Does prior concussion lead to biomechanical alterations associated with lateral ankle sprain and anterior cruciate ligament injury? A systematic review and meta-analysis.

OBJECTIVE: To determine whether individuals with a prior concussion exhibit biomechanical alterations in balance, gait and jump-landing tasks with and without cognitive demands that are associated with risk of lateral ankle sprain (LAS) and anterior cruciate ligament (ACL) injury. DESIGN: Systematic review and meta-analysis. DATA SOURCES: Five electronic databases (Web of Science, Scopus, PubMed, SPORTDiscus and CiNAHL) were searched in April 2023. ELIGIBILITY CRITERIA: Included studies involved (1) concussed participants, (2) outcome measures of spatiotemporal, kinematic or kinetic data and (3) a comparison or the data necessary to compare biomechanical variables between individuals with and without concussion history or before and after a concussion. RESULTS: Twenty-seven studies were included involving 1544 participants (concussion group (n=757); non-concussion group (n=787)). Individuals with a recent concussion history (within 2 months) had decreased postural stability (g=0.34, 95% CI 0.20 to 0.49, p<0.001) and slower locomotion-related performance (g=0.26, 95% CI 0.11 to 0.41, p<0.001), both of which are associated with LAS injury risk. Furthermore, alterations in frontal plane kinetics (g=0.41, 95% CI 0.03 to 0.79, p=0.033) and sagittal plane kinematics (g=0.30, 95% CI 0.11 to 0.50, p=0.002) were observed in individuals approximately 2 years following concussion, both of which are associated with ACL injury risk. The moderator analyses indicated cognitive demands (ie, working memory, inhibitory control tasks) affected frontal plane kinematics (p=0.009), but not sagittal plane kinematics and locomotion-related performance, between the concussion and non-concussion groups. CONCLUSION: Following a recent concussion, individuals display decreased postural stability and slower locomotion-related performance, both of which are associated with LAS injury risk. Moreover, individuals within 2 years following a concussion also adopt a more erect landing posture with greater knee internal adduction moment, both of which are associated with ACL injury risk. While adding cognitive demands to jump-landing tasks affected frontal plane kinematics during landing, the altered movement patterns in locomotion and sagittal plane kinematics postconcussion persisted regardless of additional cognitive demands. PROSPERO REGISTRATION NUMBER: CRD42021248916.

The Association of Sport Specialization and Concussion History on Self-Reported Depressive Symptoms and Quality of Life Among High School Athletes.

OBJECTIVE: To assess the association of sport specialization combined with sport-related concussion (SRC) history on depression and health-related quality of life (HRQoL) in a population of high school athletes. DESIGN: Cross-sectional study. SETTING: High schools. PARTICIPANTS: Two thousand four hundred fifty-three athletes through the State of Wisconsin. INDEPENDENT VARIABLES: Sport specialization and SRC history. MAIN OUTCOME MEASURES: Athletes completed questionnaires reporting their SRC history, sports participation (single-sport or multisport), Patient Health Questionnaire-9 (PHQ-9), and Pediatric Quality of Life 4.0 (PedsQL). We used multivariate binary logistic regression to assess the odds ratio (OR) for depressive symptoms based on SRC and sport participation history. Separate multilinear regression evaluated the association between the PedsQL, SRC, and sport participation history. The interaction of sport specialization and SRC history was explored in both regression models. RESULTS: High school athletes who participated in single-sport activities had a greater odds of reporting higher severity of depressive symptoms on PHQ-9 scores (OR, 1.50; 95% CI, 1.11-2.02) and reduced PedsQL ( P < 0.001) compared with their multisport counterparts. There were no associations between SRC history and either PHQ-9 or PedsQL scores. Statistically significant interactions between sport specialization and SRC were not found among all models. CONCLUSION: Single-sport high school athletes reported a reduction in HRQoL measures along with higher depressive symptoms when compared with the multisport athletes. The SRC history did not have a lingering effect on depression or HRQoL in this study. These findings raise some interesting concerns regarding the quality of mental health in adolescent athletes solely focused on single-sport endeavors.

Quantitative Analysis of Ball-Head Impact Exposure in Youth Soccer Players.

Since the implementation of the US Soccer heading guidelines released in 2015, little to no research on ball-head impact exposure in the United States youth soccer population has been conducted. The purpose was to compare ball-head impact exposure across sex and age in youth soccer players over a weekend tournament. Ten male and female games for each age group (Under-12 [U12], U13, and U14) were video recorded at a weekend tournament for a total of 60 games. Ball-head impact exposure for each game was then coded following a review of each recording. Male players were 2.8 times more likely to have ball-head impacts than female players, (p < 0.001) particularly in the U14 age group when compared to the U12 age group (p = 0.012). Overall 92.4% of players experienced 0-1 ball-head impacts per game with the remaining players experiencing 2+ ball-head impacts per game. Ball-head impact exposure levels are low in the youth players. Most youth soccer players do not head the soccer ball during match play and those that did, only headed the ball on average once per game. Overall, the difference in ball-head impact exposure per player was less than 1 between all the groups, which may have no clinical meaning.

Examining the influence of the Get aHEAD Safely in Soccer™ program on head impact kinematics and neck strength in female youth soccer players.

The objective was to examine the efficacy of the Get aHEAD Safely in Soccer™ intervention on head impact kinematics and neck strength in female youth soccer players. The control group (CG) consisted of 13 players (age: 11.0 ± 0.4 yrs), while the experimental group (EG) consisted of 14 players (age: 10.6 ± 0.5 yrs). Head impact kinematics included peak linear acceleration (PLA), peak rotational acceleration (PRA), and peak rotational velocity (PRV). Pre- and post-season measures included strength measures of neck/torso flexion (NF/TF) and extension (NE/TE). Data were analysed using a multilevel linear model and ANOVA techniques. No differences in PLA, PRA, or PRV were observed between groups. The EG showed significant improvement in NF strength while the CG showed significant improvement in NE strength. Both groups significantly improved in TF pre- to post-season. The foundational strength components of the Get aHEAD Safely in Soccer program appear to show a benefit in youth soccer players beginning to learn the skill of purposeful heading.

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.

Analysis of Head Impact Biomechanics in Youth Female Soccer Players Following the Get aHEAD Safely in Soccer™ Heading Intervention.

The effects of repetitive head impacts associated with soccer heading, especially in the youth population, are unknown. The purpose of this study was to examine balance, neurocognitive function, and head impact biomechanics after an acute bout of heading before and after the Get aHEAD Safely in Soccer™ program intervention. Twelve youth female soccer players wore a Triax SIM-G head impact sensor during two bouts of heading, using a lightweight soccer ball, one before and one after completion of the Get aHEAD Safely in Soccer™ program intervention. Participants completed balance (BESS and SWAY) and neurocognitive function (ImPACT) tests at baseline and after each bout of heading. There were no significant changes in head impact biomechanics, BESS, or ImPACT scores pre- to post-season. Deficits in three of the five SWAY positions were observed from baseline to post-season. Although we expected to see beneficial changes in head impact biomechanics following the intervention, the coaches and researchers observed an improvement in heading technique/form. Lightweight soccer balls would be a beneficial addition to header drills during training as they are safe and help build confidence in youth soccer players.

Does Low-Level Laser Therapy Decrease Muscle-Damaging Mediators After Performance in Soccer Athletes Versus Sham Laser Treatment? A Critically Appraised Topic.

Clinical Scenario: Low-level laser therapy (LLLT) is a controversial topic for its use in athletic recovery, mainly due to inconsistency in research regarding the application of LLLT. Articles on LLLT have assessed its effectiveness in untrained humans through pain scales, functional scales, and blood draws, and it has been found capable in nonathletic rehabilitative use. The controversy lies with LLLT in the recovering athlete. Not only do athletes need to perform at high levels, but each sport is unique in the metabolic demands placed on the athletes' bodies. This modality can alter chemical mediators of the inflammatory process, specifically blood lactate (BL) and creatine kinase (CK). During soccer contests, it is a common problem for athletes to have an average CK level of 800 U/L and BL of 8 mmol·L, increasing delayed-onset muscle soreness and fatigue. Micro-CK level elevation is associated with cellular membrane damage, localized hypoxia, and electrolyte imbalances, hindering the recovery process. Clinical Question: Does LLLT decrease muscle-damaging mediators effecting player fatigue and delayed-onset muscle soreness after performance in soccer athletes versus sham treatment? Summary of Key Findings: In 3 studies, preperformance, postperformance, or preperformance and postperformance LLLT was performed and evaluated BL (2 of 3) and CK (2 of 3). In each article, BL and CK showed a significant decrease (P < .05) when performed either preperformance or postperformance versus the control group. The greatest decrease in these mediators was noticed when postperformance laser therapy was performed. Clinical Bottom Line: LLLT at 10, 30, or 50 J performed at a minimum of 2 locations on the rectus femoris, vastus lateralis, and vastus medialis bilaterally for 10 seconds each is significant in decreasing blood serum levels of BL and CK when performed postexercise. Strength of Recommendations: All 3 articles obtained a Physiotherapy Evidence Database score of ≥8/10.

Does the FIFA 11+ Program Prevent Hamstring Injuries in College-Aged Male Soccer Players? A Critically Appraised Topic.

Clinical Scenario: Hamstring injuries are the most prevalent lower-extremity injury among soccer players. The Fédération Internationale de Football Association (FIFA) has addressed this issue by developing the FIFA 11+ program, which is focused on improving strength and decreasing the incidence of lower-extremity injuries in the sport. This critically appraised topic focuses on this program as well as one of its components, the Nordic hamstring exercise, in the prevention of hamstring injuries. Clinical Question: Does the FIFA 11+ program prevent hamstring injuries in college-aged male soccer players? Summary of Key Findings: Four studies were selected to be critically appraised. The PEDro checklist was used to score the articles on methodology and consistency. All 4 articles demonstrated support for the clinical question. Clinical Bottom Line: There is moderate evidence to support the use of the FIFA 11+ program and Nordic hamstring exercise as part of a college soccer team's warm-up routine. Strength of Recommendation: Grade B evidence exists in support of incorporating the FIFA 11+ program to reduce the incidence of hamstring injuries in male college soccer players.

Self-reported head injury symptoms exacerbated in those with previous concussions following an acute bout of purposeful soccer heading.

Rates of concussion in soccer are high, especially in female players. The primary aim of this study was to examine differences in self-reported concussion-related symptoms (CRS), balance (BESS), and neurocognitive performance (ImPACT) following an acute bout of soccer heading in a group of female collegiate players with and without a history of concussion. Eighty-seven players with 0 to 3+ previous concussions participated. The measurement variables were assessed before and after heading sessions; including one linear and one rotational bout. Players with concussion histories reported more CRS than their non-concussed teammates both before and after the heading sessions. Balance and neurocognitive scores were generally unaffected. This finding should heighten our awareness to carefully monitor soccer players who have experienced concussions and be aware that they may develop concussion-like symptoms, especially after acute bouts of heading either during practice or in matches. The long-term implications of this finding remain unknown.

Ankle Strength Deficits in a Cohort of College Athletes With Chronic Ankle Instability.

CONTEXT: Lateral ankle sprains commonly occur in an athletic population and can lead to chronic ankle instability. OBJECTIVE: To compare ankle strength measurements in athletes who have mechanical laxity and report functional instability after a history of unilateral ankle sprains. DESIGN: Retrospective cohort. SETTING: Athletic Training Research Lab. PARTICIPANTS: A total of 165 National Collegiate Athletic Association Division I athletes, 97 males and 68 females, with history of unilateral ankle sprains participated. MAIN OUTCOME MEASURES: Functional ankle instability was determined by Cumberland Ankle Instability Tool scores and mechanical ankle instability by the participant having both anterior and inversion/eversion laxity. Peak torque strength measures, concentric and eccentric, in 2 velocities were measured. RESULTS: Of the 165 participants, 24 subjects had both anterior and inversion/eversion laxity and 74 self-reported functional ankle instability on their injured ankle. The mechanical ankle instability group presented with significantly lower plantar flexion concentric strength at 30°/s (139.7 [43.7] N·m) (P = .01) and eversion concentric strength at 120°/s (14.8 [5.3] N·m) (P = .03) than the contralateral, uninjured ankle (166.3 [56.8] N·m, 17.4 [6.2] N·m, respectively). CONCLUSION: College athletes who present with mechanical laxity on a previously injured ankle exhibit plantar flexion and eversion strength deficits between ankles.

Clinical assessment of acute lateral ankle sprain injuries (ROAST): 2019 consensus statement and recommendations of the International Ankle Consortium.

Lateral ankle sprain injury is the most common musculoskeletal injury incurred by individuals who participate in sports and recreational physical activities. Following initial injury, a high proportion of individuals develop long-term injury-associated symptoms and chronic ankle instability. The development of chronic ankle instability is consequent on the interaction of mechanical and sensorimotor insufficiencies/impairments that manifest following acute lateral ankle sprain injury. To reduce the propensity for developing chronic ankle instability, clinical assessments should evaluate whether patients in the acute phase following lateral ankle sprain injury exhibit any mechanical and/or sensorimotor impairments. This modified Delphi study was undertaken under the auspices of the executive committee of the International Ankle Consortium. The primary aim was to develop recommendations, based on expert (n=14) consensus, for structured clinical assessment of acute lateral ankle sprain injuries. After two modified Delphi rounds, consensus was achieved on the clinical assessment of acute lateral ankle sprain injuries. Consensus was reached on a minimum standard clinical diagnostic assessment. Key components of this clinical diagnostic assessment include: establishing the mechanism of injury, as well as the assessment of ankle joint bones and ligaments. Through consensus, the expert panel also developed the International Ankle Consortium Rehabilitation-Oriented ASsessmenT (ROAST). The International Ankle Consortium ROAST will help clinicians identify mechanical and/or sensorimotor impairments that are associated with chronic ankle instability. This consensus statement from the International Ankle Consortium aims to be a key resource for clinicians who regularly assess individuals with acute lateral ankle sprain injuries.

The relationship between the sensory responses to ankle-joint loading and corticomotor excitability.

PURPOSE: Maintaining joint stability is dependent on the ability of the nervous system to sense and react to potentially injurious loads. In attempts to understand the neurophysiologic mechanisms underlying joint stability, this afferent and efferent activity has been quantified separately at the cortical, segmental and peripheral levels using various electrophysiologic techniques in vivo. However, no studies have attempted to quantify sensory and motor activation at multiple levels of the nervous system in a single subset, to understand potential adaptations for optimizing joint stability. MATERIALS AND METHODS: Muscle spindle afferent activity and sensory cortex event-related desynchronization were quantified during ankle-joint loading; and motor excitability was assessed through transcranial magnetic stimulation and the Hoffmann reflex in a subset of 42 able-bodied individuals. Microneurography and electroencephalography were used to collect the muscle spindle afferent and sensory cortex activation, respectively, as joint load was applied using an ankle arthrometer. Separately, motor-evoked potentials were obtained from the tibialis anterior (TA) and soleus (SOL) using transcranial magnetic stimulation over the motor cortex, and compared to the reflexive responses evoked via sciatic nerve electrical stimulation. RESULTS: Correlation coefficients revealed significant correlations between the motor threshold of the soleus and early muscle spindle afferent activity (r = -0.494) and early cortical event-related desynchronization (r = 0.470), as well as tibialis anterior motor-evoked potential size and late muscle spindle afferent activity (r = 0.499). CONCLUSIONS: The results of this study highlight the nervous system's capability to offset motor output based on the volume of sensory input at the segmental and cortical levels.

Evaluating Postural Control and Ankle Laxity Between Taping and High-Top Cleats in High School Football Players.

CONTEXT: Lateral ankle sprains are the most common injuries in high school sports. While ankle taping is a preferred method of external prophylactic support, its restrictive properties decline during exercise. The Under Armour® Highlight cleat is marketed on the premise that it provides added support without the need for additional ankle taping. OBJECTIVE: To determine if differences in ankle joint laxity and postural control exist between football players wearing the Under Armour® Highlight cleat (Under Armour Inc, Baltimore, MD) as compared to a low/mid-top cleat with ankle tape. DESIGN: Crossover trial. SETTING: Athletic training room and football practice field sideline. PATIENTS: 32 interscholastic football players (15.8 ± 1.0 y; 178.9 ± 7.4 cm; 87.1 ± 21.4 kg). INTERVENTIONS: Ankle laxity was assessed using an instrumented ankle arthrometer (Blue Bay Research Inc, Milton, FL), while postural control testing was performed on the Tekscan MobileMat™ Balanced Error Scoring System (BESS; South Boston, MA). The 2 treatments included Under Armour® Highlight cleats and a low/mid-top cleat with ankle tape applied to the nondominant ankle only. Measurements were taken before and immediately after practice. MAIN OUTCOME MEASURES: The independent variable was treatment (Highlight vs low/mid-top cleat with ankle tape). Dependent variables included ankle arthrometry measures of anterior displacement (mm), inversion/eversion rotation (deg), and the modified BESS error scores. A linear mixed-effects model was used for analysis. RESULTS: The low/mid-top cleat with tape condition had significantly higher inversion range-of-motion (ROM) and inversion/eversion rotation postexercise when compared to the Highlight cleat (P < 0.05). CONCLUSIONS: The results of this study provide some evidence that the Under Armour® Highlight cleat restricts ankle ROM following a training session better than the taped low/mid-top cleat. Further study is warranted to determine if this high-top style of football cleat can reduce the incidence of ankle sprains and how it might compare to spat taping.

Sex and age differences in head acceleration during purposeful soccer heading.

Differences in head-neck segment mass, purposeful heading technique, and cervical strength and stiffness may contribute to differences in head accelerations across sex and age. The purpose of this study was to compare head acceleration across sex and age (youth [12-14 years old], high school and collegiate) during purposeful soccer heading. One-hundred soccer players (42 male, 58 female, 17.1 ± 3.5 years, 168.5 ± 20.3 cm, 61.5 ± 13.7 kg) completed 12 controlled soccer headers at an initial ball velocity of 11.2 m/s. Linear and rotational accelerations were measured using a triaxial accelerometer and gyroscope and were transformed to the head centre-of-mass. A MANOVA revealed a significant multivariate main effect for sex (Pillai's Trace = .165, F(2,91) = 11.868, p < .001), but not for age (Pillai's Trace = .033, F(4,182) = 0.646, p = .630). Peak linear and rotational accelerations were higher in females (40.9 ± 13.3 g; 3279 ± 1065 rad/s2) than males (27.6 ± 8.5 g, 2219 ± 823 rad/s2). These data suggest that under controlled soccer heading conditions, females may be exposed to higher head accelerations than males.

The Relationship Between Joint Stiffness and Muscle Activity in Unstable Ankles and Copers.

CONTEXT: Rolling sensations at the ankle are common after injury and represent failure in neural regulation of joint stiffness. However, deficits after ankle injury are variable and strategies for optimizing stiffness may differ across patients. OBJECTIVE: To determine if ankle stiffness and muscle activation differ between patients with varying history of ankle injury. PATIENTS: Fifty-nine individuals were stratified into healthy (CON, n = 20), functionally unstable (UNS, n = 19), and coper (COP, n = 20) groups. MAIN OUTCOME MEASURES: A 20° supination perturbation was applied to the ankle as position and torque were synchronized with activity of tibialis anterior, peroneus longus, and soleus. Subjects were tested with muscles relaxed, while maintaining 30% muscle activation, and while directed to react and resist the perturbation. RESULTS: No group differences existed for joint stiffness (F = 0.07, P = .993); however, the UNS group had higher soleus and less tibialis anterior activation than the CON group during passive trials (P < .05). In addition, greater early tibialis anterior activation generally predicted higher stiffness in the CON group (P ≤ .03), but greater soleus activity improved stiffness in the UNS group (P = .03). CONCLUSION: Although previous injury does not affect the ability to stiffen the joint under laboratory conditions, strategies appear to differ. Generally, the COP has decreased muscle activation, whereas the UNS uses greater plantar-flexor activity. The results of this study suggest that clinicians should emphasize correct preparatory muscle activation to improve joint stiffness in injury-rehabilitation efforts.

2016 consensus statement of the International Ankle Consortium: prevalence, impact and long-term consequences of lateral ankle sprains.

The Executive Committee of the International Ankle Consortium presents this 2016 position paper with recommendations for information implementation and continued research based on the paradigm that lateral ankle sprain (LAS), and the development of chronic ankle instability (CAI), serve as a conduit to a significant global healthcare burden. We intend our recommendations to serve as a mechanism to promote efforts to improve prevention and early management of LAS. We believe this will reduce the prevalence of CAI and associated sequelae that have led to the broader public health burdens of decreased physical activity and early onset ankle joint post-traumatic osteoarthritis. Ultimately, this can contribute to healthier lifestyles and promotion of physical activity.

Evidence review for the 2016 International Ankle Consortium consensus statement on the prevalence, impact and long-term consequences of lateral ankle sprains.

Lateral ankle sprains (LASs) are the most prevalent musculoskeletal injury in physically active populations. They also have a high prevalence in the general population and pose a substantial healthcare burden. The recurrence rates of LASs are high, leading to a large percentage of patients with LAS developing chronic ankle instability. This chronicity is associated with decreased physical activity levels and quality of life and associates with increasing rates of post-traumatic ankle osteoarthritis, all of which generate financial costs that are larger than many have realised. The literature review that follows expands this paradigm and introduces emerging areas that should be prioritised for continued research, supporting a companion position statement paper that proposes recommendations for using this summary of information, and needs for specific future research.

Sway Area and Velocity Correlated With MobileMat Balance Error Scoring System (BESS) Scores.

The Balance Error Scoring System (BESS) is often used for sport-related concussion balance assessment. However, moderate intratester and intertester reliability may cause low initial sensitivity, suggesting that a more objective balance assessment method is needed. The MobileMat BESS was designed for objective BESS scoring, but the outcome measures must be validated with reliable balance measures. Thus, the purpose of this investigation was to compare MobileMat BESS scores to linear and nonlinear measures of balance. Eighty-eight healthy collegiate student-athletes (age: 20.0 ± 1.4 y, height: 177.7 ± 10.7 cm, mass: 74.8 ± 13.7 kg) completed the MobileMat BESS. MobileMat BESS scores were compared with 95% area, sway velocity, approximate entropy, and sample entropy. MobileMat BESS scores were significantly correlated with 95% area for single-leg (r = .332) and tandem firm (r = .474), and double-leg foam (r = .660); and with sway velocity for single-leg (r = .406) and tandem firm (r = .601), and double-leg (r = .575) and single-leg foam (r = .434). MobileMat BESS scores were not correlated with approximate or sample entropy. MobileMat BESS scores were low to moderately correlated with linear measures, suggesting the ability to identify changes in the center of mass-center of pressure relationship, but not higher-order processing associated with nonlinear measures. These results suggest that the MobileMat BESS may be a clinically-useful tool that provides objective linear balance measures.

Loaded Vertical Jumping: Force-Velocity Relationship, Work, and Power.

The aims of the current study were to explore the pattern of the force-velocity (F-V) relationship of leg muscles, evaluate the reliability and concurrent validity of the obtained parameters, and explore the load associated changes in the muscle work and power output. Subjects performed maximum vertical countermovement jumps with a vest ranging 0-40% of their body mass. The ground reaction force and leg joint kinematics and kinetics were recorded. The data revealed a strong and approximately linear F-V relationship (individual correlation coefficients ranged from 0.78-0.93). The relationship slopes, F- and V-intercepts, and the calculated power were moderately to highly reliable (0.67 < ICC < 0.91), while the concurrent validity F- and V-intercepts, and power with respect to the directly measured values, was (on average) moderate. Despite that a load increase was associated with a decrease in both the countermovement depth and absolute power, the absolute work done increased, as well as the relative contribution of the knee work. The obtained findings generally suggest that the loaded vertical jumps could not only be developed into a routine method for testing the capacities of leg muscles, but also reveal the mechanisms of adaptation of multijoint movements to different loading conditions.

Comparing Computer-Derived and Human-Observed Scores for the Balance Error Scoring System.

CONTEXT: The Balance Error Scoring System (BESS) is the current standard for assessing postural stability in concussed athletes on the sideline. However, research has questioned the objectivity and validity of the BESS, suggesting that while certain subcategories of the BESS have sufficient reliability to be used in evaluation of postural stability, the total score is not reliable, demonstrating limited interrater and intrarater reliability. Recently, a computerized BESS test was developed to automate scoring. OBJECTIVE: To compare computer-derived BESS scores with those taken from 3 trained human scorers. DESIGN: Interrater reliability study. SETTING: Athletic training room. PATIENTS: NCAA Division I student athletes (53 male, 58 female; 19 ± 2 y, 168 ± 41 cm, 69 ± 4 kg). INTERVENTIONS: Subjects were asked to perform the BESS while standing on the Tekscan (Boston, MA) MobileMat® BESS. The MobileMat BESS software displayed an error score at the end of each trial. Simultaneously, errors were recorded by 3 separate examiners. Errors were counted using the standard BESS scoring criteria. MAIN OUTCOME MEASURES: The number of BESS errors was computed for the 6 stances from the software and each of the 3 human scorers. Interclass correlation coefficients (ICCs) were used to compare errors for each stance scored by the MobileMat BESS software with each of 3 raters individually. The ICC values were converted to Fisher Z scores, averaged, and converted back into ICC values. RESULTS: The double-leg, single-leg, and tandem-firm stances resulted in good agreement with human scorers (ICC = .999, .731, and .648). All foam stances resulted in fair agreement. CONCLUSIONS: Our results suggest that the MobileMat BESS is suitable for identifying BESS errors involving each of the 6 stances of the BESS protocol. Because the MobileMat BESS scores consistently and reliably, this system can be used with confidence by clinicians as an effective alternative to scoring the BESS.