plantar-flexion contraction.

RESULTS

The high-stiffness group demonstrated significantly greater stiffness (137.41 +/- 26.99 N/cm) than the low-stiffness group did (91.06 +/- 20.10 N/cm). However, reflex latency (high stiffness = 50.11 +/- 2.07 milliseconds, low stiffness = 48.26 +/- 2.40 milliseconds) and amplitude (high stiffness = 0.28% +/- 0.12% maximum motor response, low stiffness = 0.31% +/- 0.16% maximum motor response) did not differ significantly across stiffness groups. Neither reflex latency (r = .053, P = .746) nor amplitude (r = .073, P = .653) was related significantly to musculotendinous stiffness.

CONCLUSIONS

A moderate level of pretension (eg, 30%) likely eliminates series elastic slack; thus, a greater change in force per unit-of-length change (ie, heightened stiffness) would have minimal effects on coupling of the muscle spindle and the stretch stimulus and, therefore, on spinal stretch reflex sensitivity. It appears unlikely that differences in musculotendinous stiffness influenced spinal stretch reflex sensitivity when initiated from a moderate level of pretension. Consequently, differences in musculotendinous stiffness did not appear to influence dynamic joint stability with respect to reflexive neuromuscular control.

Assessment tools for identifying functional limitations associated with functional ankle instability

CONTEXT

Assessment tools should identify functional limitations associated with functional ankle instability (FAI) by discriminating unstable from stable ankles.

OBJECTIVE

To identify assessment tools that discriminated FAI from stable ankles and determine the most accurate assessment tool for discriminating between FAI and stable ankles.

DESIGN

Case-control study.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Fifteen individuals with FAI and 15 healthy individuals; participants with unilateral FAI reported "giving-way" sensations and ankle sprains, whereas healthy participants did not.

INTERVENTION(S)

Participants answered 12 questions on the Ankle Joint Functional Assessment Tool (AJFAT). They also performed a single-leg jump landing, which required them to jump to half their maximum jump height, land on a single leg, and stabilize quickly on a force plate.

MAIN OUTCOME MEASURE(S)

Receiver operating characteristic curves determined cutoff scores for discriminating between ankle groups for AJFAT total score and resultant vector (RV) time to stabilization. Accuracy values for discriminating between groups were determined by calculating the area under the receiver operating characteristic curves.

RESULTS

The cutoff score for discriminating between FAI and stable ankles was > or =26 (sensitivity = 1, specificity = 1) and > or =1.58 seconds (sensitivity = 0.67, specificity = 0.73) for the AJFAT total score and RV time to stabilization, respectively. The area under the curve for the AJFAT was 1.0 (asymptotic significance <.05), whereas the RV time to stabilization had an area under the curve of 0.72 (asymptotic significance <.05).

CONCLUSIONS

The AJFAT was an excellent assessment tool for discriminating between ankle groups, whereas RV time to stabilization was a fair assessment tool. Although both assessments discriminated between ankle groups, the AJFAT more accurately discriminated between groups than the RV time to stabilization did. Future researchers should confirm these findings using a prospective research design.

The effects of strength training on the lower extremity biomechanics of female recreational athletes during a stop-jump task

BACKGROUND

Strength training is considered a strategy for anterior cruciate ligament injury prevention. Little is known about the contribution of strength training to knee and hip biomechanics.

HYPOTHESIS

Lower extremity muscle strength training alters knee and hip biomechanics during a stop-jump task.

STUDY DESIGN

Controlled laboratory study.

METHODS

Knee and hip 3-dimensional kinematic and kinetic data were collected for 66 female recreational athletes (33 intervention and 33 control) while performing 3 stop-jump tasks before and after completing a 9-week strength-training program targeting the quadriceps, hamstrings, gluteus medius, and gluteus maximus (intervention) or a 9-week period of no strength training (control). Maximum voluntary isometric contraction strength data were also collected for each subject before the stop-jump tasks in each data collection session. Knee and hip joint angles as well as resultant forces and moments were calculated.

RESULTS

The intervention group increased in strength (P < .001 for all muscles). No significant differences were observed in knee and hip kinematics and kinetics between groups before and after the strength-training protocol.

CONCLUSIONS

Strength training alone does not alter knee and hip kinematics and kinetics in female recreational athletes. Further research is needed to determine the effect of strength training in combination with other intervention methods on lower extremity biomechanics.

CLINICAL RELEVANCE

Strength training as a single intervention method may not be sufficient to reduce the risk of noncontact anterior cruciate ligament injury in female recreational athletes.

Measurement of head impacts in collegiate football players: relationship between head impact biomechanics and acute clinical outcome after concussion

OBJECTIVE

To determine the relationship between recorded head accelerations and impact locations and acute clinical outcome of symptomatology, neuropsychological, and postural stability tests after cerebral concussion in Division I collegiate football players.

METHODS

A prospective field study was used in which accelerometers were embedded in the football helmets of 88 collegiate football players. Linear and rotational accelerations of all head impacts sustained over the course of 2004 to 2006 National Collegiate Athletic Association football seasons were collected in real-time. Change scores were calculated on clinical measures from the players' preseason baseline to postinjury (within 48 h) and regressed against the recorded linear and rotational accelerations of the head at the time of the concussion.

RESULTS

Thirteen concussions were recorded ranging in impact magnitudes of 60.51 to 168.71 g. Linear regression showed no significant relationships between impact magnitude (linear or rotational acceleration) or impact location and change scores for symptom severity, postural stability, or neurocognitive function (P > 0.05).

CONCLUSION

Our findings suggest that football players are concussed by impacts to the head that occur at a wide range of magnitudes and that clinical measures of acute symptom severity, postural stability, and neuropsychological function all appear to be largely independent of impact magnitude and location. Because of the varying magnitudes and locations of impacts resulting in concussion as well as other factors such as the frequency of subconcussive impacts and number of previous concussions, it may be difficult to establish a threshold for concussive injury that can be applied to all football players.

Measurement of head impacts in collegiate football players: clinical measures of concussion after high- and low-magnitude impacts

OBJECTIVE

It has been speculated that a theoretical injury threshold of 70 to 75 g may exist for concussions in football players. We aimed to investigate acute balance and neurocognitive performance after head impacts exceeding a theoretical injury threshold in the absence of both self-reported symptoms and a concussion diagnosis 24 hours before testing.

METHODS

Forty-three Division I collegiate football players participated in this double-blind, repeated-measures study. Subjects participated in three test sessions (baseline, low impact, and high impact) separated by at least 2 weeks. The Head Impact Telemetry System (Simbex, Lebanon, NH) recorded real-time head impacts sustained during practices and games. The Automated Neuropsychological Assessment Metrics assessed neurocognitive performance. The NeuroCom Sensory Organization Test (NeuroCom International Inc., Clackamas, OR) assessed postural stability. The Graded Symptom Checklist evaluated symptom presence and severity in our participants.

RESULTS

After the low-impact test session (<60 g), we observed improvements in the Math Processing (F(1, 26) = 9.797; P = 0.004), Matching to Sample (F(1, 26) = 6.504; P = 0.017), and Sternberg Procedure (F(1, 26) = 5.323; P = 0.030) Automated Neuropsychological Assessment Metrics test modules. Statistically significant differences were also observed after the high-impact test session (>90 g) with improvements in Math Processing (F(1, 22) = 16.629; P < 0.001), Procedural Reaction Time (F(1, 22) = 14.668; P < 0.001), and the total number of symptoms reported (F(1, 22) = 10.267; P = 0.004). Neurocognitive improvements were likely attributed to a learning effect.

CONCLUSION

Our findings suggest that sustaining an impact greater than 90 g does not result in acute observable balance and neurocognitive deficits within 24 hours of sustaining the impact. Although previous studies have suggested a theoretical injury threshold, none have been founded on empirical data collected on the playing field in real-time. Future studies should consider the cumulative effects of impacts of varying magnitudes.

Measurement of head impacts in collegiate football players: an investigation of positional and event-type differences

OBJECTIVE

There exists a need to better understand the biomechanical forces associated with head impacts in American football. The purpose of this study was to investigate whether or not differences in head accelerations existed between different player positions and different event types in collegiate football. We also sought to identify whether or not any associations existed between high-magnitude impacts and location of head impacts.

METHODS

We conducted a prospective field study in which accelerometers were embedded in the football helmets of 72 collegiate football players. Linear accelerations of all head impacts sustained over the course of the 2005 and 2006 National Collegiate Athletic Association football seasons were collected. One-way analyses of variance and chi tests of association assessed positional, event type, and location of head impact differences.

RESULTS

Football players consistently sustained head impacts between 21 and 23 g. Positional differences were identified within our sample. Impacts sustained during helmets-only practices were greater than those sustained in games or scrimmages. There was an association between position and high-magnitude impacts, as well as between high-magnitude impacts and location of head impact, with the likelihood of impacts to the top of the head much higher than those to the front, back, left, and right sides.

CONCLUSION

Less than 0.35% of impacts exceeding theoretical injury thresholds resulted in concussion. More injury data are required before any theoretical thresholds for injury can be confirmed. Coaches and sports medicine professionals should recognize that head impacts sustained in helmets-only practices are as severe as games or scrimmages; there seem to be no "light" days for football players.

Enhanced balance associated with coordination training with stochastic resonance stimulation in subjects with functional ankle instability: an experimental trial

Background

Ankle sprains are common injuries that often lead to functional ankle instability (FAI), which is a pathology defined by sensations of instability at the ankle and recurrent ankle sprain injury. Poor postural stability has been associated with FAI, and sports medicine clinicians rehabilitate balance deficits to prevent ankle sprains. Subsensory electrical noise known as stochastic resonance (SR) stimulation has been used in conjunction with coordination training to improve dynamic postural instabilities associated with FAI. However, unlike static postural deficits, dynamic impairments have not been indicative of ankle sprain injury. Therefore, the purpose of this study was to examine the effects of coordination training with or without SR stimulation on static postural stability. Improving postural instabilities associated with FAI has implications for increasing ankle joint stability and decreasing recurrent ankle sprains.

Methods

This study was conducted in a research laboratory. Thirty subjects with FAI were randomly assigned to either a: 1) conventional coordination training group (CCT); 2) SR stimulation coordination training group (SCT); or 3) control group. Training groups performed coordination exercises for six weeks. The SCT group received SR stimulation during training, while the CCT group only performed coordination training. Single leg postural stability was measured after the completion of balance training. Static postural stability was quantified on a force plate using anterior/posterior (A/P) and medial/lateral (M/L) center-of-pressure velocity (COPvel), M/L COP standard deviation (COPsd), M/L COP maximum excursion (COPmax), and COP area (COParea).

Results

Treatment effects comparing posttest to pretest COP measures were highest for the SCT group. At posttest, the SCT group had reduced A/P COPvel (2.3 ± 0.4 cm/s vs. 2.7 ± 0.6 cm/s), M/L COPvel (2.6 ± 0.5 cm/s vs. 2.9 ± 0.5 cm/s), M/L COPsd (0.63 ± 0.12 cm vs. 0.73 ± 0.11 cm), M/L COPmax (1.76 ± 0.25 cm vs. 1.98 ± 0.25 cm), and COParea (0.13 ± 0.03 cm² vs. 0.16 ± 0.04 cm²) than the pooled means of the CCT and control groups (P < 0.05).

Conclusion

Reduced values in COP measures indicated postural stability improvements. Thus, six weeks of coordination training with SR stimulation enhanced postural stability. Future research should examine the use of SR stimulation for decreasing recurrent ankle sprain injury in physically active individuals with FAI.

Athlete characteristics and outcome scores for computerized neuropsychological assessment: a preliminary analysis

CONTEXT

Computerized neuropsychological testing is used in athletics; however, normative data on an athletic population are lacking.

OBJECTIVE

To investigate factors, such as sex, SAT score, alertness, and sport, and their effects on baseline neuropsychological test scores. A secondary purpose was to begin establishing preliminary reference data for nonsymptomatic collegiate athletes.

DESIGN

Observational study.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

The study population comprised 327 National Collegiate Athletic Association Division I athletes from 12 men's and women's sports.

MAIN OUTCOME MEASURE(S)

Athletes were baseline tested before their first competitive season. Athletes completed demographics forms and self-reported history of concussion (1 or no concussion and 2 or more concussions) and SAT scores (<1000, 1000 to 1200, and >1200). The 108 women had a mean age of 18.39 +/- 0.09 years, height of 167.94 +/- 0.86 cm, and mass of 62.36 +/- 1.07 kg. The 219 men had a mean age of 18.49 +/- 0.07 years, height of 183.24 +/- 1.68 cm, and mass of 88.05 +/- 1.82 kg. Sports participation included women's soccer, lacrosse, basketball, and field hockey; men's football, soccer, lacrosse, and wrestling; and women's and men's track and cheerleading. We used the Automated Neuropsychological Assessment Metrics (Army Medical Research and Materiel Command, Ft Detrick, MD) and measured throughput scores (the number of correct responses per minute) as the dependent variable for each subtest, with higher scores reflecting increased speed and accuracy of responses. Subsets included 2 simple reaction time (SRT) tests, math processing (MTH), Sternberg memory search (ST6), matching to sample pairs (MSP), procedural reaction time (PRO), code digit substitution (CDS), and the Stanford sleep scale Likert-type score.

RESULTS

Women scored better than men on the ST6 (P < .05), while men scored significantly better than women on the SRT and MSP tests. The highest-scoring SAT group performed better than other SAT groups on selected subtests (SRT, MTH, ST6, MSP, and CDS) (P < .05), and athletes tested during their season were more likely to score lower on the alertness scale (chi(2) (2)[n = 322] = 11.32, P = .003). The lowest alertness group performed worse on the MSP and CDS subtests (P < .05). No differences were found between the group with a history of 1 or no concussion and the group with a history of 2 or more concussions (P > .05).

CONCLUSIONS

Performance on computerized neuropsychological tests may be affected by a number of factors, including sex, SAT scores, alertness at the time of testing, and the athlete's sport. To avoid making clinical misinterpretations, clinicians should acknowledge that individual baselines vary over time and should account for this variation.

The effects of headache on clinical measures of neurocognitive function

OBJECTIVE

To examine effects of preseason baseline headache and posttraumatic headache (PTH) on neurocognitive function.

DESIGN

Retrospective repeated measures study with headache groups formed regarding baseline headache score (0 = negative headache; 1-6 = positive headache) and day 1 postinjury headache score (0 = no headache; 1-2 = mild headache; 3-6 = moderate-severe headache).

SETTING

Clinical athletic training setting and sports medicine research laboratory.

PARTICIPANTS

High-school and collegiate athletes with a concussion.

INDEPENDENT VARIABLES

Preseason baseline headache, PTH, test-day.

MAIN OUTCOME MEASURES

A Graded Symptom Checklist (GSC) was used to assess symptoms. The Automated Neuropsychological Assessment Metrics (ANAM) and the Standardized Assessment of Concussion (SAC) were used to assess neuropsychological function and mental status. The Balance Error Scoring System (BESS) was used to assess postural stability.

RESULTS

Both baseline headache groups displayed a higher symptom endorsement and higher symptom severity at day 1 postinjury and improved by day 7 postinjury. The positive headache group reported an even greater increase in symptom severity and presence (P < 0.05). ANAM revealed deficits in both groups 1 day postinjury. All PTH headache groups displayed a difference in symptom number and severity with the increase being magnified by headache severity (P < 0.05). Individuals reporting moderate-severe PTH displayed increased deficits subacutely but improved by 5-7 days postinjury on overall neuropsychological performance, reaction time, and working memory (P < 0.05). Deficits were observed for all ANAM measures except simple reaction time 1 (SRT 1) and match to sample subacutely and improved over time (P < 0.05). The SAC yielded an interaction (P < 0.05) for baseline headache. The BESS yielded no significant findings.

CONCLUSIONS

Clinicians should consider headache when assessing concussion and during preseason baseline assessments because headache may affect symptom presence and other clinical measures of concussion.

Recurrent Concussion and Risk of Depression in Retired Professional Football Players

PURPOSE

The purpose of our study was to investigate the association between prior head injury and the likelihood of being diagnosed with clinical depression among retired professional football players with prior head injury exposure.

METHODS

A general health questionnaire, including information about prior injuries, the SF-36 (Short Form 36), and other markers for depression, was completed by 2552 retired professional football players with an average age of 53.8 (+/-13.4) yr and an average professional football-playing career of 6.6 (+/-3.6) yr. A second questionnaire focusing on mild cognitive impairment (MCI)-related issues was completed by a subset of 758 retired professional football players (50 yr and older).

RESULTS

Two hundred sixty-nine (11.1%) of all respondents reported having prior or current diagnosis of clinical depression. There was an association between recurrent concussion and diagnosis of lifetime depression (chi2=71.21, df=2, P<0.005), suggesting that the prevalence increases with increasing concussion history. Compared with retired players with no history of concussion, retired players reporting three or more previous concussions (24.4%) were three times more likely to be diagnosed with depression; those with a history of one or two previous concussions (36.3%) were 1.5 times more likely to be diagnosed with depression. The analyses controlled for age, number of years since retirement, number of years played, physical component score on the SF-36, and diagnosed comorbidities such as osteoarthritis, coronary heart disease, stroke, cancer, and diabetes.

CONCLUSION

Our findings suggest a possible link between recurrent sport-related concussion and increased risk of clinical depression. The findings emphasize the importance of understanding potential neurological consequences of recurrent concussion.