Experimental Physiology最新文献

{"title":"Musculoskeletal decay and bone-muscle crosstalk during physical disuse: Mechanisms and integrated countermeasures.","authors":"Julia Margarita Reyes, Guy Hajj-Boutros, Dounia Rouabhia, José Morais, Felipe Salech, Gustavo Duque","doi":"10.1113/EP093790","DOIUrl":"10.1113/EP093790","url":null,"abstract":"<p><p>Older adults experience a markedly increased risk of falls and fractures following hospital discharge, largely due to the rapid musculoskeletal deterioration associated with bed rest. Although age-related muscle and bone loss typically develops gradually, acute physical inactivity accelerates key biological processes underlying sarcopenia and osteoporosis, including muscle atrophy, anabolic resistance, increased bone resorption and reduced mechanical loading. Emerging evidence indicates that muscle, bone and adipose tissue communicate through interconnected biochemical pathways; however, the shared biological mechanisms underlying this crosstalk during acute unloading remain poorly understood. To review the effects of disuse on the muscle-bone-adipose axis, emphasizing disruption of inter-tissue signalling pathways and evaluating integrated countermeasures, a narrative review was conducted using PubMed, Scopus and Web of Science, focusing on human bed rest and disuse studies, musculoskeletal crosstalk and multimodal interventions involving exercise and nutrition in older adults. Disuse rapidly disrupts musculoskeletal homeostasis by uncoupling bone turnover and inducing muscle anabolic resistance. These changes are accompanied by alterations in myokine and osteokine signalling, including increased myostatin, reduced irisin, elevated RANKL, bone and muscle steatosis, and sclerostin upregulation, further compromising muscle-bone interactions. Evidence supports multimodal interventions combining resistance exercise with optimized protein intake (1.2-1.5 g/kg/day) and nutritional supplements, including β-hydroxy-β-methylbutyrate, vitamin D and creatine, to attenuate muscle and bone loss. Preventing disuse-related musculoskeletal decline requires recognizing muscle and bone as an integrated functional unit. Tailored multimodal strategies may preserve musculoskeletal health and functional independence in hospitalized older adults, although implementation must consider frailty, comorbidities, safety and feasibility.</p>","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13618863/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149074007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Association between dietary fatty acids and all-cause mortality in patients with cirrhosis: A cohort study.","authors":"Ali Jafari, Ghazaleh Mahdavi-Mazdeh, Behnaz Narimani, Helia Mardani, Azita Hekmatdoost, Fereshteh Pashayee-Khamene, Sara Karimi, Saleheh Ahmadzadeh, Mehdi Saberifiroozi, Behzad Hatami, Zahra Yari","doi":"10.1113/EP093526","DOIUrl":"10.1113/EP093526","url":null,"abstract":"<p><p>Liver cirrhosis imposes a substantial global burden, with complications driving high mortality. Diet is pivotal in managing liver disease progression and cirrhosis-related death. This study investigated associations between total fat intake, specific dietary fatty acid subclasses and all-cause mortality in cirrhotic patients. In this prospective cohort study, 121 ambulatory patients with recently diagnosed cirrhosis (≤6 months) were enrolled. Baseline dietary intake was evaluated via a validated 168-item semi-quantitative food frequency questionnaire. Participants were categorized into tertiles by total fat and fatty acid subclasses: saturated (SFA), monounsaturated (MUFA), polyunsaturated (PUFA), omega-3 and omega-6 fatty acids. Cox proportional hazards models computed hazard ratios (HRs) and 95% confidence intervals (CIs), adjusted sequentially for age, sex, energy intake, BMI, smoking, alcohol use, cirrhosis aetiology, MELD score and Child-Pugh class. During the 60-month follow-up, 50 deaths (41.3%) occurred. In fully adjusted models, highest versus lowest tertiles of total fat intake (HR = 6.69; 95% CI: 1.37-13.34; P-trend = 0.017), SFA intake (HR = 8.2; 95% CI: 1.33-20.53; P-trend = 0.014) and PUFA-6 intake (HR = 5.24; 95% CI: 1.1-26.44; P-trend = 0.014) were independently associated with significantly elevated mortality risk. No significant associations were observed for MUFA, total PUFA or PUFA-3 intake. Kaplan-Meier analyses confirmed significantly reduced 5-year survival with higher total fat (log-rank P = 0.003) and SFA intake (log-rank P < 0.001). In this exploratory prospective cohort study, higher intakes of total fat, saturated fatty acids and omega-6 polyunsaturated fatty acids were associated with increased all-cause mortality among patients with cirrhosis. These preliminary findings are hypothesis-generating and require confirmation in larger, adequately powered prospective studies.</p>","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13618978/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149074011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The 'lactate paradox' revisited after 35 years: In memoriam Paolo Cerretelli.","authors":"Bruno Grassi","doi":"10.1113/EP094234","DOIUrl":"10.1113/EP094234","url":null,"abstract":"<p><p>Some decades ago significant scientific interest was raised by the concept of the 'lactate paradox' occurring during altitude acclimatization. In short, in acute hypoxia blood lactate^- concentration ([La]_b) is higher, compared to normoxia, at any given submaximal work rate, whereas peak [La]_b at exhausting exercise is unchanged. During altitude acclimatization the [La]_b vs. submaximal work rate relationship falls towards the original sea-level curve, whereas peak [La]_b progressively falls with increasing altitude. Upon the premise that lactate^- accumulation derives from lack of O₂ and anaerobic glycolysis, the lowered [La]_b at altitude was considered 'paradoxical'. After decades of research on the 'lactate shuttle' and lactate metabolism the issue should be revisited. A new scenario could be summarized as follows. Muscle and blood lactate^- accumulation during increasing intensity exercise reflect a mismatch between a faster 'speed' of glycolysis and a relatively slower speed of oxidative phosphorylation, possibly aimed at accumulating lactate^- in blood, to be distributed for different purposes throughout the body. Acute hypoxia further accelerates glycolysis through an enhanced sympatho-adrenergic stimulation, worsens intracellular hypoxia and increases [ADP]∙[P_i]/[ATP], resulting in a greater [La]_b for the same absolute work rate. During altitude acclimatization the sympatho-adrenergic stimulation falls, intracellular hypoxia is attenuated (mainly through a reduced O₂ demand), the [ADP]∙[P_i]/[ATP] increase subsides, and a tighter coupling between lactate^- production and utilization ensues, with the end result of decreased [La]_b for the same absolute work rate and lower peak [La]_b. Although the perspective is radically changed, this remarkable series of metabolic adaptations appears of interest also today.</p>","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13617963/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149069192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gastrocnemius muscle properties in children with cerebral palsy: An exploratory cross-sectional study of variability in gastrocnemius properties.","authors":"Elizabeth R Boyer, Christiana J Raymond-Pope, Daniel B Hoffman, Marshall H Taniguchi, Tom F Novacheck, Braydon A Crum, Peter D Kim, Sarah M Greising","doi":"10.1113/EP093772","DOIUrl":"10.1113/EP093772","url":null,"abstract":"<p><p>Muscle strength is a key predictor of physical functioning, yet the influence of patient and treatment factors on muscle properties in young people with cerebral palsy is not fully known. We explored whether medial gastrocnemius properties vary by age, ambulatory status and spasticity treatment (botulinum toxin or selective dorsal rhizotomy). In this exploratory cross-sectional study, microbiopsies of the medial gastrocnemius were obtained from 16 children (6-17 years of age) with cerebral palsy. Outcomes included muscle thickness, collagen content, myofibre cross-sectional area, capillaries, myofibres with centrally located nuclei, lipid area, satellite cell density and myosin heavy chain myofibre type. Myofibre cross-sectional area (P = 0.02) and myofibres with centrally located nuclei (P = 0.02) were positively correlated with age. Non-ambulatory individuals had smaller myofibre cross-sectional area (P = 0.02). The number of botulinum toxin injections was associated with more capillary contacts per myofibre (P = 0.04). Selective dorsal rhizotomy was not associated with any statistically significant findings. Preliminary data suggest that gastrocnemius muscle properties might vary across patient factors and spasticity treatment history. Confirmatory prospective studies with matched control groups are needed to evaluate properly the effects of age, ambulatory status, botulinum toxin and selective dorsal rhizotomy.</p>","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13619116/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149073976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhancing colonic anastomotic healing with a novel melatonin-loaded PLGA matrix.","authors":"Ufuk Demir, Zekiye Gülfem Yurtgezen, Gülfem Erbil, Oruç Numan Gökçe, Ayhan Oral, Metehan Uzun","doi":"10.1113/EP093987","DOIUrl":"10.1113/EP093987","url":null,"abstract":"<p><p>Anastomotic leakage continues to be a severe and prevalent complication in colorectal surgery, leading to elevated morbidity and mortality rates despite modern advancements in surgical and perioperative care. To address this persistent clinical challenge, the aim of the present study was to engineer a biocompatible poly(lactic-co-glycolic acid) (PLGA) matrix designed for the sustained release of melatonin, subsequently evaluating its therapeutic efficacy in promoting colon anastomotic repair. Seventy-two male Wistar albino rats were randomly assigned to three experimental groups: anastomosis (n = 24); anastomosis + matrix (n = 24); and anastomosis + melatonin-loaded matrix (n = 24). Anastomotic segments were harvested on postoperative days 3 and 7, and colonic bursting pressure was measured as a functional indicator of anastomotic integrity. The melatonin-loaded matrix significantly enhanced anastomotic healing on postoperative day 7. Melatonin delivery: (1) markedly reduced the gene expression of pro-inflammatory cytokines; (2) modulated iNOS, COX-2 and MPO expression on both days 3 and 7; (3) decreased HO-1 and catalase expression on day 7; (4) promoted collagen synthesis; (5) enhanced collagen deposition through upregulation of Arg-1; and (6) regulated ADAM10 and ADAM17 gene expression. These results are correlated with the histological analysis findings. Collectively, controlled release of melatonin via a PLGA-based biomaterial matrix promotes colon anastomosis healing. This strategy represents a promising translational approach for reducing postoperative anastomotic complications.</p>","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13616097/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149059380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stimulus-dependent sex differences in dyspnoea: Mechanical loading vs. hypercapnia.","authors":"Jack R Dunsford, Olga Radivojevic, Olivia N Ferguson, Alanna S Hind, Michele R Schaeffer, Owen D Harris, Satvir S Dhillon, Kathryn M Milne, Dennis Jensen, Paolo B Dominelli, Yannick Molgat-Seon, Jordan A Guenette","doi":"10.1113/EP094211","DOIUrl":"10.1113/EP094211","url":null,"abstract":"<p><p>Dyspnoea is a multidimensional sensation of breathing discomfort that varies in sensory and affective experience. During exercise, healthy adults commonly report dyspnoea sensations of 'air hunger' and 'work/effort', with females more frequently reporting air hunger at maximal exertion. Interpreting these sex differences and their underlying mechanisms is challenging due to the complex physiological responses associated with exercise. Therefore, this study used laboratory models to target respiratory stimuli and evaluate sex-differences in perceptual and physiological responses to dyspnoea. In a randomized crossover design, 34 healthy participants (n = 17M; n = 17F) completed two breathing challenges. Work/effort was targeted using incremental inspiratory pressure threshold loading (IPTL). Air hunger was targeted by constraining ventilation while incrementally increasing the partial pressure of end-tidal carbon dioxide ( <math><msub><mi>P</mi> <mrow><mi>ETC</mi> <msub><mi>O</mi> <mn>2</mn></msub> </mrow> </msub> </math> ). Ratings of dyspnea intensity, unpleasantness, work/effort and air hunger were assessed at the end of each increment. Electromyography of the crural diaphragm (EMG_di), sternocleidomastoid (EMG_scm) and scalene (EMG_sca) were measured throughout each trial. Mixed-effects models tested sex-by-stimulus interactions. During IPTL, males exhibited a significantly steeper increase in dyspnoea intensity and work/effort ratings than females. These perceptual differences occurred without a concomitant sex difference in EMG_di, while EMG_scm and EMG_sca were lower in males compared to females. During hypercapnia, there were no sex-by-stimulus interactions for perceptual or physiological outcomes, despite significantly greater EMG_scm in females than males. These findings highlight that sex differences in dyspnoea are stimulus-dependent, occurring during mechanical loading but not chemostimulation, and may partly reflect differences in perceptual anchoring to experience and expectation.</p>","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13616110/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149059558","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Peripheral non-invasive focused ultrasound alleviates constipation by reducing gastrointestinal inflammation.","authors":"Dia Shah, Kainat Akhtar, Dev Dwivedi, Amal Siddiqui, Griffin Haggas, Nicole Forman, Tatiana Gervase, Yifan Kao, John Chen, Julia Brzac, Eric Molho, Damian Shin","doi":"10.1113/EP093281","DOIUrl":"10.1113/EP093281","url":null,"abstract":"<p><p>Constipation affects approximately 20% of the US population, with diverse treatment options available due to the unclear onset and causes of the condition. Recently, focused ultrasound (FUS) has been proposed as a novel, non-invasive peripheral neuromodulatory treatment that may reduce this inflammation. We utilized a loperamide-induced constipation rat model, which is a widely used model to study constipation and potential therapeutic interventions. This study investigated the effects of FUS treatment on colonic inflammation and motility. We report that loperamide treatment did not alter colon morphology, but upregulated interleukin (IL)-6, IL-10, IL-1ra and several other cytokines. FUS treatment notably reduced the expression of IL-2, IL-4, IL-17 and other markers of inflammation. Additionally, FUS therapy also reduced the expression of chemokines, such as CXC3CL-1 and CXCL-7, and acute phase proteins, including vascular endothelial growth factor and intercellular adhesion molecule 1 in loperamide-FUS-treated rats. One week post-treatment, cytokine and chemokine profiles showed a sustained decrease of inflammation in the distal colon, with FUS treatment continuing to reduce several inflammatory mediators. These results demonstrate non-invasive FUS markedly reduced the expression of pro-inflammatory cytokines, chemokines and acute phase proteins in both the proximal and distal colon of loperamide-treated rats and can plausibly serve as a therapeutic for chronic constipation and other inflammatory gastrointestinal disorders.</p>","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13615837/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149059502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Somatosensory processing in long COVID fatigue and its relations with physiological and psychological factors.","authors":"Bethan Thomas, Rachael Pattinson, Geoffrey Cunningham, Christine Bundy, Jennifer L Davies","doi":"10.1113/EP093600","DOIUrl":"10.1113/EP093600","url":null,"abstract":"<p><p>We aimed to quantify somatosensory processing in long COVID and interactions between somatosensory processing, fatigability, fatigue, autonomic function, mood and illness beliefs. Eighty-eight participants (44 long COVID and 44 controls) were invited to complete two testing sessions, where fatigue was induced by either a cognitive or a physical task in a cross-over design; all participants completed at least one session. Baseline questionnaires assessed trait fatigue, autonomic symptoms, mood and illness beliefs. Pre- and post-task measures included somatosensory processing, state fatigue, perceived effort and heart rate variability (HRV). Group differences and task-related changes were analysed using multivariate and linear mixed models. There was no multivariate group effect on baseline somatosensory measures (P = 0.172), nor did they change following exertion or associate with post-exertion fatigue. Long COVID participants reported greater fatigue than controls, with 64% meeting criteria for severe fatigue. State fatigue was greater at baseline, throughout both exertion tasks (all P < 0.001), and increased more during exertion compared with controls. Despite this, cognitive and physical performance changed similarly across tasks, with no group differences in fatigability (P = 0.199-0.441). Long COVID participants had lower resting HRV, indicating autonomic dysfunction, but HRV was not associated with fatigue. Only group status (P < 0.001) and pre-task fatigue (P < 0.001) were associated with post-exertion fatigue. Within long COVID participants, greater depression (P < 0.001) and perceived illness threat (P = 0.033) were associated with greater trait fatigue. The absence of somatosensory abnormalities provides no support for the sensory attenuation model of fatigue in long COVID.</p>","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13614499/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149059486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sex differences in macrovascular responsiveness: Acute effects of hot water immersion versus aerobic exercise in overweight older adults.","authors":"Juliene G Costa, Joao Carlos Locatelli, Kristanti W Wigati, Louise H Naylor, Andrew Haynes, Helen Jones, Daniel J Green","doi":"10.1113/EP093959","DOIUrl":"10.1113/EP093959","url":null,"abstract":"<p><p>Recent studies have focused on the potential benefits of heat exposure for cardiovascular health. However, the acute effects of heat therapy on conduit arteries remain unclear, particularly in overweight and obese older males and females. This study aimed to compare core temperature (T_c), heart rate (HR), and brachial, femoral, and carotid artery diameter and velocity (Doppler ultrasound) responses to an acute exercise (EXE) session versus hot water immersion (HWI), and to determine whether physiological responses are sex-dependent. Twenty-five overweight older adults (10♂/15♀; age: 59 ± 7, BMI: 29.4 ± 3.4 kg/m²) underwent two experimental sessions (30 min): EXE (60-70% HR_max) and HWI (40°C). HWI resulted in a larger increase in T_c across the session with the largest difference at 30 min (0.9 ± 0.3 vs. 0.7 ± 0.3°C; P = 0.024). No differences were observed in T_c between males and females (interaction P = 0.271). HWI induced a lower rise in HR (♂ 40 ± 18 vs. ♀ 51 ± 12 bpm at 30 min; P = 0.013) than EXE, and females exhibited a larger change in HR after HWI than males (♂ 27 ± 12 vs. ♀ 48 ± 17 bpm; P = 0.003). HWI also induced a larger reduction in systolic (-6 ± 10 vs. 1 ± 7 mmHg; P = 0.012) and diastolic BP (-10 ± 9 vs. -2 ± 5 mmHg; P = 0.001) than EXE, but with no sex differences. HWI induced a larger increase in brachial diameter, brachial and femoral velocity, brachial and femoral flow, and shear rate than EXE. Females exhibited significantly higher change in femoral velocity (♀ 26 ± 8 vs. ♂ 17 ± 6 cm/s; P = 0.011) and shear rate (♀ 157 ± 55 vs. ♂ 98 ± 38 cm/s; P = 0.008) in response to HWI than males. A single session of HWI induced larger vascular responses than exercise. Males and females both benefit, but somewhat differently and possibly via different mechanisms.</p>","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13614612/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149059494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantitative MRI changes in neck muscle size and composition following long-duration spaceflight.","authors":"Diana A Madrid Fuentes, Marina S Sawires, Leon Lenchik, Janet A Tooze, Ashley A Weaver","doi":"10.1113/EP093726","DOIUrl":"10.1113/EP093726","url":null,"abstract":"<p><p>Long-duration spaceflight poses several challenges to human health, including muscle loss and fat deposition. To mitigate these effects, exercise countermeasures are prescribed. This study aimed to measure neck muscle size and composition changes with long-duration spaceflight using quantitative magnetic resonance imaging (MRI) and examine associations with in-flight exercise modality and volume. Nine astronauts (mission duration: 7.1 ± 1.8 months) underwent pre- and post-flight 3T Dixon MRI of the cervical spine. Cross-sectional area (CSA) and muscle fat fraction (MFF) were measured bilaterally in 11 neck muscles. Mixed-effects models assessed monthly percentage changes and associations with resistance (ARED), cycle ergometer and treadmill training volumes. The CSA and MFF of most neck muscles did not change across long-duration missions. CSA increased for the sternocleidomastoid (+1.21%/month, P = 0.004) and the rhomboid minor (+1.71%/month, P = 0.057). Semispinalis capitis MFF increased (+1.10%/month, P = 0.051). More ARED repetitions of different exercises were associated with CSA increases in four muscles (P < 0.001-0.097) and MFF reductions in three muscles (P = 0.040-0.093). More cycle ergometer time was associated with a CSA increase in the sternocleidomastoid (P = 0.053) and an MFF increase in the scalenus medius (P = 0.019), while treadmill time was linked to CSA decreases in the trapezius (P = 0.095) and rhomboid minor (P = 0.047). Neck muscle size and composition were generally preserved during modern long-duration missions in which structured exercise countermeasures were performed. Because all crewmembers completed in-flight exercises, these findings should not be interpreted as evidence that exercise countermeasures prevented neck muscle changes.</p>","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13602989/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149037228","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}