Frontiers in Sports and Active Living

BackgroundMeteorological factors such as barometric pressure, humidity, and temperature have been linked to weather-related symptoms in the general population, yet little is known about their influence on athletes daily well-being and performance. Individual variability in weather sensitivity has been reported in biometeorology research, suggesting that only certain individuals exhibit pronounced physiological responses to environmental fluctuations. However, no studies have examined within-person associations between multiple meteorological factors and daily condition or performance in competitive athletes. MethodsCollegiate baseball players were monitored over 10 randomly selected days during July-August 2025. Subjective condition and performance were assessed daily using a 3-point Likert scale (1 = poor, 2 = normal, 3 = good). Barometric pressure, humidity, and temperature were recorded hourly and summarized for each day using mean values, day-to-day changes, daily ranges, and rapid fluctuation indices. For each player, multivariable linear regression models were constructed to examine within-person associations between the three meteorological variables and daily condition or performance. Model fit (R2), regression coefficients ({beta}), and dominant meteorological factors were extracted. ResultsEighty players were included in the condition model and eighty-six in the performance model. High weather sensitivity (R2 [≥] 0.60) was observed in 22.5% of players for condition and 14.0% for performance, whereas low sensitivity (R2 [≤] 0.20) was found in 26.3% and 16.3%, respectively. Temperature was the dominant explanatory factor in more than 80% of players, although subsets showed dominance of barometric pressure or humidity. Directionality varied across individuals: decreases in barometric pressure were associated with worsening conditions in 62.5% of players but improvement in 37.5%; similar bidirectional patterns were observed for humidity and temperature. ConclusionDaily meteorological fluctuations explain a meaningful proportion of within-person variation in condition and performance for a subset of collegiate baseball players. The substantial individual variability and diverse directional responses highlight weather sensitivity as a personalized characteristic rather than a uniform effect. These findings suggest that meteorological factors may represent a relevant contextual variable for daily readiness monitoring in susceptible athletes.

ObjectiveTandem cycling requires a coordinated effort between the pilot and the stoker. Previous research suggests that randomly paired tandem cyclists produce lower power output than when cycling solo. This study examined how a cyclists individual ability and their position on the tandem (pilot or stoker) affects pair performance, when partners are either closely matched or differ substantially in solo cycling capacity, as this might be relevant for training and selection. MethodsTwenty-three trained cyclists completed three 10-minute time trials: solo, equal-capacity tandem ([≤]25 W difference in solo performance), and unequal-capacity tandem ([≥]40 W difference). Mean power output, heart rate, cadence, and rating of perceived exertion (RPE) were recorded. Positions (pilot or stoker) were counterbalanced. Linear mixed-effects models assessed effects of capacity and position. ResultsRelative to solo cycling, equal-capacity tandem pairs revealed lower power output (-3.9%), lower heart rate (-2.3%), and lower RPE (-11.5%). Unequal-capacity tandems differed from solo only in heart rate (-2.7%). Stokers produced lower power relative to solo (-5.3%) and relative to pilots (-3.7%) and reported lower RPE relative to solo (-13.9%), while pilots matched their solo power at a lower heart rate (-2.9%). Cadence did not differ across conditions. Total tandem power averaged 95.6% of combined solo power, and differences in partner capacity did not significantly affect combined power output. ConclusionThis study provides the first known experimental data on how partner matching affects individual and combined power output in tandem cycling. Equal- and unequal-capacity tandem pairs showed similar performance. Lower power and RPE among stokers suggest reduced engagement or a redistribution of effort between riders. These findings highlight that effective tandem performance depends on physiological capacity and rider position on the tandem, but not on the difference in capacity between partners.

Exercise affects the immune function and induces pro- and anti-inflammatory effects. The alterations concerning the immune system linked to physical activity have been documented across various studies with complex exercise tests. However, the characterization of the non-pathological, exercise-induced immunological stress regulation is highly relevant in numerous clinical and non-clinical areas for a better understanding of normal physiological adaptations and differentiation from non-healthy adaptations. Thus, it is valuable and necessary to establish simple immune-metabolic response triggering exercise tests for use in clinical and non-clinical settings. The aim of this study was to examine the effects of the 1-minute sit-to-stand test (STST) on immune-metabolic stress indices and to determine whether it elicits a sufficiently high intensity to qualify as an anaerobic exercise test, thereby supporting its application in investigating exercise-induced immunological stress regulation. 28 study participants performed the 1-minute STST. Capillary blood was taken 20 and 10 minutes before the test, immediately after, and 5, 10, 15, 30, and 45 minutes after exercise. Lactate, glucose and blood counts were determined. Lactate concentration increased significantly immediately after the STST (p < 0.001) and remained significantly elevated until 45 minutes post-exercise. Glucose concentration was significantly decreased after 10 minutes post-exercise (p < 0.05) and again 30 and 45 minutes post-exercise (p < 0.01 for both). Leucocyte count increased significantly post-exercise (p < 0.001) and returned to baseline levels 30 minutes afterwards. Lymphocyte and granulocyte count increased significantly after the test (p < 0.001 for both) and lymphocyte count slightly decreased below baseline values 30 minutes post-exercise (p = 0.07) while granulocyte count remained significantly elevated (p < 0.05). Furthermore, decreased NLR (p < 0.001) and SII (p < 0.01) immediately after the test and increased levels of NLR, SII and SIRI post-exercise could be observed. The 1-minute STST caused an increase in lactate level above the anaerobic threshold, therefore the test can be evaluated as an anaerobic exercise test. Furthermore, it was demonstrated that the STST induced shifts in leucocyte, lymphocyte, and granulocyte counts, which means that even a short intense anaerobic exercise, such as the STST causes changes in immune cell counts and therefore, the test is suitable for analyzing the exercise-induced immunological stress response.

Motor rehabilitation requiring sustained physical exercise faces poor adherence in neurological populations due to insufficient supervision and monotony. While virtual reality and musical biofeedback independently improve engagement and motivation, their comparative and combined impact on intensity control strategies during high-intensity interval training (HIIT) remains unexplored. Thirty healthy adults (16 males, 14 females; mean age 27.5 {+/-} 7.2 years) were sequentially assigned to three feedback modalities (n=10 each) during intensity-guided stationary cycling: visual-only (position-based), musical-only (speed-based), and combined audiovisual (position-based). Participants completed two 9-minute moderate-to-high intensity sessions (Set 1 and Set 2) maintaining pedaling speed within a target speed zone. Performance distinguished control strategy from effectiveness: stability via target zone exits, correction capacity via recovery time and sustained deviations, and overall effectiveness via time in zone. Heart rate (HR) assessed physiological intensity; usability and cognitive workload were evaluated via e-Rubric and NASA-TLX. Distinct regulation strategies emerged. Musical-only showed significantly lower stability (Set 1: 14.52 exits/min vs. 1.48 visual and 1.79 combined; corrected p < 0.0167) but superior correction (0.21s recovery vs. 2.48s and 1.06s; p < 0.0001) with minimal sustained deviations. Combined feedback achieved highest Set 2 effectiveness (98.13% vs. 95.17% time in zone; corrected p < 0.0167) but elevated physical demand (corrected p < 0.0167). HR variability was comparable (p = 0.85), confirming consistent cardiovascular workload despite differing strategies. Satisfaction was high, with slight preference for musical feedback; cognitive workload did not differ. Musical biofeedback promotes reactive control with frequent but rapidly corrected oscillations, maintaining physiological safety and engagement. Visual feedback ensures stable target adherence at the cost of compensatory physical effort. Combined modality offered no synergy, increasing demand without improving effectiveness. Findings reveal a trade-off between stability and correction agility, supporting tailored modality selection: musical feedback suits unsupervised rehabilitation prioritizing engagement, rapid error correction, and sustainable effort, while visual feedback suits supervised protocols requiring stable preventive control and precise adherence quantification. Author summaryMany people undergoing neurological rehabilitation struggle to maintain adherence to high-intensity exercise programs, particularly without direct supervision. While virtual reality and musical feedback have shown promise for improving engagement and motivation, we didnt know which type works best for controlling exercise intensity, or whether combining them would be better. We tested three feedback systems with 30 healthy adults performing stationary cycling: visual-only, musical-only, and both combined. We measured how well participants stayed within target speed and assessed their experience. Musical feedback prompted frequent but instant adjustments--a reactive strategy that was less physically demanding and most enjoyable. Visual feedback kept participants more precisely in the target zone but required significantly more effort. Surprisingly, combining both didnt improve performance and instead increased physical demand. Our results show that different feedback types suit different rehabilitation contexts. Musical feedback may be ideal for unsupervised home-based exercise because it keeps people engaged without requiring exhausting effort. Visual feedback works better when precise control is essential in supervised clinical settings, despite being more demanding. Combining both offers no advantage. These findings help clinicians choose the right feedback approach based on their specific rehabilitation goals.

Conventional therapy after stroke focuses on reducing physical impairments. However, the decisions that guide peoples movements may have far-reaching consequences towards recovery. We lack the tools to characterize these decisions. Recently, researchers have created a quantitative behavioral assessment of effort-based decision-making and applied it to some clinical populations. The purpose of this paper is to examine the feasibility of evaluating effort-based decision-making during walking after stroke. We recruited five neurotypical participants in an initial study. We conducted a subjective effort valuation on the neurotypical individuals with and without a knee immobilizer to simulate the biomechanics of reduced knee flexion during post-stroke gait. Participants cleared obstacles of varying heights during overground walking, followed by rating their perceived effort and then completing an effort choice paradigm to calculate subjective effort value. In a second experiment, we recruited five individuals with stroke to perform a similar protocol without an immobilizer during harnessed treadmill walking. We found that rated perceived effort increased monotonically with obstacle height across groups, that individuals could recall obstacle heights without cues, and that subjective effort value increased with knee immobilization in the control group as expected. We conclude that adapting an effort-based decision-making assessment to a walking context in people with stroke is feasible.

The aim of this study was to investigate the effects of velocity-based training (VBT) and percentage-based training of one repetition maximum (PBT), on changes in muscle mass (MM), mineral bone density (BMD), and bone mineral content (BMC), maximal squat strength (FSQ), countermovement jump (CMJ), pedaling power (PP), sprint (RV30) and neuromuscular response (EMG). Eighty-five men were randomized to VBT and PBT, and performed full squat (SQ) training three times per week for 12 weeks. Results: RT produced significant increases in FSQ, CMJ, RV30, PP, MM, CMO in both groups, and in BMD only in the VBT group. No significant changes in EMG activity were observed in either group. Significant differences were observed between VBT and PBT for BMD, PP, CMJ, and RV30, with statistical significance set at p<0.05. In conclusion, the VBT group showed better results than the PBT group in the different variables with a lower training load.

This pre-post-test study investigated 1) pre-post changes in psychosocial domains with a single virtual salsa class; 2) effect sizes relative to an in-person class, and 3) individual factors, including personality, perceived performance, and enjoyment. An experimental group (n=33) of novice dancers 18-30 years old, participated in a single virtual salsa class. Positive and Negative Affect Scale (PAS, NAS), Perceived Stress Scale (PSS), and the Inclusion in Community and Self-Scale (ICS) were administered before and after class. Participants completed the Big Five Inventory-10 (BFI-10) before, and rated their performance and enjoyment (ordinal scale 1-5) after class. Effect sizes were calculated, and pre-post changes were analyzed with Wilcoxon signed-rank tests. Relationships between pre-post changes and individual factors were analyzed with Spearmans rank correlations. PAS, NAS, PSS, and ICS significantly improved and effect sizes were larger than those for an in-person salsa class except for ICS. Change in NAS was negatively correlated with neuroticism. These results suggest that a virtual salsa class may improve mood, stress, and social connection similar to in-person classes and change in mood may be influenced by personality traits such as neuroticism. Understanding the psychosocial effects of virtual dance and the influence of individual factors will facilitate implementation of dance as an accessible rehabilitation intervention to improve psychosocial well-being.

ContextACL injury prevention in young athletes has traditionally relied on a dichotomous classification of contact versus noncontact mechanisms; however, this framework may not adequately capture the movement processes underlying many injuries. ObjectiveTo classify ACL injury mechanisms in athletes aged [&le;]22 years with a specific focus on landing-related movements and to examine their associations with sport contact characteristics and age. DesignRetrospective observational study. SettingSingle sports injury clinic. Patients or Other ParticipantsA total of 151 athletes aged [&le;]22 years (mean age, 17.7 {+/-} 2.1 years) diagnosed with ACL injury between January 2017 and November 2025. Main Outcome Measure(s)ACL injury mechanisms were classified as landing-related without contact (L), landing-related with contact (Lc), or direct contact injury (C). Landing-related injuries (L + Lc) were compared with direct contact injuries. Multivariable logistic regression was used to identify factors associated with landing-related injury. ResultsLanding-related injuries accounted for 123 cases (81.5%), including 88 noncontact and 35 contact-related landing injuries, whereas direct contact injuries occurred in 24 cases (15.9%). Athletes with direct contact injuries were significantly older than those with landing-related injuries (19.2 {+/-} 1.7 vs 17.5 {+/-} 2.5 years, p = 0.03). In multivariable analysis, participation in noncollision sports was strongly associated with landing-related injury (odds ratio [OR] = 9.80; 95% confidence interval [CI] = 3.03-31.5; p < 0.001), whereas increasing age was inversely associated with landing-related injury (OR per year = 0.71; 95% CI = 0.56-0.90). Sex was not independently associated with injury mechanism. ConclusionsMost ACL injuries in athletes aged [&le;]22 years occurred through landing-related mechanisms, regardless of contact. These findings highlight insufficient control of landing and foot contact as a fundamental mechanism of ACL injury in young athletes and support prevention strategies focused on movement quality during sport-specific tasks. Key Points{blacksquare} Most ACL injuries in athletes aged [&le;]22 years occurred during landing or foot contact, regardless of whether external contact was present. {blacksquare}Noncollision sports and younger age were strongly associated with landing-related ACL injury mechanisms. {blacksquare}ACL injury prevention in young athletes should prioritize improving landing and foot contact control rather than focusing solely on contact characteristics.

ContextClinical assessments of landing mechanics often require complex scoring systems or laboratory-based motion analysis, which can limit feasibility in routine practice. A visually based landing-mechanics score centered on a standardized optimal joint-alignment configuration ("Zero Position") may offer a simple, clinically deployable alternative. ObjectiveTo determine the intra- and inter-rater reliability of a landing mechanics score based on standardized optimal joint alignment at the moment of maximal center-of-mass (COM) descent. DesignCross-sectional reliability study. SettingUniversity athletic training facility. Patients or Other ParticipantsNinety healthy male collegiate athletes. Main Outcome MeasuresLanding mechanics were evaluated using frontal- and sagittal-plane video recordings, with scoring performed on the frame corresponding to maximal COM descent. Five criteria reflecting the standardized joint configuration ("Zero Position") were assessed. Intra- and inter-rater reliability were calculated using Cohens kappa coefficients and Kendalls W. ResultsAll five criteria demonstrated moderate to substantial intra-rater reliability and moderate to almost perfect inter-rater reliability. The total landing-mechanics score showed excellent agreement across all comparisons. The scoring system required minimal training and was feasible to implement using standard video recordings. ConclusionsThe landing-mechanics score centered on the Zero Position demonstrated high reliability and strong clinical feasibility. This simple, visually grounded assessment may support routine clinical screening, injury-risk evaluation, and return-to-sport decision-making. Future research should examine its applicability to single-leg landings and sport-specific high-risk movements.

BackgroundPsychological readiness to return to sport and subjective knee function are critical outcomes following ACL reconstruction (ACLR), yet they do not always progress in parallel. An athlete may demonstrate high subjective knee function but low psychological readiness, suggesting a mental barrier to return, or conversely, report high readiness despite persistent functional limitations, raising concerns of overconfidence and reinjury risk. Understanding how these domains change together during recovery is essential for identifying mismatches that may require targeted intervention. PurposeThe purpose of this study is to examine the relationship between changes in psychological readiness (ACL-RSI) and subjective knee function (IKDC) from early to late recovery following ACLR. Study DesignSecondary analysis of prospectively collected data. MethodsAthletes (N = 48, Age at ACLR = 17.7 {+/-} 1.8 y) aged 15-25 years who underwent ACLR with an ipsilateral autograft, had a pre-injury MARX score > 8, and completed the ACL-RSI and IKDC questionnaires at 3.5 {+/-} 1 and 7 {+/-} 1 months post-ACLR were included. Percent changes in ACL-RSI and IKDC scores between early and late recovery were calculated. Spearmans rank correlation was used to examine the association between changes in psychological readiness and subjective knee function. Significance was set to p < .05. ResultsThe mean percent change in ACL-RSI was 40.7 {+/-} 57.1% and the mean percent change in IKDC was 24.8 {+/-} 18.1% from 3.5 {+/-} 1 months to 7 {+/-} 1 months post-ACLR. The percent changes in ACL-RSI and IKDC scores from 3.5 {+/-} 1 months to 7 {+/-} 1 months post-ACLR were moderately correlated ({rho} = 0.350 (95% CI [0.089, 0.584]), p = 0.012). DiscussionThe main finding of this study was that subjective knee function and psychological readiness to return to sport changed in parallel from 3.5 to 7 months following ACLR. Clinicians can use this information regarding the concordant progression of psychological readiness to return to sport and subjective knee function to personalize ACL rehabilitation for future patients. Overall, clinicians can understand that if psychological readiness improves, subjective knee function will likely improve over the 3.5- to 7-month post-ACLR time frame, and vice versa. Therefore, focusing on both of these components at multiple time points during the recovery process may be influential to ensure the greatest likelihood of returning to sport in athletes following ACLR.

BackgroundQuadriceps weakness may reduce sagittal plane shock absorption during landing, shifting load toward the frontal plane and increasing knee abduction moment (KAM), a biomechanical risk factor for anterior cruciate ligament (ACL) injuries. PurposeThe purpose of this study was to evaluate the association between isokinetic quadriceps strength and peak KAM during drop vertical jump landing in adolescent athletes. Study DesignSecondary analysis of previously collected data. MethodsHealthy adolescent athletes completed quadriceps strength testing using an isokinetic dynamometer and a biomechanical assessment during a drop vertical jump task. Quadriceps strength was quantified as peak concentric torque and the peak external KAM was calculated during the landing phase on the dominant limb. Both strength and KAM were normalized to body mass. Linear regression was used to examine the association between normalized quadriceps strength and peak external KAM on the dominant limb. ResultsThe association between quadriceps strength and peak normalized KAM on the dominant limb was not statistically significant ({beta} = -0.053 (95% CI [-0.137 to 0.030]), F(1,119) = 1.62, R2 = 0.013, p = 0.206). Quadriceps strength explained only 1.3% of the variance in peak KAM, indicating a negligible association between these variables in this cohort. DiscussionQuadriceps strength was not associated with peak normalized KAM during landing, suggesting that frontal-plane knee loading during a drop vertical jump is not meaningfully explained by maximal concentric quadriceps strength alone. KAM appears to be driven more by multi-joint movement strategy and neuromuscular coordination than by the capacity of a single muscle group.

BackgroundTeleworking is associated with lifestyle risk factors, such as insufficient physical activity (PA) and increased sedentary time (ST); however, effective interventions tailored to teleworkers are lacking. We aimed to evaluate the effectiveness of a 12-week multicomponent occupational lifestyle intervention on daily step counts among Japanese teleworkers. MethodsThis 12-week, two-arm, parallel-group, cluster randomised controlled trial conducted across 12 clusters in six Japanese companies involved 310 teleworkers (mean age 43.0 years; 72.6% men) randomized to the intervention (6 clusters, n=156) or a waitlist control group (6 clusters, n=154). The multicomponent occupational lifestyle intervention included individual (online lectures, feedback, and email messages), physical (posters and a pop-up), and organizational (encouraging messages from an executive) strategies. The primary outcome was the change in daily step counts, measured using an accelerometer over 14 consecutive days at baseline and at week 12. Analyses were based on the intention-to-treat approach using a generalised estimating equation model. FindingsThe intervention group showed an adjusted mean change in daily step counts of +219 steps (95% confidence interval [CI] -165 to 604), compared with +188 steps (95% CI -183 to 560) in the control group. The adjusted between-group difference was +55 steps (95% CI -550 to 660; p=0.844). No significant effects on the secondary outcomes (ST, light PA, or moderate-to-vigorous PA) were observed. InterpretationThe multicomponent occupational lifestyle intervention did not significantly increase daily step counts among Japanese teleworkers. Therefore, further studies should be done on tailored interventions for teleworkers. Research in contextO_ST_ABSEvidence before this studyC_ST_ABSTeleworking has increased globally, particularly following the coronavirus disease pandemic, and has been associated with reduced physical activity and increased sedentary behaviour, both of which are risk factors for cardiovascular disease. Previous studies have also reported that telework environments may contribute to musculoskeletal and other somatic symptoms. Multicomponent interventions in traditional office settings can effectively increase physical activity and reduce sedentary time. These interventions commonly employ strategies at multiple levels of the social-ecological model, including individual approaches (e.g., lectures or incentives), interpersonal approaches (e.g., team-based activities), environmental modifications (e.g., office rearrangements or sit-stand desks), and organisational support (e.g., leadership encouragement). The applicability of such interventions to teleworking populations remains unclear because teleworkers face distinct challenges such as social isolation, blurred work-life boundaries, and heterogeneous home working environments. These contextual differences highlight the need for interventions specifically tailored to teleworkers. Added value of this studyWe evaluated the effectiveness of a multicomponent occupational lifestyle intervention specifically designed for teleworkers, a population whose work environment differs substantially from traditional office settings. Our findings provide novel evidence that can inform the development of more targeted strategies to promote physical activity in evolving work environments. This study also provides objective measurements of physical activity using accelerometers, enabling detailed evaluation of step counts, sedentary time, and different activity intensities among teleworkers. Additionally, we used daily diaries to distinguish activity patterns across workdays, weekends, teleworking days, and commuting days, providing a nuanced understanding of behavioural patterns in remote work contexts. Implications of all the available evidenceOur findings indicate that low-cost, remotely delivered multicomponent interventions may be insufficient to produce meaningful behavioural change among teleworkers. Similar strategies, including individual, physical, and organisational components, have been effective in traditional workplace interventions; however, their implementation in teleworking environments may not adequately address the specific challenges faced by remote workers. In particular, the lack of strong sociocultural support mechanisms, such as team-based step competitions or workplace champions, may limit engagement and reduce the effectiveness of such programmes. Therefore, further investigation is needed to explore more diverse and targeted intervention strategies, identify the specific needs and behavioural patterns of teleworkers, and apply more precise eligibility criteria to better address heterogeneity within teleworking populations.

PurposeDetrended fluctuation analysis alpha-1 (DFAa1) has emerged as a promising non-invasive biomarker for exercise intensity assessment. However, the standard 2-min analysis window lacks temporal resolution necessary for real-time training applications. This study systematically investigated the validity of shortened DFAa1 windows (30s and 1min) versus the 2-min reference across different intensities. MethodsPhysically active males completed three continuous cycling protocols: low-intensity training at the first lactate threshold (LOW, n=19), moderate-intensity training at the second lactate threshold (MOD, n=19), and a 30-min self-paced time trial (TT30, n=18). DFAa1 was calculated using 30-s, 1-min, and 2-min moving windows, advancing in 1s increments. Validity was assessed using intraclass correlation coefficients (ICC), Bland-Altman analysis, and standard error of measurement (SEM). ResultsDuring LOW, both shortened windows showed poor agreement with the 2-min reference (30s: ICC=0.02, mean bias of -0.05; 1min: ICC=0.37, -0.02). During MOD, the 30-s window remained unreliable (ICC=0.32, -0.01), while the 1-min window achieved moderate reliability (ICC=0.63, 0.00). During TT30, both shortened windows substantially improved performance (30s: ICC=0.78, -0.02; 1min: ICC=0.95, -0.01), with the 1-min window achieving excellent reliability. ConclusionDFAa1 analysis window validity is intensity-dependent, with shortened windows showing progressively improved agreement as exercise intensity and heart rate increases. While the 2-min window remains essential for low-intensity monitoring, 1-min or 30-s windows provide appropriate validity during high-intensity exercise, enabling more-responsive real-time feedback. These results support adaptive windowing strategies that dynamically adjust window length based on exercise intensity and the number of included data points, to optimize the analytical validity-temporal responsiveness trade-off.

Mental fatigue is induced by prolonged engagement in cognitively demanding tasks and impairs endurance performance. The neuropsychophysiological mechanisms underlying this decreased performance remain unclear, with suggestion that mental fatigue may disrupt motor command and consequently muscle activation. We aimed to test this hypothesis in a repeated cross-over design study in which 18 participants completed two experimental sessions involving a time-to-exhaustion cycling test at 80% of peak power output. Each cycling task was preceded by 1h of a prolonged Stroop task (Stroop session) or a neutral control task (Control session). Perception of effort and surface electromyography from ten lower-limb muscles of the right leg were recorded at regular intervals during cycling. Mental fatigue was higher in the Stroop compared to the Control session (p = .002). Endurance cycling time was 111 {+/-} 160 s shorter in the Stroop than in the Control session (p = .009). No significant differences in electromyography parameters were observed between Stroop and Control sessions, for any muscle (p > .05). Perception of effort was higher in the Stroop session from the onset of the cycling task (p = .006), and the rate of increase in perception of effort was significantly higher in the Stroop than Control session (p = .031). Our findings do not support the hypothesis that mental fatigue alters motor control or increases central motor command, as no changes in muscle activation were detected. Conversely, our results reinforce the notion that prolonged cognitive engagement impairs endurance performance primarily through an increased perception of effort. Future research should consider combining surface electromyography with more sensitive neurophysiological techniques to investigate potential subtle changes in motor drive during dynamic, whole-body tasks under mental fatigue. Impact statementOur study confirms that mental fatigue induced by prolonged cognitive exertion impairs cycling endurance performance. By combining measurements of perceptual responses and multi-muscle surface EMG during the endurance task, we observed that the decreased endurance performance is related to an increased perceived effort in the presence of mental fatigue, not related to alterations in motor command.

IntroductionMusculoskeletal injuries (MSKIs) are ubiquitous in the U.S. military, especially among high-performing service members such as Marines. Given that female service members only started to be assigned to ground combat roles since December 2015, evaluation of sex on MSKI risk in ground combat occupations has not been possible until there was an ample population to study. The purpose of this population-level epidemiological study was to assess (1) if female sex was a salient risk factor for MSKI in Marines serving in different military occupations, including combat arms, and (2) the effects of integration period on MSKI risk among female Marines. Materials and MethodsA population-based epidemiological retrospective cohort study of all U.S. Marines was performed assessing female sex, occupation, and integration period on the prevalence of MSKI from 2011 through 2020. The Military Health System Data Repository was utilized to identify initial healthcare encounters for diagnosed ankle-foot, knee, lumbopelvic-hip, thoracocostal, cervicothoracic, shoulder, elbow, or wrist-hand complex injuries. Prevalence was calculated for female and male Marines in each occupational category (combat, combat support, aviators, aviation support, services) during the pre-integration (2011-2015) and post-integration (2016-2020) periods. ResultsDuring the pre-integration period, 520/1,000 female Marines (n=13,985) and 299/1,000 male Marines (n=142,158) incurred MSKIs. In the post-integration period, the prevalence increased to 565/1,000 female Marines (n=17,608) and 348/1,000 male Marines (n=161,429). In the multivariable evaluation of sex, occupation, integration period, and the interaction of sex and occupation on combined MSKIs, only female sex was a significant factor for injury (prevalence ratio [PR]=1.99), with service in ground combat and aviation occupations identified as protective factors when compared with services occupations (PR=0.69). When these same factors were evaluated for specific MSKI outcomes, female sex remained a robust factor in all lower quarter (PR=1.75-2.63) and upper quarter (PR=1.38-2.36) injuries except for shoulder injuries. Service in ground combat and aviation occupations was protective for all lower quarter injuries (PR=0.46-0.71). In the upper quarter, ground combat was protective for all injuries except for elbow injuries (PR=0.67-0.77). Serving as an aviator was a risk factor for cervicothoracic (PR=1.57) and thoracocostal (PR=1.22) injuries and a protective factor for shoulder (PR = 0.73) and wrist-hand (PR = 0.46) injuries. Adjusted risk for lumbopelvic-hip (PR=1.13), ankle-foot (PR=1.53), cervicothoracic (PR=1.19), thoracocostal (PR=1.14), and elbow (PR=1.48) injuries significantly increased during the post-integration period. There was a significant sex-by-period interaction for shoulder injuries alone, with female sex in the post-integration epoch found to be salient (PR=1.26). ConclusionsFemale sex was a salient factor for MSKI, with service in ground combat and aviation occupations identified as protective factors when compared with services occupations. In the evaluation of specific MSKIs, female sex remained a robust and significant factor in all lower quarter injuries and upper quarter injuries except for shoulder injuries. There was only a significant sex-by-period interaction for shoulder conditions, with an increased risk of these injuries in female Marines in the post-integration period.

Cycling is commonly employed in sports performance, rehabilitation, and clinical contexts, while musculoskeletal (MSK) simulations enable the investigation of internal biomechanics that cannot be measured experimentally. Despite growing use, the application, validation, and standardisation of MSK simulations in cycling remain unclear. This review aimed to systematically characterise the application, validation strategies, modelling assumptions, and reporting practices of musculoskeletal simulations in lower-limb cycling biomechanics. Searches were performed in Scopus, PubMed, IEEE Xplore, and Web of Science on 1 August 2024, covering studies from January 2010 to July 2024. Peer-reviewed English-language journal articles applying MSK simulations to lower-limb cycling were included; inverse kinematics-only was excluded. No protocol was registered, and no formal risk-of-bias assessment was conducted, as there were no intervention effects and no quantitative synthesis. Twenty-eight studies met the inclusion criteria. Most of them investigated bicycle-rider configuration, neuromuscular coordination, or electrical stimulation control, with participant cohorts overwhelmingly composed of young men and minimal female representation (272 total). Model reporting was often incomplete, with wide variation in anatomical scope, inconsistent descriptions of degrees of freedom, and limited sharing of models or code. Use of experimental data was uneven across studies: while all incorporated kinematic measurements, only two-thirds included kinetic data, and only one study reported physiological measures. Model validation was generally based on literature values. Seventy-eight per cent of studies used optimisation, mainly with effort-based cost functions, and parameter variations were exploratory rather than systematic. The evidence base is limited by small, predominantly male cohorts, inconsistent reporting standards, and limited physiological validation. These results consolidate current practices and highlight the need for more transparent and open reporting, sex-balanced and clinically diverse participant representation, stronger validation, and more rigorous sensitivity analysis to enhance reproducibility and practical relevance. This review was funded by AGAUR (Spain), CAPES (Brazil) and FAP-DF (Brazil). Author summaryCycling is widely used in sports training, rehabilitation, and clinical practice, and musculoskeletal simulations are increasingly used to study how muscles and joints work during cycling. These simulations allow us to estimate internal biomechanical variables that cannot be directly measured in experiments, such as muscle forces and joint loading. However, it is currently unclear how consistently these simulations are applied, validated, and reported across the literature. In this study, we systematically reviewed research published over the past 15 years that used musculoskeletal simulations to analyse lower-limb cycling. We identified 28 relevant studies and examined their modelling choices, experimental inputs, optimisation strategies, and validation approaches. We found substantial variability in model complexity, limited transparency in reporting, and a strong reliance on simplified literature-based validation methods. Most studies focused on narrow participant groups and explored modelling parameters in an ad hoc rather than a systematic way. Our findings highlight important gaps in current practice and point to clear opportunities for improvement. We provide an overview of common approaches and their limitations, and outline key recommendations to enhance the transparency, reproducibility, and practical relevance of musculoskeletal simulations in cycling research.

When running, metabolic cost increases as muscles are simultaneously fatigued. However, the contribution of an individual muscle group to fatigue-related increase in metabolic costs remains unclear. We investigated the metabolic consequence of running with local plantar flexor or knee extensor fatigue and associated neuromuscular control strategies. Recreational and experienced male runners (N=20) completed two sessions (one per muscle group), with each including two 10 min running bouts: without and with local fatigue ([~]20% reduction in peak joint torque). Net metabolic power and muscle activity (initial and final minutes) were determined. Metabolic power was unaffected by plantar flexor (p=0.367) or knee extensor (p=0.607) fatigue in both cohorts. Plantar flexor fatigue recovered during the fatigued run (p=0.033), while knee extensor fatigue only recovered for the recreational cohort (p=0.009; experienced: p=0.826). With plantar flexor fatigue, plantar flexor muscle activity was unchanged between runs (p[&ge;]0.312), however initial soleus activity was greater in the unfatigued than fatigued run for experienced runners (p=0.022), and initial medial gastrocnemius activity was greater in the unfatigued than fatigued run for the combined cohort (p=0.009). With knee extensor fatigue, knee extensor muscle activity was mostly lower in the unfatigued than fatigued run (p[&le;]0.009), except for final vastus lateralis activity, which was unchanged between runs (p=0.061). Therefore, muscle groups respond with different activation strategies when fatigued. Running with plantar flexor or knee extensor fatigue, at levels like those induced by prolonged running (10-42 km), does not increase metabolic power and thus, submaximal running energetics may be maintained despite local muscle fatigue. NEW & NOTEWORTHYWhile muscle fatigue is suggested to increase the metabolic cost of running, the individual contributions of key lower limb muscle groups have not been explored. We examined responses after fatigue of only the plantar flexors or the knee extensors. Results indicate that local fatigue did not affect the metabolic power of male runners for either fatigued muscle group. These findings enhance our understanding of running performance and the interaction between fundamental criteria dictating human locomotion.

Objectives: To determine the impact of discharge home on physical activity and sedentary behaviour following orthopaedic trauma. Design: Observational study. Setting: Acute hospital. Participants: Between October 2022 and January 2024, 31 adult orthopaedic trauma patients were recruited during hospital admission. Participants had either an isolated hip fracture or multi-trauma (i.e., a lower limb fracture, with an upper limb and/or spinal fracture). Interventions: Participants wore two activity monitors (activPAL3 and ActiGraphGT3x) during the final days of an acute hospital admission and the first five days at home. An interrupted time series analysis evaluated changes physical activity variables during the hospital to home transition. Participants were analysed individually using mixed-effects linear regression allowing the intercept to vary by participant. Main outcome measures: Primary outcome was daily steps; secondary outcomes included sedentary time and other activity measures. Results: Daily steps (mean +- SD) were higher at home (4552.4 +- 2639.5) compared to hospital (2597.8 +- 1450.8). Modelled results indicated a 27% increase in daily steps following hospital discharge (exp(beta946;): 1.27, 95% CI: 1.01,1.59, p=0.039) and a sustained improvement at home. No significant differences were observed between hip fracture and multi-trauma participants. Conclusion: Participants recovering from orthopaedic trauma showed a significant increase in daily step count upon discharge home from hospital, highlighting the positive impact of the home environment on activity levels. Further research is warranted to assess the effectiveness of interventions to improve activity levels in hospital (e.g., early intensive therapy) and at home (e.g., immediate home-based physiotherapy) in individuals following orthopaedic trauma.

Two theoretical models are proposed on the signal processed by the brain to generate the perception of effort (PE): the corollary discharge model and the afferent feedback model. To test the validity of these models, we used electromyostimulation to manipulate the magnitude of the central motor command during voluntary (high motor command), evoked (no motor command) and combined (low motor command) contractions at similar torque outputs. As electromyostimulation evokes sensory volleys to the central nervous system, it was used to evoke muscle contractions and to stimulate afferent feedback. We hypothesized that PE would reflect the magnitude of the central motor command and that evoked muscle contractions in the absence of central motor command would not elicit any PE. Twenty participants (n=10 experienced and n=10 novice with electromyostimulation) volunteered in this study. Participants reported their PE after isometric (10% and 20% MVC) and dynamic (5% and 20% MVC) voluntary, evoked, and combined contractions. For the same torque, participants reported no PE during evoked contractions, but all reported PE during voluntary contractions. Experienced but not novice participants reported lower PE during the combined than during voluntary contractions. This study questions the validity of the afferent feedback model and highlights the key role of motor command-related signals in PE generation. However, results from the novice participants during the combined contractions suggest that other factors such as inhibitory control may affect PE. Future studies should investigate the relationship between the central motor command and PE during physical tasks at various levels of complexity.

1BackgroundHuman locomotion is a highly adaptive motor skill that adjusts to new environmental demands through learning. Split-belt treadmill paradigms have advanced our understanding of gait adaptation. Most studies have examined gait when the belts move at different speeds in the same direction. We are studying muscle activation patterns during an asymmetric gait, when the treadmill belts move at equal speed in opposite directions, i.e., bidirectional walking (BDW). MethodsTwelve healthy volunteers performed a single session on a split-belt treadmill. We simultaneously collected ground reaction forces via treadmill force plates, joint kinematics via motion capture, and surface electromyography (EMG) from bilateral soleus (SOL) and tibialis anterior (TA) muscles. Participants started with 2 min of forward walking (FW), followed with four 5-min blocks of BDW separated by 1-min standing rest intervals, and finished the session with 2 min of FW (washout). ResultsAll participants successfully completed the protocol. We analyzed EMG signals for temporal activation patterns (rhythm generation) and amplitude characteristics (pattern formation). EMG recordings revealed antiphasic activation of SOL and TA muscles bilaterally throughout all trials. During BDW, the backward-moving legs TA showed prolonged activation patterns that persisted during washout FW, suggesting retention of adaptive changes. Burst-to-cycle duration ratios showed transient changes during early adaptation but remained relatively stable across conditions, demonstrating robust rhythm generation despite adaptive modulation of activation patterns during BDW. DiscussionThese findings demonstrate that BDW induces asymmetric adjustments in muscle activation patterns. Rhythm generation (timing) did not significantly differ between BDW and FW. However, we did observe changes in pattern formation (i.e., EMG profiles) during FW pre- and post-BDW training. Burst-to-cycle duration ratios, as a measure of rhythm generation, showed changes during early adaptation, particularly the increase in right SOL and right TA during block 1, though these changes did not reach statistical significance and largely returned to baseline during washout. The underlying pattern formation structure, was maintained across all conditions, with selective amplitude modulations rather than fundamental reorganization of activation patterns. The substantial temporal adjustments in the backward-moving legs SOL and phase shifts in TA provide the neuromuscular mechanism driving the bilateral step-length reduction, altered inter-limb phasing, and asymmetric double stance timing. These results extend our understanding of locomotor control by suggesting how the central nervous system (CNS) dynamically recalibrates muscle timing and amplitude to maintain satisfactory locomotion under new environmental demands.