This study examined the associations between 24-h movement behaviors and cognitive function in cognitively unimpaired older adults, and whether Alzheimer's disease brain signatures, including gray matter mean diffusivity (GMMD) and thickness/volume signatures, moderated these associations. A total of 91 participants were enrolled in the AGUEDA trial (NCT05186090), with 89 included in this cross-sectional analysis (mean age = 71.61 ± 3.85 years; 56.2% females). Moderate-to-vigorous physical activity (MVPA), light physical activity (LPA), sedentary behavior (SB), and sleep were objectively assessed using 9-day wrist-worn accelerometry. Cognitive function was assessed across attention/inhibitory control, episodic memory, processing speed, visuospatial processing, and working memory. Thickness/volume and GMMD signatures were derived from cortical and hippocampal regions. Compositional linear regression models (CoDA) examined associations, adjusting for age, sex, and education, and tested interactions between movement behaviors and Alzheimer's disease brain signatures. No direct associations were observed between 24-h movement behaviors and cognitive domains (all p > 0.05). However, GMMD signature, but not thickness/volume signature, moderated several movement behavior-cognition associations. Moderation was most evident for episodic memory, with significant interactions for MVPA, LPA, and sleep, while LPA exhibited the broadest pattern of moderation across cognitive domains, interacting with attention/inhibitory control, episodic memory, processing speed, and working memory (all p for interaction ≤ 0.04). In conclusion, the associations between 24-h movement behaviors and cognitive function may depend on microstructural brain integrity (i.e., GMMD). These findings highlight the importance of considering Alzheimer's disease-related brain signatures when investigating lifestyle-cognition associations and support a more personalized approach to promoting cognitive health in older adults. Future prospective longitudinal studies and CoDA interventional trials are needed to establish temporal precedence and evaluate whether targeted time reallocations can actively attenuate cognitive trajectories across distinct microstructural vulnerability profiles. Trial Registration: NCT05186090.
Persistent knee offloading is well-documented after arthroscopic partial meniscectomy (APM). Yet, it remains unclear if this extends to higher-demanding change-of-direction (CoD) tasks and how step-specific strategies influence joint loading. We aimed to compare joint power and relative contributions in the surgical limb, contralateral limb, and healthy individuals during a 90° CoD. A secondary aim examined the relationship between knee negative power at the penultimate and final foot contacts across limb sequences. Kinematic and kinetic data were collected from 24 post-APM and 20 healthy individuals using motion capture with force plates. Participants performed a running approach before executing a 90° CoD. Linear mixed-effects models compared limb differences and examined the relationship between steps. During penultimate contact, APM limb showed lower magnitudes of total (mean difference 2.80 W/kg, 95% CI 0.59, 5.00) and knee (2.60 W/kg, 0.75, 4.46) negative power than healthy limbs, with lower knee (-10.57%, -19.63, -1.52) and higher ankle (10.13%, 0.47, 19.79) contributions. During final contact, APM limb showed lower magnitudes of knee negative power (0.65 W/kg, 0.06, 1.24) than contralateral limbs. Compared with healthy, APM limb showed lower positive knee and ankle power, with lower knee (-7.23%, -14.19, -0.27) and greater hip (9.73%, 0.33, 19.13) contributions. Persistent knee deficits occurred post-APM, characterized by ankle-dominant braking and hip-dominant propulsion. Limb sequence influenced knee loading, with APM penultimate contact shifting braking to the contralateral limb at final contact. These findings suggest rehabilitation approaches may benefit from prioritizing knee function while preparing the ankle and hip to tolerate redistributed loads.
This study biomechanically evaluated the eccentric phase of short and long lever Copenhagen adduction exercise (CAE) and compared them with unilateral and bilateral eccentric hip adductor exercises performed on a novel eccentric hip adductor dynamometer (EHAD). Fifteen participants completed two CAE variations and five EHAD exercises. Three-dimensional kinematics and force data were collected to compute peak hip joint torque, range of motion (ROM), and angle at peak torque as the primary dependent variables. Peak and mean external force and body-mass-normalized torque were reported. Effects of exercise type and lever length on primary dependent variables, as well as relative and absolute within-session repeatability, were evaluated. The CAE produced significantly lower peak eccentric torques than all EHAD variations, regardless of lever length or unilateral/bilateral performance. Long lever CAE elicited greater peak and average torques than the short lever CAE, although ROM was significantly lower in the long lever condition across exercises. EHAD exercises generated significantly greater peak torques during bilateral performance, demonstrating the presence of bilateral facilitation (27.9% ± 16.5%). Angle at peak torque was similar across all exercises (31°-39°). With the exception of angle at peak torque during the CAE, all measurements showed good to excellent relative and moderate to good absolute within-session repeatability. Increasing lever length during CAE effectively raises hip adductor loading, while all EHAD variations enable even greater loading and exhibit pronounced bilateral facilitation. Future intervention studies should determine whether these biomechanical advantages translate into clinically meaningful improvements in adductor-related groin injury prevention and rehabilitation outcomes.
Meniscal recovery time following marathon running remains unknown, despite the need for practical recommendations on post-race return to training. We aimed (1) to characterize the time course of medial meniscus extrusion (MME) after a full marathon and (2) to identify baseline factors associated with the magnitude of the acute increase in MME. One hundred recreational runners (200 knees; mean age 47.2 years; 77 men, 23 women) from five marathons underwent weight-bearing, fully extended-knee portable ultrasonography at baseline and immediately post-race, and 90 runners (180 knees) were reassessed on post-race Days 1-5. Meniscus extrusion was measured as the distance from the medial tibial plateau to the outer meniscal edge. Baseline medial-to-lateral load distribution was quantified as walking knee adduction moment (KAM) impulse from a tibia-mounted inertial measurement unit, normalized to body mass and height. Linear mixed-effects models evaluated associations between acute extrusion change and candidate predictors. Mean baseline MME was 1.14 mm (95% CI 1.06-1.22) and increased to 1.57 mm (1.49-1.66) immediately post-race, a 38% increase (mean ΔMME 0.44 mm, 0.41-0.47; p < 0.001). MME remained significantly elevated through Day 3 (p < 0.01) but returned to baseline from Day 4 onward (p > 0.05). In multivariable analysis, a greater acute increase was independently associated with higher normalized KAM impulse (β = 0.24, 95% CI 0.10-0.37), higher BMI (β = 0.22, 0.09-0.36), and higher monthly running distance (β = 0.18, 0.04-0.31), with a borderline association for age (β = 0.15, -0.00 to 0.31). MME increased transiently after a marathon and returned to pre-race levels by approximately Day 4; whether this transient change has clinical consequences, or warrants a specific recovery interval, requires further study.
Some competitive runners strategically regulate their body weight to optimize race performance by balancing energy intake and expenditure. The constrained total energy expenditure (TEE) model suggests that exercise energy expenditure (EEE) is sustained through compensatory reductions in other components of TEE, including resting metabolic rate (RMR) and sleeping metabolic rate (SMR). However, it remains unclear whether TEE and its components differ between athletes with and without amenorrhoea, or whether the constrained energy model applies to athletes engaged in chronic training. This study compared TEE components-SMR, RMR, non-exercise activity thermogenesis (NEAT), and EEE-between amenorrhoeic and non-amenorrhoeic runners and examined their relationship with physical activity, particularly weekly running distance. Twenty female middle- and long-distance runners (10 amenorrhoeic and 10 non-amenorrhoeic) participated. TEE and body composition were measured under free-living conditions using the doubly labeled water method, while RMR and SMR were assessed in a whole-room metabolic chamber. NEAT was estimated by accelerometry and training reports, and EEE was calculated by subtraction. TEE and its components did not differ between amenorrhoeic and non-amenorrhoeic runners. Weekly running distance did not correlate with TEE but was negatively linked to NEAT and positively to EEE, whereas its negative associations with RMR and SMR were attenuated after adjustment for body composition. Similar directional associations were observed in both groups, but the study was not powered to test effect modification by menstrual status. These findings are consistent with the constrained TEE model and suggest that higher training volume may be accompanied by a reallocation of energy expenditure among its components in chronically trained runners.
Regular endurance exercise is widely recognized for its cardiovascular health benefits, with improvements in vascular function particularly relevant for populations with impaired vascular health. However, it is unknown whether prolonged adherence to endurance exercise training in sedentary but healthy young individuals can improve vascular function in non-active limbs. This study investigated the impact of 1 year of supervised endurance exercise on vascular function in previously untrained, healthy young participants. Twelve healthy young adults (25 ± 4 years) were included in a 12-month supervised cycling program, during which maximal aerobic capacity (V̇O2max) and vascular function were assessed at baseline and after 1, 4, 6, and 12 months of training. Forearm vascular function was assessed using intra-arterial infusions of acetylcholine (ACh; endothelium-dependent vasodilation) and sodium nitroprusside (SNP; endothelium-independent vasodilation) and flow-mediated dilation (FMD). Seven participants completed the 12-month protocol and showed no change in endothelium-dependent or independent vasodilation assessment at any time point during the 12-month training period (p > 0.05), despite a substantial increase in aerobic capacity during the first 6 months of training (baseline: 40.3 vs. 6 months: 50.8 mL·min-1·kg-1, p = 0.001), with no further change observed from 6 to 12 months (51.3 mL·min-1·kg-1, p > 0.05). One year of endurance exercise training improved aerobic capacity without improving vascular function in non-trained limbs in previously untrained but healthy individuals. These findings support the idea that vascular adaptations to endurance training may reflect a region-specific training effect with vascular remodeling confined to actively engaged limbs and, thus, undetectable in vascular territories not directly involved in exercise training.
Cross-sectional studies have indicated impaired neuromuscular and cortical activities following anterior cruciate ligament (ACL) reconstruction. However, adaptations throughout the recovery process remain unclear. Therefore, this study aimed to examine neuromuscular and cortical activity over the first year following ACL reconstruction. A prospective observational study was conducted, including 31 participants following ACL reconstruction (12 females, age: 25 ± 6 years, height: 173 ± 9 cm, mass: 72 ± 11 kg) and 31 healthy controls (12 females, age: 26 ± 6 years, height: 175 ± 9 cm, mass: 70 ± 10 kg). Electroencephalography and electromyography were used to assess cortical and neuromuscular activity during joint position sense (JPS) test, while only neuromuscular activity was recorded during stair descent and single-leg hop tasks. The ACL group underwent evaluation at five postsurgical intervals (1.5, 3-4, 6, 9, and 12 months), while the control group was assessed on a single occasion. Linear mixed models were used to compute differences in neuromuscular and cortical activity across the various time points and groups in JPS testing and stair descent, while independent and dependent t-tests were employed for analysis of the neuromuscular activity during single-leg hop. ACL-reconstructed participants demonstrated sustained altered neuromuscular activity in both involved and noninvolved limbs during JPS and stair descent tasks compared to controls (p < 0.05) with differences present across all measured time points. No significant differences in cortical EEG activity during JPS test were detected. Neuromuscular alterations were observed consistently throughout the initial year of recovery. The absence of cortical activity changes suggests a reassessment of more challenging tasks. Further investigation is required into neuromuscular and motor relearning protocols to ascertain their impact on rehabilitation and return to sport.
The aim of this study was to investigate (1) whether factors related to endurance performance are associated with physiological resilience in recreational-to-competitive runners, and (2) differences between recreational and competitive runners in physiological resilience. During three test days, 33 runners (15 competitive and 18 recreational) were tested for their peak fat oxidation, maximal blood lactate concentration (Lamax) after maximal anaerobic running test (MART), maximal voluntary contraction (MVC) in isometric leg press, maximal oxygen uptake (VO2max), maximal speed of incremental test (sPeak), speeds at ventilatory thresholds (sVTs), running economy (RE), and physiological resilience. Physiological resilience was tested as deterioration of VO2max, sPeak, VTs, and RE during and after ~2.5 h moderate-intensity run at ~90% of VT1. Associations between other variables and physiological resilience were analyzed using Pearson's or sex-adjusted partial correlations in the whole sample. Recreational runners had higher deterioration of VT1 (p = 0.049), but lower deterioration in RE (p = 0.042) than competitive runners. Lower decline in sPeak was associated with higher VO2max (r = 0.37, p = 0.04) and lower Lamax (r = -0.37, p = 0.03). Lower decline in sVT1 was associated with higher VO2max (r = 0.37, p = 0.04), sVT2 (r = 0.52, p = 0.002), sVT1 (r = 0.48, p = 0.006), and sPeak (r = 0.44, p = 0.01). Lower decline in RE was associated with worse RE (r = -0.49, p = 0.004) and higher MVC (r = -0.40, p = 0.02). Lower decline VO2max was associated with worse RE (r = 0.42, p = 0.02). It appears that physiological resilience is associated with multiple different physiological systems. High aerobic fitness and MVC of the leg extensors, and lower Lamax after MART may be related to better physiological resilience.
Maximal intended velocity (MIV)-based resistance training enhances explosive performance, yet it remains unclear whether different MIV modalities induce distinct neuromuscular adaptations. This study compared the effects of two-way ballistic (TWB) and jump squat (JS) training on explosive strength and neuromuscular characteristics in highly trained sprinters. Forty highly trained male sprinters (Tier 3) were randomly assigned to TWB (n = 20) or JS (n = 20). Both groups completed 12 training sessions (5 sets of 8 repetitions at 50%-55% 1RM) over 6 weeks. Pre- and post-tests included countermovement jump (CMJ), consecutive CMJ (CCMJ), 30-m sprint, isometric mid-thigh pull (IMTP), 6-s cycle sprint, vastus lateralis (VL) muscle architecture, and VL and biceps femoris (BF) activation during CCMJ performance. Both groups improved CMJ, CCMJ height, 30-m sprint, and 6-s cycle performance (p < 0.05), with similar increases in VL muscle architecture. TWB showed a greater IMTP 100-ms impulse improvement (ηp2 = 0.25), while JS demonstrated greater improvements in the modified reactive strength index (RSImod; ηp2 = 0.11). VL activation increased more after TWB than JS during take-off (p < 0.001, ηp2 = 0.30) and during landing (p < 0.001, ηp2 = 0.58). TWB and JS training both improved explosive performance through different neuromuscular pathways. TWB training enhanced early-phase force production and was associated with greater VL activation during take-off, whereas JS training preferentially improved reactive strength, likely reflecting SSC-related adaptations. These findings highlight that movement structure within MIV condition influences the direction of adaptation and should therefore be selected according to the specific performance qualities targeted in athletic training.
This study examined the effects of 10 weeks of eccentric knee-flexor training or matched-duration static stretching on hamstring aponeurosis dimensions and muscle size, and explored the changes after 4 weeks of detraining. Eleven healthy untrained men completed a within-participant contralateral intervention (3 sessions·week-1, 10 weeks) followed by 4 weeks of detraining. One leg performed eccentric knee-flexion exercise on an isokinetic dynamometer (3 × 10 reps at 5°·s-1; 50% maximal eccentric torque), while the contralateral leg performed static stretching (3 holds matched to eccentric time under tension). Hamstring outer aponeurosis volumes, inner aponeurosis volumes and widths, and muscle volumes were quantified using magnetic resonance imaging. Outer aponeurosis volume increased after both training protocols across all muscles (p < 0.05) and was maintained during the 4 week detraining period, with comparable changes observed between stretching (~19.0%-31.8%, d = 0.91-1.69) and eccentric training (~15.8%-22.8%, d = 0.85-1.13). Inner-aponeurosis volume and width of biceps femoris long head and semimembranosus also increased after both training protocols (~7%-23%; p < 0.05; d = 0.33-0.86) and were preserved during detraining. Muscle hypertrophy occurred only after eccentric training (~22%-42%; p < 0.05; d = 0.98-1.65) in biarticular hamstrings and remained above baseline in the detraining period. Stretching exercise produced minimal changes in muscle volume (p > 0.05). Changes in muscle volume were not significantly associated with changes in aponeurosis dimensions in almost all cases (p > 0.05). These findings suggest that hamstring aponeurosis dimensions can increase after both eccentric loading and static stretching, whereas muscle hypertrophy is largely eccentric-specific and more sensitive to short-term detraining.
Sprint interval training (SIT) is promoted as a time-efficient method for improving maximal aerobic capacity (V̇O2max); however, the "classic" protocol (4-6 × 30-s all-out sprints) is less time-efficient than claimed, may be poorly tolerated, and is expected to lead to low adherence. The present study examined the effect of the number of sprint repetitions per session on training-induced changes in V̇O2max through meta-analysis of the available literature. PubMed and Web of Science were searched (May 2016-September 2024) for eligible studies involving ≥ 2 weeks of training involving repeated all-out cycling with pre- and post-training V̇O2max data. Forty-four eligible studies were combined with 34 studies from a previous meta-analysis, totalling 93 trials across 78 studies (n = 1188). A hierarchical random-effects meta-regression model was used to assess the influence of key moderators on the change in V̇O2max. SIT produced an 8.3% increase in V̇O2max (95% CrI: 7.0 to 9.5%). Increasing sprint repetitions showed a trivial association with changes in V̇O2max (-0.04% per additional sprint, 95% CrI: -0.32 to 0.24%). Increasing intervention duration was associated with the largest improvements in V̇O2max (0.7% per additional week; 95% CrI: 0.3 to 1.0%). The present study confirms that increasing sprint repetitions does not meaningfully enhance V̇O2max improvements in untrained populations. As performing fewer sprint repetitions increases time-efficiency and attenuates reductions in affect, future research into interventions for improving general health in physically inactive populations should focus on low-volume SIT protocols. Trial Registration: PROSPERO database (registration number CRD42022349104).
Injuries are a major concern in youth sport. Traditionally, injury research has focused on biomedical and psychological characteristics of the individual athlete. However, newer trends suggest that injuries result from dynamic interaction between the athletes and their surroundings. The objective of this scoping review was to identify positive and negative environmental factors associated with injury prevention and management in youth sport. This scoping review was conducted according to guidelines of The Joanna Briggs Institute. We systematically searched five databases in November 2024 and updated in October 2025. A total of 39 studies were selected of which five were reviews. Of the remaining studies, 23 used qualitative, five used quantitative, and six used mixed-method designs. Based on the Holistic Ecological Approach, 40 factors were identified and categorized into preconditions (e.g., lack of resources and equipment), processes (e.g., support from peers), structure (e.g., busy training/match schedule), and culture (e.g., culture of risk-taking). In all four categories, both positive and negative factors were identified, although negative influences predominated. Our findings support the importance of environmental factors in youth sport injury prevention and management, yet these factors have so far been studied in isolation rather than as parts of the broader environment. Collectively, they provide an initial sense of how the environment facilitates injury prevention and management, but based on the current literature, we cannot say how these factors work together. Future research should examine how the identified factors interact and cohesively influence injuries in youth sport.
Inter-limb asymmetry is frequently evaluated during bilateral tasks such as the countermovement jump (CMJ), typically using discrete peak-based metrics. However, these approaches may inadequately capture the complex, time-varying nature of inter-limb coordination. This study examined inter-limb asymmetry during CMJ in youth football players using both discrete and continuous assessments, with consideration of limb dominance. Forty-three male youth academy football players (14 ± 1.1 years) performed three maximal bilateral CMJs with data collected using dual force platforms and three-dimensional motion capture. Inter-limb asymmetry was quantified using discrete symmetry indices for peak vertical ground reaction force (GRFvert), joint displacements, and joint moments, alongside time-series approaches including statistical parametric mapping (SPM1D) and the normalized symmetry index (SInorm). Asymmetry threshold breaches (±10% and ±20%) and their duration across the movement cycle were assessed, with comparisons between dominant and non-dominant limbs. Discrete metrics indicated low levels of inter-limb asymmetry at the group level, with mean values typically within ±10% thresholds. In contrast, time-series analyses revealed frequent, phase-specific asymmetry within individual trials, particularly for joint moments, despite no significant group-level differences identified using SPM1D. A ±10% GRFvert asymmetry breach occurred in every trial. Limb dominance had minimal influence, except for longer GRFvert breach durations on the non-dominant limb. Inter-limb asymmetry during bilateral CMJ is observed frequently when assessed using time-series methods, despite apparently symmetrical discrete outcomes. These findings demonstrate that reliance on peak-based symmetry metrics may overlook substantial phase-specific asymmetry, with implications for the interpretation of bilateral loading during athlete monitoring and rehabilitation contexts.
This secondary integrative analysis of a previously published cohort investigated the molecular pathways underlying muscle recovery of the biceps femoris long head (BFLH) after a football match, by integrating newly generated transcriptomic data with clinical recovery markers over a 72-h recovery period. BFLH muscle biopsies from 10 male, regional-first division football players were obtained 7 days before a football match (MD-7) and 3 days post-match (MD+3). The final sample included 9 participants because 1 biopsy provided insufficient material for sequencing. Bulk RNA-sequencing was conducted to analyze differential gene expression considering Benjamini-Hochberg correction. Pathway enrichment analyses were conducted to identify biological processes altered between pre- and post-match conditions. Clinical markers, including creatine kinase (CK), hamstring rate of torque development (RTD), and sprint performance, were assessed before the match (MD) and at 24 (MD+1), 48 (MD+2), and 72 h (MD+3) post-match. Correlations between transcriptomic and clinical variables were calculated using Spearman's rank correlation. MYH1 was the most responsive gene, showing significant downregulation at MD+3 (log2FC = -1.116, q-value = 3.8 × 10-2). Pathway analyses identified 440 transcriptomic signatures at MD+3, reflecting stress response, immune and cytokine signaling, protein turnover, and structural remodeling. Changes in clinical variables during recovery were associated with coordinated expression shifts across genes related to different phases of the muscle damage-regeneration continuum, including muscle contraction, damage control, protein turnover, repair signaling, and myogenic regeneration. BFLH is not fully recovered 3 days after a football match, as evidenced by sustained downregulation of MYH1, pathway enrichment, and associations with clinical markers. Molecular recovery processes extend beyond 72 h, suggesting this period is insufficient for complete BFLH recovery in football players.
