Frontiers in Sports and Active Living

PurposeThe para-cycling classification system aims to minimize the impact of impairments on competition outcomes with the help of scientific evidence. This study investigated the impact of unilateral and bilateral ankle immobility on cycling performance, quantified by the maximal average mechanical power output (AMPO) over one revolution relative to that without ankle immobility. MethodsTen well-trained non-disabled cyclists performed all-out 6-second sprints on a cycle ergometer at 120 rpm under three conditions: without ankle foot orthoses (AFOs), with 1 AFO and with 2 AFOs immobilizing the ankle joint(s). Mechanical power output, pedal forces, cycling kinematics and surface-electromyography were measured. Maximal AMPO; ankle, knee and hip joint AMPO; and the amount of muscle excitation were calculated. ResultsWith 1 AFO and 2 AFOs, respectively, maximal AMPO was 96% (p<0.05) and 91% (p<0.001) of that without AFOs (1188 W). The decrease in maximal AMPO with ankle immobilization was less than the decrease in ankle joint AMPO (126 W decrease with 2 AFOs; p<0.001), due to an increase in hip joint AMPO (69 W increase with 2 AFOs; p<0.05). The amount of muscle excitation was not significantly different across conditions. ConclusionsThese findings provide a first quantitative and mechanistic indication of the impact of ankle immobility on cycling performance, which may offer valuable evidence to support the development of an evidence-based para-cycling classification system.

The role of passive muscle mechanical properties in explosive performance is important to understand to maximize training and performance in strength sports. The objective of this study was to create and test a Structural Equation Model (SEM) to analyze the interrelations between muscle mechanical properties and neuromuscular performance in competitive weightlifters. The MyotonPRO was used to measure muscle stiffness, muscle tone, muscle elasticity, relaxation time and creep of four major muscles: Quadriceps Femoris, Hamstrings, Trapezius and Biceps Brachii, on thirty elite male weightlifters. This involved performance metrics of the rate of force development (RFD), countermovement jump (CMJ) and time to contraction threshold (TCT). AMOS was used to analyze the direct and indirect relationships between variables through SEM analysis. These findings indicated that muscle stiffness and relaxation time were significant predictors of explosive performance measures (p < 0.05) but there were weak or no relationships between tone, elasticity and creep. The model proposed had good fit indices (CFI = 0.97, RMSEA = 0.049) indicating its structural soundness. These results present the significance of muscle stiffness and relaxation time as important predictors of neuromuscular performance. The proposed model suggests an effective structure of monitoring athletes, their performance optimization, and individual training design in strength-based sports.

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 ([&le;]25 W difference in solo performance), and unequal-capacity tandem ([&ge;]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.

PurposeThis study aimed to examine the effects of formative and summative assessments on college students tennis performance and basic psychological needs. MethodsA total of 128 undergraduate students (64 males, 64 females; Mage = 19.22, SD = 0.91) participated in this study. Participants were cluster-randomized to either a formative assessment group (n = 64) or a summative assessment group (n = 64). The formative assessment intervention involved setting personalized learning goals and success criteria, administering periodic tests, and providing process-oriented and individualized feedback. The summative assessment intervention involved setting uniform goals for all students, offering instructor feedback only on common problems, and requiring students to practice independently after class without personalized guidance. Both interventions were implemented over 10 weeks, with one 90-minute session each week. Tennis skills and basic psychological needs (i.e., autonomy, competence, and relatedness) were assessed before and after the intervention. Tennis skills were reassessed 1 week after the intervention. Two-way mixed-effects analysis of variance (ANOVA) was used to examine the impact of group, time, and their interaction on tennis skills and basic psychological needs. ResultsThe results showed that the interaction between group and time was significant for all of the outcome variables. Simple effects analyses indicated that, at pre-test, the two groups did not differ significantly in tennis performance or in satisfaction of autonomy, competence, and relatedness (p > 0.05). At post-intervention, the formative assessment group demonstrated significantly better performance than the summative assessment group in tennis skills (MD = 3.50, 95% CI = [1.303, 5.697], p = 0.002), autonomy (MD = 2.44, 95% CI = [1.816, 3.059], p < 0.001), relatedness (MD = 1.33, 95% CI = [0.679, 1.977], p < 0.001), and competence (MD = 1.75, 95% CI = [1.046, 2.454], p < 0.001). At the 1-week follow-up session, the formative assessment group also showed significantly better tennis performance than the summative assessment group (MD = 6.81, 95% CI = [4.667, 8.958], p < 0.001). ConclusionFormative assessment was more effective than summative assessment in improving college students tennis performance and satisfying their basic psychological needs. These findings suggest that incorporating personalized goals, process-oriented evaluation, and individualized feedback into tennis instruction could promote both skill development and psychological outcomes in college physical education.

This study examined the utility of HRV detrended fluctuation analysis alpha-1 (DFA1) to assess readiness-to-train and exercise durability under varying acute training loads. Nineteen trained cyclists completed two 20-minute time-trials (TT) under rested and fatigued conditions. DFA1 was measured during a standardized warm-up (WU), 20-min TT, and standardized cool-down (CD). Power output (PO) and DFA1 responses were compared across conditions, and associations with performance and fitness (W/kg) were examined. DFA1 values declined with increasing WU and CD exercise intensity (p<0.001) and were significantly attenuated following the 20-min TT (p<0.001). While DFA1 profiles did not differ significantly between rested and fatigued conditions, lower pre-TT DFA1 was associated with reduced TT performance (p=0.022; r=0.55), suggesting relevance to training readiness. Additionally, an 18% decline in DFA1 between 10- and 20-min during the TT (p=0.031), and lower post-TT values at matched intensities were observed (p<0.001), indicating physiological perturbation from the 20-min TT. Fitter participants exhibited lower DFA1 values during the 20-min TT (p<0.001; r=-0.77), suggesting a greater capacity to sustain physiological stress. While DFA1 is responsive to exercise intensity and stress, offering potential to assess training readiness and durability, more robust fatigue protocols are needed to validate DFA1 as training load monitoring tool.

Purposeto characterize the dynamic postural control during weight load shifting with and without support surface reduction with temporal metrics commonly used in linear control systems identification. MethodsFrom the COP coordinates temporal, global and structural parameters were calculated. Reliability of derived parameters were determined using Bland-Altman analysis. ResultsFor the observed population, temporal variables tend to decrease when the complexity of the task is increased with the reduction in the support surface and the non dominance. ConclusionDelay and rise times were significantly shorter for the non-dominant limb in the anteroposterior direction when volunteers performed the same task with different limbs. In the mediolateral direction, delay and rise times were shorter in both unipodal stances with respect to their bipodal homologues. An increase in COP path length, velocity and sample entropy was observed when the support area was reduced. All parameters showed good reliability in both directions at all stances. This framework could be used in the clinical practice to assess dynamic postural control capabilities in patients whose balance is pathologically affected. The trial was evaluated and approved by the Central Committee of Bioethics in Biomedical Practice and Research of the province of Entre Rios.

BackgroundTreadmill walking is often employed for tightly controlled gait and energetics research, but growing evidence suggests that treadmill-based metabolic and biomechanical measurements may not directly reflect the ecologically valid mode of overground walking. While many previous studies focused on older adults, much less is known about how treadmill walking influences gait energetics and spatiotemporal parameters in young healthy adults across matched speeds. Aims and ObjectivesWe investigated energy expenditure, metabolic cost of walking and spatiotemporal gait parameters in healthy young adults walking overground and on a treadmill at three speeds (slow-1.0, comfortable-1.3, fast-1.5 m/s). Our hypothesis was that at the comfortable speed, treadmill and overground energetics and gait parameters would be comparable. However, at slow and fast speeds, there would be a significant energetic penalty, accompanied by significant differences in spatiotemporal parameters. MethodsTwenty young participants (10 males and 10 females) completed a randomized cross-over walking protocol with a minimum of ten minutes treadmill familiarization at 1.3 m/s. Breath-by-breath oxygen consumption [Formula] and Respiratory Exchange Ratio were measured using a portable indirect calorimetry system and gait parameters were calculated from Inertial Measurement Units. Gross and net energy expenditures, costs of walking, cadence, average step and stride lengths were calculated. A three-way mixed ANOVA was used for primary statistical analyses. ResultsTreadmill walking was characterized by higher gross and net energy expenditures and metabolic costs (p<0.001, p2 = 0.6) across all speeds compared to overground. It was also characterized by faster cadence and shorter average step and stride lengths (p<0.001, p2 = 0.9). Additionally, there was an effect of sex (p = 0.01, p2 = 0.3) on the gait parameters, with females exhibiting a faster cadence and shorter average step and stride lengths than males. Discussion and ConclusionsOur findings show that treadmill walking imposes a medium-to-large metabolic penalty even in healthy young adults, with compensatory gait adaptations, possibly reflecting increased stabilization demands and altered neuromuscular control strategies. These results underscore the limits of generalizing treadmill derived gait data to overground walking and we caution against the uncritical use of treadmills, especially while trying to understand ecologically relevant human walking mechanics and energetics.

This cross-sectional derivation and internal validation study aimed to develop and internally validate a clinical triage scoring system (CTSS) for field-based identification of collegiate athletes requiring priority intervention for lumbopelvic-hip (LPH) dysfunction. A total of 864 collegiate athletes (mean age 21.3 {+/-} 2.4 years; 80.8% male) were recruited from 10 universities. Participants underwent standardized assessments including demographic characteristics, clinical history, and LPH functional testing. Using an expert-adjudicated binary reference standard (priority intervention vs self-management), a multivariable logistic regression model was developed to derive the weighted CTSS. Model performance was evaluated using discrimination, calibration, and decision curve analysis (DCA), and internal validation was performed using 1,000 bootstrap resamples. Of the 864 participants, 463 athletes (53.6%) were classified as requiring priority intervention. The final 14-factor CTSS comprised 12 positive-weight predictors, such as localized LPH pain, muscle weakness, and higher body mass index, and 2 negative-weight predictors, positive Lasegues sign and hamstring weakness, which functioned served as safety-related modifiers. The model demonstrated acceptable discrimination (AUROC = 0.851, 95% CI: 0.824-0.876), with minimal optimism (optimism-corrected AUROC = 0.842) and excellent calibration (calibration slope = 1.000; calibration intercept = 0.000). A total score of [&ge;]9 was identified as the optimal threshold, yielding a sensitivity of 84.4% and specificity of 71.8%. DCA showed greater net benefit than treat-all and treat-none strategies across clinically relevant threshold probabilities (20%-50%), with a net benefit of 0.319 at a 50% threshold probability. The CTSS may provide a pragmatic field-based triage tool to support early identification of athletes who may require priority intervention, although external validation is needed before broader implementation in sports medicine settings.

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.

BackgroundWork-related musculoskeletal symptoms such as pain, stiffness, and swelling are a common occupational health issue that affect well-being and increase healthcare costs. Continuous physical effort, long hours of sitting, and poor awareness of proper ergonomics often lead to or worsen these conditions. ObjectiveThis study determined the frequency of musculoskeletal symptoms and the associated risk factors with musculoskeletal symptoms among field health workers in Bin Qasim Town, Karachi. Material & MethodsA cross-sectional study was employed and collected data from Karachi based pre-urban communities i.e.: Ibrahim Hydri, Rehri Goth and Bhains Colony. Study duration was 9 months. MSK symptoms were assessed using the standardized Nordic Musculoskeletal Questionnaire (NMQ). Prevalence of MSK symptoms was assessed over 12 months and 7 days. Participants with pain in [&ge;]2 regions of the upper or lower limbs were classified as having upper or lower limb symptoms, respectively. Multivariable logistic regression was used to identify associated factors for MSK symptoms in last 12 months. Results132 participants were recruited. Most frequently reported pain region in the last 12 months was lower back 111(84%) and shoulder 81(61%). Similarly, the most affected region in the last 7 days was also lower back 39(29%) followed by shoulder 33(25%). Upper limb MSK symptoms were significantly associated with bachelors or higher educated (OR=3.38; 95% CI: 0.67-7.42), sitting 3-4 h/day (OR=3.46; 95% CI: 1.11-10.75), and walking 3-4 h/day (OR=2.88; 95% CI: 1.05-7.85). In lower limb, married workers had 2 times higher odds of lower limb MSK symptoms (OR=2.36; 95% CI:1.04 - 5.35), while those who worked > 30 hours/week had 67% lower odds of having lower limb MSK symptoms (OR=0.33, 95% CI:0.15 - 0.72). ConclusionField health workers frequently reported MSK symptoms in both limbs. Preventive strategies such as ergonomic training, task rotation, and targeted support for married female workers are recommended to reduce the long-term impact.

Background: Quadriceps strength and landing mechanics are two modifiable factors associated with anterior cruciate ligament (ACL) injury risk. Collecting detailed biomechanical data is an arduous task. Identifying a relationship using more easily measured variables, such as quadriceps strength, would offer value for athlete counseling and injury prevention programs. Although quadriceps weakness has been associated with altered landing strategies in ACL-reconstructed (ACLR) individuals, this relationship is less clear in healthy athletes. Purpose: To investigate the association between isokinetic quadriceps strength and peak knee flexion angle during a vertical drop jump in healthy adolescent athletes. Study Design: Secondary analysis of previously collected data. Methods: Healthy adolescent athletes had their dominant leg quadriceps strength measured using an isokinetic dynamometer at 60{degrees}/s from 0-90{degrees} of knee flexion. Landing mechanics were assessed during a vertical drop jump using three-dimensional motion capture synchronized with force plates. Pearson correlation was used to evaluate the association between quadriceps strength and peak knee flexion angle during landing, with statistical significance defined as p < .05. Results: There was a weak negative correlation between quadriceps strength and peak knee flexion angle (p = .017, R = -.22 [-.04, -.38]), suggesting that stronger athletes achieved greater knee flexion angles. Discussion: Greater quadriceps strength was associated with increased peak knee flexion angles during landing; however, the weak correlation suggests that strength explains only a small portion of the variability in landing mechanics. These findings deviate slightly from prior literature in healthy populations but are consistent with studies demonstrating that greater quadriceps strength is associated with achieving greater peak knee flexion in ACLR patients. Accordingly, quadriceps strengthening should remain a key component of multifactorial ACL injury prevention programs.

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.

Gait asymmetry is a common manifestation of walking impairment among clinical populations. We recently developed a novel treadmill walking approach called dynamic treadmill walking that can provide asymmetric gait training by changing the treadmill speed between fast and slow speeds within a single stride. Here, we studied the energy expenditure associated with a variety of dynamic treadmill walking conditions. We hypothesized that the metabolic power required for dynamic treadmill walking in all conditions would approximate the metabolic power associated with conventional walking at the mean of the fast and slow speeds employed in the task. Eleven young adults without gait impairment walked on an instrumented treadmill and breathed into a metabolic measurement system. During dynamic treadmill walking, the treadmill fluctuated between 0.75m/s and 1.50m/s, each for 50% of an individuals stride time. We used a metronome to synchronize participants right heel-strikes with four different timing conditions. Net metabolic power during dynamic treadmill walking was significantly greater than normal walking at the mean speed of the task (1.125m/s) and generally lower than walking at the fast speed (1.5m/s). We did not observe any significant associations between net metabolic power and several measures of gait asymmetry during dynamic treadmill walking. These findings establish dynamic treadmill walking as a promising technique for improving gait symmetry in individuals who cannot tolerate fast treadmill walking, a common gait rehabilitation approach. Future work will assess the feasibility, metabolic demands, and clinical efficacy of using dynamic treadmill walking to improve gait symmetry in clinical populations. Key Points SummaryO_LIDynamic treadmill walking (i.e., walking with oscillating treadmill speeds) has previously been shown to drive gait asymmetries, but little is known about the energy expenditure required to complete the task. C_LIO_LIOur hypothesis was that dynamic treadmill walking would have similar metabolic power requirements to normal walking at a speed that is intermediate between the two dynamic treadmill walking speeds. C_LIO_LIWe found that dynamic treadmill walking actually requires metabolic power that is greater than the average of the two belt speeds, but less than that used for fast walking. C_LIO_LIDynamic treadmill walking is a promising and clinically translatable technique for rehabilitating populations with gait asymmetries that is not more energetically costly than fast treadmill walking, a common gait rehabilitation approach. C_LI

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.

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.

ObjectivesThis study aimed to compare exercise-induced changes in serum and salivary concentrations of cardiac troponin-I (cTnI) in athletes during and after a marathon. MethodsThirty-six male runners were recruited. Eighteen participants in group 1 completed a marathon (42.195 km), while eighteen participants in group 2 did not undergo this exercise. Blood and saliva samples were collected at twelve different time points and then analyzed for cTnI using an immunoassay. ResultsBiphasic cTnI release into the circulation was observed during and after the marathon. Moreover, a similar pattern of biphasic cTnI elevation was found in saliva. In group 1, salivary and serum concentrations of cTnI first peaked after 60 min of exercise (0.67{+/-}0.08 ng/mL and 0.76{+/-}0.07 ng/mL), decreased slightly towards the end of the marathon (0.40{+/-}0.06 ng/mL and 0.46{+/-}0.06 ng/mL), and then reached a second, higher peak 4 h post-exercise (0.72{+/-}0.09 ng/mL and 0.82{+/-}0.09 ng/mL), returning to baseline by 48 h after marathon completion (0.16{+/-}0.04 ng/mL and 0.18{+/-}0.04 ng/mL). In group 2, there were no time-dependent changes in cTnI concentrations in both saliva and serum. Deming regression and Passing-Bablok regression demonstrated that there was proportional agreement between salivary and serum levels of cTnI in both groups at all twelve time points. The Bland-Altman method revealed that there was a negative differential bias but no proportional bias in the data. ConclusionsDocumenting a similar, biphasic pattern of cTnI elevations in saliva and serum during and after the marathon provides a reliable non-invasive alternative without requiring a blood draw.

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.

Athletes bodies are both performance agents and targets of evaluative scrutiny, yet little is known about the psychological processes linking body composition to body image among athletes. In this pre-registered study, we examined whether competence-related self-evaluations mediate or moderate associations between adiposity and body image in 327 Chinese collegiate athletes (78.6% male). Drawing on Self-Objectification Theory and the Sport Confidence Model, we tested two competing hypotheses, including a filter (parallel mediation) and a buffer (moderation) account. Factor analysis results of four body image scales supported a two-factor structure, comprising a proactive, functionality-oriented positive dimension and a reactive, appearance-distress-driven negative dimension. Hierarchical regressions showed that fat mass index (FMI) was associated with lower positive and higher negative body image (ps < 0.05). Importantly, parallel mediation analysis results indicated that trait sport confidence mediated between FMI and both body image dimensions, with a stronger effect for positive body image ({beta} = -0.04, 95% CI [-0.09, -0.01]) than for negative body image ({beta} = 0.03, 95% CI [0.01, 0.07]). Subjective sport performance was not evidenced as a mediator. No moderation effects were supported. These findings suggest that the body composition-body image link in athletes is interpretive: enduring competence beliefs may matter more than proximal performance appraisals in affecting how athletes make sense of their bodies. Positive body image appears especially dependent on competence-grounded meaning-making, whereas negative body image remains more directly tied to appearance-based evaluative cues. Collegiate sport environments may benefit from prioritizing functionality-centered feedback over physique-focused evaluation.