Frontiers in Sports and Active Living

Objective: The aim of the current study was to evaluate the feasibility of a multi-channel distributed wearable ultrasound (D-WUS) system capable of simultaneously probing dynamic muscle activity across multiple anatomical sites to assess neuromuscular coordination during physical activity. Methods: Twenty NCAA Division I women athletes (8 with prior knee injury) performed countermovement jumps (CMJs) on dual force plates while wearing a four-channel D-WUS system targeting the vastus lateralis (VL) and vastus medialis oblique (VMO) in both limbs. Real-time M-mode ultrasound data were processed using a composite factorization approach integrating nonnegative matrix factorization and principal component analysis (CF-PCA) to extract dominant muscle-contraction patterns. Correlation and timing metrics between VL and VMO were compared across injury status. Results: CMJ performance metrics (jump height, RSImod) did not differ between groups (p > 0.05). However, D-WUS revealed significant differences in muscle coordination in the right limb: VL-VMO correlation (p = 0.029) and timing symmetry (p = 0.019) were reduced in participants with prior knee injury; left-limb differences were not significant. Right-limb timing symmetry was negatively correlated with SMFA score (rho = -0.48, p = 0.033). Functional survey scores (SMFA) also differed significantly (p = 0.001), while VISA-P scores did not. Conclusion: These preliminary findings provide feasibility-level evidence that distributed wearable ultrasound can detect limb-specific neuromuscular coordination differences not reflected in force-plate biomechanics, motivating larger prospective studies to establish reliability and clinical utility. Significance: With further validation, this approach may offer a scalable, objective means of monitoring muscle contraction during rehabilitation.

Introduction: Knee muscle coactivation is elevated after anterior cruciate ligament reconstruction (ACLR), contributing to altered joint loading and post-traumatic osteoarthritis. Existing methods average coactivation within predefined gait phases and require priori designation of muscles roles, limiting the resolution for when differences occur. Objective: Characterize knee joint coactivation and dynamics throughout gait in individuals with ACLR using statistical parametric mapping. Methods: Ten individuals with unilateral ACLR and ten healthy matched controls performed overground walking at their preferred speed, while kinematics, kinetics, and electromyography of the quadriceps, hamstring, and gastrocnemius muscles were recorded. Coactivation was quantified using time-varying, multi-muscle coactivation, and was compared using a one-tailed statistical parametric mapping (SPM) t-test. Knee joint angle, angular speed, and moment were compared using SPM Hotelling's T2 tests with Bonferroni-adjusted post hoc comparisons (= 0.05). Results: Coactivation was greater in the ACLR group at 0.01%-6.14%, 35.23%-40.94%, 69.73-71.99%, 72.12-77.31%, 77.89-78.05%, and 94.63%-95.87% (p < 0.0001) of stride. The ACLR group also demonstrated greater knee internal-external rotation angle at 0.01%-47.34%, 52.14%-61.87%, and 66.47%-100% (p <0.0001) and lower knee flexion angle at 55.79%-65.93% (p = 0.004) of stride, than healthy controls. Finally, a smaller knee flexion-extension moment was observed in the ACLR group at 57.43%-62.18% (p = 0.005) of stride. Conclusions: Coactivation after ACLR is elevated at loading response, late mid-stance, terminal stance and early push-off phase. Greater coactivation was observed during weight-acceptance phases, whereas lower knee moments characterized initial swing. These alterations are localized rather than uniformly distributed, supporting phase-targeted rehabilitation.

BackgroundTrunk flexor and extensor measurement tools are useful for measuring progress throughout the identification, treatment and management of spinal pathologies. Handheld dynamometry is popular amongst clinicians due to its convenience. However, poor standardisation of the testing position can lead to suboptimal intra-rater reliability, which consequently reduces the validity of the results. The VALD ForceFrame Strength Testing System is a portable and standardized hybrid strength-assessment system that quantifies strength and power outputs. ObjectiveThis study aims to assess the test-retest reliability of isometric trunk flexion and extension strength using the ForceFrame testing technology. MethodsA total of 29 healthy participants undertook two testing sessions, each requiring them to perform maximal isometric trunk flexion and extension using the ForceFrame. Test re-test reliability was assessed using the Intraclass Correlation Coefficient (ICC), and the standard error of measure (SEM) was used to calculate the minimum detectable change. ResultsExcellent reliability was observed for both trunk flexion (ICC 0.92; 95% CI 0.83-0.96) and extension (ICC 0.93; 95% CI 0.86-0.97) tests, and the minimum detectable changes observed were 71.35N and 101.20N, respectively. ConclusionsThe results from this study suggest that the VALD force frame offers clinicians a reliable method of assessing change in trunk flexor and extensor strength.

The validation of objective neurophysiological monitoring of concussion from diagnosis to return to play has the potential to improve the clinical care of athletes. Extracted from event-related potentials (ERP), brain vital signs offer a non-invasive objective neurophysiological measure of three well established ERP responses that complement existing clinical assessments: 1) the N100 response related to auditory sensation; 2) the P300 response related to basic attention; and 3) the N400 response related to cognitive processing. The N400, in particular, has increasingly been demonstrated to be sensitive to head impact related cognitive impairment. Accordingly, brain vital sign measures were collected in n =165 rugby league players from two Australian professional National Rugby League clubs (NRL), with concussed players (n =26) being subsequently assessed over a total of five separate time points (Baseline, Day 2, Day 5, Day 10, and Day 42). This timeline aligned with acute (Day 2), NRL mandatory minimum return-to-play (RTP) guidelines (Day 10), and an extended post RTP period. Relative to baseline, the results revealed significant N400 cognitive processing latency delays at Day 2 post-concussion (p =0.002). The N400 latency delays persisted past day 5, significantly returning to baseline values at Day 10, consistent with the RTP mandatory minimum requirement. The findings indicated that neurophysiological recovery occurred in this cohort within an approximate 10-day time frame. Future studies monitoring brain vital sign changes across the trajectory of injury to recovery are needed in sports related concussion management.

Targeted stepping requires coordinating limb transport, preparatory postural adjustments, and accurate foot placement while maintaining balance under competing speed and accuracy demands. Although Fitts' law robustly describes speed-accuracy trade-offs (SATs) in upper-limb movements, its applicability to whole-body stepping remains unclear due to additional postural and visuomotor constraints. This study investigates how instructional emphasis and spatial demands modulate SAT regulation and pre-step postural dynamics during stepping. Twenty-four healthy young adults will perform a multidirectional stepping task across two directions (0 degrees and 45 degrees) and two distances (45% and 80% of leg length) under three instruction conditions: Fast, Accurate, and Fast & Accurate. Kinematic and force-plate data will quantify movement time, foot-placement error, and pre-step center-of-pressure dynamics. We hypothesize that instructional emphasis and increased postural demands will systematically alter stepping strategies and produce deviations from classical Fitts-type scaling, particularly during diagonal stepping.

Background: Knee osteoarthritis (OA) is characterized by progressive joint degradation and altered gait biomechanics. Inter-limb load asymmetry during daily living tasks may accelerate joint deterioration, particularly when combined with physical fatigue. This study investigates the relationship between daily physical fatigue and inter-limb load asymmetry patterns during functional activities in individuals with unilateral knee OA. Objective: To evaluate the impact of fatigue on inter-limb load asymmetry and joint loading rates during daily living tasks in patients with unilateral knee osteoarthritis, and to identify biomechanical and clinical factors associated with load distribution patterns. Methods: One hundred eighteen participants with unilateral knee OA (mean age 62.6 (SD 7.4) years, BMI 29.9 (SD 4.2) kg/m2) completed biomechanical assessments during non-fatigued and fatigued conditions. Ground reaction force measurements were obtained during functional tasks including stair climbing, sit-to-stand transitions, and level walking. Load asymmetry was quantified as the inter-limb difference in peak vertical ground reaction forces. Statistical analysis was conducted using Python (v3.9), including paired t-tests, analysis of variance, and linear regression modeling. Results: Participants demonstrated significantly increased load asymmetry under fatigue conditions (mean difference 8.7% (SD 12.3) %, p < 0.001). Fatigue-induced asymmetry was task-dependent, with stair negotiation showing the greatest increase (11.2% (SD 14.1) %). Peak loading rates on the affected knee were inversely correlated with time-to-peak load during fatigued conditions (r = -0.68, p < 0.001). Disease severity (WOMAC score) and age significantly predicted asymmetry changes (R2 = 0.52, p < 0.001). Conclusions: Physical fatigue exacerbates inter-limb load asymmetry in unilateral knee OA, potentially accelerating joint degeneration. Task-specific interventions targeting fatigue management and load redistribution may improve long-term outcomes. Future longitudinal studies should examine the temporal relationship between acute biomechanical changes and progressive structural joint damage. Keywords: Knee osteoarthritis, load asymmetry, fatigue, biomechanics, ground reaction forces, functional tasks.

Background: Head acceleration events (HAEs) are common in contact sports, but season-long exposure and its relationship with cognitive performance in amateur British American football remain poorly characterised. Methods: Thirty male players were recruited from three British American football teams. Cognitive performance was assessed pre-season, mid-season, and post-season using the Sport Concussion Assessment Tool 6 and computerised Stroop, 2-back, Go/No-go, and visual-search tasks. Seasonal cognitive analyses included 23 participants with available data. HAEs were quantified using helmet-mounted accelerometers; exposure-linked analyses were restricted to 19 participants who provided sufficiently complete sensor recordings across contact training sessions and competitive matches. Seasonal cognitive changes were assessed using mixed-effects models. Associations of in-season HAE metrics and previous contact-sport seasons with global cognitive change were examined using simple linear regression and elastic-net regression. Results: In the 19-participant exposure-linked cohort, prior contact-sport exposure showed the strongest nominal univariate association with worse global cognitive change (r squared = 0.337, p = 0.009), although this did not remain significant after correction for multiple comparisons (Benjamini-Hochberg-adjusted p = 0.055). Corrected nested cross-validation indicated little out-of-sample performance for the multivariable elastic-net model (r = 0.144, predictive R squared = -0.008). Although previous contact-sport seasons had the largest standardised coefficient in the final full-cohort fit, predictor retention varied substantially across resamples. Conclusion: Prior contact-sport exposure showed the strongest exploratory association with relatively worse global cognitive change, whereas in-season HAE metrics showed weaker associations. However, the multivariable model did not demonstrate useful out-of-sample predictive performance, and the small exposure-linked cohort precludes firm conclusions regarding the relative importance of individual predictors.

Background: School-based implementation of robot-assisted walking may support increased physical and social participation for children with physical disabilities, but evidence from an adequately powered trial is needed. This pilot study evaluated implementation strategies and study procedures to inform a future definitive trial. Methods: Participants were randomized to 12-weeks of robot-assisted walking or control, with subsequent crossover to the other condition. In the intervention arm, targeted dose was 75 minutes of robot-assisted walking, spread across three days/week. Implementation strategies for the child's classroom team included educational materials, centralized technical assistance, school champions, and on-going training. Implementation strategy evaluation focused on intervention protocol feasibility (i.e., weekly device use, troubleshooting) and fidelity (documentation of implementation strategy modifications). Preliminary estimates participation goal changes were obtained using the Canadian Occupational Performance Measure (COPM) 'Performance' scale (/10). Results: Eight children with neurodevelopmental physical disabilities participated (mean age 3.5, SD 0.5 years). Device use varied from 2.1 to 4.3 days/week (median 3.3) with a range of 48 to 96 minutes/week (median 80). Target use of >= 3 days/week was achieved for 66% of weeks and met the >=75-minute target for 33% of weeks. Troubleshooting occurred in 18.5% of sessions. Two implementation strategies were modified to improve feasibility. COPM mean change was 3.56 (SD 1.07) for robot-assisted walking and 2.11 (SD 2.41) for control (dz=0.74). Conclusions: This pilot study provided preliminary evidence regarding both the feasibility of robot-assisted walking implementation in schools and its potential effectiveness for children with physical disabilities. Findings support progression to a definitive trial.

Markerless motion capture offers a practical approach to biomechanical assessment in clinical populations outside of controlled laboratory environments. The purpose of this study was to evaluate the utility of markerless motion capture for quantifying static postural control impairment in individuals with stroke. Participants with subacute stroke (n=26) and healthy controls (n=171) performed a 30-second quiet standing task across three data collection sites in Kingston, Ontario, Canada. Video data were processed using Theia3D, and pelvis center of mass (COM) trajectories were extracted. Five discrete COM parameters were computed and transformed into Z-scores using normative models developed from the healthy population. An overall Task Score was calculated by aggregating parameter Z-scores. Forty-six percent of participants with stroke were identified as impaired on the task (Task Score > 95th percentile of the healthy distribution). At the parameter level, impairments were more prevalent in the mediolateral (ML) than anteroposterior (AP) direction (root-mean-square distance: 50% impaired ML vs. 12% impaired AP; mean velocity: 46% impaired ML vs. 35% impaired AP). Task scores and several task parameters demonstrated significant correlations with Berg Balance Scale scores (r = -0.64 to -0.81) and Functional Independence Measure Motor Sub-Scale scores (r = -0.62 to -0.77), with poorer performance associated with lower clinical scores. These findings demonstrate the utility of markerless motion capture for quantifying static postural control impairment following stroke. Future work should extend this framework to evaluate impairment in more dynamic postural control and gait tasks.

Purpose: To determine whether a cobalt-chrome genetic reactivity (CoGR) score - originally developed to identify patients at greater risk of developing adverse reaction to metal-on-metal hips - is associated with poorer patient-reported outcomes after knee arthroplasty (KA). Methods: In a prospective multicentre study, patients at a minimum two years post all cobalt-chrome KA were invited to research clinics. Participants provided samples for blood metal ion measurements and DNA sequencing and completed Forgotten Joint Scores (FJS). Component alignment was assessed on AP and lateral plain radiographs. The association between CoGR and FJS was assessed using regression adjusted for time since surgery, age, gender, BMI and tested for modification by blood cobalt. In a case-control analysis, CoGR scores of revised patients with histologically confirmed adverse reactions to metal debris (and specifically aseptic lymphocyte-dominated vasculitis-associated lesions (ALVAL)) were compared with controls (revised patients with no signs of ARMD and unrevised patients with FJS of 75 or more) using Firth logistic regression. Results: 376 patients were included: 312 unrevised patients and 64 patients who underwent revision. Each one-unit increase in CoGR score was associated with a 9.8 point lower FJS (95% confidence interval (CI) 4.2 to 15.4 points; p < 0.001). This increased to a 17.5 (9.4 to 25.5) point reduction per CoGR score unit in patients with blood cobalt above the median level. Comparing 28 ARMD cases (12 with ALVAL) with 177 controls, each one-unit CoGR increase was associated with odds ratios of 1.90 (CI 1.34 to 2.75) for ARMD and 3.05 (CI 1.89 to 5.34) for ALVAL. Conclusions: A higher CoGR score was associated with worse patient-reported outcome and higher odds of histologically confirmed adverse reaction to metal debris at revision. Adverse immune responses may be a more significant factor in unexplained pain after KA than is generally recognised.

While absolute blood biomarkers have long guided diagnosis, their rate of change often provides greater diagnostic value. For the Limb Girdle Muscular Dystrophies studied here, increased muscle weakness is associated with abnormal sarcolemma repair. Time course analyses were made to changes in muscle-derived plasma enzymes after modest physical activity of ambulatory inpatients. Blood samples at 20 selected time points at variable intervals were obtained at rest, and before and after routine morning activities and motor function testing. After these activities, plasma enzyme levels increased in a similar way, suggesting damage and leakage from skeletal muscle. The levels then decreased in a similar way, suggesting that muscle cells stopped leaking and enzymes were subsequently cleared from the blood. The complex temporal changes were modeled using both continuous time and data features to reduce the number of parameters required to describe the irregularly sampled, interrupted, time series data. Unlike individuals with cardiac muscle ischemia or following intense exercise, there was no extended post-injury rising phase of enzyme levels. In contradistinction, levels fell once activity ceased. Time series analyses of blood biomarkers most likely provide an assay and index of sarcolemma fragility and by extension skeletal muscle damage.

Background: Safely walking through complex environments requires the use of visual information to plan and regulate steps, while managing competing cognitive demands. Age-related changes in visual control of gait and executive function may contribute to unsafe stepping behaviour, particularly under cognitive load. Route previewing may support visual motor planning, but its effects under dual task conditions in older adults are not well understood. Research Question: Does cognitive dual tasking influence gait and gaze behaviour during adaptive walking in older adults, and does previewing the walking route before gait initiation mitigate these effects? Methods: Thirty nine community dwelling older adults (Mage=73.4 years, SD=8.1; 14 male) completed four adaptive walking conditions, combining single and dual-task walking with and without previewing. Per condition, participants completed six trials across different 8-m long coloured walking routes. Gait characteristics were assessed using an instrumented walkway and video-analysis, while gaze behaviour was recorded using mobile eye tracking. Cognitive load was manipulated using a serial subtraction task. Gait and gaze outcomes were evaluated using linear mixed effects models. Results: Dual task performance significantly increased stepping errors, cross-steps, and double limb support, while reducing stride length (p < .001). It also significantly increased the number and duration of task irrelevant fixations (p < .001). After previewing, participants exhibited more efficient gaze behaviour, as evidenced by looking further ahead (larger forward gaze transitions) and fewer irrelevant gaze fixations (p < .002). Significant Task-by-Preview interactions revealed that previewing mitigated the negative effects of dual-tasking on stepping errors and cross steps (p < .001). Significance: Route previewing prior to gait initiation attenuates negative effects of cognitive load on adaptive gait in older adults, likely by supporting visual motor planning. These findings highlight the potential value of simple visual planning interventions for improving adaptive gait in older adults.

Objective: To examine changes in function and pain interference among patients utilizing a digital exercise therapy application (DETA) for knee and shoulder pain. Methods: We conducted a retrospective analysis of data from patients utilizing a DETA for non-operative knee and shoulder pain. Primary outcomes for the study were 8-week changes in physical function, measured using the PROMIS-Physical Function (knee pain) and PROMIS-Upper Extremity Function (shoulder pain); and pain interference, measured using the PROMIS-Pain Interference. Data on patient characteristics was used to examine outcomes among specific patient subgroups. Results: We observed a 3.5 point (SD: 7.8) increase in function and a 3.9 point (SD: 7.5) decrease in pain interference overall (p<0.001), with changes in function and pain interference surpassing the minimal clinically important difference for patients with knee and shoulder pain. Patients with knee pain experienced greater improvements in function than those with shoulder pain (p=0.02), as did patients who report moderate-high levels of exertion during exercise compared to those reporting low levels of exertion (p=0.05). We saw greater reductions in pain interference among those with higher education (p=0.03), those with more acute symptoms (p=0.01) and those reporting moderate-high levels of exercise exertion (p=0.02). Conclusion: We observed a clinically meaningful improvement in pain interference and function among patients utilizing a DETA for knee and shoulder pain. Patients with knee pain, higher levels of education, more acute symptoms, and those who reported higher levels of exertion with exercise experienced the greatest changes in function and pain. Impact Statement: This study indicates that self-guided interventions, such as those delivered through a DETA, may be beneficial for patients with knee and shoulder pain. These results may also inform the development of patient profiles that can be used to identify patients most appropriate to receive care through a mobile application.

Altered walking mechanics in individuals with obesity can contribute to knee osteoarthritis. The gait deviations may become more pronounced during obstacle crossing. In women, body fat distribution may further influence knee load, especially when excess fat accumulates in the thighs and hips. However, relatively little is known about how regional fat distribution affects gait in women with obesity. This study investigated how obesity and, among women, different fat distributions (Apple: more abdominal fat; Pear: more lower-limb fat) influence knee biomechanics during walking with and without obstacle crossing. Participants were 15 controls without obesity (NB) and 27 with obesity (OB). Within female participants, 10 without obesity (fNB) were compared with 20 with obesity, stratified by waist-hip ratio (Apple:10, Pear:10). Speed-adjusted statistical parametric mapping applied a general linear model (NB vs. OB) and an analysis of covariance (fNB vs. Apple vs. Pear). OB exhibited a significantly greater late-stance knee extension moment than NB across all tasks, and this difference persisted among fNB, Apple, and Pear in obstacle tasks (p<0.05). OB walked with reduced knee flexion during the early-stance leading limb after crossing a medium-height obstacle (p=0.048) and a high-height obstacle (p=0.008) compared to NB. There were significant body-shape effects (p<0.05), and post-hoc comparisons confirmed that Pear had lower knee angles than fNB in both leading-limb conditions after crossing medium- and high-height obstacles (p=0.008 and p=0.001, respectively). These findings suggest that obstacle crossing helps illuminate how excess weight influences knee biomechanics, and how regional fat distribution modulates the degree of this alteration.

Aims: Our primary aim was to determine the immediate effects of using a supported stepping device on the real-time locomotor behavior of pre-walking infants with Down syndrome (DS). Our secondary aim was to characterize the role of the caregiver in facilitating infant locomotor behavior by quantifying infant-initiated and caregiver-initiated walker movement, and to test whether walker movement encourages stepping behavior. Methods: Pre-walking infants with DS played with their caregiver in two conditions--with and without assistance from a wheeled suspension walker. To examine changes across development, we recorded infants across one to four sessions from 10 to 19 months of age. Results: Across developmental stages, we found that suspension walkers robustly increased infants' locomotor behavior: The walker increased upright time, percent time stepping, stepping rate, upright bout rate, percent time locomoting, and total bout rate. Most walker movement was initiated by caregivers, and infants stepped more while the walker was moving compared to stationary. Conclusions: Even without practice, pre-walking infants with DS were able to take advantage of the suspension walker to increase their locomotor behavior. Caregivers facilitated infants' activity by moving the walker. Future work will examine the potential of overground suspension walkers for home-based intervention.

Introduction Low back pain (LBP) is a common leading cause of functional disability in adults worldwide, presenting with Modic changes that are visible within the endplates of the vertebral body under magnetic resonance imaging (MRI). Modic changes (MC) are not just a coincidental imaging finding; they reflect underlying pathology that needs treatment focus. This study aimed to ascertain the prevalence and patterns of Modic changes in the lumbar spine among adult patients with a history of low back pain attending the Kilimanjaro Christian Medical Centre (KCMC) Orthopedic clinic. Methods A descriptive cross-sectional study was conducted at the KCMC orthopedic clinic from 2nd October 2024 to 30th May 2025. Data from adult patients with a history of low back pain who had undergone lumbar spine MRI were collected, cleaned, and analyzed in SPSS (version 25). Categorical variables were summarized by frequency and proportion, while continuous variables were summarized using the mean and standard deviation. Frequency tables, histograms, and pie charts were used for results presentation. Results Of the 283 patients enrolled in the study, the mean age was (57.2 {+/-}15.7) years, with the majority (145; 51.2%) being aged > 59 years. Most patients, 203 (71.7%), were females, while 176 (62.2%) were married, and 142 (50.2%) were overweight. The prevalence of MC on the lumbar spine among patients with a history of low back pain was 66.4% (n=188). Among patients with lumbar spine MC, the majority, 112 (59.6%), were aged over 59 years, and 125 (66.5%) had lumbar spine MC type II, which was the most predominant compared to other types of MC. Conclusion Modic changes on the lumbar spine are prevalent in adult patients with low back pain, particularly those over 59 years, with type II being the most common. Healthcare professionals and policymakers should recognize Modic changes as clinically relevant findings that require consideration in the management of patients with a history of low back pain rather than dismissing them as mere incidental or coincidental observations.

Background: Long COVID can result in persistent functional limitations, pain, and fatigue after acute COVID-19. Evidence describing these outcomes among survivors in Bangladesh remains limited. This study assessed functional impairment, pain, and fatigue and explored factors associated with these outcomes among long COVID survivors in Bangladesh. Methods: This multisite cross-sectional study included 240 adults with a history of COVID-19. Functional status was assessed using the Post-COVID-19 Functional Status Scale. Pain and fatigue were assessed using the Brief Pain Inventory and Brief Fatigue Inventory, respectively. Descriptive statistics, Spearman correlation, and regression analyses were used to examine functional impairment and factors associated with pain and fatigue outcomes. Results: Functional limitations were common, with moderate limitation particularly frequent in basic activities of daily living, while slight limitation predominated across several other domains. Pain and fatigue measures showed significant correlations. Older age was associated with greater impairment in basic activities of daily living. Booster vaccination was associated with lower pain and fatigue scores, although the booster subgroup was small (n = 17). Tobacco non-use was also associated with lower scores across several pain and fatigue domains. Physiotherapy-related variables showed associations with some functional and symptom outcomes; however, these findings may reflect confounding by indication because participants with greater impairment or more complex symptoms may have been more likely to receive rehabilitation. Conclusions: Long COVID survivors in Bangladesh experience substantial and multidimensional functional, pain, and fatigue burdens. The findings support a comprehensive assessment that considers functional status, pain, fatigue, and participation together. Longitudinal studies with larger samples and standardized rehabilitation protocols are needed to clarify symptom trajectories, identify potentially modifiable factors, and evaluate the effectiveness of individualized rehabilitation interventions.

Computer mouse weight has been proposed to influence human motor performance, but existing evidence comes largely from small, short-duration controlled studies, leaving its relationship to performance during naturalistic gameplay unresolved. We analyzed one-week skill improvement in Aimlabs, a popular first-person shooter aim-training and assessment platform, among 9,067 players whose telemetry recorded a mouse-model change (switchers) during self-directed game use, using a 21-day baseline and 7-day follow-up; 4,991 players with a single mouse model (non-switchers) observed over matched pseudo-anchor intervals provided a secondary contextual comparison. Post-switch mouse weight was represented by eight bands spanning 35-124 g. The primary multivariable generalized additive regression model accounted for baseline skill, pre- and post-switch practice intensity, and pre- and post-switch mouse sensitivity, and allowed the association between weight band and improvement to vary with baseline skill, post-switch practice, and post-switch sensitivity. For each weight band, predicted mean one-week improvement was standardized to the observed distribution of these covariates among switchers and reported in percentile-rank points. Statistical significance was evaluated using 1,000 permutations in which observed mouse weights were randomly reassigned among switchers without replacement and the model was refitted to generate empirical null distributions for the weight-related test statistics. Predicted improvement differed significantly across the eight weight bands (p = 0.001). Pairwise comparisons identified significant differences between bands (p < 0.05), but no single band was associated with significantly greater predicted improvement than all seven others. In this large naturalistic cohort, predicted improvement was highest for players with 35-44 g mice, followed by 45-54 and 55-64 g, and several pairwise comparisons showed significantly greater improvement in lighter than in heavier weight bands. Across the examined baseline-skill profiles, the lowest predicted improvements occurred in either the 85-99 or 115-124 g band. Predicted improvement differed across weight bands at the 25th-percentile and median baseline-skill values (p = 0.002 and p = 0.003) but not at the 75th percentile (p = 0.153). However, the weight-band x baseline-skill interaction was not significant (p = 0.181), indicating that the analysis did not establish that weight-related differences varied by skill level.

Background: Post-stroke spasticity is commonly assessed using the Modified Ashworth Scale (MAS), despite its limited objectivity and variable reliability. This study introduces ScoreE, a novel isokinetic dynamometry-derived metric designed to quantify elbow and wrist flexor hyper-resistance by comparing patients torque-angle profiles with a healthy reference corridor. Methods: Thirty-five post-stroke patients and twenty-one healthy controls were included. Elbow and wrist hyper-resistance was assessed using the MAS and an isokinetic dynamometer in two testing conditions: seated on the dynamometer chair (ergo chair) and seated in the patient wheelchair. Two dynamometer-derived metrics were analyzed: ScoreE and peak torque (PeakT). Feasibility, inter-rater and test-retest reliability, and associations with MAS grades were assessed. Exploratory PRE-POST changes following a 10-min local vibration session were also described. Results: ScoreE showed good to excellent inter-rater and test-retest reliability across joints and testing conditions. Inter-rater ICCs ranged from 0.81 to 0.89, and test-retest ICCs from 0.76 to 0.93. PeakT showed moderate to good reliability. In contrast, MAS agreement was lower and more variable. ScoreE showed moderate associations with MAS grades, particularly at the elbow, with weaker and less consistent associations at the wrist. MAS assessment was faster, but all assessments were well tolerated, with median pain ratings of 0/10 in all testing conditions. PRE-POST vibration changes were small and heterogeneous, preventing formal assessment of responsiveness. Conclusion: ScoreE provides a reliable, objective, and visually interpretable quantification of post-stroke elbow and wrist flexor hyper-resistance. By comparing the full torque-angle profile with normative data, this approach preserves information on both the magnitude and angular span of abnormal resistance, supporting its potential for targeted longitudinal monitoring.

BackgroundPersistent postural-perceptual dizziness (PPPD) is a chronic functional dizziness disorder characterized by unsteadiness, hypersensitivity to motion and visually complex environments. Although increasingly investigated, the role of the different factors involved remains unclear. This study aims to comprehensively characterize PPPD across clinical, biological, and behavioral domains. MethodsData from 18 PPPD patients and 20 age- and sex-matched healthy control volunteers (HC) were analyzed, including clinical and psychological questionnaires, a neuropsychological battery, salivary markers, posturography under different conditions, and gait analysis under single- and dual-task demands. ResultsPatients reported greater depressive symptoms, higher perceived stress, and reduced quality of life than HC, but showed no neuropsychological deficits and comparable past psychological trauma and personality traits. Salivary stress marker levels were similar to HC. Gait analysis revealed a slower, cautious gait in patients, which worsened without vision, with no differences in automaticity (stride time variability). Postural assessments showed greater sway and enhanced low-frequency oscillations, exacerbated by absence of visual input in PPPD. Visual reliance for postural control correlated negatively with subjective symptom severity, but not other symptom-related measures. ConclusionPPPD patients have lower mood and increased perceived stress, with no increase in biological stress markers compared to HC. Cognition, personality, and exposure to past trauma might be less relevant than previously hypothesized. Patients show visual dependence for gait and postural control, likely a maladaptive compensatory mechanism. These findings support interventions targeted at reducing visual dependence and at improving mood, rather than interventions focusing on psychological trauma. SummaryO_LIWhat is already known on this topic - PPPD (Persistent Perceptual Postural Dizziness) is a functional dizziness disorder characterized by different biopsychosocial factors, often investigated in isolation. C_LIO_LIWhat this study adds - PPPD patients have higher depression and perceived stress scores, lower quality of life, but show no differences in past trauma, personality traits, and biological stress markers, compared to healthy controls. They also show a reliance on vision both for gait and for postural control, with increased low-frequency oscillations in the anteroposterior direction. Visual dependence is likely maintained by its perceived role in symptom reduction. C_LIO_LIHow this study might affect research, practice or policy - These findings support rehabilitation strategies aimed at reducing reliance on vision and increasing reliance on vestibular inputs, but not interventions focusing on past traumatic experiences. C_LI