Frontiers in Physiology最新文献

{"title":"Monitoring skeletal muscle oxygen saturation kinetics during graded exercise testing in NCAA division I female rowers.","authors":"Drake A Eserhaut, Joseph M DeLeo, Jessica A Provost, Kathryn E Ackerman, Andrew C Fry","doi":"10.3389/fphys.2025.1538465","DOIUrl":"10.3389/fphys.2025.1538465","url":null,"abstract":"<p><strong>Purpose: </strong>The purpose of this study was to analyze changes in skeletal muscle oxygen saturation (SmO₂) kinetics during exercise in female rowers both acutely and longitudinally in relation to blood lactate (BLa). We also aimed to determine the agreement and statistical equivalence between physiological thresholds derived from SmO₂ and BLa kinetics.</p><p><strong>Methods: </strong>Twenty-three female NCAA Division I rowers were tested throughout the 2023-2024 academic year. Of these, 11 athletes completed at least two near-infrared spectroscopy (NIRS)-equipped GXTs, with physiological data analyzed for longitudinal changes. A 7x4-min discontinuous GXT protocol was performed by all athletes. First and second SmO₂ breakpoints (SmO₂BP1 and SmO₂BP2) were estimated via piecewise linear regression modeling, and BLa thresholds (LT₁ and LT₂) were calculated using ADAPT software. Paired-samples t-tests assessed differences, and equivalence was tested using two one-sided tests (TOST). Agreement was determined using Bland-Altman analysis yielding mean differences (MD) and 95% limits of agreement (LoA). Intraclass correlation coefficients (ICC_2,1) were also calculated.</p><p><strong>Results: </strong>No difference was found between SmO₂BP2 and LT₂ (MD = -5.76W [95% LoA = -38.52 to 22.25W], p = 0.134), moderate-to-good levels of agreement (ICC_2,1 = 0.67 [95% CI: 0.36-0.85], p < 0.001), and no statistical equivalence (p = 0.117). This was not the case for SmO₂BP1 and LT₁, with NIRS significantly underestimating LT₁ (MD = -8.14W [95% LoA = -38.90 to 27.37W], p = 0.026), poor-to-moderate agreement (ICC_2,1 = 0.24 [95% CI: -0.13-0.58], p = 0.10), and no statistical equivalence (p = 0.487). Additionally, SmO₂ recovery kinetics (SmO₂resat) during 1-min rest intervals increased in response to graded increases in exercise intensity (p < 0.001, η² _p = 0.71), with higher intensities appearing to blunt this effect (step 6 - step 7: MD = -0.16%⋅s^-1, p = 0.69). No statistically significant changes were observed in LT's or SmO₂BP's throughout the 2023-2024 season.</p><p><strong>Conclusion: </strong>In female collegiate rowers, NIRS may be a tool that compliments BLa testing when determining the second lactate threshold (i.e., LT₂). However, significant inter-individual variablility exists between SmO₂BP2 and LT2 paired with a lack of statistical equivalence suggest the two are not interchangeable. While not a standalone replacement, if used in combination with traditional BLa testing methods NIRS may be a complimentary tool that helps inform individual athlete training zone prescription.</p>","PeriodicalId":12477,"journal":{"name":"Frontiers in Physiology","volume":"16 ","pages":"1538465"},"PeriodicalIF":3.2,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11873099/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143540817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mitochondrial dysfunction is a hallmark of woody breast myopathy in broiler chickens.","authors":"Elizabeth S Greene, Paula R Chen, Carrie Walk, Mike Bedford, Sami Dridi","doi":"10.3389/fphys.2025.1543788","DOIUrl":"10.3389/fphys.2025.1543788","url":null,"abstract":"<p><p>The woody breast (WB) myopathy poses significant economic and welfare concerns to the poultry industry, however, there is no effective strategy to mitigate this pathology due to its unknown etiology. After showing previously that hypoxia is a key factor in WB progression, we used here various techniques demonstrating dysregulated mitochondria (morphology, biogenesis, tethering, function, and bioenergetics) in WB-affected muscles and in hypoxic myoblasts compared to healthy tissues and normoxic cells, respectively. The increased levels of calcium (Ca²⁺) in both WB-affected tissues and hypoxic myoblasts suggested that mitochondrial Ca²⁺ overload is likely a leading cause for mitochondrial dysfunction that merits further in-depth investigation. These findings are the first, to the best of our knowledge, to provide fundamental insights into the underlying molecular mechanisms of WB and open new vistas for understanding the interplay between calcium, mitochondrial (dys)function, and avian muscle health for subsequent development of effective preventative/corrective strategies.</p>","PeriodicalId":12477,"journal":{"name":"Frontiers in Physiology","volume":"16 ","pages":"1543788"},"PeriodicalIF":3.2,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11872917/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143540750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The effect of transcranial pulse current stimulation on the accumulation of exercise-induced fatigue in college students after moderate intensity exercise evidence from central and peripheral sources.","authors":"Qingchang Wu, Siyan Liu, Changli Wu, Jian Liu","doi":"10.3389/fphys.2025.1502418","DOIUrl":"10.3389/fphys.2025.1502418","url":null,"abstract":"<p><strong>Objective: </strong>To investigate the intervention effect of cranial pulse current stimulator (tPCS) on fatigue accumulation after moderate-intensity exercise by using blood analysis and functional near-infrared spectroscopy, and to analyze the type and magnitude of the fatigue effect of tPCS on fatigue in combination with behavioral performance.</p><p><strong>Methods: </strong>Ninety healthy college students were randomly and equally divided into an experimental group (Group A) and a control group (Group B), and both groups underwent moderate-intensity training for 7 days. Before and after the experiment, all subjects received physiological, biochemical, behavioral, and subjective fatigue indexes, followed by exercise training, and each day of exercise training was followed by tPCS intervention (stimulus intensity of 1.5 mA, stimulus duration of 20 min) and subjective fatigue scale (RPE) test.</p><p><strong>Results: </strong>① After the tPCS intervention, the daily RPE scores of group A were smaller than those of group B; ② The values of the indexes oxygenated hemoglobin concentration (Oxy-Hb), deoxyhemoglobin concentration (HHb), testosterone (T), and testosterone-to-cortisol ratio (T/C) of group A did not differ significantly from those of the pre-intervention period, and the values of all the indexes of group B were significantly different from those of the pre-intervention period. ③ After tPCS intervention, the values of Oxy-Hb, T, T/C, and on-attention decreased in Groups A and B, with Oxy-Hb decreasing the most; the values of HHb, total hemoglobin concentration (HbTot), hemoglobin concentration difference (HbDiff), cortisol (C), creatine kinase (CK), and reaction time (RT) increased, with the greatest increase in HbDiff; and the Group A The magnitude of change of each index was smaller than that of Group B. After tPCS intervention, the contribution of central fatigue to the effect of reaction time science was greater than that of peripheral fatigue.</p><p><strong>Conclusion: </strong>① tPCS can delay the development of central fatigue and peripheral fatigue. ② The effect of tPCS on central fatigue is greater than on peripheral fatigue. ③ The effect of tPCS on reaction timing is mainly realized by changing the state of central fatigue.</p>","PeriodicalId":12477,"journal":{"name":"Frontiers in Physiology","volume":"16 ","pages":"1502418"},"PeriodicalIF":3.2,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11873560/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143540820","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the nose: nasal neurostimulation as a technology countermeasure for sinonasal congestion in astronauts.","authors":"Timon Ax, Philipp H Zimmermann, Tomas L Bothe, Karen Barchetti, Cintia S de Paiva, Francesc March de Ribot, Slade O Jensen, Thomas J Millar","doi":"10.3389/fphys.2025.1536496","DOIUrl":"https://doi.org/10.3389/fphys.2025.1536496","url":null,"abstract":"<p><p>Human spaceflight subjects the body to numerous and unique challenges. Astronauts frequently report a sense of sinonasal congestion upon entering microgravity for which the exact pathomechanisms are unknown. However, cephalad fluid shift seems to be its primary cause, with CO₂ levels and environmental irritants playing ancillary roles. Current management focuses on pharmacotherapy comprising oral and nasal decongestants and antihistamines. These are among the most commonly used treatments in astronauts. With longer and more distant space missions on the horizon, there is a need for efficacious and payload-sparing non-pharmacological interventions. Neurostimulation is a promising countermeasure technology for many ailments on Earth. In this paper, we explore the risk factors and current treatment modalities for sinonasal congestion in astronauts, highlight the limitations of existing approaches, and argue for why neurostimulation should be considered.</p>","PeriodicalId":12477,"journal":{"name":"Frontiers in Physiology","volume":"16 ","pages":"1536496"},"PeriodicalIF":3.2,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11868271/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143540818","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Laboratory comparison of consumer-grade and research-established wearables for monitoring heart rate, body temperature, and physical acitivity in sub-Saharan Africa.","authors":"Stefan Mendt, Georgi Zout, Marco Rabuffetti, Hanns-Christian Gunga, Aditi Bunker, Sandra Barteit, Martina Anna Maggioni","doi":"10.3389/fphys.2025.1491401","DOIUrl":"10.3389/fphys.2025.1491401","url":null,"abstract":"<p><strong>Background: </strong>Consumer-grade wearables are becoming increasingly popular in research and in clinical contexts. These technologies hold significant promise for advancing digital medicine, particularly in remote and rural areas in low-income settings like sub-Saharan Africa, where climate change is exacerbating health risks. This study evaluates the data agreement between consumer-grade and research-established devices under standardized conditions.</p><p><strong>Methods: </strong>Twenty-two participants (11 women, 11 men) performed a structured protocol, consisting of six different activity phases (sitting, standing, and the first four stages of the classic Bruce treadmill test). We collected heart rate, (core) body temperature, step count, and energy expenditure. Each variable was simultaneously tracked by consumer-grade and established research-grade devices to evaluate the validity of the consumer-grade devices. We statistically compared the data agreement using Pearson's correlation <i>r</i>, Lin's concordance correlation coefficient (LCCC), Bland-Altman method, and mean absolute percentage error.</p><p><strong>Results: </strong>A good agreement was found between the wrist-worn Withings Pulse HR (consumer-grade) and the chest-worn Faros Bittium 180 in measuring heart rate while sitting, standing, and slow walking on a treadmill at a speed of 2.7 km/h (<i>r</i> ≥ 0.82, |bias| ≤ 3.1 bpm), but this decreased with increasing speed (<i>r</i> ≤ 0.33, |bias| ≤ 11.7 bpm). The agreement between the Withing device and the research-established device worn on the wrist (GENEActiv) for measuring the number of steps also decreased during the treadmill phases (first stage: <i>r</i> = 0.48, bias = 0.6 steps/min; fourth stage: <i>r</i> = 0.48, bias = 17.3 steps/min). Energy expenditure agreement between the Withings device and the indirect calorimetry method was poor during the treadmill test (|<i>r</i>| ≤ 0.29, |bias | ≥ 1.7 MET). The Tucky thermometer under the armpit (consumer-grade) and the Tcore sensor on the forehead were found to be in poor agreement in measuring (core) body temperature during resting phases (<i>r</i> ≤ 0.53, |bias| ≥ 0.8°C) and deteriorated during the treadmill test.</p><p><strong>Conclusion: </strong>The Withings device showed adequate performance for heart rate at low activity levels and step count at higher activity levels, but had limited overall accuracy. The Tucky device showed poor agreement with the Tcore in all six different activity phases. The limited accuracy of consumer-grade devices suggests caution in their use for rigorous research, but points to their potential utility in capture general physiological trends in long-term field monitoring or population-health surveillance.</p>","PeriodicalId":12477,"journal":{"name":"Frontiers in Physiology","volume":"16 ","pages":"1491401"},"PeriodicalIF":3.2,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11865084/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143522841","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Alteration of mitochondrial function in arthropods during arboviruses infection: a review of the literature.","authors":"María E Santana-Román, Santos Ramírez-Carreto, Paola Maycotte, Victoria Pando-Robles","doi":"10.3389/fphys.2025.1507059","DOIUrl":"10.3389/fphys.2025.1507059","url":null,"abstract":"<p><p>Arthropods serve as vectors for numerous arboviruses responsible for diseases worldwide. Despite their medical, veterinary, and economic significance, the interaction between arboviruses and arthropods remains poorly understood. Mitochondria in arthropods play a crucial role by supplying energy for cell survival and viral replication. Some arboviruses can replicate within arthropod vectors without harming the host. Successful transmission depends on efficient viral replication in the vector's tissues, ultimately reaching the salivary glands for transmission to a vertebrate host, including humans, via blood-feeding. This review summarizes current knowledge of mitochondrial function in arthropods during arbovirus infection, highlighting gaps compared to studies in mammals and other pathogens relevant to arthropods. It emphasizes mitochondrial processes in insects that require further investigation to uncover the mechanisms underlying arthropod-borne transmission.</p>","PeriodicalId":12477,"journal":{"name":"Frontiers in Physiology","volume":"16 ","pages":"1507059"},"PeriodicalIF":3.2,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11865064/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143522839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Trimethylamine N-oxide (TMAO) acutely alters ionic currents but does not increase cardiac cell death.","authors":"Simona Esposito, Lauren R McGuinness, Parveen Sharma, Amy E Chadwick, Richard D Rainbow","doi":"10.3389/fphys.2025.1505813","DOIUrl":"10.3389/fphys.2025.1505813","url":null,"abstract":"<p><strong>Background: </strong>Trimethylamine N-oxide (TMAO) is a product of the action of gut microbiota on choline and other choline-containing compounds ingested in the diet. The presence of TMAO at high concentrations has been reported in the blood of patients with cardiovascular disease, suggesting the role for TMAO as either a marker or causative agent of the disease. These investigations examined whether TMAO had an effect on cardiomyocyte contractile function, calcium homoeostasis, and survival from metabolic insult.</p><p><strong>Results: </strong>TMAO had no effect on metabolic function or the ability of cells to survive a metabolic insult; however, it did cause transient changes to contractile function. These changes included an increase in calcium current and an increase in Kir6.1 channel activity in the cell, causing a shortening of the action potential duration to 90% repolarised but lengthening the action potential to 30% repolarised. These effects occurred within minutes of TMAO application; however, they were not observed following 24 h culture. These data suggest that TMAO does modulate contractile function, albeit only in the short-term, but has no effect on metabolic behaviour or the ability to withstand a metabolic challenge.</p><p><strong>Conclusion: </strong>These data suggest that high TMAO concentrations in the blood of patients may be a marker of potential cardiovascular disease rather than playing a causative role.</p>","PeriodicalId":12477,"journal":{"name":"Frontiers in Physiology","volume":"16 ","pages":"1505813"},"PeriodicalIF":3.2,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11865236/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143522798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanisms of blood flow restriction training for knee pain: a mini review.","authors":"Shi-Yu Xie, Xue Jiang, Jia-Bin Yuan, Jing Luo, Shun Song, Hao-Yu Hu","doi":"10.3389/fphys.2025.1542322","DOIUrl":"10.3389/fphys.2025.1542322","url":null,"abstract":"<p><p>Knee pain, affecting an estimated 654 million people worldwide, so blood flow restriction training (BFRT) is catching the spotlight as an effective intervention. Evidence continues to demonstrate the effectiveness of BFRT in managing knee pain. However, the mechanism by which BFRT alleviates knee pain remains unclear, thereby limiting its application in clinical pain management. This study aims to elucidate the underlying mechanisms of BFRT to better understand its efficacy in treating knee pain. This review will discuss the influence of muscle hypertrophy, endogenous opioid system, endocannabinoids, inflammation regulation, and conditional pain regulation on BFRT treatment of knee pain. Current studies on BFRT have limitations, such as small sample sizes, relatively low-quality evidence, and lack of mechanistic studies. Therefore, further research on BFRT is needed, particularly high-quality and large-sized randomized controlled trials.</p>","PeriodicalId":12477,"journal":{"name":"Frontiers in Physiology","volume":"16 ","pages":"1542322"},"PeriodicalIF":3.2,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11865041/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143522843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The role of starting knee angle in squat jump force-velocity profiles: interactions with subjects' strength levels and imputed push-off distance.","authors":"Xuelin Qin, Beibei Liu, Ruolin Tang, Yan Liu, Amador García-Ramos","doi":"10.3389/fphys.2025.1551488","DOIUrl":"10.3389/fphys.2025.1551488","url":null,"abstract":"<p><strong>Introduction: </strong>This study investigated whether differences in the force-velocity (F-v) profile obtained using Samozino's method during squat jumps (SJ) performed at varying knee angles are influenced by subjects' strength levels and the push-off distance (HpO) used in the analysis.</p><p><strong>Methods: </strong>Twenty-one resistance-trained men were classified as stronger (n = 10) or weaker (n = 11) based on the external load required to achieve a 10 cm SJ height. F-v profiles were randomly assessed over three sessions, with SJs performed at starting knee angles of 70° (SJ70), 90° (SJ90), and 110° (SJ110), using either the actual HpO specific to each condition or a standardized HpO corresponding to SJ90.</p><p><strong>Results: </strong>Significant differences between SJ types were observed for maximum force (<i>F</i> ₀) and the F-v slope (SJ110 > SJ90 > SJ70). These differences were never influenced by subjects' strength levels. The standardized HpO produced similar outcomes for maximum power (P_max) and maximum velocity (<i>v</i> ₀), and more consistent results for <i>F</i> ₀ and the F-v slope compared to the actual HpO.</p><p><strong>Discussion: </strong>Regardless of strength levels, standardizing HpO at 90° and allowing subjects to select a starting knee angle between 70° and 90° could simplify the evaluation process and improve the comparability of F-v profiles across subjects when using Samozino's method.</p>","PeriodicalId":12477,"journal":{"name":"Frontiers in Physiology","volume":"16 ","pages":"1551488"},"PeriodicalIF":3.2,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11860981/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143515261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A four-compartment controller model of muscle fatigue for static and dynamic tasks.","authors":"James Yang, Ritwik Rakshit, Shuvrodeb Barman, Yujiang Xiang","doi":"10.3389/fphys.2025.1518847","DOIUrl":"10.3389/fphys.2025.1518847","url":null,"abstract":"<p><strong>Introduction: </strong>Compartment based models of muscle fatigue have been particularly successful in accurately modeling isometric (static) tasks or actions. However, dynamic actions, which make up most everyday movements, are governed by different central and peripheral processes, and must therefore be modeled in a manner accounting for the differences in the responsible mechanisms. In the literature, a three-component controller (3CC) muscle fatigue model (MFM) has been proposed and validated for static tasks. A recent study reported a four-compartment muscle fatigue model considering both short- and long-term fatigued states. However, neither has been validated for both static and dynamic tasks.</p><p><strong>Methods: </strong>In this work we proposed a new four-compartment controller model of muscle fatigue with enhanced recovery (4CCr) that allows the modeling of central and peripheral fatigue separately and estimates strength decline for static and dynamic tasks. Joint velocity was used as an indicator of the degree of contribution of either mechanism. Model parameters were estimated from part of the experimental data and finally, the model was validated through the rest of experimental data that were not used for parameter estimation.</p><p><strong>Results: </strong>The 3CC model cannot capture the fatigue phenomenon that the velocity of contraction would affect isometric strength measurements as shown in experimental data. The new 4CCr model maintains the predictions of the extensively validated 3CC model for static tasks but provides divergent predictions for isokinetic activities (increasing fatigue with increasing velocity) in line with experimentally observed trends. This new 4CCr model can be extended to various domains such as individual muscle fatigue, motor units' fatigue, and joint-based fatigue.</p>","PeriodicalId":12477,"journal":{"name":"Frontiers in Physiology","volume":"16 ","pages":"1518847"},"PeriodicalIF":3.2,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11861306/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143515260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}