Frontiers in Sports and Active Living

Abstract Objective HYROX is a rapidly growing hybrid fitness competition combining running with functional exercise stations. Our objective was to describe the 12-month prevalence, characteristics and severity of self-reported HYROX-related injuries. Methods We conducted an international cross-sectional online survey of 418 HYROX athletes. The primary outcome was the self-reported 12-month period prevalence of at least one HYROX-related injury; secondary outcomes included an exposure-adjusted lower-bound rate per 1000 hours of total training exposure and the profile and severity of the most significant injury. Associated factors were examined by multivariable logistic regression. Results Overall, 208 of 418 participants (49.8%, 95% CI 45.0 to 54.5) reported at least one HYROX-related injury. The exposure-adjusted lower-bound rate was 1.65 reported injuries per 1000 hours of total training exposure. Injuries mainly affected the lower extremity, most commonly the knee (20.8%); tendon-related complaints were the leading type (41.6%) and most were of gradual onset. Among participants with severity data, 20.3% reported more than 28 days of training interruption or no return to their previous performance level. Higher HYROX-specific training frequency was the only factor independently associated with injury reporting (adjusted OR 1.61, 95% CI 1.20 to 2.16; p = 0.001). Conclusion Approximately half of respondents reported at least one HYROX-related injury during the preceding 12 months, predominantly involving gradual-onset lower-extremity complaints. Higher HYROX-specific training frequency was associated with injury reporting, although the cross-sectional design precludes causal interpretation. Prospective, exposure-based surveillance is needed to quantify HYROX-specific injury incidence and burden and examine whether training frequency, load distribution and recovery contribute to injury risk.

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.

ObjectiveDescribe and compare the biomechanical severity of head acceleration events (HAEs) associated with diagnosed concussion in elite mens and womens rugby league using instrumented mouthguards (iMGs) and evaluate the diagnostic accuracy and screening performance of severity metrics within the current Head Injury Assessment (HIA) process. MethodsA prospective cohort of 398 men and 252 women from Super League teams wore iMGs across 515 matches. Following a matching and data quality screening procedure, 123 HIAs (106 men, 17 women) were matched to HAEs, 52 of which were diagnosed concussions (44 men, 8 women). High-magnitude asymptomatic control HAEs (22,676 men, 3,200 women) were sampled proportionally to the number of HIAs. A range of biomechanical severity metrics were calculated for HAEs. Statistical comparisons between outcomes were made. Receiver operating characteristic (ROC) analysis evaluated diagnostic accuracy (ability to predict diagnosed concussions within the HIA). Precision-recall analysis evaluated screening performance (ability to discriminate observable concussion signs from asymptomatic events). ResultsDiagnosed concussions had greater severity than asymptomatic HAEs across all metrics in both sexes. For diagnostic accuracy, area under the ROC curve ranged from 0.61 to 0.72 in men and 0.53 to 0.86 in women. For screening performance, optimal thresholds in several metrics provided theoretical improvements to precision over current thresholds used in rugby, but recall remained <0.20. ConclusionThese findings support integrating iMG-derived severity metrics into a multimodal, clinician-led HIA pathway as objective adjuncts for diagnosis and screening, while reinforcing that they cannot replace clinical judgement or other assessment modalities. What is already known on this topicInstrumented mouthguards are increasingly used in rugby to quantify head acceleration events and trigger Head Injury Assessment (HIA) alerts, but current screening thresholds based on simple peak kinematics have low sensitivity for identifying HAEs linked with visible concussion signs, and very few iMG-measured concussions, particularly in women, have been reported in current research. What this study addsThis study provides the largest dataset of iMG-measured concussions in any sport, shows that concussive HAEs are more severe than asymptomatic events across multiple biomechanical metrics in both sexes, and identifies several severity metrics with diagnostic accuracy comparable to existing HIA sub-tests and modest theoretical improvements over current screening thresholds. How this study might affect research, practice or policyThese findings support incorporating iMG-derived severity metrics as objective adjuncts within clinician-led HIA pathways, highlight the need for sex-inclusive iMG datasets and multimodal concussion identification, and may inform future refinement of iMG screening thresholds in elite rugby and other contact sports.

Background: Sweeping sliders with large horizontal break are hypothesized to be associated with arm injury, and prior work suggests a link between slider usage, arm angle, and injury. Purpose: To evaluate whether arm angle and slider horizontal movement are associated with elbow or forearm injury risk in MLB pitchers. Study Design: Retrospective cohort study; Level of evidence, 3 Methods: Statcast data from 2020-2025 and injury data were used to study the relationship between sliders and arm injuries. Pitchers with at least 30 innings pitched (IP) were evaluated for same- and next-season injury incidence to the Elbow, Forearm, or Elbow/Forearm. A generalized additive model (GAM) related pitch-level variables to injury incidence, and average marginal effect (AME) odds ratios are reported for main effects. Results: All fits were significant at p<.01. Fits for same-season (N=1,957, p=.00008, R2=.066) and next-season (N=2,511, p=.00005, R2=.053) Elbow/Forearm injury were significant at p<.001. Same-season (R2=.061) and next-season (R2=.055) Forearm injury fits had p=.001. Main effects for slider glove-side movement and fastball usage, their interactions with arm angle, and arm angle main effects were the most predictive features. Across the three fits where the slider glove-side movement main effect was significant, odds ratios ranged from 1.03 to 1.07, meaning that each additional inch of slider glove-side movement was associated with a 3% to 7% increase in the observed injury incidence. Furthermore, this effect was magnified at high arm angle and muted at low arm angle. Conclusion: We observed that slider horizontal movement, arm angle, and their interaction were significantly associated with incidence of Forearm and combined Elbow/Forearm injury. This effect was weak or non-existent at low arm angles and strong at high arm angles, suggesting that arm angle moderates the risk of slider horizontal movement, and providing evidence that sliders with large horizontal break (e.g. sweepers) may pose an injury risk. Keywords: baseball; sweeper; slider; arm angle; horizontal movement; elbow injury; forearm injury

Static force plates (FP) are the gold standard for measuring ground reaction forces (GRF) and computing joint moments through inverse dynamics in gait analysis. However, they are restricted to controlled environments, and the number of steps analyzed is limited by the plates embedded in the floor. To address these limitations, portable solutions such as sensorized insoles, socks, or shoes have emerged. Yet, creating wearable systems capable of measuring three-dimensional GRF in real-world conditions remains challenging. Current sensorized shoes often incorporate thick sensors (up to 2 cm), reducing usability and limiting their application in pathological populations or dynamic tasks like running. This study evaluates the usability of ShokacShoes, a novel sensorized shoe integrating three thin, three-dimensional force sensors, and explores its potential as a Wearable Force Plate (WFP). Eight healthy participants performed slow, natural, and fast walking using two insole configurations. Force and temporal metrics were derived from WFP and FP data. Results indicate that WFP enables accurate step segmentation and detects significant effects of speed and insole type on temporal and force metrics, confirming its reliability under different walking conditions. Comparisons with FP revealed differences in force metrics and signal morphology, though temporal parameters remained consistent. These results are likely due to sensor quantity and positioning. Thereby, ShokacShoes represent a valid solution capable of measuring three-dimensional forces within commercial footwear. Future work will focus on validating the applicability of a new version of ShokacShoes against gold-standard FP in a comprehensive validation study involving diverse real-world scenarios and pathological conditions.

Background: Newly available arm angle data offers a new dimension to understand rising rates of arm injury in MLB pitchers. Purpose: To evaluate the relationship between arm angle, pitch characteristics, and elbow and forearm injury in MLB pitchers.<br><br> Study Design: Retrospective cohort study; Level of evidence, 3 Methods: Statcast data from 2020 to 2025 and MLB injured list (IL) data were used to evaluate arm angle and pitch characteristics in relation to elbow and forearm injuries. Results are presented with and without requirements on prior season workload and for same-season and next-season injury incidence. A generalized additive model (GAM) was used to capture non-linear dependence and interactions between selected features and injury incidence to the elbow or forearm. Average marginal effect (AME) odds ratios are reported for main effect terms. Results: N = 3,812 pitcher-seasons were included. 29% pitchers who underwent UCLR did so in the same season as a forearm injury (tmean=44, tmedian=27 days to surgery). Arm angle, fastball usage, and their interaction were the three most predictive features. Arm angle was positively related to incidence of injury (ORmeanAME=1.014), fastball usage was inversely related to incidence of injury (ORmeanAME=0.243), and arm angle moderated the effect fastball usage at high arm angle, where increased usage was no longer protective. Slider velocity (ORmeanAME=1.072), spin rate (ORmeanAME=1.001), and usage (ORmeanAME=2.039) also significantly predicted injury risk. Fastball velocity was not significant in any fit, with ORmeanAME=0.999 across all fits. Fit-level Nagelkerke R2 values ranged from .019 to .052. Conclusion: Fastball usage and arm angle, not velocity, predicted elbow and forearm injury risk among MLB pitchers, and arm angle was the single most predictive feature. The heterogeneity of risk factors as a function of arm angle, and the novelty of MLB arm angle data, may explain why fastball usage has been previously underexplored as a risk factor. Keywords: baseball; arm angle; fastball velocity; fastball usage; spin rate; UCL; ulnar collateral ligament; elbow injury; forearm injury; Statcast

Few studies have focused on plyometric interventions lasting over 24 weeks in team-sport athletes, and little research has validated the practical utility of personalized force-velocity assessment. A total of 36 university volleyball athletes (21.35{+/-}1.87 years) were randomly allocated into either a 32-week plyometric training group (PT, n=18) or a low-intensity active control group (CON, n=18); 34 players completed the trial (17 per group). PT completed three weekly training sessions, while CON maintained routine technical practice and general low-intensity conditioning. CMJ height, RSImod, and force-velocity profiles (F, V, peak power, FV imbalance) were evaluated at baseline and at weeks 8, 16, 24, and 32. PT increased CMJ height from 33.1{+/-}4.8 cm to 38.4{+/-}5.2 cm, a net gain of 5.3 cm (p<0.01, d=0.99, 95% CI [0.57, 1.41]); CON showed negligible change (+0.5 cm, p=0.68). The PT group also improved RSImod by 31.6% (d=0.87, 95% CI [0.45, 1.29], p<0.01) and peak power by 18.4% (d=0.76, 95% CI [0.35, 1.17], p=0.004). Meanwhile, FV imbalance dropped markedly by 31.4%, from 28.3% to 19.4% (d=-0.68, 95% CI [-1.09, -0.27], p=0.024). No significant F-V changes occurred in CON. The reduction in FV imbalance correlated moderately with CMJ gain (r= - 0.53, p=0.024), whereas the change in peak power did not (r=0.21, p=0.39). Overall, 32 weeks of periodized plyometric training enhanced jump performance, reactive strength, and power, and reduced the force-velocity (FV) imbalance by approximately 31%. The magnitude of improvements in jump performance (16%) and FV imbalance reduction (31%) observed in this 32-week periodized program fall within a similar range to previously reported effects of individualized F-V training (14% and 40%, respectively). However, direct numerical comparisons are confounded by differences in study design, population, and methodology; head-to-head trials are needed.

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.

Purpose: Identifying head impacts linked to brain injury in sport remains challenging. Instrumented mouthguards quantify head-impact kinematics, and finite element (FE) modelling can transform these data into brain strain estimates, which may better reflect injury risk than kinematics alone. Here, we examined associations between mouthguard-measured kinematics, FE-derived strain, and plasma brain injury biomarker GFAP following head impacts. Methods: We analysed 41 video-verified impacts from male Australian football players, including 22 assessed for concussion (17 diagnosed) and 19 unassessed. Instrumented mouthguards recorded peak linear acceleration (PLA), peak rotational acceleration, and peak rotational velocity (PRV). Brain strain was estimated using the Imperial College FE brain model, and plasma GFAP was quantified using Simoa. Biomechanical-GFAP associations were examined using Spearman correlations and segmented regression. Results: For impacts overall, plasma GFAP was moderately correlated with PLA ({rho}=0.46, 95% CI: 0.20-0.66), PRV ({rho}=0.53, 95% CI: 0.20-0.78), and strain ({rho}=0.60, 95% CI: 0.32-0.80). Associations were stronger within concussion cases for strain ({rho}=0.86, 95% CI: 0.58-0.97) and PRV ({rho}=0.64, 95% CI: 0.15-0.93). Piecewise regression identified strain levels above which strain-GFAP relationships steepened across the whole-brain and brainstem. In concussion cases, supra-threshold brainstem strain was associated with greater symptoms. Conclusion: Finite element brain strain may better predict brain injury risk following a sport-related head impact than peak acceleration metrics. Stronger associations with plasma GFAP, particularly among concussion cases, and evidence of a biomechanical threshold, support the use of biomarker-informed strain measures in future risk modelling and the development of brain injury screening thresholds.

Importance: There are very few interventions designed for individuals with the most severe mobility impairments. Robotic walking may be an effective way to facilitate exercise in this population. Objective: To examine how robot-assisted walkers physical parameters and user characteristics moderate the exercise intensity achieved by individuals with neuromotor disorders causing mobility impairments. Design: A prospective study. Intervention: A single-session intervention involving an overground robot-assisted walker that can be used in an endurance mode requiring no voluntary movement or a strength mode during which voluntary movement could impact the gait pattern. Participants: Individuals with pediatric-onset mobility impairments Main Outcome Measures: Participants were characterized based on their age, sex, diagnosis, and Gilette Functional Assessment Questionnaire (FAQ) levels. Heart rate during the final minute of four 5-minute walking conditions: strength mode at fast speed, strength mode at slow speed, endurance mode at fast speed and endurance mode at slow speed was expressed as a percentage of each participant heart rate reserve (%HRR). Linear mixed-effects models were used to evaluate the impact of speed, device mode and user characteristics on the level of exercise achieved. Results: 29 individuals (aged 2-26 years) with mobility impairments (FAQ levels 1-6) completed this study. Fast speeds were associated with a higher %HRR (beta= 2.11, SE = 1.03, p = 0.044). Participants in FAQ class 1 exhibited significantly higher %HRR compared with those in FAQ classes 2 and 3 (beta=18.6, SE=7.31, p=0.017; beta= 16.9, SE = 8.13, p = 0.047, respectively). No other device or participant characteristics were associated with exercise intensity. Conclusions: To facilitate higher exercise levels, users of robot-assisted walkers can increase their speed. Individuals who cannot take steps due to their neuromotor impairments experience the highest levels of exercise. Relevance: The findings in this study highlight the promise of robot-assisted walkers to improve health, particularly in those who often face the greatest barriers to exercise.

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.

Introduction: Daytime sleepiness (DS) can compromise athletic performance; however, its influence on Brazilian Jiu-Jitsu (BJJ) athletes remains poorly understood. Daytime naps have been suggested as a strategy to alleviate the effects of DS; however, their impact on physical and specific performance remains inconsistent. Thus, this study investigated the influence of different levels of daytime sleepiness on the physical and specific performance of BJJ athletes and verified the effects of daytime napping on these outcomes. Methods: This investigation employed a randomized, controlled, crossover clinical trial design involving 19 amateur Brazilian Jiu-Jitsu (BJJ) athletes who exhibited excessive daytime sleepiness. Participants performed two experimental conditions, with a 30-minute nap (N30) and without a nap (NN), in a randomized order. Vertical jump (CMJ and SJ), anaerobic power (Wingate ), kimono grip strength (KGST), and specific performance were evaluated using the Jiu-Jitsu Anaerobic Performance Test (JJAPT). Data were analyzed using mixed linear models. Results: Daytime sleepiness significantly influenced all parameters of specific performance (JJAPT), with worse performance observed in athletes classified as having abnormal sleepiness. The opportunity to nap increased the total number of repetitions in the JJAPT of four sets ({approx}20 repetitions; p < 0.001), without consistent changes in physical performance tests. An interaction between napping and sleepiness was observed in relation to isometric endurance strength, indicating that napping may provide greater benefits to athletes experiencing abnormal sleepiness. Conclusion: High levels of daytime sleepiness are associated with reduced specific performance in BJJ athletes. Daytime naps are a simple and potentially effective strategy to mitigate these effects and improve specific performance, reinforcing the importance of monitoring sleepiness and individualizing recovery strategies.

[Purpose] By pairing repeated peripheral muscle fatigue induction with a functional and ADL-based assessment, this study tests whether hand muscle fatigue alone is sufficient to im pair fine motor performance in healthy adults performing ADL-inspired tasks. [Participants and Methods] Thirty healthy male and female university students performed 11 tasks twice, once in the pre-fatigue condition and once in the post-fatigue condition. The performance of each task was graded on a 0-4 scale. The score and the time to finish the task (TTFT) were recorded twice, for both the pre- and post-fatigue phases. Maximum force gen eration (MFG) of each participant's grip was recorded prior to the tasks in the pre-fatigue phase and again in the fatigue condition after performing the fatigue protocol. [Results] Muscle fatigue did not have a significant effect on the fine motor performance of the thirty participants, neither (TTFT) nor the scores of each task (p > 0.05) (r=0.08). In contrast, hand muscle fatigue led to a significant decrease in the mean (MFG) for both males and females (p<0.01). [Conclusion] Hand muscle fatigue led to a significant decrease in the mean grip MFG for both sexes. However, this reduction did not translate into impaired fine motor performance during ADL-like tasks. Consequently, under muscle fatigue, hand grip changes during fine tasks tested are rare and have minor to no impact on hand performance. This study suggests that acute peripheral muscle fatigue can coexist with preserved fine motor performance in healthy populations.

Purpose: Treadmills (TM) are widely used for gait assessment in older adults (OA), yet their ecological validity across inclined terrain remains underexplored. This study compared spatiotemporal, physiological, and kinetic gait outcomes between TM and overground (OG) walking across flat, uphill, and downhill terrain in OA and younger adults (YA), and examined sensorimotor predictors of speed discrepancies. Methods: Twenty-six OA (70{+/-}6 years; 22 women) and 24 YA (26{+/-}5 years; 7 women), none with prior TM experience, completed matched TM and OG trials across three terrain conditions. Self-selected TM speed was determined using a bidirectional protocol. The modified Clinical Test of Sensory Interaction in Balance quantified sensorimotor profiles. Mixed-design ANCOVAs and multiple regression examined condition, inclination, and group effects with sex as a covariate. Results: TM speeds were consistently slower than OG across all conditions in both groups ({Delta} = -0.35 m/s, d = -1.67), with shorter stride length, lower cadence, and altered support phase timing; YA showed larger reductions and a greater shift toward double support than OA. Foot clearance at midswing was largely preserved across modalities. TM walking elicited higher heart rate and RPE despite slower speeds, most pronounced in OA uphill. Ground reaction forces and loading rates were substantially reduced on the TM. Sensorimotor profiles predicted the downhill speed discrepancy (R2 = 0.49), with vestibular and somatosensory contributions as independent predictors alongside age group. Conclusion: TM-derived speed, spatiotemporal, and physiological measures are not interchangeable with real-world ambulation data in OA across inclined terrain.

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.

Therapeutic footwear with rocker soles is widely used to reduce plantar pressure in individuals at risk of diabetic foot ulceration. Of the various rocker sole characteristics, apex position, rocker angle, and apex angle have been extensively studied; however, the effect of forefoot rocker curvature has been seldom investigated. The aim of this study was to assess the isolated effect of forefoot rocker curvature on plantar pressure distribution, lower limb gait kinematics, and comfort. Ten healthy adults walked in a modular footwear setup with three interchangeable midsoles featuring a straight-line rocker profile (CRi), a rocker radius of 60% (CR60), and 45% (CR45) of the shoe length. In-shoe plantar pressure was measured using 99-sensor capacitive insoles. Kinematics of lower limb joints were measured via inertial measurement units. Comfort-related parameters were assessed using a Visual Analog Scale. Data were analyzed using non- parametric tests. CRi demonstrated significantly lower pressure at the metatarsal heads than CR60 and CR45 (kPa; median[Q1-Q3]; mean pressure=80 [67-81]; peak pressure=151 [139-169]; p=0.002). CR45 showed significantly lower mean pressure and pressure-time integral in the midfoot than CRi (p=0.002). CR60 showed the largest maximum dorsiflexion angle (deg, median [Q1-Q3]: CR60=17.8[13.4-23.5]; p<0.001) and range of motion (deg: CR60=20.3[18.8-23.3]; p=0.007). CRi was perceived as the least comfortable rocker condition (score 0-100; median[Q1-Q3]; overall comfort=44 [35-57]; p=0.008). A straight rocker maximizes offloading at the expense of ankle kinematics and comfort; lower rocker radii enhance comfort, thus making the rocker curvature a key design parameter for therapeutic footwear.

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.