Pharmacokinetic-pharmacodynamic cutoff values for benzylpenicillin in horses to support the establishment of clinical breakpoints for benzylpenicillin antimicrobial susceptibility testing in horses.

Introduction: The aim of this international project was to establish a species-specific Clinical Breakpoint for interpretation of Antimicrobial Susceptibility Testing of benzylpenicillin (BP) in horses. Methods: A population pharmacokinetic model of BP disposition was developed to compute PK/PD cutoff values of BP for different formulations that are commonly used in equine medicine around the world (France, Sweden, USA and Japan). Investigated substances were potassium BP, sodium BP, procaine BP, a combination of procaine BP and benzathine BP and penethamate, a prodrug of BP. Data were collected from 40 horses that provided 63 rich profiles of BP corresponding to a total of 1022 individual BP plasma concentrations. Results: A 3-compartment disposition model was selected. For each of these formulations, the PK/PD cutoff was estimated for different dosage regimens using Monte Carlo simulations. The fAUC/MIC or fT>MIC were calculated with a free BP fraction set at 0.4. For fAUC/MIC, a target value of 72 h (for a 72h treatment) was considered. For fT>MIC, efficacy was assumed when free plasma concentrations were above the explored MIC (0.0625-2 mg/L) for 30 or 40 % of the dosing interval. For continuous infusion, a fT>MIC of 90 % was considered. It was shown that a PK/PD cutoff of 0.25 mg/L can be achieved in 90 % of horses with routine regimen (typically 22,000 IU/kg or 12.4 mg/kg per day) with IM procaine BP once a day (France, Japan, Sweden but not USA1) and with IM sodium BP at 14.07 mg/kg, twice a day or IV sodium BP infusion of 12.4 mg/kg per day. In contrast, penethamate and the combination of procaine BP and benzathine BP were unable to achieve this PK/PD cutoff not even an MIC of 0.125 mg/L. Discussion: The PK/PD cutoff of 0.25 mg/L is one dilution lower than the clinical breakpoint released by the CLSI (0.5 mg/ L). From our simulations, the CLSI clinical breakpoint can be achieved with IM procaine BP twice a day at 22,000 IU i.e. 12.4 mg/kg.

Youth intentions to provide social support to a peer with a concussion.

OBJECTIVES: 1) To describe demographic factors, concussion knowledge, attitudes, subjective norms, self-efficacy and intentions to provide social support to a peer with a concussion and 2) to examine if demographic factors and concussion knowledge are associated with components of the Theory of Planned Behavior. METHODS: The survey was completed between October 2018 and February 2019 by 200 youth (M = 15.30 years, SD = 1.52). Questions were designed for athletes and non-athletes and inquired about various types of social support. Data analysis included descriptive statistics, Wilcoxon Rank Sum Tests and Spearman's Rank-Order Correlation Coefficients. RESULTS: More favorable attitudes and intentions to provide social support were observed among females (W = 2576, p ≤ 0.001; W = 2411, p ≤ 0.001), older youth (rho = 0.32, p ≤ 0.001; rho = 0.41, p ≤ 0.001) and those with higher concussion knowledge (rho = 0.29, p ≤ 0.001; rho = 0.22; p ≤ 0.001). Participating in sports with a high-risk of concussion was associated with lower attitudes and intentions to provide social support (W = 6677; p ≤ 0.001; W = 6721; p ≤ 0.001). Self-reported concussion history or knowing someone with a concussion history was not significantly associated with social support intentions. CONCLUSION: This study identified characteristics of youth who had positive intentions to provide social support. These findings identify individuals who may model providing social support to a peer, as well as opportunities for future concussion education.

Delivering concussion education to pre-service teachers through the SCHOOLFirst website: Evaluating usability and satisfaction.

BACKGROUND: Return-to-school processes indicate 'when' to initiate activities and 'what' activities should be accomplished, but are missing 'how' to implement the process. The SCHOOLFirst website provides the 'how' through building concussion knowledge, creating a supportive culture, and defining roles. Due to the involvement of pre-service teachers in schools during training and imminent transition to becoming teachers, it is important that pre-service teachers are trained in concussion and can optimally support current and future students. OBJECTIVE: To determine: 1) pre-service teachers' knowledge and confidence surrounding the return-to-school process before and after using the SCHOOLFirst website; 2) the usability, intended use and satisfaction of the SCHOOLFirst website from the perspective of pre-service teachers. METHODS: Thirty pre-service teachers completed the demographic survey, knowledge and confidence survey, System Usability Scale, and satisfaction and intended use survey after participating in a workshop. RESULTS: Significant increases in concussion knowledge (Z = -4.093, p < 0.001) and confidence in helping students return-to-school (Z = -4.620, p < 0.001) were measured after using the SCHOOLFirst website. Participants were satisfied with the SCHOOLFirst website (93.4%) and intend to use it in the future when supporting a student post-concussion (96.4%). CONCLUSION: The SCHOOLFirst website is a valuable tool for pre-service teachers to support students' return-to-school post-concussion.

Potassium penicillin and gentamicin pharmacokinetics in healthy conscious and anesthetized horses.

OBJECTIVE: To determine the effects of general anesthesia on the safety and efficacy of co-administered potassium penicillin G (PEN) and gentamicin (GENT) in horses. STUDY DESIGN: Nonrandomized crossover. ANIMALS: Six adult, Thoroughbred horses. METHODS: Horses were administered PEN (22 000 IU/kg IV) and GENT (6.6 mg/kg IV). Plasma samples were collected over a 6 h period and synovial fluid was collected at 30 min and 6 h respectively. Drug administration and sample collection protocols were repeated after at least a 48 hour washout period and induction of anesthesia using xylazine/ketamine and maintenance with isoflurane gas. Drug concentrations were determined using ultrapressure liquid chromatography with mass spectrometry. A 2-compartment model was used to determine pharmacokinetics and differences were determined between conscious and anesthetized horses using paired t-tests (significance P < .05). RESULTS: Potassium penicillin g and GENT had higher minimum plasma concentrations (PEN 0.44 vs. 0.11 µg/mL, P = .002; GENT 3.0 vs. 1.9 µg/mL, P = .009), longer half lives (PEN 71 vs. 59 min, P = .018; GENT 149 vs. 109 min, P = .038), and slower clearances (PEN 3.41 vs. 5.1 mL/kg/min, P = .005; GENT 1.18 vs. 1.48 mL/kg/min, P = .028) in anesthetized horses vs. conscious horses. The PEN concentrations remained above the breakpoint minimum inhibitory concentration (MIC, 0.5 µg/mL) for 332 min in anesthetized vs. 199 min in conscious horses. The GENT concentrations reached 10 times higher than the breakpoint MIC (2 µg/mL) in all horses and were maintained for 58 vs. 59 min in anesthetized and conscious states, respectively. Synovial fluid concentrations were higher in conscious horses vs. anesthetized horses at 30 min for PEN (7.0 vs. 0.93 µg/mL, P < .001) and 30 (5.3 µg/mL vs. 0.79 µg/mL, P < .001) and 360 min (3.4 vs. 1.82 µg/mL, P < .003) for GENT. CONCLUSION: General anesthesia resulted in lower intrasynovial concentrations and delayed clearance of PEN/GENT in horses. CLINICAL SIGNIFICANCE: Redosing healthy anesthetized horses with PEN prior to 4-5 h is not necessary. When administered to anesthetized horses, intravenous PEN/GENT may not reach adequate intrasynovial concentrations to treat or prevent common pathogens. The doses or dosing intervals of antimicrobials administered to horses undergoing anesthesia may need to be adjusted to ensure maintenance of safe and effective plasma concentrations.

Comparison of two glucose-monitoring systems for use in horses.

OBJECTIVE: To determine the accuracy of 2 interstitial glucose-monitoring systems (GMSs) for use in horses compared with a point-of-care (POC) glucometer and standard laboratory enzymatic chemistry method (CHEM). ANIMALS: 8 clinically normal adult horses. PROCEDURES: One of each GMS device (Dexcom G6 and Freestyle Libre 14-day) was placed on each horse, and blood glucose concentration was measured via POC and CHEM at 33 time points and compared with simultaneous GMS readings. An oral glucose absorption test (OGAT) was performed on day 2, and glucose concentrations were measured and compared. RESULTS: Glucose concentrations were significantly correlated with one another between all devices on days 1 to 5. Acceptable agreement was observed between Dexcom G6 and Freestyle Libre 14-day when compared with CHEM on days 1, 3, 4, and 5 with a combined mean bias of 10.45 mg/dL and 1.53 mg/dL, respectively. During dextrose-induced hyperglycemia on day 2, mean bias values for Dexcom G6 (10.49 mg/dL) and FreeStyle Libre 14-day (0.34 mg/dL) showed good agreement with CHEM. CLINICAL RELEVANCE: Serial blood glucose measurements are used to diagnose or monitor a variety of conditions in equine medicine; advances in near-continuous interstitial glucose monitoring allow for minimally invasive glucose assessment, thereby reducing stress and discomfort to patients. Data from this study support the use of the Dexcom G6 and Freestyle Libre 14-day interstitial glucose-monitoring systems to estimate blood glucose concentrations in horses.

The Concussion Challenge Assessment: Development and reliability of a novel gross motor assessment tool for paediatric concussion.

Aims: The aim of this study was to develop a gross motor performance clinical assessment tool, the Concussion Challenge Assessment (CCA), for paediatric concussion populations. Methods: An expert panel evaluated tasks from the Acquired Brain Injury Challenge Assessment to determine relevant tasks for a paediatric concussion population. These tasks were administered to a convenience sample of 854 healthy youth. An analysis of the response options for each task, considering task difficulty, was performed. The test-retest reliability of each task was considered to finalise the tool. Results: The Acquired Brain Injury Challenge Assessment was reduced to six tasks (three coordination, two speed and agility, and one strength) to create the CCA. Population-specific 4-point response options were generated, which, upon examination of task difficulty, were revised as 5-point response sets to better capture performance differences. The test-retest reliability results led to acceptance of all six: three performance tasks and three exertion tasks. Conclusion: This development of the CCA is an important step in creating a gross motor performance assessment tool that can assist in the determination of when youth are able to safely return to activity following a concussion.

Modelling dielectric elastomer circuit networks for soft biomimetics.

In order to obtain entirely soft bio-inspired robots, fully soft electronic circuits are needed. Dielectric elastomers (DEs) are electroactive polymers that have demonstrated multifunctionality. The same material can achieve different tasks like actuation, sensing, or energy harvesting. It has been shown that basic logic and memory functions can be realized with similar soft structures by combining multiple DE actuators and DE switches. Thus it would be possible to build, with the same materials and processes, a soft structure that mimics a biological being with all these capabilities. This contribution is focused on the modelling of the aforementioned soft electro-mechanical circuit networks. It is here reported the building process of a comprehensive SIMULINK model including the electro-mechanical behaviour of DE logic units and their interconnections. Conventional models deal with a single aspect of DEs, generating complex finite-element simulations. This contribution, based on a former model for an inverter-based DEO, shows how to integrate these various mathematical models and, with the help of direct measurements, create a software representation of DE circuit networks. This work is intended to demonstrate the validity of a recently introduced model and apply it to more complex circuit networks that have a higher number of components. Since, at the present state, the building processes are by hand, adding components generates more variability due to sample-to-sample variation and human error. Despite this, the model still shows a qualitatively good prediction of the devices' behaviour. Furthermore, the introduction of new materials and automatic processes will help to reduce this variability, allowing the model to reach even better performance.

Sensitivity and Specificity of a Multimodal Approach for Concussion Assessment in Youth Athletes.

CONTEXT: Current international consensus endorses a multimodal approach to concussion assessment. However, the psychometric evaluation of clinical measures used to identify postconcussion performance deficits once an athlete is asymptomatic remains limited, particularly in the pediatric population. OBJECTIVE: To describe and compare the sensitivity and specificity of a multimodal assessment battery (balance, cognition, and upper and lower body strength) versus individual clinical measures at discriminating between concussed youth athletes and noninjured controls when asymptomatic. DESIGN: Prospective cohort study. SETTING: Hospital laboratory setting. PARTICIPANTS: A total of 32 youth athletes with a concussion and 32 matched (age and sex) noninjured control participants aged 10-18 years. INTERVENTION(S): Participants were administered preinjury (baseline) assessments of cognition (Immediate Post-Concussion Assessment and Cognitive Testing [ImPACT]), balance (BioSway), and upper and lower body strength (grip strength and standing long jump). Assessments were readministered when concussed participants reported symptom resolution (asymptomatic time point). Noninjured control participants were reassessed using the same time interval as their concussion matched pair. Sensitivity and specificity were calculated using standardized regression-based methods and receiver operating characteristic curves. MAIN OUTCOME MEASURES: Outcome measures included baseline and postinjury ImPACT, BioSway, grip strength, and standing long jump scores. RESULTS: When asymptomatic, declines in performance on each individual clinical measure were seen in 3% to 22% of the concussion group (sensitivity = 3%-22%) compared with 3% to 13% of the noninjured control group (specificity = 87%-97%) (90% confidence interval). The multimodal battery of all combined clinical measures yielded a sensitivity of 41% and a specificity of 77% (90% confidence interval). Based on discriminative analyses, the multimodal approach was statistically superior compared with an individual measures approach for balance and upper and lower body strength, but not for cognition. CONCLUSIONS: Results provide a foundation for understanding which domains of assessment (cognition, balance, and strength) may be sensitive and specific to deficits once symptoms resolve in youth athletes. More work is needed prior to clinical implementation of a preinjury (baseline) to postinjury multimodal approach to assessment following concussion in youth athletes.

Social support during youth concussion recovery.

PURPOSE: We explored the lived experience of high-school aged girls receiving social support during concussion recovery to better understand (1) how they define meaningful social support and barriers/facilitators to receiving it; (2) who provides that support; and (3) the role of peers. METHODS: In person, semi-structured interviews were conducted with 10 girls (aged 14-19 years) with a personal history of concussion. RESULTS: Close friends, youth with personal history of concussion, and parents were identified as key providers of meaningful social support during concussion recovery. Participants identified specific examples of support provided by each group. Close friends built a sense of social inclusion that mitigated feelings of social isolation. Youth with a personal history of concussion used their lived experiences to communicate empathy and validate the participant's challenges. Parents assisted with practical challenges (e.g. accessing accommodations) by leveraging their "adult power". Participants identified that lack of understanding of their lived experiences was a key barrier to receiving support. They proposed solutions focused on education initiatives highlighting personal accounts from youth with concussion, and specific examples of how peers can help. CONCLUSIONS: Fostering social support may require strategies tailored to each group of key providers as they mitigate different challenges in recovery.

The youth concussion awareness network (You-CAN) - a school-based peer-led intervention to improve concussion reporting and social support: the protocol for a cluster randomized trial.

BACKGROUND: Concussion prevalence is increasing in the pediatric population, and is a matter of public health concern. Concussion symptoms can be physical, cognitive, emotional and behavioural, and last longer in high school aged youth than adults. Concussions are underreported in youth due to their lack of knowledge, social environment, perceived outcomes of reporting, norms, and self-efficacy. The Youth Concussion Awareness Network (You-CAN) is a school-based peer-led program designed to increase high school students' intent to report a concussion, and provide social support to a peer. This study aims to investigate whether participation in You-CAN, a program grounded in service learning principles, impacts concussion knowledge, attitudes, intent to report a suspected concussion to an adult, and intent to provide social support to a peer. Secondary aims include assessing the implementation fidelity and acceptability of the intervention. METHODS: This longitudinal study will use a cluster randomized trial design. Three high schools from six randomly selected Canadian school boards will participate and be randomized to three study arms: (1) You-CAN led by school staff; (2) You-CAN led by school staff and research team; and (3) untreated comparison group. Intervention arms 1 and 2 will deliver the You-CAN program and create a Concussion Council at their school. The Concussion Council will deliver a concussion awareness campaign and participate in an online showcase with other participating schools. In addition, arm 2 will have monthly video-calls with the research team. A survey based on the Theory of Planned Behaviour will be administered school-wide with all arms (1, 2, 3) at two time points (beginning {T0} and end {T1} of the school year). Exit interviews will be completed with the Concussion Councils and participating school staff. DISCUSSION: This study will provide evidence of the effectiveness of a school-based peer-led concussion program on increasing concussion knowledge, attitudes, subjective norms, perceived behavioural control, intent to report a concussion to an adult, and intent to provide social support to a peer amongst Canadian high school students. It will also provide important information about the implementation and acceptability of the You-CAN program for high school students and staff. TRIAL REGISTRATION: This trial is registered with the ISRCTN registry (ISRCTN64944275, 14/01/2020, retrospectively registered).

Online concussion resources for Canadian high school aged youth: A systematic search strategy.

Objective: To identify online concussion resources that are suitable for Canadian youth and accurate according to the current International Consensus Statement on Concussion in Sport.Methods: A five-phased systematic search strategy was used to identify concussion resources. This included 1. searching key Canadian stakeholder websites (sport organizations, injury prevention groups, children's hospitals, governments, public health agencies, and physical and health education associations), 2. pediatric concussion expert consultation, 3. applying inclusion and exclusion criteria, 4. reviewing content for accuracy according to the consensus statement and 5. evaluating resources for readability, usability and suitability.Results: A total of 456 resources were initially identified however, only 32 met the final criteria. Across all resources, 34.6% (n=109) were excluded as they were not designed primarily for youth. Among resources reviewed for content accuracy according to the consensus statement, 53.1% (n=51) were excluded. When evaluating resources for readability, usability and suitability, 28.5% (n=13) were excluded as they were not suitable for youth.Implications: Most concussion resources available online are not written for youth and do not contain accurate information on pediatric concussion. The identified evidence-based resources can ensure that accurate and suitable information is provided to youth in order to enhance their concussion knowledge.

Meeting the needs of patients with disabilities: how can we better prepare the new dental graduate?

Background Over the last two decades, the introduction of equality legislation has resulted in disabled people having improved opportunities and better access to services. Within the field of oral health care, the specialty of special care dentistry exists to act as an advocate for those with disabilities and it is recognised that there is a need to reduce health inequalities. To ensure the future dental workforce is able to respond to the needs of those with disabilities, education is key. This raises the question: 'are we adequately preparing future dental professionals to fulfil their obligations?'.Aim To explore final year dental students' insight into issues of disability in order to inform the undergraduate special care dentistry programme.Method Qualitative methods using focus groups were employed to address the research issue. The data were analysed using thematic analysis.Results Four main themes were identified: 'perceptions of disability', 'experience of disability', 'patient management' and 'teaching and learning'. The level of preparedness varied among students and could be attributed to: knowledge of disability issues; previous experience of people with disabilities; how education in the field of special care dentistry was delivered. Students identified the need for more structure to their teaching and increased exposure to the disabled community.Conclusion The issues identified reflect current literature and highlight the importance of addressing disability within the wider undergraduate curriculum. Responding to the 'student voice' has the potential to tailor elements of the special care dentistry programme, in order to address their educational needs.

Conscious sedation in children: the need to strengthen the evidence base remains.

Data sources Cochrane Oral Health's Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL), Medline and Embase. The US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov) and World Health Organisation International Clinical Trials Registry Platform were searched for ongoing trials. Reference lists of eligible studies were checked for additional studies and specialists in the field contacted for any unpublished data. No restrictions were placed on language or publication date.Study selection Studies were selected which met the following criteria: randomised controlled trials of conscious sedation undertaken by a dentist, anaesthetist or one of the dental team comparing two or more drugs/techniques/placebo in children (up to 16 years of age) receiving dental treatment. Crossover trials and studies involving complex surgical procedures were excluded. Data extraction and synthesis Two authors independently selected studies for inclusion, extracted data and assessed for risk of bias. Results were compared and inconsistencies noted, with disagreements resolved by discussion. Where information was unclear or incomplete the authors of trials were contacted for clarification. Results Fifty studies (3704 participants) were included and grouped into placebo-controlled, dosage and head-to-head comparisons. There was wide variation in sedation technique and agent(s) employed across studies (34 different sedatives with or without nitrous oxide). Risk of bias was high for forty studies (81%), low for one study and unclear for the remaining nine studies (18%). Meta-analysis of available data for the primary outcome measure (behaviour) was possible for oral midazolam versus placebo only. There is moderate-certainty evidence from six small clinically heterogeneous studies at high or unclear risk of bias, that oral midazolam in doses between 0.25 mg/kg to 1 mg/kg is associated with more co-operative behaviour compared to placebo. It was not possible to draw conclusions regarding secondary outcome measures (completion of treatment, postoperative anxiety, adverse events) due to inconsistent and/or inadequate reporting.Conclusions There is some moderate-certainty evidence that oral midazolam is an effective sedative for dental treatment in children. Improvements and greater consistency in the design and reporting of future research will enable further evaluation of sedation agents and their potential implications for practice; with it being suggested future trials evaluate experimental regimens in comparison with oral midazolam or inhaled nitrous oxide.

Heart rate variability following youth concussion: how do autonomic regulation and concussion symptoms differ over time postinjury?

OBJECTIVES: Following youth concussion, objective physiological indicators are needed to corroborate changes in subjective clinical measures. The objectives of the current study were to: (1) explore the effect of concussion on heart rate variability (HRV) across days postinjury in youth athletes aged 13-18 years old, compared with healthy age-matched and sex-matched controls and (2) examine the relationship between postconcussion symptom domains (physical, cognitive, fatigue and emotional) and HRV. METHODS: Prospective, longitudinal, case-control study (N=44). This study comprised 29 concussed athletes between the ages of 13 and 18 years old (21 females, 8 males) and 15 age-matched and sex-matched controls). All participants completed baseline testing, which included demographic information (age, sex, concussion history), self-reported concussion symptoms (Post-Concussion Symptom Inventory [PCSI]) and a 24-hour heart rate recording via the Polar RS800CX system. The PCSI and HRV were collected weekly while the participant was symptomatic and then 1, 3 and 6 months following symptom resolution. HRV variables included time and frequency domain measures. Data visualisations and mixed effects modelling were used to derive parsimonious models. RESULTS: HRV increased across days postinjury. Concussion symptom domains (physical, cognitive, fatigue and emotional) all had a significant main effect on HRV; concussed participants who reported more symptoms had higher HRV compared with those who reported fewer symptoms. Visualisations of HRV depict the recovery trajectory as non-linear across time. No significant differences on HRV measures were found between concussed and control participants. CONCLUSION: These preliminary findings provide the foundation to understand the varied trajectory and relationship between objective physiological measures and subjective symptom reporting.

Grip Strength in Youth Ice Hockey Players: Normative Values and Predictors of Performance.

Toong, T, Wilson, KE, Urban, K, Paniccia, M, Hunt, AW, Keightley, M, and Reed, N. Grip strength in youth ice hockey players: Normative values and predictors of performance. J Strength Cond Res 32(12): 3503-3511, 2018-Grip strength is a simple, valid, and reliable tool for estimating overall muscular strength, a key component of health-related fitness and sport performance. To date, there is a paucity of up-to-date and developmentally sensitive grip strength norms specific to youth-athlete populations. The objectives of this study are to (a) establish normative grip strength values in youth ice hockey players, (b) descriptively compare these values with existing Canadian pediatric norms, and (c) explore the relationship between age, sex, body mass, and hockey playing level on grip strength performance. A sample of 690 male and female youth ice hockey players between the ages of 10 and 16 years were included. Participants completed assessments of maximal grip strength using a hand dynamometer on both hands. In addition, age, sex, body mass, and hockey playing level were collected. Maximal absolute grip strength, stratified by age and sex, was higher than previously published Canadian pediatric norms. Grip strength increased with age in both sexes. Males and females performed similarly until 12 years of age, after which point males had greater strength. Individuals with greater body mass had greater strength. For the nondominant hand, competitive players had greater strength than those playing house league or select. This study describes normative grip strength values in youth ice hockey players according to age, sex, body mass, and playing level. These athlete-specific norms may be used to help evaluate and monitor changes in grip strength over time in youth ice hockey players.

Modeling of dielectric elastomer oscillators for soft biomimetic applications.

Biomimetic, entirely soft robots with animal-like behavior and integrated artificial nervous systems will open up totally new perspectives and applications. However, until now, most presented studies on soft robots were limited to only partly soft designs, since all solutions at least needed conventional, stiff electronics to sense, process signals and activate actuators. We present a novel approach for a set up and the experimental validation of an artificial pace maker that is able to drive basic robotic structures and act as artificial central pattern generator. The structure is based on multi-functional dielectric elastomers (DEs). DE actuators, DE switches and DE resistors are combined to create complex DE oscillators (DEOs). Supplied with only one external DC voltage, the DEO autonomously generates oscillating signals that can be used to clock a robotic structure, control the cyclic motion of artificial muscles in bionic robots or make a whole robotic structure move. We present the basic functionality, derive a mathematical model for predicting the generated signal waveform and verify the model experimentally.

Postural Stability in Healthy Child and Youth Athletes: The Effect of Age, Sex, and Concussion-Related Factors on Performance.

BACKGROUND: Postural stability plays a key role in sport performance, especially after concussion. Specific to healthy child and youth athletes, little is known about the influence development and sex may have on postural stability while considering other subjective clinical measures used in baseline/preinjury concussion assessment. This study aims to describe age- and sex-based trends in postural stability in uninjured child and youth athletes at baseline while accounting for concussion-related factors. HYPOTHESES: (1) Postural stability performance will improve with age, (2) females will display better postural stability compared to males, and (3) concussion-like symptoms will affect postural stability performance in healthy children and youth. STUDY DESIGN: Cross-sectional study. LEVEL OF EVIDENCE: Level 3. METHODS: This study comprised 889 healthy/uninjured child and youth athletes (54% female, 46% male) between the ages of 9 and 18 years old. Participants completed preseason baseline testing, which included demographic information (age, sex, concussion history), self-report of concussion-like symptoms (Post-Concussion Symptom Inventory [PCSI]-Child and PCSI-Youth), and measures of postural stability (BioSway; Biodex Medical Systems). Two versions of the PCSI were used (PCSI-C, 9- to 12-year-olds; PCSI-Y, 13- to 18-year-olds). Postural stability was assessed via sway index under 4 sway conditions of increasing difficulty by removing visual and proprioceptive cues. RESULTS: In children aged 9 to 12 years old, there were significant age- ( P < 0.05) and sex-based effects ( P < 0.05) on postural stability. Performance improved with age, and girls performed better than boys. For youth ages 13 to 18 years old, postural stability also improved with age ( P < 0.05). In both child and youth subgroups, postural stability worsened with increasing concussion-like symptoms ( P < 0.05). CONCLUSION: There are developmental and baseline symptom trends regarding postural stability performance. CLINICAL RELEVANCE: These findings provide a preliminary foundation for postconcussion comparisons and highlight the need for a multimodal approach in assessing and understanding physical measures such as postural stability.

Effects of Wrist Posture and Fingertip Force on Median Nerve Blood Flow Velocity.

Purpose. The purpose of this study was to assess nerve hypervascularization using high resolution ultrasonography to determine the effects of wrist posture and fingertip force on median nerve blood flow at the wrist in healthy participants and those experiencing carpal tunnel syndrome (CTS) symptoms. Methods. The median nerves of nine healthy participants and nine participants experiencing symptoms of CTS were evaluated using optimized ultrasonography in five wrist postures with and without a middle digit fingertip press (0, 6 N). Results. Both wrist posture and fingertip force had significant main effects on mean peak blood flow velocity. Blood flow velocity with a neutral wrist (2.87 cm/s) was significantly lower than flexed 30° (3.37 cm/s), flexed 15° (3.27 cm/s), and extended 30° (3.29 cm/s). Similarly, median nerve blood flow velocity was lower without force (2.81 cm/s) than with force (3.56 cm/s). A significant difference was not found between groups. Discussion. Vascular changes associated with CTS may be acutely induced by nonneutral wrist postures and fingertip force. This study represents an early evaluation of intraneural blood flow as a measure of nerve hypervascularization in response to occupational risk factors and advances our understanding of the vascular phenomena associated with peripheral nerve compression.

Using a dual-task protocol to investigate motor and cognitive performance in healthy children and youth.

OBJECTIVES: Mild traumatic brain injury (or concussion) is a prevalent yet understudied health concern in children and youth. This injury can cause dysfunction in both motor and cognitive domains; however, most literature focuses on single-task neuropsychological tests which only assess cognition. Although dual-task research on concussed children and youth is needed as many daily activities require both motor and cognitive domains, we must first investigate whether performing simultaneous motor and cognitive tasks of varied complexity impact these domains in healthy children and youth. PARTICIPANTS AND DESIGN: Data collected from 106 healthy children and youth (5-18 years) created a normative dataset. Participants performed motor (postural stability) and cognitive (visual attention) tasks under single- and dual-task conditions. The cognitive task difficulty remained constant while the motor task had four conditions of increasing difficulty. The relationship between the number of correct responses (cognitive performance) and sway index (motor performance) was determined using two repeated measures ANOVAs (p<0.05). RESULTS: Dual-task conditions resulted in reduced postural stability, with greater differences on the foam surface (F2,206=16.070, p<0.0005). No statistically significant differences were observed in attention (F4,101=0.713, p=0.584). CONCLUSIONS: Postural stability decreased under dual-task conditions, but attention was maintained or improved. Consequently, attention took precedence over postural control when performing tasks concurrently, demonstrating the ability for dual-task methodology to isolate specific processes. This study provides a normative dataset to be used during clinical management to identify functional deficits following concussion and acts as a starting point to explore dual-task protocols in children and youth following concussion.

Heart Rate Variability in Healthy Non-Concussed Youth Athletes: Exploring the Effect of Age, Sex, and Concussion-Like Symptoms.

BACKGROUND: Heart rate variability (HRV) is a non-invasive neurophysiological measure of autonomic nervous system regulation emerging in concussion research. To date, most concussion studies have focused on the university-aged athlete with no research examining healthy active youths. Corroborating changes in HRV alongside traditional subjective self-report measures (concussion symptoms) in the non-concussed state provides a foundation for interpreting change following concussion. The objectives were to (1) explore the influence of age and sex on HRV and (2) examine the relationship between HRV and baseline/pre-injury concussion symptom domains (physical, cognitive, emotional, and fatigue) in healthy youth athletes. METHOD: Healthy, youth athletes 13-18 years of age [N = 294, female = 166 (56.5%), male = 128 (43.5%)] participated in this cross-sectional study. Age, sex, and concussion-like symptoms were collected as part of a baseline/pre-injury assessment. The Post-Concussion Symptom Inventory-SR13 (PCSI-SR13) was used to collect domain scores for physical, cognitive, emotional, and fatigue symptoms. HRV was collected for 24 h. HRV measures included time (SDNN, RMSSD, and pNN50) and frequency (HF, HFnu, LF, LFnu, and total power) domain HRV measures. Variables were logarithmically transformed to increase robustness of linear regression models. RESULTS: Older youth participants displayed significantly higher HRV compared to younger participants (p < 0.05). Females displayed significantly lower HRV compared to males (p < 0.05). A significant interaction effect between concussion-like symptoms and HRV indicated differential patterns as a function of sex (p < 0.05). Youth athletes who reported more cognitive symptoms had lower HRV (p < 0.05). CONCLUSION: HRV was found to have a significant relationship with a traditional clinical measure (subjective self-report of concussion-like symptoms) utilized in concussion assessment and management. Baseline/pre-concussion trends in HRV were significantly associated with age and sex, highlighting the value in understanding key demographic factors within the context of concussion-like symptoms.