Medicine and Science in Sports and Exercise最新文献

{"title":"A Re-Examination of the Relationship Between Foot Strike Angle and Early Stance Loading Variables during Running.","authors":"Caleb D Johnson, Torstein E Dæhlin, Lauren K Sara, Katelyn I Guerriere, Leila A Walker, Stephen A Foulis, Julie M Hughes, Irene S Davis","doi":"10.1249/MSS.0000000000003764","DOIUrl":"https://doi.org/10.1249/MSS.0000000000003764","url":null,"abstract":"<p><strong>Purpose: </strong>To compare nonlinear and piecewise linear models for FSA with VLR/VTA during running, controlling for competitive running experience.</p><p><strong>Methods: </strong>475 U.S. Army trainees completed surveys on their participation in sports and a running gait assessment on an instrumented treadmill while VLRs, VTAs, and FSAs were measured (via force plates, tibial-mounted accelerometers, and high-speed cameras, respectively). A 3-minute warm-up was given and then participants ran for one minute at 2.68-2.91 m/s, followed by 14 strides of data collection. Multiple regression was used to assess the prediction of VLR and VTA by FSA, including nonlinear/piecewise terms and controlling for competitive running experience.</p><p><strong>Results: </strong>A nonlinear, quadratic relationship was found for FSA x VLR (R2= 0.25, p<0.001) and VTA (R2= 0.14, p<0.001), and with a significant effect of running experience (p<0.02). Models showed similar shapes but better fit for those with (VLR: R2=0.38, VTA: R2=0.16) versus without (VLR: R2=0.21, VTA: R2=0.11) competitive running experience. Finally, VLRs peaked at similar FSAs as in previous work (≈10-12° current vs 5-10° previous). Piecewise linear regression produced similar results to quadratic models (R2 Difference< 0.02).</p><p><strong>Conclusions: </strong>Our results show that nonlinear or piecewise linear models can be used to represent the relationship between VALR/VTA and FSA. While VLRs/VTAs were lowest with the lowest FSAs (i.e, most forefoot), participants with the highest FSAs (i.e., most rearfoot) showed reduced values compared to FSAs typical of a more moderate/flatter rearfoot strike pattern.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144160132","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":"Sensory Reweighting Revealed by Superior Parietal Cortex-Based Functional Connectivity in Chronic Ankle Instability: A Resting-State fMRI Study.","authors":"Xiao'ao Xue, Shanshan Zheng, Zikun Wang, Yushi Chen, Lin Chang, Ziyuan Wang, Chang Liu, Ziyu Lu, Rong Lu, Yang Sun, He Wang, Yinghui Hua","doi":"10.1249/MSS.0000000000003762","DOIUrl":"https://doi.org/10.1249/MSS.0000000000003762","url":null,"abstract":"<p><strong>Purpose: </strong>Individuals with chronic ankle instability (CAI) are believed to rely more heavily on visual input during postural control due to impaired somatosensory function; however, the neural mechanisms underlying sensory reweighting in CAI are not well understood. This study explored the neural and behavioral correlates of increased visual reliance in CAI through functional connectivity (FC) analysis.</p><p><strong>Methods: </strong>This cross-sectional study enrolled 37 patients with CAI and 36 healthy individuals. Participants underwent postural stability assessments using the single-leg stance test, both with their eyes open and closed. Traditional and modified Romberg ratios were calculated. Resting-state functional magnetic resonance imaging was used to estimate FC between the superior parietal cortex (SPC) and visual, sensorimotor, and cerebellar regions, as well as the coefficient of variation of these FCs.</p><p><strong>Results: </strong>Compared with healthy individuals, patients with CAI displayed significantly higher visual reliance, as indicated by the traditional and modified Romberg ratios of sway length (Cohen's d = 0.47-0.57). Patients with CAI also exhibited stronger FC between the SPC and higher-level visual cortices (Cohen's d = 0.56-0.62) and more unstable coefficient of variation for FC between the SPC and the cerebellar anterior lobe (Cohen's d = 0.64). Subregion analysis revealed that variability in FC between subregions I-IV of the cerebellar anterior lobe and anterior lateral area 7 of the SPC was negatively correlated with the modified Romberg ratio in the anterior-posterior direction (r = -0.35) among the patients.</p><p><strong>Conclusions: </strong>The study revealed high visual reliance, strong yet variable SPC-based connections with visual cortices and variable SPC-based connections with the cerebellum among patients with CAI, suggesting that neural changes associated with sensory reweighting mechanisms underlie increased visual reliance during postural stability.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144160259","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":"Velocity specific adaptations to three widely used strength training methods.","authors":"Glenn Trane, Stine Pedersen, Håkon André Mehus, Jan Helgerud, Runar Jakobsen Unhjem","doi":"10.1249/MSS.0000000000003630","DOIUrl":"10.1249/MSS.0000000000003630","url":null,"abstract":"<p><strong>Aim: </strong>We examined bench press adaptations to three widely used strength training methods; maximal strength training (MST), hypertrophy training (HT) and explosive strength training (EST). To reflect how these methods are typically applied by practitioners, MST and EST were volume matched, whereas HT were performed at higher volume.</p><p><strong>Methods: </strong>Sixty-three moderately trained subjects (32 males; 31 females) were assigned into 8 weeks of MST, HT, EST or control (CON), 3 sessions/week. MST performed 4 x 4 repetitions bench press at ≥85% of 1RM. HT performed 3 x 8-12 repetitions at ∼70-80% of 1RM. EST performed 4 x 6-7 repetitions bench press throws at 40% of 1RM. Maximal-, explosive- and endurance strength characteristics were assessed, as well as muscle hypertrophy.</p><p><strong>Results: </strong>1RM increased more after MST (+21.5%) and HT (+17.9%) compared to EST (+5.9%) and CON (all p ≤ 0.001). Rate of force development (RFD) at 50% of 1RM increased more after MST (+58.4%) and HT (+38.9%) compared to CON ( p ≤ 0.001 and p ≤ 0.05, respectively). Mean propulsive velocity (MPV) increased more after MST and HT compared to CON across all loads (20-80% of 1RM), and more than EST at 80% and 60% (all p ≤ 0.05-0.001). MST increased MPV more than EST at 40% of 1RM ( p ≤ 0.05). Δ1RM correlated with ΔMPV at all loads of the L-v profile ( r = 0.40-0.56, p ≤ 0.001).</p><p><strong>Conclusion: </strong>MST and HT were more effective than EST for improving maximal strength and concentric velocity against moderate and high loads. At low loads, EST was not more effective than MST and HT, despite high degree of velocity specificity. Changes in muscle strength appear to be more important than velocity specificity to increase performance across the L-v profile.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142829314","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":"Postprandial Bioavailability and Efficacy of Recombinant Bovine β-lactoglobulin for Resistance Training-Induced Skeletal Muscle Adaptation in Young Adults.","authors":"Lucy M Rogers, Jonathan I Quinlan, Karen Lau, Archie E Belfield, Marie Korzepa, Sarkis J Hannaian, Ari Gritsas, Tyler A Churchward-Venne, Gareth A Wallis, Leigh Breen","doi":"10.1249/MSS.0000000000003756","DOIUrl":"https://doi.org/10.1249/MSS.0000000000003756","url":null,"abstract":"<p><strong>Introduction: </strong>Increasing concerns surrounding the environmental impact of animal- and plant-derived proteins warrants further investigations of alternative protein sources and their efficacy for supporting skeletal muscle anabolism. Herein, the postprandial amino acid bioavailability of a novel protein derived from recombinant bovine β-lactoglobulin (rBLG) was determined, alongside the muscle adaptive response to resistance exercise (RE) with rBLG, compared with dairy-derived whey (WHEY).</p><p><strong>Methods: </strong>Healthy adults (n = 8; age: 24 ± 4 yrs; BMI: 23.5 ± 2.1 kg·m2) completed a randomised crossover study and ingested 0.3 g·kg body mass-1 of rBLG or WHEY with arterialised blood sampled in the fasted state and 240 min postprandially for measurement of plasma amino acid concentrations via UPLC-MS. In a separate double-blind randomised parallel group design, 24 healthy adults completed thrice-weekly lower-body RE for 8 weeks, with twice daily supplementation of 0.3 g·kg body mass-1 rBLG (n = 12; age: 23 ± 6 yrs; BMI: 25.6 ± 3.4 kg·m2) or WHEY (n = 12; age: 25 ± 6 yrs; BMI 25.1 ± 3.1 kg·m2). Training-induced changes in muscle strength and DEXA-derived leg lean body mass (LBM) were assessed.</p><p><strong>Results: </strong>Plasma essential amino acid concentrations increased following protein ingestion (P < 0.001), but did not differ between trials (P = 0.554). Mean plasma leucine incremental area under curve was greater following rBLG compared to WHEY (mean diff(95%CI) 10727 (7738 to 13716) μmol·240 min·L-1P < 0.001). LBM and leg press 1RM increased following training (mean diff±SD: 0.65 ± 0.70 kg and 81.46 ± 42.81 kg, respectively; P < 0.05), with no differences between groups (P > 0.05). Training volume and daily protein intake did not differ between groups (P > 0.05 for all).</p><p><strong>Conclusions: </strong>These data highlight rBLG, a sustainable, precision-engineered mimetic of dairy-derived whey as a novel protein source with the capacity to support skeletal muscle anabolism and exercise-induced remodelling similarly to dairy-derived whey.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144160142","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":"Response.","authors":"Christopher R Harnish, Gregory P Swinand","doi":"10.1249/MSS.0000000000003709","DOIUrl":"https://doi.org/10.1249/MSS.0000000000003709","url":null,"abstract":"","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143971449","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":"Running Distance and Biomechanical Risk Factors for Plantar Fasciitis: A 1-yr Prospective 4HAIE Cohort Study - Corrigendum.","authors":"Jan Plesek, Joseph Hamill, Michal Burda, Steriani Elavsky, Jiri Skypala, Jan Urbaczka, Julia Freedman-Silvernail, David Zahradnik, Jaroslav Uchyti, Daniel Jandacka","doi":"10.1249/MSS.0000000000003711","DOIUrl":"https://doi.org/10.1249/MSS.0000000000003711","url":null,"abstract":"","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144024951","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-Intensity Intervallic Exercise (HIIE) Is Superior to Isocaloric Moderate-Intensity Continuous Exercise (MICE) at Reducing Postprandial Hyperglycemia.","authors":"Ricardo Mora-Rodriguez, Alfonso Moreno-Cabañas, Laura Alvarez-Jimenez, Diego Mora-Gonzalez, Felix Morales-Palomo","doi":"10.1249/MSS.0000000000003625","DOIUrl":"10.1249/MSS.0000000000003625","url":null,"abstract":"<p><strong>Purpose: </strong>We investigated if a bout of high-intensity intervallic exercise (HIIE) is more efficacious at reducing postprandial hyperglycemia than an isocaloric bout of moderate-intensity continuous exercise (MICE).</p><p><strong>Methods: </strong>Nineteen healthy physically active individuals (21% women) completed three trials in a randomized order: i ) HIIE cycling consisting of five bouts of 4 min at 83 ± 9% of subjects' maximal oxygen consumption ( O 2MAX ) with active recoveries at 53 ± 8%, for a total of 50 min; ii ) MICE cycling at 65 ± 8% of O 2max for 50 min; and iii ) CONTROL no exercise. All trials were followed by a standard oral glucose tolerance test (OGTT) ingesting 74 g of glucose traced with 1 g of uniformly labeled [ 13 C]-glucose. Plasma glucose and insulin concentrations, and plasma glucose kinetics ([6,6 2 H 2 ] glucose infusion) were measured before exercise, during exercise, and during the OGTT. Insulin sensitivity was estimated by the Matsuda index (ISI). Energy expenditure and carbohydrate oxidation (CHOxid) were monitored.</p><p><strong>Results: </strong>At rest, blood glucose, insulin concentrations, and CHOxid were similar in all three trials. During exercise, energy expenditure was similar in HIIE versus MICE (548 ± 131 vs 560 ± 125 kcal; P = 0.340). However, CHOxid, plasma glucose concentration, and its rates of appearance in plasma (Ra) were higher in HIIE versus MICE (Ra glucose 34.3 ± 9.8 vs 28.9 ± 6.8 μmol·kg -1 ·min -1 ; P = 0.021). During the OGTT, plasma glucose and insulin concentrations were lower, and insulin sensitivity was higher in HIIE versus CONTROL (ISI MATSUDA ; 12.4 ± 4.7 vs 10.8 ± 4.7 au; P = 0.007). Exercise delayed blood incorporation of [ 13 C]-glucose into blood ( P = 0.023). Early during the OGTT, glucose clearance rates were higher in HIIE versus CONTROL (7.1 ± 3.1 vs 5.5 ± 3.0 mL·kg -1 ·min -1 ; P = 0.015).</p><p><strong>Conclusions: </strong>HIIE is more effective than MICE to reduce hyperglycemia and hyperinsulinemia after glucose ingestion. HIIE improves glycemic control by increasing splanchnic glucose retention and glucose clearance rates.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":"1019-1031"},"PeriodicalIF":4.1,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142813622","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":"Alternating Aerobics with Resistance Exercise Improves Bone Density and Circulating Irisin Levels in Postmenopausal Women.","authors":"Mingxian Chen, Yuan Zhang, Xinkai Yu, Qun Zuo","doi":"10.1249/MSS.0000000000003627","DOIUrl":"10.1249/MSS.0000000000003627","url":null,"abstract":"<p><strong>Purpose: </strong>Irisin plays an important role in bone-muscle crosstalk. The aim of this study was to elucidate the association of long-term exercise-induced irisin response with body composition and bone mineral density (BMD) in postmenopausal women.</p><p><strong>Methods: </strong>We recruited 29 postmenopausal women (age: 62.67 ± 3.9 yr) without regular exercise habits to participate in a 24-wk program of alternating aerobic and resistance training exercise. Blood samples, body composition, and BMD were measured before and after exercise intervention.</p><p><strong>Results: </strong>Upper and lower limb bone density ( P = 0.004, P = 0.039), calf circumference ( P = 0.001), circulating levels of irisin ( P = 0.003), and osteocalcin ( P < 0.001) increased by exercise, whereas waist circumference ( P = 0.000), blood osteoprotegerin (OPG) ( P = 0.041), receptor activator of NF-κB ligand (RANKL) ( P < 0.001), RANKL/OPG ratio ( P < 0.001), and estradiol levels ( P = 0.003) decreased by training, respectively. According to the observed changes in the measured variables, the irisin circulating levels were significantly and separately related to upper limb BMD ( r = 0.462, P = 0.006), lower limb BMD ( r = 0.566, P = 0.001), total BMD ( r = 0.490, P = 0.008), and T-score of dual-energy X-ray absorptiometry ( r = 0.489, P = 0.010). The increase in serum irisin levels was found to be positively and separately related to upper limb BMD ( r = 0.414, P = 0.026), total BMD ( r = 0.453, P = 0.014), calf circumference ( r = 0.400, P = 0.031), and appendicular skeletal muscle mass/height 2 ( r = 0.309, P = 0.031) improvements.</p><p><strong>Conclusions: </strong>Long-term alternating exercise training improves bone density, body composition, and circulating irisin levels in postmenopausal women, and irisin would mediate bone-muscle crosstalk to exert positive effect of exercise on bone health in postmenopausal women.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":"921-931"},"PeriodicalIF":4.1,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142950925","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":"Sleep Deprivation Elevates Resting and Exercise Blood Pressures and Augments Pressor Response at Exercise Onset.","authors":"Amane Hori, Xin Su, Shota Sagasaki, Ryuji Saito, Kenichi Suijo, Seiko Miyata, Daisuke Hasegawa, Masaki Mizuno, Norio Hotta","doi":"10.1249/MSS.0000000000003640","DOIUrl":"10.1249/MSS.0000000000003640","url":null,"abstract":"<p><strong>Purpose: </strong>Sleep deprivation and elevated blood pressure (BP) increase the risk of cardiovascular diseases. However, the effects of sleep deprivation on BP response, especially at exercise onset, remain unclear. We aimed to elucidate the effects of experimental sleep deprivation (ESD) on resting and exercise BPs, including that at exercise onset, and investigate whether a nighttime nap during ESD changes the ESD-altered BP.</p><p><strong>Methods: </strong>Twelve healthy young men underwent 2-min submaximal isometric elbow flexion (IEF) exercise to measure BP after 7 d of normal sleep (control trial), 24-h ESD (ESD trial), and ESD with a 2-h nighttime nap (ESD + NAP trial), which were randomly performed.</p><p><strong>Results: </strong>ESD significantly elevated the mean arterial pressure (MAP) at rest (85.8 ± 8.0 to 93.3 ± 5.1 mm Hg, P = 0.003) and at the last minute of IEF (116.9 ± 13.0 to 126.2 ± 11.8 mm Hg, P = 0.003) compared with that observed in the control trial. At IEF onset (the initial 15 s), ESD significantly elevated the MAP (88.7 ± 12.6 to 103.1 ± 8.8 mm Hg, P < 0.001) and augmented the MAP responsiveness from baseline, compared with that observed in the control trial (Δ2.9 ± 11.4 to Δ9.8 ± 6.6 mm Hg, P = 0.017). The MAP responsiveness in the ESD + NAP trial (Δ7.3 ± 5.2 mm Hg) was not significantly different from that in the control trial ( P = 0.165) and the ESD trial ( P = 0.129).</p><p><strong>Conclusions: </strong>ESD significantly elevated both resting BP and the BP during submaximal isometric exercise and significantly augmented the initial pressor response to the exercise. A 2-h nighttime nap during ESD appears to be insufficient to completely attenuate ESD-induced augmented pressor responses.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":"996-1007"},"PeriodicalIF":4.1,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142950941","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":"Loading Speed and Intensity in Eccentric Calf Training Impact Acute Changes in Achilles Tendon Thickness and Stiffness: A Randomized Crossover Trial.","authors":"Lauren Pringels, Dries Pieters, Sarah VAN DEN Berghe, Erik Witvrouw, Arne Burssens, Luc Vanden Bossche, Evi Wezenbeek","doi":"10.1249/MSS.0000000000003638","DOIUrl":"10.1249/MSS.0000000000003638","url":null,"abstract":"<p><strong>Purpose: </strong>Eccentric calf training for Achilles tendinopathy shows variable success in athletes. Recent insights suggest a role for tendon fluid flow (exudation or redistribution) during exercise, which explains post-exercise reductions in thickness and increases in stiffness of the tendon. This fluid flow is thought to be beneficial as it may promote tendon remodeling, reduce intratendinous pressure, and alleviate pain. In this perspective, slow, high-load exercises are promoted as they theoretically facilitate tendon fluid flow. However, evidence supporting this assumption is lacking. Therefore, this study aimed to investigate whether loading speed and intensity during eccentric calf training impact acute changes in midportion Achilles tendon thickness and stiffness, reflecting alterations in local tendon fluid content.</p><p><strong>Methods: </strong>A randomized, assessor-blinded, crossover trial was conducted with 34 healthy athletes (17 men, 17 women, age: 23.7 ± 6 yr). Participants underwent three single-leg eccentric heel-drop interventions with 20% additional bodyweight, varying in loading speed (fast: 1 s, slow: 3 s) and loading intensity (low: to plantigrade, high: to maximal dorsiflexion). Achilles tendon anteroposterior diameter, cross-sectional area, and shear wave velocity were assessed in the midportion region using ultrasonography and shear wave elastography pre- and immediately post-intervention.</p><p><strong>Results: </strong>The slow, high-load intervention produced greater immediate reductions in tendon anteroposterior diameter and cross-sectional area (8.9% and 10.1%), compared with the slow, low-load (3.8% and 4.7%) and fast, high-load (2.9% and 3.4%) interventions ( P < 0.001). Moreover, only the slow, high-load intervention increased tendon shear wave velocity (54.5%, P < 0.001).</p><p><strong>Conclusions: </strong>These findings provide the first evidence that both loading speed and intensity during eccentric calf training impact acute changes in Achilles tendon thickness and stiffness, likely mediated by changes in fluid flow, which could be relevant for tendinopathy rehabilitation.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":"895-903"},"PeriodicalIF":4.1,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142950935","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}