Medicine and Science in Sports and Exercise最新文献

{"title":"Fractal Correlation Properties of Heart Rate Variability Differentiates Training Intensity During and After Energy-Matched Cycling Sessions.","authors":"Anton Olieslagers, Yoram Müller-Jabusch, Jens De Maeseneer, Maura Seynaeve, Toon T de Beukelaar","doi":"10.1249/MSS.0000000000004146","DOIUrl":"https://doi.org/10.1249/MSS.0000000000004146","url":null,"abstract":"<p><strong>Introduction/purpose: </strong>Recovery optimization requires precise monitoring of physiological stress. This study examines whether detrended fluctuation analysis alpha 1 (DFAa1), a non-linear heart rate variability index, exhibits intensity-dependent responsiveness across energy-matched training sessions in cycling.</p><p><strong>Methods: </strong>Nineteen endurance-trained male participants (18-35yrs) completed three equalized workload protocols at different intensities: light (LIGHT), moderate (MOD), and high-intensity interval training (HIIT). Training sessions were matched for energy expenditure by adjusting time via the formula E=P×Δt (E=Energy (J); P=power (W); Δt=time (s)). LIGHT and MOD training were conducted at first and second lactate threshold power (i.e. LT1 and LT2), respectively. HIIT followed a 10x1min protocol at 110% V̇O₂peak power, alternated with 1min rest at 80% LT1 power. Heart Rate (HR) and DFAa1 were assessed throughout the different intensity training sessions as well as during a standardized 10min warm-up (WU) and cool-down (CD) at LT1.</p><p><strong>Results: </strong>DFAa1 showed apparent stability during LIGHT (p=0.997) and MOD sessions (p=1.000), while showing deterioration during HIIT (p<0.001). On the other hand, HR drift was apparent for all intensities (LIGHT: p=0.003; MOD: p<0.001; HIIT: p<0.001). When directly comparing DFAa1 and HR via ΔZ-scores, a significant effect was found only in MOD (p=0.008). Interestingly, DFAa1 demonstrated significant WU to CD differences for MOD and HIIT (p<0.001), but not for LIGHT (p=0.210), while HR responses showed significant WU to CD differences for all intensities (p<0.001). ΔZ-scores showed significant differences between DFAa1 and HR in MOD (p=0.039) but no significant differences in LIGHT (p=0.098) and HIIT (p=0.071).</p><p><strong>Conclusions: </strong>These findings seem to reinforce that DFAa1 holds promise as an objective, system-wide marker of internal workload across varying exercise domains.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148969938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exploring Neuromuscular and Biomechanical Factors Associated with Improvements in Running Economy Following Plyometric Training in Male Master Endurance Runners.","authors":"Yuuri Eihara, Sumiaki Maeo, Kenji Takao, Hiroaki Kanehisa, Tadao Isaka","doi":"10.1249/MSS.0000000000004145","DOIUrl":"https://doi.org/10.1249/MSS.0000000000004145","url":null,"abstract":"<p><strong>Purpose: </strong>While running economy can be improved following plyometric training, the factors associated with running economy improvements remain unclear, particularly in master endurance runners. This study aimed to identify neuromuscular and biomechanical factors associated with running economy improvements following plyometric training in male master endurance runners.</p><p><strong>Methods: </strong>Thirty-five male master endurance runners performed plyometric training twice weekly for 10 weeks. Isokinetic knee extension/flexion torques, isometric ankle dorsiflexion/plantarflexion torques, and countermovement, drop, and rebound jump performance were measured pre- and post-intervention. Running biomechanical variables and running economy at 80% velocity of V̇O2max were also recorded during a 30-minute run. To assess measurement reliability, a subset of 21 runners repeated the same protocol over ≥3 months before the intervention. A linear mixed-effects model was applied, with changes in running economy as the dependent variable and significantly associated factors (P<0.05) as predictors, and running volume as a covariate.</p><p><strong>Results: </strong>Running economy was improved following plyometric training (-3.9%, P=0.002), with 77.1% of runners exceeding the typical error (1.45%) derived from the repeatability dataset. Changes in running economy were significantly associated with those in drop/rebound jump height and step frequency (standardized β=-0.569 to 0.490, P=0.008-0.035), explaining 51.4% of the variance in running economy improvement (P=0.005). A significant interaction between rebound-jump height and step frequency was found (P=0.048), indicating that runners who increased rebound-jump height while reducing step frequency showed greater running economy improvement. No such associations were observed in the repeatability dataset, suggesting that the observed relationships are unlikely to be explained by measurement variability.</p><p><strong>Conclusions: </strong>Enhanced reactive jump ability combined with a reduced step frequency following plyometric training may underlie running economy improvements in male master endurance runners.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148969970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Altered Central Motor Control After ACL Reconstruction: A Muscle Synergy Analysis During High-Risk Landing.","authors":"Ze Gong, Yueqi Han, Tingni Li, Yameng Li, Ming Zhang, Le Li, Di Ao","doi":"10.1249/MSS.0000000000004147","DOIUrl":"10.1249/MSS.0000000000004147","url":null,"abstract":"<p><strong>Purpose: </strong>Anterior cruciate ligament reconstruction (ACLR) patients face elevated secondary injury risk due to residual neuromuscular deficits, yet the neuromuscular coordination strategies underlying altered muscle coordination remain unclear. Muscle synergy (MS) analysis offers a valuable framework for elucidating these mechanisms. This study characterized MS patterns in ACLR patients during high-risk landing and their correlation with lower-extremity biomechanics.</p><p><strong>Methods: </strong>Twenty-two patients who had undergone unilateral ACLR performed a single-leg drop-land-lateral jump task using both affected and nonaffected limbs, whereas sixteen healthy controls performed the task using their dominant limb. with the limb-level data were subsequently categorized into three groups: affected, nonaffected, and control. Surface electromyography (14 muscles), kinematics, and ground reaction forces were recorded. Non-negative matrix factorization was used to extract MS spatial (muscle weighting vectors) and temporal (activation profiles) components across pre-landing, impact, and loading phases. Joint angles/moments were computed via OpenSim musculoskeletal models. Mixed-effects models and Pearson correlations assessed group differences and synergy-biomechanics associations.</p><p><strong>Results: </strong>Compared to controls, ACLR limbs showed lower hip abduction and ankle plantarflexion angle but greater knee flexion angle at landing, accompanied by excessive pre-landing quadriceps weighting, reduced gluteal/semimembranosus contributions, and earlier but lower-amplitude synergy recruitment. Post-landing, quadriceps weighting decreased and knee-dominant synergy recruitment delayed, with compensatory redistribution toward gluteal, gastrocnemius, and tibialis anterior muscles, corresponding to reduced knee extension and increased hip extension moments. Critically, during impact, ACLR limbs lacked a dedicated frontal-plane stabilization synergy, MS4 (gluteus medius/peroneus longus), relative to the control group. A greater number of synergies in the affected limb was associated with more normative joint biomechanics.</p><p><strong>Conclusions: </strong>ACLR limbs exhibit persistent, limb-specific MS abnormalities across all landing phases, including altered sagittal-plane quadriceps weighting, impaired frontal-plane modular control, and dysregulated synergy timing. These central neuromuscular coordination alterations correlate with maladaptive knee biomechanics, potentially increasing secondary ACL injury risk. From a sports training perspective, targeting these specific synergy alterations, particularly the missing frontal-plane stabilization module, may inform more effective neuromuscular training protocols for safe return to sport.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148970005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Regression Equations for Femoral Neck Loading Assessment During Hip-Targeted Resistance Training.","authors":"Georgios Giarmatzis, Ilse Jonkers, Remco Baggen, Sabine Verschueren","doi":"10.1249/MSS.0000000000004139","DOIUrl":"https://doi.org/10.1249/MSS.0000000000004139","url":null,"abstract":"<p><strong>Purpose: </strong>To develop regression equations predicting femoral neck (FN) strains during hip-targeted resistance training in elderly women, enabling individualized exercise prescription for osteoporosis prevention.</p><p><strong>Methods: </strong>Twelve community-dwelling postmenopausal women (69.4±3.4 years) performed four resistance exercises (hip abduction, adduction, flexion, extension) at 40%, 60%, and 80% of one-repetition maximum (1RM). Three-dimensional motion capture combined with musculoskeletal modeling calculated hip contact forces (HCFs). Finite element analysis determined tensile and compressive strains in superior and inferior FN regions. Forward stepwise linear mixed models examined relationships between external loading parameters (weight lifted, leg length) and FN strain magnitudes.</p><p><strong>Results: </strong>Hip abduction generated the highest HCFs (4.14 body weights at 80% 1RM), followed by hip extension (3.08 BW), hip flexion (2.58 BW), and hip adduction (1.89 BW). Two-way repeated measures ANOVA revealed significant effects of exercise type and intensity on all outcomes (p<0.001). Weight lifted alone adequately predicted most strain metrics (R²=0.354-0.764), with leg length significantly improving prediction only for tensile superior strain during hip extension (R²=0.586). Hip abduction and extension at 80% 1RM produced strain magnitudes exceeding osteogenic thresholds (>1500-2500 με), particularly in the superior FN region. Compressive superior strain during hip extension showed the strongest weight-strain relationship (R²=0.764).</p><p><strong>Conclusions: </strong>High-intensity hip abduction and extension exercises generate substantial FN loading that may stimulate bone formation. The developed regression equations provide practical tools for estimating individual strain responses based on weight lifted, supporting personalized exercise prescription. Only exercises performed at 80% 1RM consistently reached osteogenic strain thresholds, emphasizing the importance of high-load resistance training for bone health in elderly populations.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148969954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The LC-NE System as a Candidate Mechanism Linking the Acute Benefits of Exercise on Cognitive and Brain Function in Children.","authors":"Christina M Bertrand, Lauren B Raine, Yan Luo, Tatsuya T Shigeta, Katherine M Lloyd, Jennifer N H Watrous, Alexandra Hill, Nicolas Collao, Kayleigh Beaudry, Shu-Shih Hsieh, Arthur F Kramer, Sean P Mullen, Michael De Lisio, Charles H Hillman","doi":"10.1249/MSS.0000000000004132","DOIUrl":"https://doi.org/10.1249/MSS.0000000000004132","url":null,"abstract":"<p><strong>Purpose: </strong>Physical activity supports cognitive and brain health, however the biological mechanisms underlying these benefits remain unclear. This study investigated changes in salivary alpha-amylase (sAA), a marker of sympathetic nervous system activity, and salivary cortisol (CORT), reflecting hypothalamus-pituitary-adrenal (HPA) axis activity, as candidate mechanisms mediating the effects of acute exercise on brain function, cognition, and academic achievement in children.</p><p><strong>Methods: </strong>In a pre-post randomized crossover design, 104 children (ages 9-10) completed exercise, the Trier Social Stress Test for Children (TSST-C; active control), and seated rest (passive control) conditions, with neuroelectric activity (P3 amplitude and latency), attentional inhibition, and academic achievement as outcomes. Structural equation modeling was performed to examine sAA and CORT as mediators of the relationship between exercise and outcomes. Moderated mediation tested whether the magnitude of the sAA-mediated path varied as a function of pre-intervention baseline CORT.</p><p><strong>Results: </strong>Exercise led to lower sAA than both controls and lower CORT than the TSST-C, controlling for pre-intervention baselines. Post-exercise reductions in sAA mediated reductions in trial-to-trial reaction time variability (SDRT) on incongruent trials, indexing more consistent inhibitory control. Exercise effects on neuroelectric activity (P3 amplitude) varied with baseline CORT.</p><p><strong>Conclusions: </strong>This study is among the first to investigate the biological underpinnings of acute exercise-induced changes in cognition in children using molecular, behavioral, neuroelectric, and academic achievement measures. Findings implicate sAA-indexed sympathetic activity as a candidate mechanism through which acute exercise may support specific aspects of inhibitory control in children, reflected behaviorally as more consistent responding on trials requiring the upregulation of inhibitory control. These findings also suggest that individual differences in baseline HPA axis activity moderate exercise effects on neural markers of attentional inhibition.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148906711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High Reliability, Limited Validity: Assessment of a 3D Body Scanner to Estimate Anthropometric and Body Composition Measurements.","authors":"Rhiannon A Campbell, Jordan T Andersen, AuraLea Fain, Ayden McCarty, Jodie A Wills, Timothy L A Doyle","doi":"10.1249/MSS.0000000000004116","DOIUrl":"https://doi.org/10.1249/MSS.0000000000004116","url":null,"abstract":"<p><strong>Introduction: </strong>Body composition and anthropometric measurements are valuable for predicting health and performance outcomes. Three-dimensional body scanners provide a portable, cost-effective, and rapid method for collecting anthropometric and body composition metrics; however, their accuracy must be validated against clinical reference methods to ensure that the outputs are reliable and valid.</p><p><strong>Methods: </strong>This study evaluated the reliability and validity of a portable 3D body scanner (Styku S100X) compared to manual anthropometry and dual-energy X-ray absorptiometry (DXA). Fifty participants (25 male, 25 female) underwent manual anthropometric assessments, two 3D full-body scans, and a full-body DXA scan. Reliability was assessed using intra-class correlations (ICC; k = 3, absolute agreement, two-way mixed-effects model), while validity was examined using Pearson's r correlations with manual anthropometry and DXA measurements. Data were stratified by sex, body mass index, body mass, stature, and age to provide exploratory insight into the potential influence of these factors on the 3D scanner's accuracy. For each group, mean difference with 95% CI, root mean square error (RMSE), and mean absolute percentage error (MAPE) were calculated.</p><p><strong>Results: </strong>The 3D body scanner demonstrated excellent reliability for segment circumferences and body composition (ICC > 0.95, p < 0.001) and good to excellent reliability for segment lengths and widths (ICC = 0.80-0.97, p < 0.001). Segment circumference estimates showed very large to nearly perfect correlations with manual anthropometry (r = 0.78-0.99, MAPE < 8%), but length and width estimates did not accurately reflect ISAK-standard measurements due to differences in landmark identification (r = 0.09-0.81, MAPE: 6-42%). Lean mass estimates demonstrated the strongest agreement with DXA (r = 0.61-0.95, MAPE < 8%), whereas body fat percentage (MAPE: 11-29%), fat mass (MAPE: 11-29%), and android and gynoid fat mass (MAPE: 59-74%) showed poor agreement.</p><p><strong>Conclusions: </strong>These findings suggest that while the 3D scanner is suitable for tracking anthropometric and body composition measurements over time, body composition estimates (aside from lean mass) should not be considered accurate representations of an individual's body composition. Caution is advised when using 3D body scanner estimates for body composition assessment in clinical, sport, or fitness settings.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148906713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Positive Joint Work Redistribution in Running: The Role of Plantar Flexor Fatigue and the Effect of Advanced Footwear Technology.","authors":"Key Nahan, Steffen Willwacher, John Kerr, Martin Héroux, Kirsty A McDonald","doi":"10.1249/MSS.0000000000004134","DOIUrl":"https://doi.org/10.1249/MSS.0000000000004134","url":null,"abstract":"<p><strong>Introduction: </strong>Over the course of a near-maximal effort 10 km run, positive mechanical work decreases at the ankle and increases at the knee. Although plantar flexor fatigue is believed to be responsible for the proximal shift in mechanical work generation, this has yet to be confirmed experimentally.</p><p><strong>Purpose: </strong>To 1) determine the effect of plantar flexor fatigue on lower limb positive joint work during running and 2) determine the effect of running shoes on this relationship.</p><p><strong>Methods: </strong>Trained male runners (n = 12) were analyzed over two 30 s runs at their 10 km race pace, without and with local plantar flexor fatigue induced via a calf-raise protocol to a level commensurate with that accumulated over an exhaustive run (~24% reduction in peak torque). Both the unfatigued and fatigued runs were performed in a traditional shoe and in advanced footwear technology on an instrumented treadmill while three-dimensional motion capture and ground reaction force data were collected.</p><p><strong>Results: </strong>Plantar flexor fatigue led to a redistribution of joint work, with lower positive ankle work (p < 0.001), greater positive knee work (p = 0.001), and similar positive hip work (p = 0. 550) in the fatigued run as compared to the unfatigued run. The relative positive joint contributions shifted proximally with fatigue (ankle -4%, knee +3%); however, this shift was not influenced by shoe condition (p > 0.05).</p><p><strong>Conclusions: </strong>Plantar flexor fatigue contributes to the proximal redistribution of positive joint work during running. However, the adoption of this gait strategy appears to occur regardless of whether a runner wears traditional shoes or advanced footwear technology.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148906715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pre-Exercise Caffeine Ingestion Leads to Greater Exercise-Induced Torque Reduction by Increasing Eccentric Load During Resistance Exercise.","authors":"Teppei Matsumura, Shunya Nonoyama, Kosuke Endo, Kazushi Fukuzawa, Tomohiro Yamamoto, I Wayan Yuuki, Kento Dora, Chihiro Kojima, Motoyuki Iemitsu, Tadao Isaka, Takeshi Hashimoto","doi":"10.1249/MSS.0000000000004135","DOIUrl":"https://doi.org/10.1249/MSS.0000000000004135","url":null,"abstract":"<p><strong>Purpose: </strong>This study examined the impact of pre-exercise caffeine supplementation on post-exercise torque reduction, an indirect marker of exercise-induced muscle damage (EIMD), while focusing on the changes in eccentric load induced by the ergogenic effects of caffeine.</p><p><strong>Methods: </strong>In double-blind, crossover trials, 15 healthy young men ingested 6 mg/kg caffeine or placebo, followed by an eccentric exercise task at 30-120° of knee extension: 100 isokinetic eccentric maximal voluntary knee extensions in Study 1 (i.e., variable eccentric load by caffeine) and 100 isoload (fixed at 120% of concentric one-repetition maximum) eccentric leg extensions in Study 2 (i.e., invariable eccentric load by caffeine). Maximal voluntary isometric torque (MVIT) of the knee extensors, an indirect EIMD marker, was evaluated at 24 and 48 h after exercise.</p><p><strong>Results: </strong>In Study 1, caffeine supplementation resulted in higher eccentric torques during exercise (P ≤ 0.001), but lower post-exercise MVITs (P < 0.001) than placebo. Conversely, in Study 2, there were no significant differences in post-exercise MVITs between the conditions (P = 0.242). In Study 1, post-exercise MVITs were negatively correlated with the total torque-time integral (rrm = -0.53; P = 0.034).</p><p><strong>Conclusions: </strong>Pre-exercise caffeine supplementation induces greater exercise-induced torque reduction during the 48-h post-exercise period after eccentric exercise, potentially suggesting greater EIMD. Additionally, increased eccentric load in accordance with caffeine's ergogenic effect may contribute to this greater post-exercise torque-reduction. Therefore, the potential impact on post-exercise muscle function should be considered when caffeine is used as a preworkout supplement for resistance exercise.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148906728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Association of Reallocation of Movement Behaviours with Ectopic Fat Accumulation: A Cross-Sectional Analysis of the UK Biobank Cohort.","authors":"Jiajin Li, Alice E Thackray, James A King, Emily S Petherick, Zhuoxiu Jin, Masashi Miyashita, William Johonson, David J Stensel","doi":"10.1249/MSS.0000000000004117","DOIUrl":"https://doi.org/10.1249/MSS.0000000000004117","url":null,"abstract":"<p><strong>Purpose: </strong>Ectopic fat in non-adipose tissues is linked to higher chronic-disease risk. Using the UK Biobank, this study examined associations of device-measured physical activity (PA) and sedentary time with ectopic fat.</p><p><strong>Methods: </strong>Liver and pancreas proton density fat fraction (PDFF), and anterior-thigh skeletal muscle fat infiltration (MFI) were assessed by magnetic resonance imaging. Reallocations among accelerometer derived time spent sedentary and in light intensity PA (LPA), and moderate-to-vigorous intensity PA (MVPA) were examined using isotemporal substitution. Multi-variable linear regression was employed with stepwise adjustment for sex, age, height, socioeconomic factors, and counts of cancer and non-cancer illnesses. Sex*activity interaction terms were then added to the models, and sex-stratified analyses were conducted where interactions were significant.</p><p><strong>Results: </strong>The final sample comprised 9,213 participants with liver PDFF, 6,521 participants with pancreatic PDFF, and 9,197 participants with MFI (mean age ~64 years). Replacing 30 minutes of sedentary time with LPA was associated with lower ectopic fat, with relative percentage differences in fully adjusted models of -2.2% [-2.7%, -1.8%] for liver PDFF, 1.9% [-2.4%, -1.3%] for pancreas PDFF, and -0.5% [-0.7%, -0.4%] for MFI. Substituting sedentary time with MVPA showed greater differences (-9.9% [11.0%, 8.7%], 7.9% [-9.2%, -6.6%], and -3.6 % [-3.9%, -3.2%], respectively). Replacing LPA with MVPA was also associated with lower ectopic fat (-7.6% [-8.9%, -6.4%], -6.0% [7.5%, -4.6%], and -3.0% [-3.4%, -2.6%] for liver PDFF, pancreas PDFF, and MFI. Associations were stronger in females for liver and pancreas PDFF and MFI when sedentary time was replaced with LPA or MVPA.</p><p><strong>Conclusions: </strong>Reallocation of sedentary time or lower-intensity PA to higher intensity PA is linked to lower ectopic fat. These relationships are stronger in women than men.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148906751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Energy Expenditure During Walking in Adults: Impact of Body Mass Index and Sex.","authors":"Joshua S Beaumont, Glenn A Gaesser, Marc A Adams, Daniel S Peterson, Jared M Dickinson, James T Patrie, Siddhartha S Angadi","doi":"10.1249/MSS.0000000000004141","DOIUrl":"https://doi.org/10.1249/MSS.0000000000004141","url":null,"abstract":"<p><strong>Purpose: </strong>The aim of this study was to determine if the linear and nonlinear coefficients of the energy expenditure-walking speed relationship are influenced by body mass index (BMI; kg/m 2) and sex.</p><p><strong>Methods: </strong>Participants (n=182; 96 females) ages 18-60 yr walked at 0.89 m/s (2.0 mph), 1.34 m/s (3.0 mph), and 1.79 m/s (4.0 mph) for six min each while oxygen uptake (V̇O2; mL/kg/min) was calculated via indirect calorimetry and converted to energy expenditure (EE; W/kg). Net W/kg was calculated by subtracting standing W/kg from gross W/kg. Polynomial random coefficient regression (PRCR) was employed to produce individual-level linear and quadratic coefficients to assess whether BMI influenced W/kg during walking. Net energy cost of walking (Cw; J/kg/m) was also determined for each walking speed.</p><p><strong>Results: </strong>Net W/kg and Cw were not significantly correlated with BMI at 0.89 m/s and 1.79 m/s, but were weakly inversely correlated (r 2 < 0.03) with BMI at 1.34 m/s. BMI was not significantly correlated with the linear coefficient for net or gross W/kg (both r = 0.07), but was weakly correlated with the quadratic coefficient for net (r = 0.17, P = 0.02) and gross (r = 0.16, P = 0.04) W/kg (r 2 < 0.03 for both). However, PRCR coefficients did not differ between normal weight BMI (n=32; 18.5-<25.0 kg/m 2), overweight (n=74; 25-<30.0 kg/m 2) and obese (n=76; >30.0 kg/m 2) groups. Females had higher W/kg, but sex differences were eliminated after controlling for height.</p><p><strong>Conclusions: </strong>We conclude that BMI has little impact on the EE of walking at speeds between 0.89 m/s and 1.79 m/s, and that sex differences in walking EE are eliminated after controlling for height.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148906723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}