J. Funct. Morphol. Kinesiol., Volume 11, Issue 3 (September 2026) – 130 articles

Background: Concentric knee and trunk strength may contribute differently to maximal force and stretch-shortening cycle performance in youth sailors. This study evaluated the predictive value of concentric knee and trunk isokinetic strength for these outcomes in highly trained youth Optimist sailors. Methods: Forty highly trained Optimist sailors (20 boys and 20 girls; age, 13.03 ± 1.40 years) completed knee and trunk isokinetic testing at 60°·s⁻¹ and 180°·s⁻¹, isometric mid-thigh pull, squat jump, and countermovement jump tests. Velocity-specific multiple linear regression models included a composite of dominant and nondominant knee extensor and flexor strength, trunk extensor strength, trunk flexor strength, and sex. Results: The models explained 60.7% and 49.4% of the variance in isometric mid-thigh pull peak force at 60°·s⁻¹ and 180°·s⁻¹, respectively. The knee strength composite was independently associated with peak force at both velocities (β = 0.51, p = 0.003; β = 0.56, p = 0.006). The models explained 1.3–3.5% of dynamic strength index variance and 17.8% and 4.5% of eccentric utilization ratio and elastic index variance at 60°·s⁻¹ and 180°·s⁻¹, respectively. Trunk flexor strength was associated with eccentric utilization ratio and elastic index at 60°·s⁻¹ (β = 0.52, p = 0.029), although these outcomes are mathematically dependent. Sex was not associated with any outcome. Conclusions: Concentric isokinetic strength showed greater predictive value for maximal force than for stretch-shortening cycle performance. Combined knee extensor and flexor strength was consistently associated with maximal force, whereas limited variance was explained in stretch-shortening cycle outcomes. Full article

Background and Objectives: Acute responses to exercise interventions may vary within individuals across repeated exposures, potentially limiting the interpretation of individuals as “responders” or “non-responders”. This study investigated whether acute changes in range of motion following short-term static stretching are reproducible within individuals. Methods: Twenty-six healthy young adults completed two identical sessions separated by one week. Flexibility was assessed before and after static stretching using the Sit-and-Reach Test (SRT) and ankle dorsiflexion range of motion (ADF ROM). The intervention consisted of three 30 s static stretches for the hamstrings and gastrocnemius. Results: Baseline measurements showed excellent reproducibility (SRT: ICC = 0.98; ADF ROM: ICC = 0.95). SRT performance and ADF ROM increased significantly after stretching (p < 0.001), with no evidence of a systematic difference in the mean response between visits (time × visit interactions: p > 0.05). Reproducibility of individual pre-to-post change scores was moderate by point estimate but imprecisely estimated (SRT: ICC = 0.74; 95% CI: 0.50–0.88; ADF ROM: ICC = 0.57; 95% CI: 0.25–0.78). Conclusions: Individual change scores showed limited reproducibility. The design cannot separate measurement error, normal day-to-day variation, and variability specifically attributable to the stretching response. Classifying individuals as “responders” or “non-responders” based on a single acute stretching session should therefore be approached with caution. Full article

Background/Objectives: Minimalist footwear has been proposed as a passive means of reducing knee loading, but its effects during walking in healthy adults, the population relevant to primary prevention of knee osteoarthritis (KOA), have not previously been synthesized. Methods: Following PRISMA 2020 (PROSPERO CRD420261396693), four databases and ClinicalTrials.gov were searched to September 2026 without date restriction. Primary outcomes were peak knee adduction moment (KAM), KAM impulse, peak knee flexion moment (KFM), and patellofemoral contact force; secondary outcomes were vertical loading rate, stride length, cadence, foot strike angle, and foot progression angle as a registered post hoc amendment. Risk of bias was assessed in duplicate with the Cochrane RoB 2 tool for crossover trials; synthesis was narrative; certainty was rated with GRADE. Results: Six publications met the criteria, but they derive from only four independent cohorts and 100 unique participants: three of the six report the same cohort of 40, a shared structure disclosed in none of them. Two of the four primary outcomes were reported by a single study in one cohort of 16, which found no difference between minimalist and conventional footwear in either peak KAM or peak KFM; KAM impulse and patellofemoral contact force were not reported by any study. Vertical loading rate, spatiotemporal parameters, and foot progression angle were discordant or non-comparable between cohorts. The meta-analysis was precluded by overlapping samples, absent discrete data and non-comparable outcome definitions; certainty was very low for every outcome. Conclusions: The evidence is smaller and less independent than its publication count suggests, and no recommendation for or against minimalist footwear in KOA prevention is currently supportable. Whether these loading markers, studied mainly in relation to progression in established osteoarthritis rather than incident disease in healthy joints, are appropriate prevention targets also remains unclear. Full article

Objectives: Thoracic kyphosis is a common postural condition associated with impaired functional performance, reduced balance, and lower levels of physical activity. Women may be particularly susceptible due to age-related musculoskeletal and hormonal changes. This study investigated the effects of a 12-week aquatic Pilates program on thoracic alignment, functional performance, and self-reported physical activity in women aged 55–65 years with thoracic kyphosis. Methods: Twenty women aged 55–65 years with thoracic kyphosis were randomly allocated to an Aquatic Pilates intervention group (n = 10) or a non-exercising control group (n = 10). Participants in the intervention group completed supervised aquatic Pilates sessions twice weekly for 12 weeks, while the control group maintained their usual daily activities. Pre- and post-intervention assessments included thoracic kyphosis angle measured using a DeBrunner kyphometer, the Modified Physical Performance Test (mPPT), and the Physical Activity Scale for the Elderly (PASE). Data were analyzed using 2 × 2 mixed-design repeated-measures ANOVA. The trial was registered retrospectively at ClinicalTrials.gov (NCT07674251). Results: A significant group × time interaction was observed for thoracic kyphosis angle, F_1,18 = 66.31, p < 0.001, partial η² = 0.786), with the Aquatic Pilates group showing a reduction from 42.6° ± 3.4° to 40.7° ± 3.1°. Significant improvements were also observed in the analyzed mPPT functional tasks (all p < 0.001). PASE scores showed a statistically significant group × time interaction (F_1,18 = 9.48, p = 0.006, partial η² = 0.345), with the Aquatic Pilates group showing an increase compared to the control group. Conclusions: Participation in a 12-week aquatic Pilates program was associated with improvements in thoracic kyphosis, functional performance as assessed by the mPPT, and self-reported physical activity in women aged 55–65 years with thoracic kyphosis. Full article

Background: Paired-set (PS) resistance exercise is widely used to increase training density; however, evidence-based guidance remains limited due to heterogeneous exercise sequences and rest configurations. This systematic review aimed to synthesize acute mechanical, training-efficiency, and perceptual responses across distinct PS configurations compared with traditional sets (TSs) in young resistance-trained adults. Methods: Eight databases were searched through 5 August 2026, for acute randomized crossover/parallel trials. PS protocols were categorized into PS-A (alternating exercises with preserved TS rest after each exercise), PS-B (interleaved exercises during recovery), and PS-C (modified post-pair rest). Study-level means and unstandardized percentage differences for volume load (VL), completed repetitions, training efficiency (VL accumulated per unit of time), and rating of perceived exertion (RPE) were synthesized descriptively. Results: Fifteen reports representing 14 studies (223 participants) were included, and all exhibited “some concerns” according to RoB 2. PS-A consistently elicited higher work-output point estimates (VL: 7.9–27.2%; repetitions: 6.3–26.7% vs. TS) with negligible changes in session duration. PS-B consistently reduced session duration by 44.8–50.0%, though repetitions and VL were often compromised depending on the exercise. PS-C responses were configuration-dependent; matched post-pair rest (PS-C_MPR) decreased duration (39.7–46.9%) with variable VL (−8.2% to +30.1%) and higher RPE, whereas extended rest (PS-C_EPR) showed distinct protocol-specific trade-offs between volume retention and training efficiency. Conclusions: Based on acute trials in young trained populations, PS configurations should be selected by session priority (PS-A for work capacity, PS-B for time constraints, PS-C for versatility). Given the consistent “some concerns” regarding risk of bias, these practical recommendations warrant caution. Full article

Background and Objectives: Wearable technologies increasingly monitor internal training load in high-performance sport, but their alignment with coach-prescribed physiological objectives remains unclear. This study examined within-athlete associations between WHOOP Activity Strain, coach-prescribed objectives, athlete-perceived load, and completed swimming exposure in one elite junior swimmer. Methods: An exploratory longitudinal single-case secondary analysis was conducted using routinely collected training and athlete-monitoring data from 4 January to 3 July 2026. WHOOP Activity Strain and Session-RPE were synchronized by session, and generalized estimating equations assessed differences across prescribed objectives and variable associations. Results: Of 161 sessions with exact-plan cards, 134 were classified and 128 had strict WHOOP matches. Conventional robust-covariance GEE suggested an objective-related difference (exchangeable p = 0.013; AR(1) p = 0.014), but this was not statistically detectable with the bias-reduced covariance estimator (p = 0.080 and p = 0.075, respectively) and was not reproduced using the legacy classification. WHOOP Activity Strain was consistently associated with Session-RPE Load, Session-RPE, and actual swimming distance. Conclusions: Within this athlete, WHOOP Activity Strain was associated with perceived load and completed swimming distance. Objective-related differences were post hoc and sensitive to the classification source and covariance estimator; they should therefore be considered exploratory and hypothesis-generating. Full article

Despite major advances in exercise physiology, biomechanics, and mechanobiology, exercise science still lacks a clear conceptual definition of the mechanical stimulus experienced by skeletal muscle during resistance training. Current approaches rely on diverse external, internal, and biomechanical variables (e.g., volume-load, force, power, velocity, time under tension, or muscle architecture), yet none individually captures the muscle-specific mechanical exposure relevant to muscular adaptation. This conceptual inconsistency limits comparisons across studies, complicates training prescription, and hinders the development of individualized monitoring strategies. This integrative review critically synthesizes current evidence from mechanobiology, skeletal muscle physiology, biomechanics, and resistance training to examine how mechanical stimuli are currently conceptualized, quantified, and interpreted. Based on this synthesis, we propose a working definition of Mechanical Dose as the cumulative, muscle-specific mechanical exposure experienced over a defined time window, characterized by loading magnitude, rate, duration, frequency, and spatial distribution, and conditioned by contraction mode and muscle–tendon geometry. Rather than representing a directly measurable variable, mechanical dose is presented as a latent conceptual construct that can only be estimated through combinations of biomechanical, physiological, and morphological indicators. Building upon this definition, we introduce an integrative conceptual framework linking external load, movement biomechanics, mechanical dose, mechanotransduction, and tissue adaptation. We further discuss how this framework may guide future research on the interpretation of field-based monitoring, resistance training prescription, recovery management, and future explainable artificial intelligence approaches in sport science. By reframing mechanical dose as the central construct connecting biomechanics and biological adaptation, this review provides a unified conceptual basis for future research and contributes toward a more biologically informed paradigm of exercise prescription and monitoring. Full article

Background: The Body Shape Index (ABSI) and somatotype components represent different approaches to assessing body morphology. This study aimed to examine the associations between physical activity, sedentary behaviour, sleep duration, ABSI, and somatotype components in young adults. Methods: A cross-sectional study was conducted among 371 university students from Poland and Slovenia (202 men and 169 women; mean age: 21.46 ± 1.07 years). ABSI and somatotype components were determined based on anthropometric measurements. Data on physical activity, sedentary behaviour, and sleep duration were obtained using a seven-day activity record. Associations were assessed using Spearman’s rank correlation coefficients and multiple linear regression models adjusted for sex, age, and country of origin. Results: Weak negative correlations were observed between walking time and ABSI (r_s = −0.135; p < 0.01) and between sleep duration and mesomorphy (r_s = −0.111; p < 0.05). Additional weak associations were identified in analyses conducted separately for women and men. After adjustment for potential confounders, walking time was positively associated with endomorphy (β = 0.158; p = 0.009) and mesomorphy (β = 0.117; p = 0.041), and negatively associated with ectomorphy (β = −0.192; p = 0.002). All significant associations were characterized by small effect sizes. No significant associations were found for ABSI in the primary adjusted model for the total sample. Conclusions: Despite the small magnitude of the observed associations, different patterns of associations were observed for ABSI and the somatotype profile, reflected by the combined pattern of its endomorphic, mesomorphic, and ectomorphic components. However, the identified associations were few in number and weak in strength; therefore, further research is needed to better explain their significance in young adult populations. Full article

Background and Objectives: Low-volume plyometric conditioning may elicit post-activation performance enhancement (PAPE), but the early response to pogo-jump exercise in adolescent basketball players remains uncertain. This randomized crossover pilot study estimated the effect of adding 24 bilateral pogo jumps to a standardized warm-up on countermovement-jump (CMJ) and drop-jump (DJ) height, compared with time-matched low-intensity walking. Methods: Twenty-seven male basketball players were recruited, and 21 (age, 16.55 ± 0.88 years) completed both conditions. In randomized order, separated by a 7-day washout, participants performed 3 sets of 8 bilateral pogo jumps with 1 min between sets or approximately 3 min of low-intensity walking. Post-condition jump assessments began after a 1 min recovery and comprised three consecutive CMJs, a 30 s transition, and three consecutive DJs, with all measurements completed within approximately 2 min after each condition. The highest valid trial was retained for each jump type. Period-adjusted treatment effects were estimated using separate linear mixed-effects models, with repeated-measures ANOVA and Wilcoxon analyses retained as sensitivity analyses. Results: The period-adjusted between-condition difference in change was −0.89 cm for CMJ (95% CI, −2.92 to 1.14; p = 0.389) and 0.34 cm for DJ (95% CI, −1.77 to 2.45; p = 0.753). Sensitivity analyses yielded the same overall interpretation. All completers performed the protocol, and perceived exertion was 11.4 ± 1.2. The pogo-jump protocol showed favorable immediate tolerability, with all completers reporting 0/10 anterior-knee pain immediately after the condition. Conclusions: The pilot estimates did not indicate a detectable group-level improvement in CMJ or DJ height during the early post-conditioning assessment. However, the confidence intervals were compatible with potentially meaningful effects in either direction. The small sample, single dose, single early assessment window, and variable DJ reliability limit the precision and generalizability of the findings. Full article

Static stretching is one of the most widely prescribed interventions in sports medicine, rehabilitation, and exercise science for improving joint range of motion (ROM) and flexibility. Despite decades of research, however, the biological mechanisms underlying its effects remain incompletely understood. Traditional explanations have primarily focused on muscle extensibility and passive tissue stiffness, whereas emerging evidence suggests that stretching may engage multiple mechanically and biologically interconnected systems. This integrative narrative review aimed to synthesize current evidence on the biological mechanisms underlying static stretching and to propose a conceptual, hypothesis-generating framework linking externally applied mechanical loading with biological responses across multiple levels of organization. Evidence from biomechanics, fascial biology, mechanotransduction, connective tissue biology, vascular physiology, and neuroscience was critically integrated, while distinguishing direct human static-stretching evidence from indirect human, preclinical, and general mechanobiological evidence. Although evidence supports contributions from several of these individual domains, direct human evidence demonstrating their integrated operation during static stretching remains limited. The available evidence therefore suggests that static stretching may be understood more broadly than as a muscle-centered flexibility intervention alone. Mechanical loading during stretching may be transmitted across muscular and connective tissues and interact with mechanosensitive cellular, extracellular-matrix, vascular, inflammatory, and neural processes; however, the directness and strength of evidence for these proposed links vary substantially. The resulting framework provides a plausible, testable hypothesis for how interactions among these processes may contribute to heterogeneous findings and inter-individual variability following stretching interventions, rather than an established explanatory model. Accordingly, this review conceptualizes static stretching as a biologically active mechanical stimulus whose effects may involve interacting responses across multiple levels of biological organization. By integrating evidence from previously separated biological domains while explicitly recognizing differences in evidence directness, the proposed framework provides a theoretical basis for future mechanistic research and for testing the causal and temporal relationships among these candidate processes in humans. Full article

Background: This study examined training-to-match transferability of positional coordination in semi-professional football players, comparing responses between defensive and midfield/offensive positional sectors. Methods: Twenty-nine players were monitored during the 2023–2024 season. Positional data and external load were collected using global positioning system (GPS) technology. Technical–tactical key performance indicators (KPI) were obtained from SportsBase. Internal training load was assessed using the rating of perceived exertion (RPE), and wellness status was evaluated using the Hooper Index (HI). Results: Official matches were associated with greater total distance, average and maximum speed, speed events, acceleration and deceleration events, and mechanical power outputs (p < 0.001), with the largest effects for maximum speed (d = 1.25), deceleration events (d = 1.14), speed events (d = 1.13), and relative mechanical power (d = 1.05). Positional responses showed distinct training-to-match patterns. In the defensive sector, the official matches showed higher spread rate (SR; p = 0.031, d = −1.83) and contraction time (CT; p = 0.007, d = −2.20). In the midfield/offensive sector, matches showed greater effective playing space, width, length, longitudinal synchronization, distance to sector centroid, and stretch index (p = 0.005–0.017; d = 1.73–2.61), whereas dyadic-distance variability was greater during training (p < 0.001, d = 4.46). Linear mixed-effects models confirmed greater locomotor and high-intensity demands during matches, while positional differences were more selective. No statistically robust tactical-sector differences were observed for KPIs, internal load, or wellness after adjustment for multiple comparisons. Conclusions: Training-to-match transferability was positional sector-dependent, with greater spatial expansion and longitudinal coordination in offensive players and higher overall locomotor demands during matches. Full article

Background and Objectives: Comprehensive physical profiling is important for monitoring athletic development in youth soccer players (YSP), yet integrated data from competitive South American players remain limited. This study aimed to characterize the anthropometric profile, neuromuscular performance, and cardiorespiratory fitness of competitive Chilean YSP and explore associations among these components. Methods: This cross-sectional study included 24 male YSP from a Chilean professional club academy. Participants underwent anthropometric assessment, bilateral quadriceps isometric strength testing, vertical jump testing (Squat Jump [SJ], Countermovement Jump [CMJ], and Abalakov Jump [ABK]), and maximal cardiopulmonary exercise testing. The primary analysis was an integrated characterization of anthropometric, neuromuscular performance, and cardiorespiratory fitness. Secondary exploratory analyses included correlations with false discovery rate adjustment and multiple linear regression. Results: Participants had a median age of 13.5 years (IQR: 13.0–14.0) and a BMI of 21.1 ± 1.6 kg·m⁻². Mean bilateral quadriceps strength was 406.1 ± 70.0 N, while mean jump heights were 24.6 ± 4.2 cm for SJ, 28.4 ± 3.7 cm for CMJ, and 33.4 ± 5.3 cm for ABK. The average relative VO₂peak was 55.0 ± 4.7 mL·kg⁻¹·min⁻¹, while absolute VO₂peak was slightly higher than predicted. Bilateral quadriceps strength was positively associated with all three jumps before FDR adjustment; after FDR correction, the associations with CMJ and ABK remained statistically significant, whereas the association with SJ did not. Relative VO₂peak was not associated with CMJ performance. Conclusions: This study provides an integrated characterization of physical performance within this cohort of youth soccer players. Quadriceps strength was associated with vertical jump performance, whereas relative VO₂peak was not associated with CMJ, supporting assessment of neuromuscular and cardiorespiratory capacities. Full article

Background and Aim: The identification of factors that optimize competitive performance is a primary focus for athletes and coaches in any sport, particularly variables that are modifiable through tailored nutritional and training strategies. Since data regarding volleyball remain scarce, this investigation aimed to explore the association between the baseline preseason anthropometry, body composition, and dietary habits of elite adult male volleyball players and the key performance indicators (KPIs) retrieved as match-by-match data during an official tournament. Methods: Nineteen elite male volleyball players (mean age: 23.79 ± 5.72 years; BMI: 23.88 ± 1.97 kg/m²) underwent comprehensive assessments. Anthropometric data and muscle strength (MS) were evaluated via body circumferences and handgrip dynamometry, respectively. Body composition was analyzed using bioelectrical impedance vector analysis (BIVA), while Mediterranean diet adherence was assessed with the validated Mediterranean diet adherence score (MEDAS) questionnaire, all measured cross-sectionally at one time point, identified as the baseline preseason phase of the competitive season. The tournament KPIs included serving, attack, and reception efficiencies, and block points per set were retrieved longitudinally during each match of the competitive season. Data were analyzed utilizing correlation and linear mixed-model regressions. Results: Right-hand MS correlated positively with higher MEDAS scores (ρ = 0.488, p < 0.05). Furthermore, both right-hand MS (β = 1.005, 95% CI [0.178, 1.831], p = 0.026) and thigh circumference (β = 3.030, 95% CI [0.083, 5.977], p = 0.046) were found to be positively associated with higher serving efficiency (adjusted R²_m ≈ 0.12). Conclusions: Monitoring muscle strength and thigh circumference alongside targeted nutritional and training strategies may be considered in elite male volleyball, as these factors were associated with serving efficiency. However, due to the observational nature of the research, our findings require replication in larger, multicenter intervention studies. Full article

Background: Achilles tendon viscoelasticity and ankle neuromuscular co-contraction are functionally linked, yet how they jointly adapt during brief high-speed repetitive loading remains unclear. We simultaneously quantified Achilles tendon viscoelasticity (MyotonPRO) and ankle agonist–antagonist co-contraction (surface electromyography, sEMG) under two stance conditions and three repetition counts. Methods: Twenty-seven active male collegiate American football players (23.19 ± 2.63 years) performed rapid heel-raise/landing cycles in a bilateral ground stance (BGS) and a unilateral box stance (UBS) at 1, 5, and 10 repetitions. Tendon decrement (D), stiffness (S), and tone (F), the co-activation index (CoAct), and the co-contraction index (CCI) were analyzed using two-way (2 × 3) repeated-measures ANOVA. Results: D decreased significantly as repetitions increased (pooled across stance conditions: 1 rep 0.973 → 10 reps 0.937; F (2, 52) = 4.68, p = 0.014, ηp² = 0.153), indicating improved elastic-recovery efficiency, whereas S and F remained stable. CoAct was maintained constantly at ≈72% regardless of stance or repetition (all p > 0.05), and the medial gastrocnemius was consistently activated first (agonist-led feedforward priming). Tissue-level elastic adaptation thus occurred without a concurrent change in neuromuscular co-contraction—a tissue–neural dissociation confirmed in both change scores and correlation structure. Conclusions: Acute enhancement of Achilles tendon elasticity during high-speed repetition appears to be a peripheral, tissue-level mechanical phenomenon expressed independently of neuromuscular co-contraction. Combined myotonometric–sEMG assessment reveals functional information not captured by imaging alone. Full article

Background and Objectives: Upper-extremity strength is considered an important contributor to badminton stroke performance; however, the independent contributions of specific muscle groups to shuttlecock velocity in young players remain unclear. This study investigated the associations between segmental upper-extremity isometric strength and shuttlecock velocity in young badminton players. Methods: Twenty-four competitive U11 badminton players (12 males and 12 females; mean age, 10 years) participated in this cross-sectional study. Handgrip and segmental upper-extremity isometric strength (elbow, shoulder, and wrist muscle groups) were assessed using dynamometry. Shuttlecock velocity during a badminton smash was measured using a radar gun. Results: Shuttlecock velocity was positively correlated with all measured upper-extremity strength variables (r = 0.408–0.704, all p < 0.05). After adjustment for sex and upper-limb length, only shoulder extension (r = 0.529, p = 0.011), shoulder flexion (r = 0.557, p = 0.007), shoulder external rotation (r = 0.430, p = 0.046), and shoulder internal rotation strength (r = 0.495, p = 0.019) remained significantly associated with shuttlecock velocity. Multiple regression analyses confirmed these shoulder-specific strength measures as independent predictors of shuttlecock velocity (β = 0.343–0.468, all p < 0.05), explaining 57.2–63.8% of the adjusted variance. Conclusions: Although shuttlecock velocity was initially associated with all upper-extremity strength measures, only shoulder-specific strength remained associated with performance after adjustment for sex and upper-limb length. These exploratory findings suggest that shoulder strength may represent a relevant physical correlate of badminton smash performance in young athletes; however, confirmation in larger, adequately powered studies is required. Full article

Objectives: This study evaluated sex differences in physical activity levels, anthropometric parameters, strength–endurance performance, and acute physiological responses to high-intensity strength–endurance exercise in emergency medical services students. Methods: Participants included 36 male and 23 female students aged 19–29 years. Body composition was assessed using bioelectrical impedance analysis. Physical activity was measured using the International Physical Activity Questionnaire, and strength–endurance performance was assessed with the 3-Minute Burpee Test (3-MBT). Blood pressure, heart rate, oxygen saturation, perceived exertion, and handgrip strength were recorded before and after the 3-MBT. Results: Men reported significantly higher PA levels than women (1963 vs. 1367 MET·min/week, p < 0.001). Women had a significantly higher percentage of body fat (31.0% vs. 19.4%, p < 0.001). Men completed more 3-MBT cycles than women (44 vs. 33 cycles/3 min, p < 0.001), whereas the between-sex difference in mean heart rate was not significant after Benjamini–Hochberg correction (170.2 vs. 162.2 bpm; adjusted p = 0.075). Systolic blood pressure was higher in men before and after the test (p < 0.001 and p = 0.004, respectively) and increased significantly in both sexes (p < 0.001). Oxygen saturation and handgrip strength decreased significantly after the 3-MBT in both groups (p < 0.001). Conclusions: Men demonstrated greater strength–endurance performance than women, although both sexes were classified as having “poor” performance according to established 3-MBT normative values. Men reported higher physical activity, whereas women had a higher body fat percentage. These findings demonstrate sex-based differences in physical activity, body composition, and strength–endurance performance among paramedic students. Full article

Background: The aging population in Portugal requires interventions such as multicomponent exercise to maintain the functionality of older adults. The aim of this exploratory pilot study was to investigate preliminary changes in body composition, physical fitness, quality of life and satisfaction with life following a low-frequency multicomponent exercise program delivered in two different community-based contexts (conventional exercise room and Snoezelen room). Methods: This study followed a non-randomized quasi-experimental methodology based on participant preference and logistical availability. Following the baseline assessment, participants self-selected their participation context. Participants who chose to participate in the exercise intervention were assigned to either the Snoezelen Room Group or the Exercise Room Group according to their preference, whereas participants who did not participate in either intervention because of personal preference or logistical constraints formed a non-participating comparison Control Group. The final sample comprised 27 older women: Snoezelen Room Group (n = 14), Exercise Room Group (n = 7), and Control Group (n = 6). The intervention consisted of a 12-week multicomponent program (1 session/week, 45–60 min) carried out in different environments. Body composition, functional physical fitness, quality of life and satisfaction with life were assessed before and after the intervention. Results: The primary between-group analysis of change scores (Δ = post−pre) identified significant differences for body mass (H(2) = 9.516, p = 0.009), with a significant Bonferroni contrast between the Snoezelen and Exercise Room Groups (1 vs. 2; adjusted p = 0.008). For Back Scratch, the Δ-based omnibus test was also significant (H(2) = 7.398, p = 0.025), with Snoezelen differing from the Exercise Room Group (1 vs. 2; adjusted p = 0.020). For quality of life, the Δ-based omnibus test was significant (H(2) = 11.356, p = 0.003), with significant contrasts between Exercise Room and Control Groups (2 vs. 3; adjusted p = 0.003). Secondary between-group analyses at specific time points also identified differences in post-intervention bone mass (H(2) = 8.460, p = 0.015; 1 vs. 2, adjusted p = 0.026; 2 vs. 3, adjusted p = 0.038), muscle mass (H(2) = 7.748, p = 0.021; 1 vs. 2, adjusted p = 0.034), Back Scratch (H(2) = 7.947, p = 0.031; 1 vs. 2, adjusted p = 0.031; 2 vs. 3, adjusted p = 0.050), and 6-Minute Walk (H(2) = 9.015, p = 0.011; 1 vs. 2, adjusted p = 0.012). Conclusions: The findings suggest that a low-frequency multicomponent exercise program may be feasible in community social centers; however, the observed within-group changes and exploratory between-group differences should be interpreted cautiously given the non-randomized design, small sample size, and baseline differences. Larger controlled studies are needed to determine whether the exercise environment contributes to differential outcomes. Full article

Background/Objectives: Markerless video-based gait assessment has emerged as a promising alternative to laboratory motion capture systems because it enables objective, low-cost, and accessible mobility assessment. However, evidence supporting the validity of deep learning (DL)-based markerless video systems for gait speed assessment during the 10-meter walk test (10-MWT) in real-world clinical environments remains limited. This study evaluated the concurrent validity of a DL-based markerless video system for estimating gait speed during the 10-MWT under outdoor clinical conditions. Methods: Thirty-two healthy participants from three age groups completed the 10-MWT under comfortable, slow, and fast walking conditions. Gait speed was simultaneously measured using the proposed DL-based markerless video system with the YOLOv11x model and Tracker video analysis software (version 6.3.2). Gait speed was calculated across six consecutive 1 m walking segments. Concurrent validity was evaluated using Pearson’s correlation coefficients and Bland-Altman analysis. Results: Pearson’s correlation coefficients ranged from 0.92 to 0.98 across all six walking segments and walking-speed conditions, indicating very high concurrent validity. Bland-Altman analysis demonstrated good agreement between the proposed system and the reference method, with mean differences close to zero and most observations falling within the 95% limits of agreement. The proposed system maintained high agreement across comfortable, slow, and fast walking conditions while enabling segment-specific gait speed analysis throughout the 10-MWT. Conclusions: The proposed DL-based markerless video system demonstrated high agreement with Tracker for gait speed assessment during the 10-MWT under outdoor non-laboratory conditions, supporting its potential as an accessible approach for gait speed assessment. Full article

Background: Wrist joint position and hand anthropometric measurements may affect grip strength and hand performance. This pilot, analytical cross-sectional study aimed to investigate the relationship between different wrist positions and grip strength, as well as the association between grip strength and hand size in healthy individuals. Methods: An analytic cross-sectional study was conducted with undergraduate medical students. We assessed grip strength using a hand dynamometer in different wrist positions, including wrist flexion, extension, ulnar deviation, and radial deviation. Hand anthropometric measurements, including HB, MHB, PL, TFL, IFL, MFL, RFL, and LFL, were performed using a sliding digital caliper. Results: Grip strength varied significantly across wrist positions, with the highest mean value observed in the neutral position (30.53 kg), followed by ulnar deviation (28.94 kg), radial deviation (18.02 kg), extension (14.75 kg), and flexion (14.67 kg). The repeated-measures ANOVA demonstrated significant main effects of wrist position and sex, as well as a significant interaction between wrist position and sex (all p < 0.001). Males demonstrated higher mean grip strength than females in the neutral position (42.56 ± 8.98 kg vs. 18.54 ± 4.20 kg, respectively). Grip strength measurements across wrist positions showed strong positive correlations, with the strongest associations observed between flexion and neutral grip strength (ρ = 0.84) and between ulnar deviation and neutral grip strength (ρ = 0.81). The wrist angle was negatively correlated with grip strength during flexion (ρ = −0.24, p < 0.05) and extension (ρ = −0.41, p < 0.05), representing weak and moderate associations, respectively. Females demonstrated greater mean flexion and extension than males, whereas males demonstrated higher mean values for ulnar and radial deviation. Among males, grip strength was significantly positively correlated with maximum hand breadth (ρ = 0.365, p = 0.001), hand breadth (ρ = 0.326, p = 0.003), palm length (ρ = 0.304, p = 0.006), thumb length (ρ = 0.289, p = 0.009), and index finger length (ρ = 0.229, p = 0.039). No statistically significant associations were observed between grip strength and the assessed hand anthropometric measurements among females. Conclusions: Grip strength is markedly influenced by wrist position, with the highest grip strength measured in the neutral position and decreased in flexion, extension, or radial deviation. The results of this study may have implications for rehabilitation, ergonomic design, and sports performance in the future. Full article

Background/Objectives: Cardiac autonomic modulation, as assessed by heart rate variability (HRV), is a key indicator of physiological status. Although aging has traditionally been associated with reduced variability, morphological characteristics may be its main correlates. This study aimed to identify phenotypes of suppressed vagal modulation in women using a machine learning approach, specifically by correcting for HRV’s intrinsic mathematical dependence on heart rate (HR). Methods: Seventy-five women (30–69 years old) were recruited during fitness center enrollment. To control for hormonal fluctuations, the younger cohort (30–49 years old) was assessed during the follicular phase, whereas the older cohort (50–69 years old) was postmenopausal. Electrocardiogram data for HRV, bioimpedance, and anthropometric measurements were collected. Intrinsic vagal modulation was isolated by adjusting root mean square of successive differences (RMSSD) for the mean R–R interval (RMSSD_adj). The machine learning pipeline used LASSO for feature selection and multivariate logistic regression to identify suppressed vagal phenotypes (RMSSD_adj ≤ 0.0232). Model stability was verified using 1000 bootstrap iterations, and a cumulative Z-score index (ISCA) was used to characterize the morphologic–hemodynamic burden. Results: LASSO identified central adiposity, measured by the waist-to-hip ratio, as the primary independent correlate of suppressed vagal phenotypes (RMSSD_adj ≤ 0.0232). The model achieved an area under the curve (AUC)–ROC of 0.633 (95% CI: 0.490–0.771) with high specificity (0.900) and sensitivity of 0.360. No significant differences in intrinsic vagal modulation were observed between age cohorts (p > 0.05). However, women classified as having a high morphologic–hemodynamic burden (high-overload ISCA) exhibited a significantly higher resting heart rate, averaging 8.3 bpm more than the low-overload group (p < 0.05), reflecting a higher physiological demand in this phenotype. Conclusions: The autonomic status of women is characterized more accurately by morphological phenotypes than by chronological age. Integrated kinanthropometric monitoring is essential for identifying reduced autonomic resilience regardless of birth year. Full article

Background: Small-sided games (SSGs) are widely used in soccer training to develop physical, physiological, and technical–tactical capacities under game-representative conditions. Although task constraints have been investigated individually, evidence integrating their effects across major categories remains limited. This systematic review synthesized the effects of six task-constraint domains on SSG demands in association football. Methods: Following PRISMA 2020 guidelines, systematic searches were conducted in PubMed, SPORTDiscus, Web of Science, and Scopus. Forty studies published between 2015 and 2025 met the eligibility criteria and were categorized into six task-constraint domains: pitch size or area per player (n = 13), player number (n = 8), goalkeeper inclusion (n = 6), goal type (n = 5), numerical imbalance and floater players (n = 8), and transition games (n = 6). The review protocol was prospectively registered in PROSPERO. Results: Larger pitch areas consistently increased high-speed running but were insufficient to reproduce match-level sprint demands. Goalkeeper exclusion increased physiological intensity, particularly in smaller formats, whereas mini-goals reduced external locomotor load while maintaining comparable internal responses. Numerical disadvantage increased sprinting and high-intensity running demands for outnumbered players, while floaters experienced substantially lower physical loads than regular players. Transition games elicited the greatest locomotor demands, exceeding match values for high-speed running and sprinting across several playing positions. Conclusions: No single SSG format adequately addresses all match-relevant physical demands. Accordingly, practitioners should systematically manipulate and combine task constraints in accordance with specific training objectives. These findings provide evidence-informed guidance for optimizing SSG design to elicit targeted physical, physiological, and technical–tactical adaptations. Full article

Background and Objectives: The purpose of this study was to investigate the acute fatigue response to a standardized friendly football match in elite adolescent players and to describe the subsequent recovery of neuromuscular performance, biochemical markers, and subjective perceptions over a 72-h period. Methods: Thirty-seven elite male youth football players (16.3 ± 0.7 years) participated in this repeated-measures study. Neuromuscular function was assessed using the countermovement jump (CMJ) and repeated sprint ability (RSA) tests. Muscle damage was evaluated by measuring blood creatine kinase (CK) concentrations, while subjective recovery was monitored using a visual analog scale (VAS) for muscle soreness and the Well-Being Questionnaire (WBQ). Measurements were obtained before the match, immediately after the match, and again 24, 48, and 72 h later. Results: The friendly match induced significant neuromuscular, biochemical, and perceptual fatigue. CMJ height, reactive strength index, and repeated sprint performance decreased significantly immediately post-match (p < 0.001). Perceived muscle soreness increased markedly and remained elevated at 24 h. Neuromuscular performance largely recovered within 48 h, with 20-m sprint performance no longer significantly different from pre-match values at 48 h. In contrast, CK concentrations peaked at 24 h and remained significantly elevated throughout the 72-h recovery period. Significant correlations were observed between subjective soreness, CK concentrations, and neuromuscular performance during recovery. Recovery following match play differed depending on the marker used. Functional performance largely returned to baseline within 48 h, whereas CK concentrations remained elevated throughout the 72-h observation period. Conclusions: These findings emphasize the value of combining objective performance tests with subjective measures when monitoring post-match recovery in elite youth football players. Full article

Background: The aim was to investigate the stride-by-stride development of spatiotemporal parameters, joint kinematics, kinetics, and electromyographic (EMG) activity during a 50 m sprint, providing a comprehensive analysis of the biomechanical and neuromuscular changes throughout the entire sprint. Methods: Fifteen male sprinters (age 20.5 ± 1.3 years, body mass 66.8 ± 4.5 kg, body height 1.74 ± 0.06 m, 100 m personal best: 11.24 ± 0.34 s) performed a 50 m sprint, while the spatiotemporal parameters, joint kinematics, kinetics, and EMG activity of nine muscles were measured. Results: The main findings were that the 50 m sprint could be divided into three phases: initial acceleration, transition and maximal velocity and involve tightly coordinated changes across multiple biomechanical domains. The initial acceleration (the first 3–5 strides) was dominated by rapid increases in stride frequency, rapid changes in joint angles, and rising EMG activity in key muscles. In the transition phase (up to ~30–35 m), continued increases in stride length, decreasing contact time, and stabilization of kinematics and EMG activity were the main characteristics. In the maximal-velocity phase, a plateau in velocity, increased flight time, greater reliance on vertical force (an increase in vertical force relative to the horizontal forces), and stabilized neuromuscular patterns were observed. Conclusion: The phased progression supports contemporary biomechanical models of sprinting and emphasizes the importance of both mechanical and neuromuscular efficiency in achieving optimal sprint performance. Full article

Introduction: Most studies evaluating low-carbohydrate diets in resistance-trained individuals have focused on short-term ketogenic interventions. Whether habitual carbohydrate intake maintained under free-living conditions is associated with body composition and muscle strength remains unclear. Therefore, this study compared body composition and maximal isometric strength between recreationally resistance-trained men with a habitual low or normal carbohydrate intake. Methods: A cross-sectional analytical study was conducted in 53 recreationally resistance-trained men aged 18–35 years. Habitual dietary intake was assessed using three non-consecutive 24 h dietary recalls. Participants were classified as having low (<3 g/kg/day; n = 28) or normal (3–5 g/kg/day; n = 25) carbohydrate intake; participants also reported maintaining their respective dietary pattern for at least three months. Body composition was estimated using the Ross and Kerr anthropometric model, whereas fat mass was calculated using the Martin equation. Maximal isometric handgrip and knee extension strength were also assessed. Between-group comparisons were performed using Welch’s t-test or the Mann–Whitney U test, and multiple linear regression models were adjusted for age, height, and relative energy intake. Sensitivity analyses were additionally adjusted for relative protein intake. Results: Participants with a habitual low carbohydrate intake presented significantly lower adipose mass (β = −2.42 kg; 95% CI: −4.49 to −0.35; p = 0.02), adipose percentage (β = −4.64%; 95% CI: −7.47 to −1.80; p < 0.01), fat mass (β = −2.33 kg; 95% CI: −4.08 to −0.57; p = 0.01), and body fat percentage (β = −4.06%; 95% CI: −6.52 to −1.59; p < 0.01) than participants with a normal carbohydrate intake. No significant differences were observed in muscle mass, handgrip strength, or absolute knee extension strength after adjustment. In sensitivity analyses additionally adjusted for relative protein intake, associations with adiposity were attenuated and no longer statistically significant, whereas low carbohydrate intake was associated with lower absolute and relative handgrip and knee extension strength (all p < 0.05). No significant associations with skeletal muscle mass were observed. Conclusions: In recreationally resistance-trained men, habitual carbohydrate intake below 3 g/kg/day was associated with lower adiposity in the primary analyses; however, these associations were attenuated after additional adjustment for relative protein intake. Conversely, associations with lower maximal isometric strength emerged after adjustment for protein intake, while no associations with skeletal muscle mass were observed. These findings suggest that the associations of habitual carbohydrate intake with adiposity and muscle strength may be influenced by overall dietary composition and should be interpreted cautiously given the cross-sectional design. Full article

Background and Objectives: Running-related musculoskeletal injuries remain highly prevalent among recreational runners, and the absence of population-specific biomechanical reference values limits clinical and sports interpretation in Latin American populations. This study aimed to establish reference values for spatiotemporal and selected running kinematic/mechanical values (initial contact angle, vertical leg stiffness, and vertical oscillation) in healthy adult recreational runners from Barranquilla (Colombia) using three-dimensional motion capture. Methods: A cross-sectional observational study was conducted in 25 healthy adults (13 men, 12 women; mean age 32.7 ± 7.4 years, range 20–47 years). Running biomechanics were assessed using a BTS SMART-DX three-dimensional motion capture system and a Modified Helen Hayes marker model with 30 reflective markers. Participants completed treadmill running trials at 7, 9, 11, and 13 km/h. Key spatiotemporal parameters and global kinematic/mechanical metrics were processed using BTS Smart Clinic software. Reference values were defined using the 10th and 90th percentiles, stratified by sex and running speed, and accompanied by bootstrap 95% confidence intervals. Effects of sex and speed were tested by two-way ANOVA with partial eta squared and Holm-adjusted p values, with a linear mixed-effects model as a robustness check. Results: Motorized treadmill-specific biomechanical reference values (10th and 90th percentiles) were established and stratified strictly by running speed (7, 9, 11, and 13 km/h) and sex. Under the primary linear mixed-effects model, running speed significantly affected all ten evaluated biomechanical variables (all adjusted p < 0.001), including initial contact angle and vertical oscillation, confirming that speed-disaggregated estimates are mandatory for clinical interpretation. Conversely, sex effects were robust to multiplicity adjustment only for flight time and vertical leg stiffness. Compared with a European reference cohort, and after adjustment for sex, age, stature, body mass and speed through the published reference equations, this cohort showed a 6.6% shorter flight time, a 19.0% lower vertical oscillation, a 3.8% shorter stride length, and a 3.1% higher cadence. Conclusions: This study provides the preliminary regional reference database for running spatiotemporal and selected kinematic parameters in a cohort of healthy adult recreational runners from Barranquilla (Colombia). These preliminary values provide a baseline restricted to motorized treadmill running at fixed speeds; while they support standardized treadmill screening and rehabilitation tracking, their direct applicability to overground or self-paced running remains limited and warrants caution. Full article

Background: Maximal fat oxidation (MFO) is the highest rate of fat oxidation attained during incremental exercise, with cardiorespiratory fitness being its primary correlate. How body composition and regional anthropometry explain MFO variability remains poorly understood. While fat-free mass is a known correlate, regional morphology, such as skinfold-corrected girth, has been proposed to capture local muscle mass contributions. However, MFO is an absolute rate (g·min⁻¹) whereas peak oxygen uptake (VO₂peak, typically mL·kg⁻¹·min⁻¹) is conventionally reported relative to body mass. The statistical consequences of this dimensional mismatch, and the question of whether regional girths independently account for MFO variance or merely reflect body size artefacts, remain unexamined. Methods: Forty-three national-team collegiate athletes (21 men, 22 women) underwent a maximal incremental treadmill test with breath-by-breath indirect calorimetry, dual-energy X-ray absorptiometry (DXA), bioelectrical impedance analysis and a full International Society for the Advancement of Kinanthropometry (ISAK) anthropometric profile including six skinfold-corrected girths. The primary model regressed absolute MFO on absolute peak oxygen uptake (VO₂peak, L·min⁻¹). Sensitivity models added corrected girths, fat-free mass, sex, stature and body mass. Internal validity was assessed by leave-one-out cross-validation (Q²) and 5000-sample bootstrapping, with Benjamini–Hochberg control of the false discovery rate. Results: Absolute VO₂peak explained 60.4% of the variance in MFO (Q² = 0.563; β = 0.191 g·min⁻¹ per L·min⁻¹, 95% CI 0.142 to 0.240; bootstrap CI 0.133 to 0.227). Adding corrected calf girth changed the explained variance by 0.006 (p = 0.424) and reduced Q² to 0.541. No corrected girth survived the false-discovery-rate control, and fat-free mass added nothing (p = 0.268). When aerobic capacity was instead expressed per kilogram of body mass, model fit was substantially worse (R² = 0.415) and corrected calf girth appeared to be strongly and independently associated with MFO (p < 0.001). Conclusions: In trained athletes, absolute aerobic capacity explains MFO variance, whereas regional anthropometry and body composition provide no incremental information. Normalising predictor variables by body mass creates statistical artefacts that falsely attribute explanatory power to structural girths. Future studies with larger sample sizes and diverse athletic populations are needed to confirm these findings across different training statuses and metabolic profiles. Full article

Background: Patellar tendinopathy is a persistent load-related condition in athletes, and exercise is recommended as first-line care; however, the comparative value of specific tendon-loading prescriptions remains uncertain. This systematic review aimed to synthesize exercise-based interventions for adults with patellar tendinopathy, map reported loading prescription parameters, and estimate comparative effects when sufficiently comparable active-loading data were available. Methods: We conducted a PROSPERO-registered systematic review following PRISMA 2020. MEDLINE/PubMed, Web of Science Core Collection, Scopus, SPORTDiscus, and CENTRAL via Ovid/EBMR Reviews were searched. Two reviewers independently screened studies, extracted data, and assessed risk of bias. The primary outcome was VISA-P/VISA final score. Randomized active exercise/loading comparisons with extractable final-score data were pooled as mean differences on the original 0–100 scale using random-effects restricted maximum likelihood models with Hartung–Knapp adjustment. Results: The searches identified 942 records; 96 full-text reports were assessed and 40 reports were retained for qualitative synthesis. Six active exercise/loading comparisons contributed to the primary comparative synthesis. The pooled mean difference was 5.16 VISA-P/VISA points (95% CI 2.39 to 7.93) in favour of the first-listed intervention, with negligible statistical heterogeneity (tau2 = 0.000; I2 = 0.0%; Q = 3.50, p = 0.624). All contributing studies had some concerns in RoB 2, and GRADE certainty was low. Conclusions: Structured tendon-loading exercise remains central to rehabilitation. The pooled estimate should be interpreted as a small average comparative signal across clinically distinct active-loading contrasts, not as evidence that one specific loading strategy is universally superior. Full article

Background and Objectives: Artificial intelligence (AI) has rapidly emerged as a promising tool for delivering personalized interventions in physical activity, exercise prescription, and weight management. AI technologies may facilitate individualized recommendations, behavioral support, and lifestyle modification through adaptive digital health solutions, although their effectiveness remains to be established across different populations and settings. However, the current evidence remains heterogeneous, and the practical implementation of AI in personalized training and weight management requires further evaluation. This scoping review aimed to summarize the current evidence regarding the application of artificial intelligence for the personalization of training and weight reduction, with particular emphasis on the types of AI technologies used, their reported outcomes, practical applications, and current limitations. Methods: A scoping review was conducted following a structured literature search of studies investigating AI-supported interventions related to physical activity, exercise, dietary behavior, and weight management. Eight studies involving diverse populations, intervention designs, and AI technologies were included. Data were extracted on study characteristics, AI technologies, intervention characteristics, reported outcomes, and research gaps. The literature search was subject to access-based restrictions, including the use of “Free full text” in PubMed and “Open Access” in Web of Science, as well as language restrictions. Results: The included studies investigated a wide range of AI technologies, including conversational chatbots, natural language processing systems, machine learning algorithms, computer vision applications, knowledge-based systems, and large language models. Selected studies reported favorable or modest changes in exercise adherence, physical activity participation, dietary behaviors, user engagement, and weight-related outcomes; however, the magnitude and consistency of these findings varied across studies. Personalized coaching, real-time feedback, and continuous behavioral support were common features of interventions reporting favorable outcomes. However, considerable heterogeneity existed across study designs, participant populations, intervention protocols, AI technologies, and outcome measures, and evidence regarding long-term effectiveness remains limited. The findings should be interpreted in the context of the adopted search strategy, including access-based restrictions and the inability to retrieve eight of 57 reports sought for retrieval, which may have contributed to availability bias. Conclusions: Current evidence suggests that artificial intelligence may have potential as a tool for supporting the personalization of training and weight management interventions, particularly through individualized behavioral support, feedback, and user engagement. However, the available evidence is heterogeneous and does not yet allow firm conclusions regarding the effectiveness or mechanisms of AI-supported interventions. AI should currently be viewed as a complement rather than a replacement for healthcare and exercise professionals. Future large-scale randomized controlled trials with longer follow-up periods and standardized outcome measures are needed to clarify the effectiveness, sustainability, and practical implementation of AI-supported interventions. Full article

Background and Objectives: Military parachuting combines landing impact, carried load, and restricted visual information. This study examined the concurrent associations of two primary task exposures—recent jump volume and participation in at least one night jump with equipment—with self-reported parachuting-related musculoskeletal problems; individual characteristics were treated as adjustment variables or exploratory factors. Methods: A cross-sectional study was conducted in 105 parachutists from the Sapper Battalion of the Spanish Parachute Brigade. Exposure and outcome were both recalled for the same preceding 12 months, and their temporal sequence was not recorded. Prevalence was estimated with Wilson 95% confidence intervals, and the two primary exposures were entered simultaneously in Firth bias-reduced logistic regression adjusted for age and body mass index. A modified Poisson model with robust standard errors estimated adjusted prevalence ratios as a sensitivity analysis. Results: Forty-eight participants (45.7%) reported at least one parachuting-related musculoskeletal problem during the preceding year, most frequently at the knee, low back, and upper back or neck. Problems were reported by 79.4% of participants who had performed night jumps with equipment and by 29.6% of those who had not. Night jumps with equipment were associated with the outcome (odds ratio 7.13, 95% confidence interval 2.71–20.66), whereas recent jump volume was not. The adjusted prevalence ratio for the combined exposure was 2.44 (95% confidence interval 1.63–3.64). Conclusions: Night jumps with equipment showed a concurrent association with self-reported musculoskeletal problems, but the design cannot establish whether the exposure preceded the problem or separate the contributions of darkness and equipment. The findings should be treated as hypothesis-generating for prospective, jump-level surveillance. Full article

Background: Subjective autoregulation methods are gaining interest among resistance-trained athletes. In particular, velocity perception (PV) and velocity loss perception (PVL) have shown promising practical applicability. This study aimed to investigate the temporal stability of PV and PVL across an eight-week period. Methods: Fifteen participants, after sessions of familiarization with PV and PVL, completed three test sessions: the first 48 h after the familiarization, and the others 4 and 8 weeks later. Each test session included five sets of back squats with light (55%–60%–65% 1RM) and heavy (75%–85% 1RM) loads. Light loads were executed with a 10–20–30%VL, while heavy loads with a 10–20%VL. PV accuracy was assessed using the |DeltaScore|, defined as the absolute difference between perceived velocity (Vp) and the velocity provided by the encoder (Vr): |DeltaScore| = |Vp − Vr|. PVL was measured by the |Vscore|, defined as the absolute difference between the number of repetitions perceived as correct relative to the target %VL (Np) and the repetitions that actually met it (Nr): |Vscore| = |Np − Nr|. Results: The results demonstrated that both PV and PVL are stable after 4 weeks at all loads and %VL (p > 0.05). In contrast, after 8 weeks, PV accuracy significantly decreased at all loads (p < 0.05; η²p = 0.04), whereas PVL accuracy decreased only at light loads (p < 0.05; η²p = 0.18). Moreover, PV error values remained below the previously suggested acceptability threshold of 0.09 m·s⁻¹ for up to 4 weeks. This error threshold corresponds to a load variation of ~10% 1RM in the back squat. Conclusions: The present results support the applicability of PV and PVL in real training contexts for a maximum of 4 weeks when monitoring devices are unavailable. Full article