This study aimed to (I) evaluate the influence of maturity and sex on the horizontal force-velocity (F-V) profile and multidirectional speed performance in youth basketball players and (II) analyze the sex- and maturity-specific associations of the mechanical variables derived from the horizontal FV profile with curvilinear sprint (CS) and change of direction (COD) performance. Ninety-nine youth basketball players from an elite academy were classified into two maturational groups based on their estimated years from peak height velocity (PHV) (mid-PHV and post-PHV). A cross-sectional design was implemented to compare the mechanical variables of the F-V profile (theorical maximal force (F0) and velocity (V0), maximal power output (Pmax) and ratio of horizontal-to-resultant force (RFpeak) across maturation and between sexes. These variables were also analyzed in relation to CS and COD performance. Post-PHV group exhibited significantly greater horizontal FV profile parameters (ES from 0.70 to 2.06), and faster CS and COD performances (ES from 0.29 to 2.49), compared to mid-PHV group in both sexes. Additionally, V0, Pmax and RFpeak were moderately to largely associated (rrange from 0.41 to 0.81) with faster CS and COD performance in both mid- and post- PHV men players. These findings highlight the relevance of considering individual FV profiles to monitor performance and better understand multidirectional speed across maturation.
Abstract:This study investigated the magnitude of the association of the regional muscular architecture of the pectoralis major and triceps brachii muscles on the maximum dynamic strength in Paralympic powerlifting athletes. Twenty-six athletes participated in this study. Architectural analysis included cross-sectional area and muscle thickness of the pectoralis major at 15 and 30% of the clavicle length and of the triceps brachii at 50, 60 and 70% of the humerus length, in addition to the pennation angle and fascicle length of triceps brachii at 60%, obtained by panoramic ultrasound. A generalized linear model was used. The significance level was 0.05. The muscle thickness of the pectoralis major at 30% was positively associated with maximum dynamic strength (β=0.2023; p=0.008), for each additional centimeter in the muscle thickness of the pectoralis major, performance is expected to increase by about 56%. The muscle thickness of the triceps brachii at 60% had a significant positive association with performance (β=0.290; p=0.001), corresponding to a potential 34% increase in performance for each centimeter increase. Arm length was negatively associated with performance (β=-0.039; p=0.033), each 1 cm increase in arm length corresponds to an approximately 4% reduction in performance. The muscle thickness of the pectoralis major is the parameter with the greatest magnitude of association with performance.
Abstract:This study aimed to determine whether active ischemic preconditioning, incorporating exercise during the reperfusion phases, would enhance Yo-Yo Intermittent Recovery Test Level 2 performance in soccer players. Seventeen male amateur soccer players (24.0±1.8 y) completed three different preconditioning sessions before the Yo-Yo Intermittent Recovery Test Level 2. The ischemic preconditioning protocol consisted of three cycles of 4-minute occlusion (220 mm Hg), followed by 4-minute reperfusion (0 mm Hg) in both thighs (at rest). Active protocols were similar to ischemic preconditioning; however, during reperfusion, participants performed intermittent running (ischemic preconditioning+Yo-Yo Intermittent Recovery Test Level 2) or three-repetition maximum squat repetitions (ischemic preconditioning+SQUAT). We assessed countermovement jump and Yo-Yo Intermittent Recovery Test Level 2 performance, heart rate, muscle oxygen saturation, blood lactate, rating of perceived exertion, and session-rating of perceived exertion. Ischemic preconditioning+SQUAT resulted in a greater Yo-Yo Intermittent Recovery Test Level 2 distance compared to ischemic preconditioning (p=0.02 and effect size=0.3) and ischemic preconditioning+YOYO (p=0.01, effect size=0.2). Countermovement jump performance was affected by condition (p<0.01), with ischemic preconditioning+YOYO presenting higher values compared with ischemic preconditioning (effect size=1.1), although no time effect was observed. No significant differences were observed for muscle oxygen saturation (p=0.09), blood lactate (p=0.32), and rating of perceived exertion/session-rating of perceived exertion (p=0.96); however, the mean heart rate was higher with active reperfusion conditions than ischemic preconditioning. Active reperfusion combined with heavy squat exercise slightly improved high-intensity intermittent running performance in soccer players, while also eliciting higher heart rate responses, which should be considered during training monitoring.
Abstract Acute exercise markedly alters blood glucose levels and the secretion of glucose-regulating hormones. However, as a central organ involved in glucose homeostasis, the molecular mechanisms underlying pancreatic responses to acute exercise remain poorly understood. Therefore, this study aimed to investigate the molecular adaptations of pancreatic tissue to acute exercise using a mouse treadmill exercise model combined with integrated multi-omics analyses. C57BL/6 mice were randomly assigned to either an exercise group or a control group, and pancreatic tissues were collected immediately after exercise intervention for transcriptomic and metabolomic analyses. Acute exercise significantly increased blood glucose and glucagon levels while reducing circulating insulin levels. Metabolomic analysis revealed significant elevations in several metabolites related to amino acid metabolism, including tryptophan, kynurenic acid, leucine, isoleucine, and valine. Transcriptomic analysis further identified significant upregulation of multiple genes, including Ins1, Ins2, Cdkn1a, Dusp1, Fkbp5, and Pdk4. These findings suggest that acute exercise induces rapid transcriptional and metabolic remodeling in pancreatic tissue and that these differential metabolites and genes may contribute to the pancreatic adaptive response to acute exercise.
Abstract The aim of this study was to examine the associations of body composition, physical performance, and inflammatory/oxidative stress biomarkers with aerobic capacity, indexed by peak oxygen uptake, among tactical personnel, and to develop predictive models for health, performance, and readiness assessment. Complete case data were available for 102 occupational personnel. Variance inflation factors assessed multicollinearity. Linear models tested associations with peak oxygen uptake, while generalized additive models explored nonlinear relationships. A 10-fold cross-validation procedure evaluated model performance, and diagnostic and sensitivity analyses assessed robustness. Variance inflation factors indicated no problematic multicollinearity. The baseline linear model explained moderate variance in peak oxygen uptake, and adding estimated pulse wave velocity and high-density lipoprotein (HDL) cholesterol modestly improved fit. Fat mass remained a strong negative predictor, while HDL cholesterol showed an independent positive association with the peak oxygen uptake. The generalized additive model provided better fit and identified nonlinear relationships for fat mass and estimated pulse wave velocity. Cross-validation also supported better predictive performance for the generalized additive model than the linear model. Overall, higher fat mass and estimated arterial stiffness were associated with lower aerobic capacity, whereas HDL cholesterol was positively associated with peak oxygen uptake. Modeling nonlinear relationships improved prediction, suggesting that adiposity, estimated arterial stiffness, and metabolic health jointly contribute to aerobic capacity beyond age in occupational personnel.
Abstract:The aim of the current study was to compare modelled maximal lactate steady state with the field-based assessment of critical power in a group of highly trained pro cyclists. As a secondary objective, the relationships of the maximal rate of blood lactate accumulation and maximal oxygen consumption with outdoor maximal mean power output of different durations were explored. Twelve highly trained male professional cyclists performed six successive maximal tests. The maximal lactate steady state was calculated using the maximal rate of blood lactate accumulation, maximal oxygen consumption, resting oxygen uptake and body mass as input parameters. The critical power was estimated using the 3-minute and 20-minute maximal mean power outputs. The mean of the modelled maximal lactate steady state was 357±30.6 W, while the mean of critical power was 364±21.5 W; the modelled maximal lactate steady state and critical power correlated significantly (r=0.881 and p<0.001). The maximal oxygen consumption correlated with the 3-minute maximal mean power (r=0.646 and p=0.023), 20-minute maximal mean power (r=0.846 and p<0.001) and critical power (r=0.858 and p<0.001). No significant correlations were found between maximal rate of blood lactate accumulation and any of the outdoor maximal mean power outputs. The modelled maximal lactate steady state seems to predict critical power well on a group level; however, a substantial individual variation in the difference between the modelled maximal lactate steady state and critical power was observed. This individual variation would argue against conceptual similarity between the critical power and maximal lactate steady state model, which practitioners working within cycling should be aware of.
Abstract:The association between reduced Achilles tendon structural integrity and ankle instability may reflect alterations in muscle-tendon properties and impairments throughout the lower-extremity kinetic chain following ankle sprain. This study aimed to investigate the effect of an intervention program on Achilles tendon organization in military recruits and to evaluate its impact on tendon structure in participants with ankle instability and those who sustained ankle sprains during training. A total of 387 male recruits (160 intervention and 227 control groups) were screened for Achilles tendon structure (echo types III and IV representing disorganized fibers) at baseline (PRE) and 12 weeks of infantry training (POST). The cohorts reported pre-induction chronic ankle instability and were followed for ankle sprains during training. The intervention group undertook an injury prevention program (5min, five times/wk) while the control group continued their routine physical-fitness sessions. Significanttime×group interactions were found for echo types III and IV fibers (p=0.005 and p=0.032, respectively). The time×instability×groupinteraction was found for echo type IV (p=0.005); the time×instability interaction was found for echo type III (p=0.017). In participants who received exercises, the Achilles tendon structure improved during training. Participants with pre-induction chronic ankle instability and participants who sprained their ankles were more likely to present the disorganized PRE-training tendon structure. Neuromuscular injury-prevention intervention training might be associated with improved tendon quality in those who sprained their ankles during training.
Abstract:Mindfulness-based interventions have gained increasing attention in sport psychology as approaches to enhance attentional control, emotion regulation, and performance consistency under competitive pressure. This study examined the effects of an 8-week mindfulness-based intervention on volleyball-specific technical performance in elite female athletes. Twenty-eight volleyball players aged 17 to 19 years were randomly assigned to an experimental group (n=14), which completed 12 mindfulness sessions over 6 weeks (two 60-min sessions/wk) before regular volleyball training, or a control group (n=14), which continued standard volleyball training only. Training load was standardized across groups and monitored to ensure consistency. Volleyball performance was assessed before and after the intervention using a standardized skill test battery, including forearm pass, overhead pass, serve, spike, and block accuracy measures. The experimental group demonstrated significantly greater improvements than the control group across all five performance measures (group×time interactions, all p<0.05, anf η² range=0.074-0.174), with the largest effects observed for spike accuracy (F(1.26)=34.2, p<0.001, and η²=0.174) and serve accuracy (F(1.26)=13.2, p<0.001, and η²=0.121). These findings indicate that mindfulness-based training may serve as an effective complementary approach to technical and physical preparation in volleyball, supporting skill execution and performance consistency in competitive contexts.
Abstract Muscle mass is essential for both general health and athletic performance because it supports strength, functional capacity, and physical performance. Hormonal contraceptives are used by a variety of individuals, including athletes and those who exercise. Most contraceptives contain ethinyl estradiol and a progestin, hormones that may impact muscle adaptations and hypertrophy. A limited number of studies, predominantly focused on oral contraceptives, have examined the relationship between hormonal contraceptives and muscle hypertrophy, with mixed findings. This narrative review synthesizes the current literature on how oral contraceptives may affect hypertrophic responses, considering both mechanistic and applied perspectives. The evidence generally suggests that oral contraceptive use does not consistently alter muscle hypertrophy following resistance training, although a small number of studies have reported significant negative effects. These findings may be attributable, in part, to the use of more androgenic progestins. However, variability in contraceptive formulation, training protocols, and cohort sizes limits direct comparisons across studies. While mechanistic studies suggest that endogenous and synthetic sex hormones influence pathways involved in skeletal muscle remodeling, clinical studies of oral contraceptive use have not consistently demonstrated clinically meaningful differences in muscle hypertrophy. We recommend well-powered studies comparing progestins with differing androgenic activity, as well as mechanistic studies on muscular growth pathways, to better understand the influence of oral contraceptives on muscle adaptation.
Abstract:Dynamic postural control in Canadian canoeing depends on coordinated load distribution and center of pressure regulation across three support points in a highly asymmetrical kneeling posture. However, the integrated organization of these biomechanical domains under varying stability demands remains poorly characterized. This exploratory study examined 13 Canadian canoeing athletes using three synchronized strain-gauge force platforms during a standardized canoe-specific kneeling position under stable and unstable support conditions. Three dynamic variables, percentage load distribution (%DCA), dynamic force (N. kg⁻¹), and center-of-pressure displacement (Dynamic SigmaPath), were assessed simultaneously. Principal component analysis showed that PC1 (62.5% variance) and PC2 (24.1% variance) captured the main structure of postural control, with Dynamic SigmaPath displaying loading patterns opposite to the percentage load distribution and force. Exploratory K-means clustering (k=2) suggested moderate organization into two biomechanical patterns. Correlation analyses revealed significant associations between load-distribution metrics and Dynamic SigmaPath (ρ=0.657 and p=0.015), and between force production and load-distribution asymmetry (ρ=-0.635 and p=0.020). These findings indicate that biomechanical affinity, quantified through multivariate analysis, characterizes athlete-specific postural-control strategies. A Composite Biomechanical Index is proposed as an exploratory framework for describing postural-control strategies and generating hypotheses regarding athlete monitoring and crew compatibility in paddling sports.
Abstract:Despite growing research, the health effects of COVID-19 on soccer players remain poorly integrated. This meta-analytic review synthesized evidence across competitive levels and pandemic phases to characterize the effects of SARS-CoV-2 infection and pandemic-related restrictions. The study adhered to PRISMA 2020 and Cochrane standards, with searches conducted in PubMed, Scopus, SPORTDiscus, and Web of Science. Eligibility criteria followed the P.E.C.O.S. framework. From 6,048 records screened, nine studies (>1,525 players from Tiers 1-5) met the inclusion criteria. These observational investigations included predominantly male samples (94.2%) and assessed cardiovascular, respiratory, endocrine, metabolic/biochemical, hematologic, anthropometric, musculoskeletal, and gastrointestinal outcomes. Comparisons between pre- and during-pandemic periods suggested preserved cardiac integrity with infrequent post-infection sequelae, alongside mild pulmonary effects in infected players that tended to resolve with training resumption. Amid inconsistent endocrine findings, testosterone-to-cortisol ratios declined in non-infected players. Metabolic, hematologic, and anthropometric parameters were mostly stable, whereas hemoglobin exhibited a significant pooled increase. Musculoskeletal and gastrointestinal data were insufficient for broad conclusions. Moreover, meta-analytic estimates require cautious interpretation owing to few studies and very low certainty. Altogether, COVID-19 was associated with modest and mostly reversible effects, with structured home-based training potentially offsetting detraining. Rare cardiac abnormalities still warrant careful medical supervision.
Abstract:This study described the epidemiology of elbow medial ulnar collateral ligament injuries in collegiate baseball players between the 2014 to 2015 and 2018 to 2019 academic years using National Collegiate Athletic Association Injury Surveillance Program data. Injury rate ratios and descriptive statistics were used to characterize the epidemiology of these injuries. The overall medial ulnar collateral ligament injury rate in National Collegiate Athletic Association baseball players between 2015 and 2019 was 0.95/10,000 athletic exposures. Medial ulnar collateral ligament injury rates rose annually from 2015 to 2019. The medial ulnar collateral ligament injury rate was statistically significantly higher in competition (1.36/10,000 athletic exposures) than practice (0.61/10,000 athletic exposures; injury rate ratio: 2.22; confidence interval: 1.27-3.88). Pitchers accounted for 83.3% of injured players. Forty-three percent of medial ulnar collateral ligament injuries required athletes to miss the remainder of the season, and 18.5% of medial ulnar collateral ligament injuries required surgical intervention. In conclusion, the rate of medial ulnar collateral ligament injuries in collegiate baseball players increased steadily each year from 2015 to 2019. Medial ulnar collateral ligament injuries occur at a significantly higher rate during competition compared to practice, and pitchers account for the greatest number of medial ulnar collateral ligament injuries among college baseball players.
Post-exercise hypotension (PEH) has been proposed as a promising biomarker for predicting the long-term blood-pressure (BP) response to exercise training. This study assessed the reliability of PEH-from single- and averaged-session measurements-in 33 sedentary adults completing an 8-week aerobic exercise program. Resting BP was measured before and after the intervention; acute PEH was defined as the change in BP from pre-exercise to 10-minute post-exercise recovery and was measured across five separate sessions. Data were analysed using mixed-effects models. The impact of aggregating measurements on reliability and its correlation with chronic BP reduction was assessed using analytical formulas and Monte Carlo resampling. The reliability of single-session PEH measurements was poor, with a high standard error of measurement (systolic BP: 4.5 [4.0, 5.1] mmHg; diastolic BP: 4.3 [3.8, 4.9] mmHg) and low intraclass correlation coefficients (systolic BP: 0.24 [0.08, 0.29]; diastolic BP: 0.31 [0.13, 0.43]). Reliability improved substantially when values were averaged across multiple sessions. The correlation between acute PEH and chronic BP reduction also strengthened with averaging, albeit with diminishing returns. These findings support the potential of PEH as a predictive biomarker, particularly when averaged over several training sessions. The optimal number of sessions should balance statistical improvement with practical feasibility.
Abstract:This randomized controlled trial examined the effects of adding neuromuscular electrical stimulation to rehabilitation exercise on quadriceps muscle strength (primary outcome) and secondary exploratory outcomes after anterior cruciate ligament reconstruction. Twenty-four male participants were randomly allocated to rehabilitation exercise alone or combined with neuromuscular electrical stimulation. Both groups performed range of motion exercises during weeks 1 to 3, followed by progressive quadriceps strengthening three times weekly for 9 weeks. Both groups improved in isokinetic muscle function, with larger effect sizes in the resistance exercise+neuromuscular electrical stimulation group (d=0.883-1.488) than in the resistance exercise group. Patient-reported outcomes improved in both groups for the Lysholm score (d=1.527 vs. 0.653), whereas changes in the International Knee Documentation Committee score were greater in resistance exercise+neuromuscular electrical stimulation (d=1.006 vs. 0.034). Balance improved with larger effects in resistance exercise+neuromuscular electrical stimulation under stable (d=0.710 vs. 0.160) and unstable conditions (d=1.988 vs. 0.029), while Y-balance showed similar changes. Muscle morphology showed greater increases in resistance exercise+neuromuscular electrical stimulation for the cross-sectional area (d=1.127 vs. 0.070) and thickness (d=0.737 vs. 0.203). Biomarker responses were also larger in resistance exercise+neuromuscular electrical stimulation. Overall, the neuromuscular electrical stimulation was associated with favorable trends across several functional and clinical outcomes.
Abstract:Circulating irisin, a myokine linked to exercise-induced metabolic adaptation, may respond to exercise intensity and serve as a marker of training status. This study assessed intensity-dependent acute irisin responses in master athletes and recreationally trained men, baseline irisin associations with maximal oxygen uptake and body fat, and fibronectin type III domain-containing protein 5-related pathways using bioinformatics. Master endurance athletes (n=11; 49.9±5.8 y) and recreationally trained men (n=10; 49.9±7.2 y) completed two running sessions (moderate and severe), and plasma irisin was measured at rest and 15- and 120-minutes post-exercise. Exercise intensity significantly modulated acute irisin responses (time×intensity, p=0.006), with greater and earlier increases after severe exercise. Master endurance athletes exhibited consistently higher irisin than recreationally trained men (p<0.001), with intensity effects in both groups; baseline irisin was inversely associated with body fat (p=0.018) and positively with maximal oxygen uptake (p<0.001). Complementary RNA-seq analyses showed an age-related decline in skeletal muscle fibronectin type III domain-containing protein 5 expression, preserved by long-term endurance training via upregulated mitochondrial and energy metabolism pathways. Together, these findings indicate that exercise intensity and lifelong training modulate irisin regulation, supporting its use as a biomarker of aerobic fitness, metabolic adaptation, and healthy aging.
