BACKGROUND:Human muscle-tendon units (MTUs) exhibit significant plasticity and are subject to structural and functional alterations in response to various pathological conditions, such as diseases or disorders. The assessment of these pathological modifications, as well as the evaluation of therapeutic interventions, necessitates the application of robust and scientifically validated examination methodologies. In this study, a simple approach combining two-dimensional (2D) ultrasound and three-dimensional (3D) motion capture was developed and evaluated with regard to the reliability of dynamic length measurements of the gastrocnemius medialis (GM) muscle-tendon unit (MTU), muscle belly, and Achilles tendon. METHODS:Ten participants were included in the study. To evaluate the reliability of the novel approach, two ultrasound measurement sessions were performed. By combining ultrasound tracking of the myotendinous junction with 3D motion capture, the tissue lengths were assessed during overground walking. The intra-day and inter-day reliability of one examiner was determined using the coefficient of variation, standard error of measurement (SEM), minimal detectable change (MDC95), and intraclass correlation coefficient (ICC). RESULTS:The ultrasound approach showed excellent intra-day as well as inter-day reliability, with high ICC (≥0.95), small SEM (≤0.72 mm), and good MDC95 (≤2.1 mm) values for all investigated tissues. CONCLUSION:The proposed ultrasound approach demonstrated reliability in evaluating the GM MTU, GM muscle belly, and Achilles tendon tissue lengthening behavior during overground walking. These findings underscore its potential as an effective tool for examining the impact of training interventions or therapeutic strategies, including surgical procedures and conservative treatments such as stretching exercises and orthotic management.

This study examined the acute effects of combining short-duration static stretching with resistance-based activation, designed to induce post-activation performance enhancement (PAPE), on upper-limb muscle mechanics and neuromuscular performance. Fourteen competitive swimmers (7 male, 7 female) completed three randomized warm-up protocols: (1) general aerobic activity (CON), (2) Aerobic activity + 2 × 30 s of static stretching for latissimus dorsi and pectoralis major (SS), and (3) Aerobic activity + static stretching + 3 × 5 reps of resistance-band pull-overs (SS/PAPE). Shoulder extension range of motion (ROM), pectoralis- and latissimus dorsi-passive muscle stiffness and elasticity as well as isometric/dynamic torque, rate of force development (RFD), and power (isokinetic dynamometer) were assessed pre- and 10 min post-intervention. Results showed significant Time × Protocol interactions for ROM, maximal torque, RFD, and average torque. SS/PAPE elicited the largest ROM gain and improvements in dynamic performance, with significant increases in average torque and RFD, while SS led to modest ROM increases but small and non-significant declines in average torque and RFD. Passive muscle stiffness and elasticity exhibited non-significant changes in all groups. Although relative changes were comparable across sexes, males consistently outperformed females in torque and RFD, while females presented higher ROM than males. These findings demonstrate that integrating brief static stretching with sport-specific, high-intensity upper-limb activation can acutely enhance flexibility and explosive force generation without impairing performance. The Stretching + PAPE approach offers a practical, time-efficient warm-up strategy for overhead athletes, particularly in contexts where rapid force production at extended joint positions is essential.

Phasic increase of frontal midline theta (Fm theta) power has been described as a key indicator of cognitive processing, while relatively lower task-related Fm theta power is associated with reduced cognitive strain, reflecting less intensive cognitive processing. In a previous investigation, reduced task-related Fm theta power in relation to higher expertise, as well as higher setting anticipation performance in the domain of volleyball was identified. In the present study a single-session sham-controlled neurofeedback training (NFT) intervention was conducted to investigate the feasibility of Fm theta downregulation for the improvement of volleyball setting anticipation. A total of 24 volleyball novices was allocated to “Real” (n = 12) and “Sham” (n = 12) Fm theta downregulation NFT groups. Event-related de−/synchronization (ERD/S) of Fm theta during the NFT intervention, as well as pre−/post-NFT setting anticipation task performance and corresponding Fm theta ERD/S were analyzed. Additionally, resting EEG power directly before and after the experiment was examined. Incongruous with our expectations, the Real NFT group showed a tendency toward stronger event-related Fm theta synchronization compared with the Sham group during NFT. Anticipation task performance did not change significantly from before to after NFT in both groups, yet a significantly stronger event-related desynchronization of Fm theta was observed in the Real NFT group, during the post-NFT anticipation task measurement. A post-NFT rebound of Fm theta power could be responsible for this result. With our findings we provide further evidence for the existence of an apparent paradox of Fm theta downregulation, in which cognitive control mechanisms, associated with oscillatory Fm theta activity, appear to hinder explicit downregulation of Fm theta power through classical neurofeedback learning mechanisms.

In this Current Opinion, we revisit key terminological distinctions in sports sciences, emphasizing the implications of conflating related but distinct concepts, particularly range of motion (ROM) versus flexibility and flexibility training versus stretching. While often used interchangeably, these terms represent nuanced constructs with distinct physiological and practical implications. ROM encompasses both modifiable (e.g., soft tissue extensibility, neural control) and non-modifiable factors (e.g., bone structure), whereas flexibility is only one of several trainable components of ROM, largely referring to the extensibility of periarticular soft tissues. Misunderstanding these distinctions risks erroneous assessments and inappropriate exercise prescriptions. We also challenge the common practice of equating flexibility training with stretching. While stretching is effective to enhance flexibility, other methods, such as strength training at long muscle lengths and foam rolling, produce comparable chronic ROM gains. Furthermore, stretching has a diverse array of effects that extend beyond flexibility, including strength development and neural modulation. Mischaracterizing flexibility training as synonymous with stretching perpetuates myths and constrains innovation in training practices. By differentiating these terms, we advocate for clearer language in research and practice to avoid miscommunication and ensure effective training interventions. In summary, we propose that flexibility is only one component of ROM, and that flexibility training and stretching should not be equated. We hope this Current Opinion paper generates a healthy discussion within the sports science and medicine communities.

The 3D center of mass (CoM) is a primary quantity in the biomechanical analysis of sport, rehabilitation, and clinical movement, yet existing 3D pose tracking, mesh recovery, and multi-view triangulation methods either optimize 3D keypoint accuracy without anatomical constraints or carry compute and capture infrastructure too heavy to deploy where CoM tracking is most useful. As a result, the metric CoM remains difficult for coaches and movement analysts to measure from a single camera where athletes train and compete. In this work, we introduce MuyBridge, an on-device system that estimates the athlete's segmental center of mass trajectory from a single phone camera video stream. MuyBridge couples a compact 2D pose network and a distilled single-step monocular depth network through an analytic metric fusion that uses anatomical and physical priors to anchor the metric CoM, requiring no 3D or task-specific supervision. Evaluated on the athletic movements of AthletePose3D (running, track and field, and figure skating), MuyBridge achieves 33-41 mm vertical CoM error and 2.3-6.6

Tendinopathy is a disabling and painful condition commonly associated with repetitive mechanical loading. Eccentric training (ECC) has been widely used in rehabilitation but can be mechanically demanding and pain-provoking. Heavy-Slow Resistance Training (HSRT) has emerged as an alternative loading strategy for treatment of tendinopathies. This study aims to investigate the changes of chronic eccentric training (ECC) and HSRT on morphological, mechanical, and clinical outcomes in patients with patellar and Achilles tendinopathy. An electronic search was conducted in Pubmed, Scopus, and Web of Science in January 2024, with updated in January 2025 and April 2026. In total, 7176 studies were identified. After removing duplicates (n = 2543) the remaining articles were screened by two researchers by title and, if necessary, by abstract or full text to check eligibility. Studies investigating adults with Achilles or patellar tendinopathy who underwent ECC or HSRT were eligible. The outcomes assessed were tendon thickness, stiffness, cross-sectional area, neovascularization and young’s modulus, along with pain, muscle strength, and the Victorian Institute of Sports Assessment (VISA) questionnaire. After a thorough screening process, 16 studies were included in the review. Both interventions showed beneficial results on clinical and functional outcomes, increasing muscle strength and VISA questionnaire score on both tendons, and decreasing pain. Descriptively, the reduction in neovascularization was larger following HSRT than ECC (-23.2

Resistance training is crucial for athletic performance and clinical rehabilitation (El-Kotob et al., 2020). Practitioners frequently use acute surface electromyography (sEMG) to select exercise variations (AdavamPurath et al., 2020), assuming greater acute muscle excitation equates to superior long-term adaptations. However, sEMG amplitude does not directly reflect neural drive, and this paradigm lacks robust empirical validation (Vigotsky et al., 2022). Furthermore, stretch-mediated hypertrophy evidence suggests that training in lengthened partial ranges of motion (ROM) drives growth via passive mechanical tension, with almost no active sEMG excitation (Warneke et al., 2023). This PhD project therefore tests whether acute sEMG amplitude predicts 12-week changes in regional muscle hypertrophy and strength, regardless of whether the relationship proves strong or absent. Secondarily, the study contrasts full ROM (FROM) with lengthened partial ROM (LROM) to test the predictive utility of sEMG across mechanical stimuli (Plotkin et al., 2023). Methods: The project implements a three-stage framework: Phase 1: Evidence Synthesis (Completed): A scoping review mapped how training intensity, ROM, and repetition duration influence acute sEMG amplitude. Phase 2: Acute Biomechanical Investigations (Completed): Two laboratory studies (10RM bench press and prone barbell row) quantified neuromuscular responses across full, upper-half, and lower-half ROM conditions. Phase 3: Longitudinal Trial: A 12-week unilateral, intra-individual intervention in untrained adults (target n = 20, a priori sample size estimation based on Pallarés et al., 2021). In bi-weekly leg extension and leg curl sessions (8-10RM), the right leg trains with FROM (2s/2s), while the left leg trains with LROM (fully stretched position, 1s/1s). Regional muscle thickness (ultrasound) and MVIC torque will be correlated with standardized baseline 10RM sEMG recordings normalized to MVIC. Results: Phases 1 and 2 have been published, demonstrating that exercise execution parameters modulate acute sEMG amplitude significantly and muscle-specifically. The Phase 3 trial is currently underway with high participant compliance (>95%). Post-intervention data collection will conclude in August 2026. Conclusion: This project directly tests a widely applied but under-validated assumption. If predictive validity is confirmed, sEMG will be justified as a resource-efficient tool for evaluating training protocols. Conversely, if the relationship proves weak, or if LROM yields differential adaptations independent of baseline sEMG, this will caution against relying on acute sEMG and underscore passive mechanical tension as a driver of hypertrophy. Either way, and accounting for the likely muscle-specificity of the relationship, this work advances evidence-based exercise prescription from athletic performance to sarcopenia counter-measures. References AdavamPurath, F., et al. (2020). Activity of shoulder girdle muscles during the perfect push-up and push-up bar exercises using different hand positions in young overhead athletes. Sport Sciences for Health. El-Kotob, R., et al. (2020). Resistance training and health in adults: An overview of systematic reviews. Applied Physiology, Nutrition, and Metabolism. Pallarés, J. G., et al. (2021). Effects of range of motion on resistance training adaptations: A systematic review and meta-analysis. Scandinavian Journal of Medicine and Science in Sports. Plotkin, D. L., et al. (2023). Hip thrust and back squat training elicit similar gluteus muscle hypertrophy and transfer similarly to the deadlift. Frontiers in Physiology. Vigotsky, A. D., et al. (2022). Longing for a Longitudinal Proxy: Acutely Measured Surface EMG Amplitude is not a Validated Predictor of Muscle Hypertrophy. Sports Medicine. Warneke, K., et al. (2023). Physiology of Stretch-Mediated Hypertrophy and Strength Increases: A Narrative Review. Sports Medicine.

Introduction & Purpose Tendinopathy is a disabling and painful condition, with a prevalence of up to 45% in specific sports like running, basketball, and volleyball (Nutarelli et al., 2023). Mechanical overuse of the tendon due to repetitive strain beyond physiological limits, results in a degenerated and weakened tendon (Radovanović et al., 2022). Eccentric training (ECC), has been the gold standard of treatment in tendinopathies for the last 30 years. However, alternative protocols like Heavy-Slow Resistance Training (HSRT) have attracted the interest of researchers since eccentric training can be mechanically demanding and painful (Sayana and Maffulli, 2007). This scoping review aims to synthesize the available evidence on the effects of chronic eccentric training and HSRT on structural, morphological, and clinical outcomes in patients with patellar and Achilles tendinopathy. Methods An electronic search was conducted in three databases (PubMed, Scopus, and Web of Science). In total, 7176 studies were identified. Articles were screened based on sample age (18-50 years old), intervention type, and duration (> 8 weeks). Tendon thickness, stiffness, cross-sectional area, neovascularization and Young’s modulus, along with pain, muscle strength, and the Victorian Institute of Sports Assessment (VISA) questionnaire were assessed. To estimate changes due to the different interventions, percentages of changes between pre and post values were calculated for each study. Percentage changes were weighted based on sample size of each study. Pooled mean percentages were classified into different magnitudes, ranging from trivial to very large, based on those suggested by Behm et al., 2016. Results After a thorough screening process, 16 studies were included in the review. Both interventions showed beneficial results on clinical and functional outcomes, increasing muscle strength and VISA questionnaire score in both tendons, and decreasing pain. HSRT yielded superior results when compared to ECC by reducing (pathologic) tendon thickness (-2.1%, n=8 vs 1.3%, n=5) and neovascularization (-23.2%, n=6 vs -11.7%, n=5), while ECC training showed greater increases in tendon stiffness (7.1%, n=6 vs 0.3%, n=3) (Fig.1). Discussion Tendon-specific responses were observed, with an increase in stiffness in individuals with Achilles tendinopathy, and a decrease in those with patellar tendinopathy. While these differences may reflect underlying anatomical and physiological characteristics as well as tendon-specific functions (Finni, 2001; Biewener and Roberts, 2000), the heterogeneity of measurement methods limits direct comparisons (Khair et al., 2024). Both protocols showed beneficial effects on the Achilles and patellar tendons, and their associated muscles (triceps surae and vastus lateralis, respectively), and showed large to very large improvements in clinical outcomes, including pain (ECC: -37.5%, HSRT: -54.6%), muscle strength (ECC: 7.8%, HSRT: 17.0%), and the VISA questionnaire (ECC: 31.2%, HSRT: 32.6%). Conclusions As both protocols reduced pain and increased function significantly, HSRT could be a promising time-saving alternative to ECC training for the rehabilitation of tendinopathies, when the latter is not possible. Further research is needed to elucidate if ECC or HSRT is superior to the other. Matching and standardizing training parameters when prescribing resistance training is the first step to try and elucidate the real effects of both interventions on tendon characteristics. References Behm DG, Blazevich AJ, Kay AD, McHugh M. (2016). Acute effects f muscle stretching on physical performance, range of motion, and injury incidence in healthy active individuals: a systematic review. Appl Physiol Nutr Metab, Jan;41(1):1-11. doi: 10.1139/apnm-2015-0235 Biewener AA, Roberts TJ. (2000). Muscle and tendon contributions to force, work, and elastic energy savings: a comparative perspective. Exerc Sport Sci Rev, Jul;28(3):99–107. PMID: 10916700 Finni T. Muscle mechanics during human movement revealed by in vivo measurements of tendon force and muscle length. (2001). Khair RM, Sukanen M, Finni T. (2024). Achilles Tendon Stiffness: Influence of Measurement Methodology. Ultrasound Med Bio, Oct;50(10):1522–9. doi:10.1016/j.ultrasmedbio.2024.06.005 Nutarelli S, da Lodi CMT, Cook JL, Deabate L, Filardo G. Epidemiology of Patellar Tendinopathy in Athletes and the General Populations: A Systematic Review and Meta-analysis. Orthop J Sports Med, 2023 Jun 5;11(6). doi:10.1177/23259671231173659 Radovanović G, Bohm S, Peper KK, Arampatzis A, Legerlotz K. (2022) Evidence-Based High-Loading Tendon Exercise for 12 Weeks Leads to Increased Tendon Stiffness and Cross-Sectional Area in Achilles Tendinopathy: A Controlled Clinical Trial. Sports Med – Open, Dec;8(1):149. doi:10.1186/s40798-022-00545-5 Sayana MK, Maffulli N. Eccentric calf muscle training in non-athletic patients with Achilles tendinopathy. (2007). J Sci Med Sport, Feb;10(1):52–8. doi:10.1016/j.jsams.2006.05.008.

Introduction & Purpose Ultrasound imaging is widely used to assess muscle and tendon properties and function, including muscle cross-sectional area, pennation angle, fascicle length, and musculotendinous behavior in vivo (Van Hooren et al., 2020). Recent technological advances in ultrafast ultrasound imaging (UUI) allow recordings at up to 5000 frames per second, thereby enabling the investigation of muscle dynamics even during rapid contractions (Deffieux et al., 2006). However, accurately and reliably quantifying metrics such as fascicle contraction velocity from these recordings remains challenging. One approach involves manually measuring fascicle length to calculate shortening velocity. As this process is highly time-consuming, semi-automated tracking methods have been developed to estimate fascicle length frame by frame. One commonly used tool is UltraTrack (UT), which has been shown to provide reliable and accurate measurements (Farris & Lichtwark, 2016; Gillett et al., 2013). Nevertheless, UT has not yet been evaluated during rapid contractions recorded with UUI. Furthermore, findings by Cronin et al. (2011) suggest that the accuracy of this algorithm may decrease as movement velocity increases. Therefore, this study aimed to investigate the reliability of UT and a custom semi-automated tracking method for assessing fascicle contraction velocity from UUI recordings of fast muscle contractions induced by supramaximal neuromuscular electrical stimulation (NMES), using manual analysis (MA) as the reference method. Methods Fifteen healthy physically active male participants completed two identical testing sessions on consecutive days using a test-retest design. Muscle contractions of the gastrocnemius muscle were induced via supramaximal NMES (STMISOLA, Biopac®, rectangular pulse, 1 ms) and recorded at 1000 frames/s using UUI (Aixplorer, Supersonic Imaging®). Several fascicle contraction velocity parameters were assessed using three analysis approaches: MA, a custom-developed block tracking method (BT), and UT. Test-retest reliability was determined using intraclass correlation coefficients (ICC 3, k), and agreement between methods was evaluated by comparing extracted contraction velocity parameters across sessions and analysis techniques. Results Manual analysis demonstrated good to excellent test-retest reliability (ICC = 089–0.92 for the analyzed velocity parameters, with average contraction velocity in the first 40 ms showing the highest reliability values). UT showed higher reliability than BT (ICC = 0.62–0.88 vs. ICC = 0.39–0.79). Between methods, only BT and UT showed significant correlation (r = 0.72; p < 0.05 for 40 ms mean velocity). Discussion The findings suggest that MA remains the most reliable approach for assessing contraction velocity from UUI recordings. Among the semi-automated methods, UT appears to be the more reliable. These findings confirm previous results reported by Gillett et al. (2013) and extend their applicability to UUI recordings. However, the low interchangeability between methods limits the significance of these findings. Conclusion This study demonstrates that UT represents a reliable semi-automated alternative for assessing fascicle contraction velocity from UUI. However, the low agreement between methods limits the interpretability of the findings. Future studies should include a broader comparison of currently available tracking approaches like UltraTimTrack (Zee et al., 2025) or the hybrid tracking method by Verheul & Yeo (2023) to identify the most accurate and reliable method. References Cronin, N. J., Carty, C. P., Barrett, R. S., & Lichtwark, G. (2011). Automatic tracking of medial gastrocnemius fascicle length during human locomotion. Journal of Applied Physiology, 111(5), 1491–1496. https://doi.org/10.1152/japplphysiol.00530.2011 Deffieux, T., Gennisson, J.-L., Tanter, M., Fink, M., & Nordez, A. (2006). Ultrafast imaging of in vivo muscle contraction using ultrasound. Applied Physics Letters, 89(18), 184107. https://doi.org/10.1063/1.2378616 Farris, D. J., & Lichtwark, G. A. (2016). UltraTrack: Software for semi-automated tracking of muscle fascicles in sequences of B-mode ultrasound images. Computer Methods and Programs in Biomedicine, 128, 111–118. https://doi.org/10.1016/j.cmpb.2016.02.016 Gillett, J. G., Barrett, R. S., & Lichtwark, G. A. (2013). Reliability and accuracy of an automated tracking algorithm to measure controlled passive and active muscle fascicle length changes from ultrasound. Computer Methods in Biomechanics and Biomedical Engineering, 16(6), 678–687. https://doi.org/10.1080/10255842.2011.633516 Van Hooren, B., Teratsias, P., & Hodson-Tole, E. F. (2020). Ultrasound imaging to assess skeletal muscle architecture during movements: a systematic review of methods, reliability, and challenges. Journal of Applied Physiology, 128(4), 978–999. https://doi.org/10.1152/japplphysiol.00835.2019 Verheul, J., & Yeo, S.-H. (2023). A Hybrid Method for Ultrasound-Based Tracking of Skeletal Muscle Architecture. IEEE Transactions on Biomedical Engineering, 70(4), 1114–1124. https://doi.org/10.1109/TBME.2022.3210724 Zee, T., Tecchio, P., Hahn, D., & Raiteri, B. (2025). UltraTimTrack: a Kalman-filter-based algorithm to track muscle fascicles in ultrasound image sequences. PeerJ Computer Science, 11, e2636. https://doi.org/10.7717/peerj-cs.2636

Introduction & Purpose Training interventions targeting physical capacities, such as muscle strength and joint flexibility, require adequate execution and training-load monitoring to enable individualized adjustments and accurate interpretation of adaptations. Short-term interventions (< 6 weeks) can often be performed under direct supervision, but this approach becomes impractical for long-term interventions. Home-based training is therefore the most realistic solution for studying long-term adaptations, yet maintaining motivation, adherence, and exercise quality over months of training remains challenging. This is important because exercise adherence depends not only on completing prescribed sessions, but also on performing the required quantity and quality of exercise (Argent et al., 2018). Although digital interventions may improve adherence more consistently in short-term home-exercise interventions, longer-term effects remain uncertain (Lang et al., 2022). Objective remote monitoring is therefore a key methodological requirement for studying long-term training adaptations, not merely a digital convenience. The aim of the planned research is to develop and validate an IMU-based system to objectively monitor home-based flexibility and strength training. Methods The system includes two exercise-monitoring modules. The stretching module quantifies stretch angle from pedal rotation (stretching device), defined as the change in pedal orientation from the unloaded resting position. The system automatically extracts imposed stretch angle, median and peak hold angle, hold-angle variability, valid hold duration, and repetition count. The eccentric plantarflexion module automatically quantifies repetition count within prescribed sets, eccentric and concentric phase durations, rest intervals, while external resistance is entered by the participant and recorded alongside the IMU-derived metrics. The experimental protocol will include 15 healthy adults of both sexes completing standardized stretching and eccentric plantarflexion protocols during two identical laboratory sessions. Criterion validity will be examined by comparing IMU-derived outcomes with 3D motion capture during both exercise tasks. Reliability will be assessed by repeating the protocol across two days. A mechanical validation block, in which the pedal is manually moved to reproducible positions, will isolate sensor and algorithm reliability from biological variability. Inter-device agreement will be evaluated by mounting two IMUs simultaneously on the same pedal and comparing both sensors against each other and against motion capture. Finally, participants will complete 3-5 unsupervised home sessions with different combinations of repetitions, sets and stretch hold durations, reporting the completed training via a training log to compare self-reported and IMU-derived exercise metrics and evaluate real-world feasibility. Agreement and reliability will be assessed using bias, root mean square error, mean absolute error, Bland–Altman limits of agreement, and intraclass correlation coefficients. Results Preliminary 2D video analysis showed close agreement between IMU-derived and video-derived pedal angles in rest and stretched positions, supporting feasibility before full motion-capture validation. Discussion This framework addresses a central limitation of long-term home-based interventions: the lack of objective information about exercise dose and execution quality. Conclusion This open-source exercise-tracking framework provides a methodological foundation for future long-term home-based intervention studies on strength and flexibility adaptations. References Argent, R., Daly, A., & Caulfield, B. (2018). Patient involvement with home-based exercise programs: Can connected health interventions influence adherence? JMIR mHealth and uHealth, 6(3), Article e47.https://doi.org/10.2196/mhealth.8518 Lang, S., McLelland, C., MacDonald, D., & Hamilton, D. F. (2022). Do digital interventions increase adherence to home exercise rehabilitation? A systematic review of randomised controlled trials. Archives of Physiotherapy, 12, Article 24. https://doi.org/10.1186/s40945-022-00148-z

Background/Objectives: Neurological impairments in children with Cerebral Palsy (CP) often lead to altered muscle architecture and function, resulting in calf muscle contractures. Orthotic immobilization aims to promote muscle-tendon unit lengthening through sustained stretch but may also induce disuse atrophy. This study investigated whether combining immobilization with daily activity yields different effects on muscle strength and gait function compared with immobilization alone. Methods: Fourteen ambulant children with spastic CP and equinus deformity (8 unilateral, 6 bilateral; mean age 9.93 ± 3.0 years; GMFCS I: 10, GMFCS II: 4) participated in a 12-week randomized controlled trial. Participants were assigned to either continuous immobilization (23 h/day) using a dynamic ankle-foot orthosis or a combined protocol consisting of 14 h/day immobilization and 10 h/day of activity involving ankle mobility and calf muscle activation. Outcomes included isometric muscle strength, joint range of motion, gait parameters, and functional measures (Gait Outcomes Assessment List (GOAL) and the Paediatric Outcome Data Collection Instrument (PODCI)). Data were analyzed using linear mixed models with Bonferroni correction. Results: Significant time effects were observed for the knee angle at initial contact (IC), the ankle angle at IC, maximum dorsiflexion, and maximum dorsiflexion during swing. A significant group × time interaction was found only for hindfoot-tibia angle at IC. Within-group improvements were noted in activities of daily living, body image and self-esteem, and basic mobility. No significant changes were found for muscle strength or for most questionnaire subscales. Conclusions: The findings indicate time-related improvements in gait, with no consistent advantage of the combined intervention. Further studies with larger samples are needed to evaluate potential long-term effects.

BackgroundDifferent spike techniques in volleyball may vary in performance and shoulder loading, potentially influencing injury risk. However, no previous study has systematically examined the association between spike technique and shoulder injuries in competitive volleyball players.MethodsAn online questionnaire was distributed via coaches to competitive volleyball players from Austria, Brazil, Germany, Greece, Portugal, and the USA between December 2024 and February 2025. The survey collected demographic data, spike technique (bow & arrow or circular), self-reported shoulder injuries or symptoms, and related treatments. Coaches classified players’ spike techniques based on provided descriptions. Group differences were analyzed using Chi-square tests (p < 0.05).ResultsA total of 175 players (90 females, 85 males; mean age 24.3 ± 9.4 years) participated in the study. The bow & arrow technique was most common (71.4%), followed by circular (25.7%). Overall, 32% of the players reported shoulder injuries and 44.7% reported shoulder symptoms. No significant differences in injury or symptom frequency were found between techniques, either overall or within genders (p > 0.05). In females, the circular technique showed lower injury (18.2% vs. 31.2%) and symptom (36.4% vs. 51.6%) rates descriptively compared to bow & arrow, but without statistical significance. Males showed very similar rates for the techniques (injury: 39.1% vs. 34.4%; symptoms: 39.1% vs. 42.6%).ConclusionThe present data do not demonstrate a clear advantage of either spike technique with respect to shoulder injuries or symptoms. Gender-specific trends towards a greater injury risk for women using bow & arrow technique warrant further investigations. Future studies should increase sample size, include a broader range of competitive levels, and also integrate objective biomechanical and medical assessments.

Introduction & Purpose Flexibility and range of motion (ROM) are key determinants of movement efficiency, injury risk, and rehabilitation outcomes. At the tissue level, ROM and related mechanical behavior depend on the properties of the muscle–tendon unit and its extracellular matrix, which may be modulated by menstrual hormones (Hansen, 2018). Although previous work has not shown consistent menstrual-cycle effects on global athletic performance (Eloduy-Terrado et al., 2025), it is unclear whether sensitive endpoints (ROM, passive stiffness, and morphology) vary systematically across the cycle. This systematic review with meta-analysis aimed to determine whether these characteristics differ between menstrual phases, and how any effects depend on cycle-tracking quality, tissue type, and measurement conditions. Methods This review followed PRISMA guidelines and was registered in the PROSPERO database (CRD420261359522). Two independent reviewers (JN, AS) screened records found in three databases and extracted data. Eligible studies were original research in females comparing at least two out of three menstrual phases (follicular, ovulation, luteal) and reporting either ROM (e.g., sit and reach), mechanical muscle–tendon properties (e.g., shear wave velocity, stiffness), or muscle/tendon morphology. Paired standardized mean differences (Hedges’ g) between phases were computed using within-subject formulas accounting for repeated measures. Multiple outcomes were combined to a single study-level effect (Borenstein et al., 2009). Random-effects meta-analyses (Borenstein et al., 2009) were conducted for phase contrasts (follicular vs. ovulatory, follicular vs. luteal, ovulatory vs. luteal) for ROM, stiffness, and morphology, with subgroup analyses by cycle-tracking quality, tissue type, and muscle activation. All analyses were conducted in MATLAB (R2024a, Massachusetts, The MathWork Inc.) Results Across 25 eligible studies, cycle effects on ROM and stiffness were small and largely inconclusive. Muscle and muscle–tendon morphology showed effect sizes close to zero, indicating no meaningful phase-related changes in gross structure. However, when analyses were restricted to studies with accurate cycle tracking or muscle stiffness, a clearer pattern emerged: ROM was higher around ovulation than in the early follicular phase, and muscle stiffness was lower at ovulation than in both early follicular and luteal phases. These effects were small-to-moderate and based on few studies, so they remain provisional. Discussion Menstrual-cycle phase appears to exert small but coherent effects on ROM and muscle stiffness, whereas muscle–tendon morphology remains largely unchanged. The observed pattern aligns with hormonal mechanisms whereby high estradiol and low progesterone near ovulation reduce collagen cross-linking, which might promote a more compliant muscle–tendon unit, whereas elevated progesterone in the luteal phase may counteract estradiol’s effects and increase stiffness (Hansen, 2018; Hansen & Kjaer, 2016). This is consistent with epidemiological evidence of greater joint laxity around ovulation and supports the view that short-term hormonal fluctuations primarily modulate tissue mechanics rather than gross structure, although current evidence remains scarce (Hansen & Kjaer, 2016). Conclusion Menstrual-cycle phase may fine-tune flexibility and muscle stiffness in eumenorrheic women and could support phase-informed adjustments to flexibility training, load management, and injury prevention. However, the modest effect sizes, small number of high-quality studies, and variability in cycle verification highlight the need for research with precise hormonal profiling and standardized mechanical testing to confirm and refine these findings. References Hansen, M. (2018). Female hormones: do they influence muscle and tendon protein metabolism? Proceedings of the Nutrition Society, 77(1): 32-41. https://doi.org/10.1017/S0029665117001951 Eloduy-Terrado, A., Torres-Luque, G., Radesca, K., Muñoz-Andradas, G., Saenz-Bravo, M., Domíniquez-Balmaseda, D. (2025). Evaluation the Impact of Hormonal Fluctuations During the Menstrual Cycle on the Performance of Female Athletes-Systematic Review. Muscles 4. https://doi.org/10.3390/muscles4020015 Borenstein M., Hedges L.V., Higgins J.P.T., Rothstein H.R. (2009). Introduction to meta-analysis. https://doi.org/10.1002/9780470743386 Hansen, M., Kjaer, M. (2016). Sex Hormoes and Tendon. Advances in experimental medicine and biology, 920, 139–149. https://doi.org/10.1007/978-3-319-33943-6_13

Adjustment for multiple statistical tests has become a default marker of rigor in clinical and health research. We argue that its routine application is often conceptually inappropriate and can obscure meaningful results. The need for multiplicity correction depends not simply on how many tests are performed, but on the inferential question being asked. When the aim is to determine whether any detectable effect exists, an omnibus test is the appropriate inferential tool, and subsequent post hoc comparisons serve a descriptive role. When a small number of directed hypotheses are specified a priori, routine blanket correction across all conceivable contrasts is not required, provided the hypothesis set is fixed independently of the data. By contrast, when the aim is to identify where an effect is visible across a broader set of candidate contrasts, the problem is one of multiple inference and calls for explicit error control, such as false discovery rate control or, where stricter control is required, familywise error control. A related but distinct issue arises when multiple variables reflect different aspects of the same underlying biological process. Here, simple count-based adjustment penalizes measurement richness without addressing a coherent inferential problem and should be replaced by consideration of the latent structure of the outcome space. We propose a context-dependent framework, operationalized through a small set of guiding questions, that links inferential aims to appropriate statistical procedures across three modes: global detection, directed hypothesis testing, and exploratory localization. This framework supports more transparent and defensible statistical practice.

Introduction & Purpose Overhead sports like volleyball require a balance of maximum strength, joint mobility, and muscle stiffness to optimize performance and minimize injury risks. Repetitive, asymmetric loading during spiking and serving drives distinct muscular adaptations (Hadžic et al., 2014). This study compared isometric maximum strength (FMAX), joint mobility (MOB), and muscle stiffness (STIF) between the dominant and non-dominant upper limbs in elite volleyball players (VB) and healthy controls (KG), while also identifying specific inter-group differences. Methods Professional male volleyball players (n = 16) and recreational male athletes without overhead sports experience (n = 11, control group) were examined. FMAX was measured using a strain gauge force sensor (VPG, Model1022) and MOB using a goniometer app during glenohumeral internal and external rotation for both limbs. FMAX values were bodyweight-normalized to ensure inter-individual comparability. STIF was evaluated bilaterally across eight muscle groups (M. latissimus dorsi, M. trapezius [middle/upper], M. infraspinatus, M. deltoideus [anterior/middle/posterior], M. pectoralis major) using MyotonPro. Normal distribution was verified using the Shapiro-Wilk test (α = 0.05). To evaluate intra-subject asymmetries (dominant vs. non-dominant), paired t-tests or Wilcoxon signed-rank tests were applied. Inter-group differences (VB vs. KG) were analyzed using independent samples t-tests or Mann-Whitney-U tests. Results Significant intra-subject asymmetries emerged mostly within the VB group: players exhibited higher dominant internal rotation strength (p = 0.047; Means: 2.60 vs. 2.47 N/kg) but higher non-dominant internal rotation mobility (p = 0.023; Means: 58.31 vs. 53.31°). Conversely, the KG showed asymmetry only for the internal rotation mobility, also favouring the non-dominant side (p = 0.045; Means: 49.59 vs. 44.75°). For STIF, the VB displayed higher non-dominant stiffness in the M. latissimus dorsi (p = 0.034; Means: 236.94 vs. 226.76 N/m) and higher dominant stiffness in the M. trapezius middle (p = 0.008; Means: 303.27 vs. 284.55 N/m). Inter-group analyses revealed no differences for FMAX, but higher non-dominant internal rotation mobility in VB than KG (p = 0.038; Means: 58.31 vs. 49.59°). Regarding STIF, the VB showed lower stiffness in the dominant M. deltoideus middle (p = 0.020; Means: 252.85 vs. 276.25 N/m), but higher stiffness in the non-dominant M. infraspinatus (p = 0.048; Means: 206.63 vs. 194.39 N/m). Discussion The results indicate that regular, high-level volleyball training induces specific mechanical and muscular adaptations. Internal rotation strength dominance combined with restricted dominant internal rotation mobility in the VB group highlights the glenohumeral internal rotation deficit tendency often observed in competitive overhead athletes (Johnson et al., 2018). This pattern likely serves to generate maximum acceleration during a spike while maintaining joint stability. Interestingly, lower stiffness in athletes’ dominant middle deltoid might reflect functional flexibility requirements, whereas elevated stiffness of the non-dominant infraspinatus suggests altered stabilizing demands. The greater non-dominant internal rotation mobility in the VB group compared to non-overhead controls further underlines these sport-specific, unilateral adaptation patterns. Conclusion Competitive volleyball players present distinct, asymmetric mechanical alterations and localized stiffness variations compared to non-overhead controls. These findings underscore the value of bilateral musculoskeletal screening to tailor specific prevention and conditioning programs in overhead sports. References Hadžic, V., Sattler, T., Veselko, M., Markovic, G., & Derviševic, E. (2014). Strength Asymmetry of the Shoulders in Elite Volleyball Players. Journal of Athletic Training, 49(3), 338–344. https://doi.org/10.4085/1062-6050-49.2.05 Johnson, J. E., Fullmer, J. A., Nielsen, C. M., Johnson, J. K., & Moorman, C. T., III. (2018). Glenohumeral internal rotation deficit and injuries: A systematic review and meta-analysis. Orthopaedic Journal of Sports Medicine, 6(5), https://doi.org/10.1177/2325967118773322

Introduction & Purpose Although mechanical traction (MT) has been used for years to treat people with lower back pain (LBP) (Cavagnaro, 2014; Werners et al., 1999), its possible acute effects are not yet well understood. Mechanical tension is supposed to decrease muscle stiffness and tonus of the muscle and should therefore decrease LBP. However, while Cheng et al. (2020) were able to measure an acute positive effect, Wegner et al. (2013) reported that MT alone or in combination with other interventions has little to no effect on pain of patients with LBP. A reason for these mixed results could be the complex nature of LBP and the missing understanding of the exact mechanical mechanism of MT. Given that the clinical efficacy of MT remains uncertain, understanding its immediate mechanical effects is particularly relevant. Therefore, the aim of this study was to investigate the acute mechanical and functional effects of MT in healthy individuals as a first-step mechanistic assessment. Methods 22 healthy physically active participants (27,8 ± 6,79 years, recruited via personal contact) volunteered for the study and were randomized into two groups: intervention (IG, n=12) and placebo (PG, n=10). Prior to the warm-up and intervention (and following the intervention), participants were asked about current level of LBP through VAS (Bijur et al., 2001). Subsequently, the participants started with a five-minute warm-up on an ergometer with 100 Watts resistance. After the warm-up and following the intervention, we measured muscle stiffness on four measurement points of the M. erector spinae with the MyotonPRO device, maximum isometric force of the M. erector spinae with a handheld dynamometer, pain threshold with an algometer, the flexibility of the posterior chain using a sit-and-reach box, the distance between the spinous processes L4 and L5 with b-mode ultrasound (Aixplorer, Supersonic), and the elasticity of the M. erector spinae with ultrasound (US) shear wave elastography (Aixplorer Supersonic). For the intervention, the participants lay supine on a DORSI traction system (https://dorsi.at/). The intervention for the IG consisted of 10% bodyweight (BW) traction force for the first seven minutes, then one minute break following 13 minutes of 20% BW traction force. For the PG we used 5% BW traction force throughout the whole 20 minutes with a one-minute break after seven minutes. We analyzed the results using paired t-tests to identify within group changes and t-tests between groups’ changes (PRE to POST). Results All participants tolerated the MT very well. Both the IG (Pre: 34,99 ± 5,84 cm; Post: 37,05 ± 5,75 cm, p=0,01) and the PG (Pre: 30,73 ± 10,67 cm; Post: 32,11 ± 9,78 cm, p=0,03) significantly increased the flexibility of the posterior chain without any difference between the groups. The distance between the spinous processes significantly increased from Pre (2,89 ± 0,29 cm) to Post (3,06 ± 0,29 cm, p=0,01) in the IG but remained unchanged in the PG (Pre: 3,18 ± 0,25 cm; Post: 3,11 ± 0,24 cm, p=0,55). This was accompanied with a trend (p=0.07) in the comparison of group’s changes. In contrast, muscle stiffness assessed by elastography decreased in the PG (Pre: 129,31 ± 73,93 kPa; Post: 105,18 ± 58,46 kPa, p=0,01) but not in the IG (Pre: 107,72 ± 71,85 kPa; Post: 80,47 ± 52,67 kPa, p=0,08) without any difference between the groups. There was a significant difference in the group’s changes of pain threshold (p=0,04), however, this changes were not significant in either group (IG: Pre: 69,79 ± 33,91 N; Post: 74,69 ± 43,71 N, p=0,3; PG: Pre: 72,88 ± 20,77 N; Post: 63,29 ± 11,9 N, p=0,07). Muscle stiffness did not change significantly on either of the four measurement points from pre to post. Similarly, the maximum isometric force did not change significantly for the IG (Pre: 32,69 ± 6,8 N; Post: 33,61 ± 11,94 N, p=0,73) or the PG (Pre: 30,53 ± 9,41 N; Post: 29,89 ± 8,61 N, p=0,47). The acute sensation of pain did not change for the IG (Pre: 9,02 ± 18,67%; Post: 3,52 ± 6,90%, p=0,33) or the PG (Pre: 11,75 ± 13,70%; Post: 7,01 ± 10,70%, p=0,34). Neither of these results showed a difference between the groups (p>0.05). Discussion We were able to show that a MT with 20% BW traction force is well tolerated by healthy individuals. The MT significantly increased the distance between the spinous processes (p=0,01), indicating a real stretching effect of the vertebra in the IG. However, muscle stiffness measured with the MyotonPRO did not change. As expected in a healthy sample, baseline pain was minimal and did not change, confirming a floor effect. A particular strength of this study is the comprehensive set of mechanical and functional measures, which allowed a differentiated characterization of the acute effects of MT. However, as the study was conducted in healthy individuals, extrapolation to patients with low back pain is limited; factors such as pain, muscle guarding, and altered tissue properties may substantially modify the response to traction.Moreover, only immediate post-intervention effects were assessed, so neither the duration nor the clinical relevance of the observed changes can be determined. Conclusion The device was well tolerated in this sample of healthy individuals and produced an immediate increase in interspinous distance. As the study addresses only acute mechanical responses, further research in patients with LBP is needed to evaluate any clinical effects. References Bijur, P. E., Silver, W. & Gallagher, E. J. (2001). Reliability of the visual analog scale for measurement of acute pain. Academic emergency medicine: official journal of the Society for Academic Emergency Medicine, 8(12), 1153–1157. https://doi.org/10.1111/j.1553-2712.2001.tb01132.x Cavagnaro, L. (2014). Lumbar Traction in the Management of Low Back Pain: A Survey of Latest Results. Journal of Novel Physiotherapies, 04(05). https://doi.org/10.4172/2165-7025.1000231 Cheng, Y.‑H., Hsu, C.‑Y. & Lin, Y.‑N. (2020). The effect of mechanical traction on low back pain in patients with herniated intervertebral disks: a systemic review and meta- analysis. Clinical rehabilitation, 34(1), 13–22. https://doi.org/10.1177/0269215519872528 Wegner, I., Widyahening, I. S., van Tulder, M. W., Blomberg, S. E. I., Vet, H. C. de, Brønfort, G., Bouter, L. M. & van der Heijden, G. J. (2013). Traction for low-back pain with or without sciatica. The Cochrane database of systematic reviews, 2013(8), CD003010. https://doi.org/10.1002/14651858.CD003010.pub5 Werners, R., Pynsent, P. B. & Bulstrode, C. J. (1999). Randomized trial comparing interferential therapy with motorized lumbar traction and massage in the management of low back pain in a primary care setting. Spine, 24(15), 1579–1584. https://doi.org/10.1097/00007632-199908010-00012 Wu, Z., Ye, X., Ye, Z., Hong, K., Chen, Z., Wang, Y., Li, C., Li, J., Huang, J., Zhu, Y., Lu, Y., Liu, W. & Xu, X. (2022). Asymmetric Biomechanical Properties of the Paravertebral Muscle in Elderly Patients With Unilateral Chronic Low Back Pain: A Preliminary Study. Frontiers in Bioengineering and Biotechnology, 10, 814099. https://doi.org/10.3389/fbioe.2022.814099

Background/Objectives: Children with cerebral palsy (CP) often develop altered muscle architecture and calf muscle contractures. Orthotic immobilization aims to provide prolonged stretch to lengthen the muscle belly and muscle-tendon unit (MTU), but immobilization may also cause atrophy. This study investigated whether immobilization combined with periods of daily muscle activation has a different effect on calf muscle properties than continuous immobilization alone. Methods: Fourteen children with CP and equinus deformity (mean age: 9.9 ± 3.0 years; GMFCS Level I: 10, II: 4) were enrolled in a 12-week randomized controlled trial. Participants were allocated to one of two groups: continuous immobilization (23 h per day) with a dynamic ankle-foot orthosis (AFO), or a combined regimen consisting of immobilization (14 h) and a daily activity phase (10 h). Gastrocnemius medialis (GM) MTU properties, including muscle belly and Achilles tendon (AT) length, fascicle length, and muscle volume, among others, were assessed four times using three-dimensional (3D) freehand ultrasound. Results: Significant within-group increases in MTU and AT lengths were observed over time at both a 90° ankle position (p < 0.01) and a more dorsiflexed ankle position (4 Nm applied torque, p < 0.01). However, no significant group × time interactions were observed for any parameter. Conclusions: Contrary to our hypothesis, combining activity and immobilization did not confer additional benefits. Nevertheless, shorter orthosis-wearing time had the same effect on the MTU and could lead to improved compliance with orthosis treatment in CP. Larger trials are needed to support our findings.

Introduction: Supramaximal accentuated eccentric loading (SAEL) is a resistance-training strategy in which the eccentric phase is performed with greater loads than the concentric phase. Although previous studies have reported beneficial effects on strength and muscle hypertrophy (Friedmann-Bette et al. 2010), evidence from short-duration, low-volume interventions remains limited. Therefore, this pilot study investigated the feasibility and short-term effects of a six-week motor-controlled SAEL squat intervention compared with traditional resistance training on strength, explosive performance, flexibility, and muscle hypertrophy. Methods: Nine resistance-trained participants were randomly allocated to either a SAEL group (n = 4) or a traditional resistance training group (TRAD; n = 5). Participants completed a total of six supervised squat training sessions (3 × 5 repetitions, once weekly) using a motor-controlled Smith machine. The TRAD group trained with 78% of concentric 1RM during both movement phases, whereas the SAEL group performed the concentric phase at 78% of concentric 1RM and the eccentric phase at 78% of eccentric 1RM (~112% concentric 1RM). Outcome measures included squat 1RM, eccentric 1RM, countermovement jump (CMJ), squat jump (SJ), loaded CMJ performance, passive knee range of motion (ROM), and ultrasound-derived vastus lateralis (VL) and rectus femoris (RF) cross-sectional area (CSA). Results: Significant improvements over time were observed for squat 1RM (p = 0.005), passive knee ROM (p = 0.044), and VL CSA (p = 0.016). No significant group or group × time interaction effects were found for any outcome. Within-group analyses showed significant increases in squat 1RM (+7.2%) and VL CSA (+5.1%) in TRAD, while SAEL demonstrated comparable but non-significant improvements in squat 1RM (+8.7%) and VL CSA (+8.2%). No significant changes were observed for RF CSA or jump performance. Discussion: Both training approaches produced comparable short-term adaptations following six weeks of low-volume squat training, with no evidence supporting the superiority of motor-controlled SAEL over traditional loading. The observed improvements in squat 1RM and vastus lateralis CSA are generally consistent with previous SAEL interventions reporting positive effects on strength and muscle hypertrophy (Friedmann-Bette et al. 2010; Walker et al. 2016). However, the relatively large strength gains observed within only six training sessions may also partly reflect learning effects associated with maximal testing on the motor-controlled Smith machine. Given the exploratory nature of this pilot study and its small sample size, these findings should be interpreted with caution. Conclusion: Motor-controlled SAEL appears to be a feasible, safe, and practical method for implementing eccentric overload within a low-volume, time-efficient squat training program. Under the present conditions, coaches may select either loading strategy based on equipment availability and practical considerations rather than expected differences in training adaptations. Future studies should include larger samples, familiarization sessions, and longer intervention periods to determine whether motor-controlled SAEL provides additional long-term benefits for strength, muscle hypertrophy, and explosive performance. References: Friedmann-Bette, B., Bauer, T., Kinscherf, R., Vorwald, S., Klute, K., Bischoff, D., Müller, H., Weber, M. A., & Metz, J. (2010). Effects of strength training with eccentric overload on muscle adaptation in male athletes. European Journal of Applied Physiology, 108(4), 821–836. https://doi.org/10.1007/s00421-009-1292-2 Walker, S., Blazevich, A. J., Haff, G. G., Tufano, J. J., Newton, R. U., & Häkkinen, K. (2016). Greater strength gains after training with accentuated eccentric than traditional isoinertial loads in already strength-trained men. Frontiers in Physiology, 7, Article 149. https://doi.org/10.3389/fphys.2016.00149

This study investigated the comparative acute effects of 3 × 30 s of vibration foam rolling (VFR) or percussive massage (PM) on the hamstring muscles, specifically range of motion (ROM), maximum voluntary isometric contraction (MVIC), and muscle stiffness, using shear wave elastography (SWE), tensiomyography (TMG), and the MyotonPro. Further, the correlation between the three stiffness measures was examined. Seventeen participants (27.1 ± 3.1 years; 7 females) were randomized to VFR or PM on two occasions. Muscle stiffness of the biceps femoris (BF) was assessed at baseline and immediately post-intervention with SWE, TMG, and the MyotonPro. A sit-and-reach test was conducted and MVIC of the hamstring muscles was measured unilaterally. A significant time effect was observed for MVIC torque (p = 0.01, ƞ² = 0.319). ROM and BF muscle stiffness were unaffected by either intervention. No significant associations were found between the stiffness measurements from the three techniques. The acute application of 3 × 30 s of VFR or PM did not enhance ROM or alter BF muscle stiffness. However, both interventions reduced MVIC torque, with no significant difference between them. The lack of correlation between the SWE, TMG, and MyotonPro measurements suggests that these techniques cannot be used or interpreted interchangeably.

Perceptual-cognitive comparisons of experts and novices have consistently shown that experts use specific visual strategies to process visual scenes in their domain of expertise, reflected in eye movement metrics such as fixation rates and durations. We present an investigation of the gaze behavior from professional volleyball players (experts; n = 14) during a volleyball anticipation task and compare them to intermediate level volleyball players (amateurs; n = 25) and individuals with only basic volleyball experience (novices; n = 19). The task consisted of the observation of videos, which were recorded during official national level volleyball matches, each showing unique setting situations. Our results replicate previous findings showing lower fixation rates as well as longer fixation durations in relation to higher expertise. Yet, this trend was only present in the later phase of video observation, i.e., during the course of the rally. In the early phase, i.e., during players' preparation before the service, experts did not differ from amateurs on all fixation metrics, while novices performed comparatively higher rates of fixations. Our findings emphasize the importance of investigating temporal dynamics, as well as using a comprehensive operationalization of perceptual-cognitive processes related to expertise.