Medicine and Science in Sports and Exercise最新文献

{"title":"Exogenous Ketosis during Early Acclimatization at High Altitude: Ventilatory, Cardiovascular and Muscular Responses to Maximal Exercise.","authors":"Domen Tominec, Myrthe Stalmans, Benjamin J Narang, Grégoire P Millet, Chiel Poffé, Tadej Debevec","doi":"10.1249/MSS.0000000000003791","DOIUrl":"https://doi.org/10.1249/MSS.0000000000003791","url":null,"abstract":"<p><strong>Background: </strong>Exogenous ketosis, induced via ketone monoester (KE) ingestion, can attenuate blood desaturation and muscle deoxygenation during hypoxic exercise. However, its effect(s) on exercise capacity and underlying integrated physiological responses to incremental exercise to exhaustion during early acclimatization at terrestrial high altitude remain unexplored.</p><p><strong>Methods: </strong>Healthy active adults were randomised to an intermittent exogenous ketosis (IEK; n = 16) or placebo (PLA, n = 17) group, before performing two incremental cycling tests to volitional exhaustion. The first was conducted at sea level (295 m) without prior supplementation. The second was conducted at high altitude (3375 m) following ~69 hours of acclimatization, during which participants intermittently ingested KE (IEK) or placebo (PLA). During exercise, gas exchange, cardiac output, and both blood and muscle oxygenation were recorded continuously using a metabolic cart, transthoracic impedance, earlobe oximetry and near-infrared spectroscopy, respectively.</p><p><strong>Results: </strong>Pre-exercise blood ketone concentrations were higher in IEK than PLA (~2.1 mM vs. ~0.3 mM, P < 0.001). However, both experimental groups exhibited comparable (P = 0.525-0.644) high altitude-induced reductions in peak power output (P < 0.001), as well as in blood (P < 0.001) and muscle oxygenation (P < 0.001) during maximal exercise and submaximal power levels. Furthermore, high altitude significantly increased resting and/or exercising ventilation (P < 0.001) and cardiac output (P < 0.001), yet irrespective of the KE vs. placebo ingestion (P = 0.529-0.828).</p><p><strong>Conclusions: </strong>These findings indicate that intermittent exogenous ketosis during early acclimatization does not mitigate altitude- and exercise-induced reductions in blood and muscle oxygenation. Moreover, it does not importantly modulate ventilatory and cardiac output responses, and therefore does not seem to confer ergogenic advantage during subacute high altitude exposures.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144310171","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 Effects of Ingesting a Single Bolus of Hydrolyzed Collagen versus Free Amino Acids on Muscle Connective Protein Synthesis Rates.","authors":"Thorben Aussieker, Jeremias Kaiser, Floris K Hendriks, Tom A H Janssen, Joan M Senden, Janneau M X van Kranenburg, Joy P B Goessens, Antoine Zorenc, Esther Kornips, Tjinta Brinkhuizen, Keith Baar, Tim Snijders, Andrew M Holwerda, Luc J C van Loon","doi":"10.1249/MSS.0000000000003788","DOIUrl":"https://doi.org/10.1249/MSS.0000000000003788","url":null,"abstract":"<p><strong>Purpose: </strong>To assess the impact of ingesting a single bolus of hydrolyzed collagen or free amino acids on myofibrillar and muscle connective protein synthesis rates.</p><p><strong>Methods: </strong>In a randomized, double-blind, parallel design, 45 young male (n = 21) and female (n = 24) adults (age: 23 ± 3 y; BMI: 22.3 ± 2.2 kg/m2) received intravenous infusions with L-[ring-13C6]-phenylalanine. Following unilateral resistance exercise, participants ingested either 30 g hydrolyzed collagen (COLL, n = 15), 30 g free amino acids reflecting the collagen amino acid profile (AA, n = 15), or a non-caloric placebo (PLA, n = 15). Blood and muscle tissue samples were collected over 6 h to assess myofibrillar and muscle connective protein synthesis rates and associated signaling responses.</p><p><strong>Results: </strong>Both collagen and free amino acid ingestion substantially increased circulating plasma amino acids concentrations and effected collagen turnover proteins. Collagen and free amino acid ingestion did not significantly increase myofibrillar protein synthesis rates in the rested (0.039 ± 0.011, 0.037 ± 0.010, and 0.036 ± 0.015%·h-1 in PLA, COLL and AA, respectively) or the exercised (0.049 ± 0.010, 0.048 ± 0.011, and 0.045 ± 0.013%·h-1) leg (P > 0.05). Similarly, both collagen and free amino acid ingestion did not significantly increase muscle connective protein synthesis rates in the rested (0.065 ± 0.014, 0.063 ± 0.017, and 0.061 ± 0.025%·h-1 in PLA, COLL and AA, respectively) or the exercised (0.098 ± 0.023, 0.092 ± 0.028, and 0.085 ± 0.024%·h-1) leg (P > 0.05).</p><p><strong>Conclusions: </strong>Ingestion of a single bolus of collagen hydrolysate or free amino acids substantially increases circulating amino acids concentrations, particularly glycine, but does not further increase myofibrillar or muscle connective protein synthesis rates at rest or during recovery from exercise in healthy, recreationally active young men and women.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144310174","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":"Changes in Body Composition in Relation to Metabolic Syndrome: A Compositional Analysis in Adults with Overweight and Obesity.","authors":"Erin Miller, Ian Janssen, Robert Ross","doi":"10.1249/MSS.0000000000003778","DOIUrl":"https://doi.org/10.1249/MSS.0000000000003778","url":null,"abstract":"<p><strong>Background/purpose: </strong>Current knowledge of the association between body composition and health outcomes is based on traditional regression techniques, where the components of body composition are treated as non-compositional independent variables. Mounting evidence suggests that body tissues are biologically co-dependent and therefore, require a statistical technique that considers this. This study used a compositional data analysis framework to explore the longitudinal association between body composition and a continuous metabolic syndrome score.</p><p><strong>Methods: </strong>Participants included 288 physically inactive adults (age: 56 ± 12 years [mean ± SD]; 56% female) with overweight or obesity (BMI: 31.3 ± 3.5 kg/m2) who participated in randomized controlled trials that determined the effects of exercise on adipose tissue (visceral, abdominal subcutaneous, peripheral subcutaneous, other adipose tissues) and lean tissues (skeletal muscle, other lean tissues) assessed by whole-body magnetic resonance imaging.</p><p><strong>Results: </strong>Visceral adipose tissue, relative to the mass of the remaining tissues, was significantly associated with the metabolic syndrome score pre- and post-intervention (P < 0.05). The slopes and intercepts of the pre- and post-intervention regression lines between relative visceral adipose tissue mass and metabolic syndrome did not differ (P > 0.2). For a given weight loss, the greater the relative reduction in visceral adipose tissue, the larger the decrease in the predicted metabolic syndrome score.</p><p><strong>Conclusions: </strong>This novel compositional data analysis reinforces that visceral adipose tissue is an important marker of cardiometabolic risk and should be a primary target for therapeutic strategies in individuals with overweight or obesity.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144275245","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":"Heavy Intensity Priming Exercise Attenuates the Rate of Quadriceps Muscle Fatigue and Improves Time-to-Task Failure during Severe Intensity Cycling.","authors":"Keenan B MacDougall, Saied J Aboodarda, Austin B Wickenberg, Brian R MacIntosh","doi":"10.1249/MSS.0000000000003785","DOIUrl":"https://doi.org/10.1249/MSS.0000000000003785","url":null,"abstract":"<p><strong>Background: </strong>Prior high-intensity exercise (priming) has been shown to accelerate the V̇O2 kinetics, as well as improve exercise tolerance during subsequent high-intensity exercise, yet the mechanisms underpinning the performance changes are unclear. In theory, a reduced reliance on non-oxidative energy input afforded by the faster V̇O2 response may improve subsequent performance by delaying muscle fatigue, however, this effect has yet to be conclusively shown.</p><p><strong>Purpose: </strong>Our purpose was to explore the impact of priming exercise on the energetic response, exercise tolerance, and the kinetics of muscle fatigue during severe intensity cycling exercise.</p><p><strong>Methods: </strong>Fourteen participants completed constant power cycling trials in the severe domain, preceded by either a bout of heavy intensity, or an equivalent duration cycling at 20 W. Muscle fatigue was assessed in real-time via femoral nerve stimulation while pedaling, and energetic contributions were assessed via V̇O2 and changes in blood lactate concentration. Quadriceps oxygenation and surface electromyography (EMG) were also measured.</p><p><strong>Results: </strong>Priming improved time-to-task failure (450 ± 74 s) compared to control (391 ± 92 s) (P = 0.008). Relative oxidative contributions increased following priming (P = 0.001), while the non-oxidative glycolytic contribution was reduced (P < 0.0001), and this was accompanied by a reduction in the rate of quadriceps twitch force decline (P = 0.041). Vastus lateralis EMG root mean square amplitude and M-wave amplitude increased across the trial similarly in both conditions, but priming resulted in a relative \"downshift\" in both measures (P ≤ 0.027).</p><p><strong>Conclusions: </strong>Priming exercise resulted in an improvement in exercise tolerance, attenuation in muscle fatigue, and reduction in EMG and M-wave amplitude. We speculate that these effects may arise in part from the interaction between a reduction in metabolite accumulation and altered sarcolemmal excitability.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144275246","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":"Supplemental Oxygen during Exercise Training in Chronic Obstructive Pulmonary Disease.","authors":"Sara Faggian, Francesca Battista, Marco Vecchiato, Richard Casaburi, Margareta Emtner, Nicola Borasio, Michael Studnicka, Andrea Ermolao, Josef Niebauer, Daniel Neunhaeuserer","doi":"10.1249/MSS.0000000000003782","DOIUrl":"https://doi.org/10.1249/MSS.0000000000003782","url":null,"abstract":"<p><strong>Introduction: </strong>chronic obstructive pulmonary disease is a leading cause of mortality worldwide and a debilitating condition that leads to years of poor quality of life. Physical exercise training is an evidence-based treatment well documented to improve these outcomes as well as morbidity, dyspnoea and functional capacity. Moreover, scientific evidence from pooled analyses currently provides equivocal evidence for oxygen supplementation to overcome ventilatory limitations during exercise training, with several studies reporting no additional benefits when compared with training in room air. However, when individually analyzing the underlying studies from an exercise physiology perspective, some critical aspects arise.</p><p><strong>Purpose: </strong>this review aims to systematically investigate and highlight the impact of patients' characteristics, exercise induced desaturation, oxygen delivery, influence of breathing conditions during exercise testing and prescription, outcome-training specificity, exercise intensity and modality, as well as progressive work rate adjustments over the course of the training intervention.</p><p><strong>Methods: </strong>the research methodology is based on a literature search of the available evidence starting from the published systematic reviews and meta-analyses, and integrating available original articles from the respective reference lists.</p><p><strong>Results: </strong>although evidence is still limited, supplemental oxygen might be specifically useful for certain responding patients and in specific clinical conditions, when high-intensity training is performed, thereby increasing exercise tolerance in order to improve training adaptations and thus peak exercise capacity/endurance.</p><p><strong>Conclusions: </strong>future well-designed clinical trials may better implement these methodological training principles in their study design and investigate if advantages from normoxic and hyperoxic exercise training can be weighed, showing how, when and in which patients supplemental oxygen could be best used in order to reach predefined training goals in pulmonary rehabilitation.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144275248","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 to Letter to the Editor Re: Allostatic Load Is Associated with Overuse Musculoskeletal Injury during US Marine Corps Officer Candidates School.","authors":"Evan D Feigel, Matthew B Bird, Kristen J Koltun, Mita Lovalekar, Jennifer N Forse, Elizabeth J Steele, Christopher K Kargl, Brian J Martin, Bradley C Nindl, Angelique Bannister, Angelito V Cruz, Tim L A Doyle, Karl E Friedl","doi":"10.1249/MSS.0000000000003784","DOIUrl":"https://doi.org/10.1249/MSS.0000000000003784","url":null,"abstract":"","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144275247","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":"CARDIORESPIRATORY FITNESS PREDICTS EEG-BASED SOMATOSENSORY RESPONSES FOLLOWING NOXIOUS MECHANICAL STIMULATION IN A CONDITIONED PAIN MODULATION MODEL.","authors":"Elias Dreismickenbecker, Holger Stephan, Joschua Wiese, Malte Anders, Matthias Kreuzer, Johannes Fleckenstein, Ulf Henkemeier, Jörg Faber, Thomas Hilberg, Fabian Tomschi","doi":"10.1249/MSS.0000000000003781","DOIUrl":"10.1249/MSS.0000000000003781","url":null,"abstract":"<p><strong>Purpose: </strong>Existing literature indicates that physical fitness affects endogenous pain modulation capacity, potentially impacting populations with impaired pain modulation ability. However, current evidence remains inconsistent, and there is a lack of studies employing objective measures to examine this relationship. The objective of this study was to assess whether individual physical performance levels can predict endogenous pain modulation variables in the electroencephalogram (EEG).</p><p><strong>Methods: </strong>The EEG-based somatosensory response following noxious mechanical stimulation was recorded as pinprick-evoked potentials (PEP) during conditioned pain modulation (CPM) in 32 healthy adults. To analyze physical fitness, cardiorespiratory fitness (CRF) was measured by using spiroergometric analysis and strength was tested using isokinetic strength testing. Bivariate linear regressions were calculated to analyze a potential relationship between physical performance parameters and CPM variables.</p><p><strong>Results: </strong>Subjects with higher CRF exhibited a greater decrease in the ERSP in the CPM paradigm in the EEG and a correspondingly lower activation during a conditioning stimulus (CS). The CRF predicted 14.0% of the variance in the activation during the CS (large effect), and 10.2% of the decrease in the ERSP in the CPM paradigm (moderate effect). No such relationship was observed between strength and EEG-based variables. When the groups were separated according to their physical fitness levels, no differences were observed between the groups during isolated mechanical stimulation.</p><p><strong>Conclusions: </strong>The results indicate that CRF is associated with altered somatosensory responses during the CPM paradigm in our EEG-based pattern. Higher CRF appears to facilitate pain modulation processes without affecting central sensitivity to noxious mechanical stimulation, highlighting the potential benefits of higher levels of endurance exercise, but not strength levels.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144266551","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":"Effects of Low Load Blood-Flow-Restriction Training on Body Composition and Strength in Cancer Cachexia: A Case Study.","authors":"Frieder Krause, Nils Schaffrath, Ingeborg Rötzer, Jenny Hoffart, Michael Behringer, Elke Jäger, Katharina Graf","doi":"10.1249/MSS.0000000000003779","DOIUrl":"https://doi.org/10.1249/MSS.0000000000003779","url":null,"abstract":"<p><strong>Purpose: </strong>A common side effect from cancer and anti-cancer treatment is cancer-associated cachexia (CAC), a multifactorial syndrome characterized by the loss of bodyweight, skeletal muscle and adipose tissue. Recommended therapeutic options are multidimensional, including nutritional, pharmacological and exercise interventions. A novel therapeutic approach is the use of low-load resistance training combined with blood-flow-restriction to the trained limbs (LL-BFR). It has been shown to induce adaptations in muscle mass and strength despite low training load in various clinical populations and might be a suitable training modality for cancer patients suffering from CAC.</p><p><strong>Methods: </strong>A 56-year-old female patient diagnosed with stage IV gallbladder cancer, suffering from CAC performed LL-BFR training twice weekly for twelve weeks and received a guideline-based nutritional intervention. All outcome measures (maximal strength (8-RM), handgrip strength, body mass, lean body mass, body cell mass, quality of life and symptom burden) were evaluated before and directly after the training period.</p><p><strong>Results: </strong>Adherence was moderate (67% of all training sessions completed) and no adverse events were noted. All measures of physical capacity and body composition improved between 19-55% and 9-11%, respectively. Quality of life decreased in 5/6 subscales while symptom burden increased in 2/4 subscales.</p><p><strong>Conclusions: </strong>Treatment of CAC requires a multitargeted and interdisciplinary approach. This is the first case study using LL-BFR training in an oncological patient during active therapy. Our results show that LL-BFR was feasible and, despite no positive effect on quality of life and symptom burden, could induce relevant changes of muscle strength and muscle mass in a relatively short training period. Further research is necessary to confirm the results of this case study in randomised controlled trials.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144258394","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":"What is the Effect of Breast Size on Running Economy and Upper Body Biomechanical Factors Contributing to Running Economy?","authors":"Madeline J Bennett, Nicholas A Brown, Wayne A Spratford, Cody Lindsay, Jocely K Mara, Isabel S Moore, Brad Clark, Celeste E Coltman","doi":"10.1249/MSS.0000000000003780","DOIUrl":"https://doi.org/10.1249/MSS.0000000000003780","url":null,"abstract":"<p><strong>Introduction/purpose: </strong>This study investigated the effect of breast size on running economy, breast displacement, total body centre of mass excursion, trunk angular velocity and exercise induced breast pain at different running velocities.</p><p><strong>Methods: </strong>Fifteen female recreational runners with a small breast size (volume range: 90 - 338 ml per breast) and fifteen female recreational runners with a medium-large breast size (volume range: 351 - 1029 ml per breast) were matched for age and body mass index. Kinematic and oxygen consumption (V̇O2) data were collected while participants completed an 8-minute treadmill protocol at two incremental velocities (8 km·h-1 and 10 km·h-1).</p><p><strong>Results: </strong>Running economy was not affected by breast volume. Multiplanar breast displacement was significantly greater for larger breast volumes, despite participants wearing a high-support sports-bra. A higher breast volume was also associated with less vertical centre of mass excursion at velocity of 10 km·h-1 and higher trunk lateral flexion angular velocity at foot flat.</p><p><strong>Conclusions: </strong>Women with large breast volumes experience significantly more breast motion compared to their smaller breasted counterparts during running, despite the presence of a high-support sports bra. Although increased breast motion as a result of breast size did not translate to differences in running economy, it did alter upper body biomechanical factors known to influence running economy - total body centre of mass vertical excursion and peak angular velocity of the trunk in the frontal plane. Future research should explore what effect excessive trunk motion has on the mechanics of the lower limb during running among women across the breast size spectrum, as well as how this may influence neuromuscular control and coordination between the upper and lower limb during running.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144258328","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":"Sequential Oxygen Mismatch from Skeletal Muscle to Prefrontal Cortex Underpins the Rate of Exhaustion During All-Out Exercise.","authors":"Mark E Hartman, Michael Kantor, Kirsten Thornhill, Susannah L Reiner, Brad J Winn, Mark Kramer, Robert W Pettitt, Brett S Kirby","doi":"10.1249/MSS.0000000000003771","DOIUrl":"https://doi.org/10.1249/MSS.0000000000003771","url":null,"abstract":"<p><strong>Purpose: </strong>We tested the overarching hypothesis that the expended rate of work above critical power (W' Balance) during all-out whole-body exercise is related to a decline in prefrontal cortex (PFC) oxygenation secondary to an organized systemic outstripping of muscle O2 supply relative to O2 demand.</p><p><strong>Methods: </strong>We concomitantly measured (N = 16 males) skeletal muscle O2 saturation (vastus lateralis near infrared spectroscopy, NIRS; %SmO2), pulmonary O2 uptake (V̇O2), and Hb differential (∆[O2Hb-HHb]) as an index of PFC O2 mismatch (pfcO2) via functional NIRS bi-laterally in the ventrolateral (VLPFC), dorsolateral (DLPFC), and orbitofrontal (OFC) cortices during brief all-out cycling exercise (highest instantaneous power for three minutes).</p><p><strong>Results: </strong>All-out exercise evoked significant changes in %SmO2 (∆-28.8 ± 14.1%), V̇O2 (∆27.7 ± 10.3%), and global pfcO2 (∆-7.6 ± 4.8%). Decreases in regional pfcO2 were greater in the VLPFC (∆-10.9 ± 6.1 μM) vs DLPFC (∆-4.8 ± 4.5 μM) or OFC (∆-5.9 ± 4.2 μM). Spatiotemporal analysis by O2 measurement location revealed a steep rate of change transition phase followed by a maximal sustaining plateau, and progression of this pattern occurred sequentially first in muscle (~13 sec) → pulmonary (~44 sec) → PFC (~80 sec). Transition phase O2 indices were strongly correlated to the rate of W' Balance expended (muscle, R2 = 0.91; pulmonary, R2 = 0.997; PFC, R2 = 0.968), with crossover between regional O2 mismatches occurring at the same %W' Balance (end muscle = 71% vs start pulmonary = 65%, P = 0.56; end pulmonary = 26% vs start PFC = 30%, P = 0.83) and end PFC transition phase occurring at complete depletion of W' (end PFC = -0.9%).</p><p><strong>Conclusions: </strong>We conclude that whole-body all-out exercise tolerance may arise from a progressive O2 mismatch from skeletal muscle to the brain.</p>","PeriodicalId":18426,"journal":{"name":"Medicine and Science in Sports and Exercise","volume":" ","pages":""},"PeriodicalIF":4.1,"publicationDate":"2025-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144258326","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}