Journal of applied physiology最新文献

{"title":"Effects of hyperthermia and acidosis on mitochondrial oxidative phosphorylation.","authors":"Michael S Davis, Warwick M Bayly, Cristina M Hansen, Montana R Barrett, Cara A Blake","doi":"10.1152/japplphysiol.00418.2024","DOIUrl":"10.1152/japplphysiol.00418.2024","url":null,"abstract":"<p><p>The intracellular environment of skeletal muscle can develop pronounced hyperthermia and acidosis during strenuous exercise, and these alterations in the typical intracellular conditions have been shown to alter mitochondrial respiration. However, the impact of these conditions on ATP synthesis is poorly understood. We used Thoroughbred racehorses to test the hypothesis that both hyperthermia and acidosis decrease the rate of ATP synthesis, but that athletic conditioning mitigates this loss of phosphorylation capacity. Isolated mitochondria were harvested from skeletal muscle before and after a 9-wk racetrack conditioning program that increased whole body aerobic capacity by 19%, and oxidative phosphorylation capacity was tested ex vivo under normothermic and hyperthermic conditions, as well as normal pH and acidic pH created by the addition of lactic acid. In unfit horses, hyperthermia caused a 30-55% decrease in the rate of ATP synthesis and loss of phosphorylation efficiency (P/O ratio decreased from 4.2 to 1.7 during maximal oxidative phosphorylation). Aerobic conditioning resulted in increased phosphorylation efficiency under hyperthermic conditions. Lactic acidosis had a small negative effect on ATP synthesis in unfit horses, but aerobic conditioning increased the sensitivity of isolated mitochondria to the deleterious effects of lactic acidosis. These data support the prominent role of hyperthermia in skeletal muscle fatigue during exercise, particularly in unfit subjects. However, acidosis may be a more important cause of failure of ATP synthesis in fit subjects.<b>NEW & NOTEWORTHY</b> This study reports the use of a novel method for the measurement of ATP synthesis and concurrent mitochondrial respiration. Although acidosis is often considered a leading cause of exercise fatigue, this study shows that tissue hyperthermia, which often occurs concurrently with acidosis, has a larger role in decreasing the maximal rate of skeletal muscle ATP synthesis.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"1678-1689"},"PeriodicalIF":3.3,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142728892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 inorganic nitrate supplementation on muscular power and endurance across the menstrual cycle.","authors":"Austin C Hogwood, Joaquin Ortiz De Zevallos, Ka'eo Kruse, Meredith Buckley, Jeison De Guzman, Alexandra DeJong Lempke, Arthur Weltman, Jason D Allen","doi":"10.1152/japplphysiol.00323.2024","DOIUrl":"10.1152/japplphysiol.00323.2024","url":null,"abstract":"<p><p>Oral inorganic nitrate ([Formula: see text]) supplementation increases nitric oxide (NO) bioavailability and may improve muscular power in males and females, although data in females are limited. Estrogen increases NO bioavailability and fluctuates throughout the menstrual cycle, with low levels in the early follicular (EF) phase and peaking during the late follicular (LF) phase. The purpose of the present study was to examine the effects of [Formula: see text] supplementation on isokinetic peak power, maximal voluntary isometric contraction (MVIC) force, muscular endurance, and recovery from fatigue in healthy young females during the EF and LF phases of the menstrual cycle. Ten eumenorrheic females were tested in a double-blinded, randomized, placebo-controlled design. Participants consumed ∼13 mmol [Formula: see text], in the form of 140 mL beetroot juice (BRJ), or an identical [Formula: see text]-depleted placebo (PL), for ∼5 days prior to visits and 2 h prior to testing. Plasma estradiol was elevated in the LF phase, and plasma nitrite and nitrate were elevated in the BRJ condition (<i>P</i> < 0.05). Although isokinetic peak power was unchanged, calculated maximal power (Pmax) and maximal velocity (Vmax) were significantly worsened in the BRJ treatment independent of the menstrual cycle phase (<i>P</i> = 0.02 and 0.03, respectively). Muscular endurance, MVIC, and fatigue recovery were unaltered by BRJ or the menstrual cycle. These data indicate that [Formula: see text] supplementation decreased maximal power and velocity in females and suggest that the benefits of [Formula: see text] supplementation previously found in males may not extend to young females.<b>NEW & NOTEWORTHY</b> Recent data have suggested that inorganic nitrate ([Formula: see text]) supplementation may benefit males, however, females may experience worsened endurance capacity independent of menstrual cycle phase. This study revealed neither [Formula: see text] supplementation nor the follicular phase of the menstrual cycle influenced maximal isometric voluntary contraction or endurance capacity in healthy, young, naturally menstruating females, whereas [Formula: see text] supplementation significantly worsened estimated peak power (Pmax) and velocity (Vmax) independent of the menstrual cycle phase.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"1503-1511"},"PeriodicalIF":3.3,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142466240","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Validation of livability environmental limits to heat and humidity.","authors":"Xiaojiang Xu, Timothy P Rioux, John W Castellani, Scott J Montain, Nisha Charkoudian","doi":"10.1152/japplphysiol.00225.2024","DOIUrl":"10.1152/japplphysiol.00225.2024","url":null,"abstract":"<p><p>Rising global temperatures, driven by climate change, pose a threat to human health and regional livability. Empirical data and biophysical model-derived estimates suggest that the critical environmental limits (CELs) for livability are dependent on ambient temperature and humidity. We use a well-validated, physiology-based, six-cylinder thermoregulatory model (SCTM) to independently derive CELs during sustained minimal, light, and moderate activity across a broad range of ambient temperatures and humidity levels and compare with published data. The activity and environments were considered livable if predicted core temperatures did not reach 38 ± 0.25°C within 6 h. The outcomes for minimal activity revealed CELs ranging from 34°C/95% relative humidity (RH) to 50°C/5% RH. Corresponding dry heat losses ranged from 14 to -72 W·m^-2 (negative = heat gain) and evaporative heat losses ranged from 39 to 104 W·m^-2. The wet-bulb temperature (<i>T</i>_wb) at the CELs ranged from 33.3°C to 20.9°C. Activity shifted CELs toward lower temperatures and humidities. Importantly, our predicted CELs largely agree with observed livability CELs from physiology and those from a biophysical model. The physiology-grounded SCTM has utility for assessing the impact of climate change on regional livability.<b>NEW & NOTEWORTHY</b> This study is the first to use a physiology-grounded thermoregulatory model to predict critical environmental limits (CELs) above which human thermoregulatory capacity is exceeded. The model outcomes closely approximate empirically derived CELs, showing it is a strong model for estimating and preparing for the impact of climate warming on local, regional, and world human population livability and migration.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"1642-1648"},"PeriodicalIF":3.3,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142621096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Intravenous bolus injection of fentanyl triggers an immediate central and upper airway obstructive apnea via activating vagal sensory afferents.","authors":"Jianguo Zhuang, Xiuping Gao, Shan Shi, Fadi Xu","doi":"10.1152/japplphysiol.00614.2024","DOIUrl":"10.1152/japplphysiol.00614.2024","url":null,"abstract":"<p><p>Intravenous bolus (IVb) injection of fentanyl induces an immediate apnea, but the characteristics of the apnea and relevant mechanism remain unclear. Here, we tested whether IVb injection of fentanyl induced an immediate central and upper airway obstructive apnea associated with chest wall rigidity via activating vagal C-fibers (VCFs) and vagal afferent opioid receptors (ORs). Cardiorespiratory and electromyography of external and internal intercostal, thyroarytenoid, and superior pharyngeal constrictor muscles (EMG_EI, EMG_II, EMG_TA, and EMG_SPC) responses to IVb injection of fentanyl were recorded in anesthetized and spontaneously breathing rats with or without bilateral perivagal capsaicin treatment or intravagal microinjection of naloxone. An immunohistochemical approach was employed to define the presence of opioid mu-receptor (MOR) expression in vagal C-neurons, and a patch clamp technique was utilized to determine the evoked current responses of vagal C-neurons to fentanyl in vitro. Fentanyl induced an immediate apnea and subsequent respiratory depression. The apnea was characterized by cessation of EMG_EI activity and augmentation of tonic discharges of EMG_II, EMG_TA, and EMG_SPC, i.e., central expiratory apnea, laryngeal closure, and pharyngeal constriction/collapse accompanied with chest wall rigidity. The apneic response was abolished by blockade of VCF signal conduction and largely attenuated by antagonism of vagal afferent ORs. The latter significantly alleviated the initial (within 5-min postinjection), but not the latter, respiratory depression. Vagal C-neurons expressed MORs and were activated by fentanyl. We conclude that IVb injection of fentanyl causes a VCF- and vagal afferent OR-mediated immediate central apnea, upper airway obstruction, and chest wall rigidity.<b>NEW & NOTEWORTHY</b> Intravenous bolus injection of fentanyl triggers an immediate apnea, but the nature of apnea and relevant mechanisms remain unknown. Results in this study reveal that this fentanyl injection concurrently triggers an immediate central and upper airway obstructive apnea associated with chest wall rigidity via activating vagal sensory C-fibers.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"1666-1677"},"PeriodicalIF":3.3,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142466237","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of natural hyoid bone position and surgical repositioning on upper airway patency: a computational finite element modeling study.","authors":"Diane Salman, Jason Amatoury","doi":"10.1152/japplphysiol.00657.2024","DOIUrl":"10.1152/japplphysiol.00657.2024","url":null,"abstract":"<p><p>The hyoid bone's inferior baseline position in obstructive sleep apnea (OSA) has led to surgical hyoid repositioning (SHR) treatment, yet outcomes vary widely. The influence of baseline hyoid position (BHP; phenotype) and SHR on upper airway (UA) function remains unclear. We aimed to investigate their impact on the UA using computational modeling. A validated finite element model of the rabbit UA was advanced and used to simulate changes in BHP and SHR, alone and in combination. The hyoid was displaced in cranial, caudal, anterior, anterior-cranial, and anterior-caudal directions from 1 to 4 mm. Model outcomes included UA collapsibility, measured using closing pressure (Pclose), cross-sectional area (CSA), and soft tissue mechanics (displacement, stress, and strain). Graded BHP increments increased Pclose for all directions and up to 29%-43% at 4 mm (relative to the original BHP). Anterior-based SHR decreased Pclose (approximately -115% at 4 mm) and increased ΔCSA (approximately +35% at 4 mm). Cranial SHR decreased ΔPclose (-29%), minimally affecting CSA. Caudal SHR increased ΔPclose (+27%) and decreased ΔCSA (-7%). Anterior-cranial and anterior-caudal SHR produced the highest stresses and strains. SHR effects on UA outcomes were dependent on BHP, with more caudal BHPs leading to less effective surgeries. In conclusion, BHP (phenotype) and SHR both alter UA outcomes, with effects dependent on hyoid displacement direction and magnitude. BHP influences the effectiveness of SHR in reducing UA collapsibility. These findings provide further insights into the hyoid's role in UA patency and suggest that considering the hyoid's baseline position and surgical repositioning direction/increment may help improve hyoid surgeries for OSA treatment.<b>NEW & NOTEWORTHY</b> Using computational modeling, this study directly shows that any shift from the healthy natural hyoid bone position increases upper airway collapsibility. Surgical hyoid repositioning alters upper airway outcomes in a direction- and magnitude-dependent manner, with its effects influenced by the natural hyoid position. Accounting for both the natural hyoid position and individually prescribed surgical repositioning may enhance upper airway stability and improve outcomes in obstructive sleep apnea (OSA) treatment.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"1614-1631"},"PeriodicalIF":3.3,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142604662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Combined exercise hinders the progression of pulmonary and right heart harmful remodeling in monocrotaline-induced pulmonary arterial hypertension.","authors":"Luciano Bernardes Leite, Leôncio Lopes Soares, Alexandre Martins Oliveira Portes, Bruna Aparecida Fonseca da Silva, Tais Rodrigues Dias, Thayana Inácia Soares, Mirian Quintão Assis, Luiz Otávio Guimarães-Ervilha, Miguel Araújo Carneiro Júnior, Pedro Forte, Mariana Machado-Neves, Emily Correna Carlo Reis, Antônio José Natali","doi":"10.1152/japplphysiol.00379.2024","DOIUrl":"https://doi.org/10.1152/japplphysiol.00379.2024","url":null,"abstract":"<p><p>The aim of this study was to test whether combined physical exercise training of moderate intensity executed during the development of monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH) hinders the progression of pulmonary and right heart harmful functional and structural remodeling in rats. Wistar rats were injected with MCT (60 mg/kg) and after 24 hours were exposed to a combined exercise training program: aerobic exercise (Treadmill running - 60 min/day; 60% of maximum running speed); and resistance exercise (Vertical ladder climbing - 15 climbs; 60% of maximum carrying load), on alternate days, 5 days/week, for approximately 3 weeks. After euthanasia, lung, and right ventricle (RV) were excised and processed for histological, single myocyte and biochemical analyses. Combined exercise increased the tolerance to physical effort (time until fatigue and relative maximum load), and prevented increases in pulmonary artery resistance (TA/TE) and reductions in RV function (TAPSE). Moreover, in myocytes isolated from the RV, combined exercise preserved contraction amplitude, as well as contraction and relaxation velocities, and inhibited reductions in the amplitude and maximum speeds to peak and to decay of the intracellular Ca²⁺ transient. Furthermore, combined exercise avoided RV (RV weight, cardiomyocyte, extracellular matrix, collagen, inflammatory infiltrate, and extracellular matrix) and lung (pulmonary alveoli and alveolar septum) harmful structural remodeling. Additionally, combined exercise restricted RV (NO and CP) and lung (CAT, GST, and NO) oxidative stress. In conclusion, the applied combined exercise regime hinders the progression of pulmonary and right heart functional and structural harmful remodeling in rats with MCT-induced PAH.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142750395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New insights into the impact of bed rest on lumbopelvic muscles: A computer-vision model approach to measure fat fraction changes.","authors":"Evert O Wesselink, Julie Hides, James M Elliott, Mark Hoggarth, Kenneth A Weber, Sauro E Salomoni, Vienna Tran, Kirsty Lindsay, Luke Hughes, Tobias Weber, Jonathan Scott, Paul W Hodges, Nick Caplan, Enrico De Martino","doi":"10.1152/japplphysiol.00502.2024","DOIUrl":"https://doi.org/10.1152/japplphysiol.00502.2024","url":null,"abstract":"<p><p>Space agencies plan crewed missions to the Moon and Mars. However, microgravity-induced lumbopelvic deconditioning, characterized by an increased fat fraction (FF) due to reduced physical activity, poses a significant challenge to spine health. This study investigates the spatial distribution of FF in the lumbopelvic muscles to identify the most affected regions by deconditioning, utilizing a computer-vision model and a tile-based approach to assess FF changes. Twenty-four healthy individuals (8F) were recruited, and automatic segmentation of the lumbopelvic muscles was applied before and after 59 days of head-down tilt bed rest (HDTBR+59) and 13 days of reconditioning (R+13). Axial Dixon sequence images were acquired from 3T magnetic resonance imaging. FF in the lumbar multifidus (LM), lumbar erector spinae (LES), quadratus lumborum, psoas major, gluteus maximus (GMax), gluteus medius (GMed) and gluteus minimus (GMin) muscles from the upper margin of L1 vertebra to the inferior border of GMax muscle were automatically derived using a computer-vision model. Lumbar muscles were segmented into eight tiles (superficial and deep, lateral to medial), and gluteal muscles into regions (anterior/superior for GMed and GMin, superior/inferior for GMax). At HDTBR+59, the deep centro-lateral region at L5/S1 for LM (18.7±15.7%, p<0.001; d=0.97) and the deep medial region at Upper L4 for LES (5.4±5.9%, p<0.001; d=0.34) showed the largest increase in FF compared to BDC. These regions did not recover at R+13 (p<0.05; d≥0.25). These findings highlight the need to target deep fascicles of LM and LES in countermeasure strategies to mitigate microgravity-induced lumbopelvic deconditioning, optimizing spine health and performance.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142750410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The interaction of adenosine and dopamine in modulating the consequences of central nervous system oxygen toxicity.","authors":"Benming You, Guorong Shi, Yanan Zhang, Xiang Fu, Qian Li, Yu Wang, Guoyang Huang, Yiqun Fang, Runping Li","doi":"10.1152/japplphysiol.00500.2024","DOIUrl":"https://doi.org/10.1152/japplphysiol.00500.2024","url":null,"abstract":"<p><p>Hyperbaric oxygen (HBO) refers to pure oxygen with a pressure greater than 1 atmospheres absolute (ATA), and when the pressure is too high, it can cause convulsive attacks. Adenosine and dopamine have been shown to be closely associated with HBO induced convulsion seizures, and their receptors exhibited a coexisting relationship of mutual antagonism on the membrane of nerve cells. We explored the influence of adenosine and dopamine interplay on the occurrence of oxygen convulsion. Rats were individually exposed to HBO of 6 ATA and treated with adenosine, dopamine, and their receptor modulators separately and jointly, with the latency of convulsion onset recorded. Additionally, after administering adenosine to rats and exposing them to HBO for 30 min, the content of dopamine and its metabolites, as well as the activity of enzymes related to their metabolism, were measured. The results revealed that dopamine was effective in resisting convulsion (> 60 min <i>vs</i> 32.53±5.31 min, <i>P</i>=0.000), and low-dose adenosine partially counteracted its effect (> 60 min <i>vs</i> 28.18±6.24 min, <i>P</i>=0.002). The combined use of adenosine A1 and dopamine D1 receptor modulators significantly impacted the incidence of convulsion. The activation or inhibition of A2A receptor had a particularly significant impact on convulsion, while modulating D2 receptor did not affect their effects. The combination of A1 agonist and D2 agonist was highly effective in resisting convulsion (> 60 min <i>vs</i> 32.53±5.31 min, <i>P</i>=0.000). Exposure to HBO accelerated the metabolism of dopamine to its end products, which may be related to the enhanced activity of monoamine oxidase (MAO). Adenosine can inhibit MAO activity (0.0766±0.0150 U/mg.prot <i>vs</i> 0.1055±0.0086 U/mg.prot, <i>P</i>=0.004), maintaining a higher level of dopamine (1.820±0.379 mg/g <i>vs</i> 0.602±0.087 mg/g, <i>P</i>=0.000). The study demonstrated that dopamine plays a significant role in oxygen convulsion, and adenosine can affect dopamine metabolism. The interaction between them can have a crucial impact on the occurrence of oxygen convulsion. The findings offer a novel perspective for further investigating the mechanism of oxygen convulsion and exploring effective preventive strategies.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142728909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"N₂ exchanges in hyperbaric environments: towards a model based on physiological gas transport (O₂ and CO₂).","authors":"Michael Theron, Alexis Blasselle, Lisa Nedellec, Pascal Ballet, Emmanuel Dugrenot, Bernard Gardette, François Guerrero, Anne Henckes, Jean-Pierre Pennec","doi":"10.1152/japplphysiol.00357.2024","DOIUrl":"https://doi.org/10.1152/japplphysiol.00357.2024","url":null,"abstract":"<p><p>Decompression sickness can occur in divers even when recommended decompression procedures are followed. Furthermore, the physiological state of individuals can significantly affect bubbling variability. These informations highlight the need for personalized input to improve decompression in SCUBA diving. The main objective of this study is to propose a fundamental framework for a new approach to inert gas exchanges. A physiological model of oxygen delivery to organs and tissues has been built and adapted to nitrogen. The validation of the model was made by transferring the N₂ to CO₂. Under normobaric conditions (air breathing, oxygen breathing, and static apnea) and hyperbaric conditions, the O₂ model replicates the reference physiological Po₂ (Spearman correlation tests p<0.001). The inert gas models can simulate inert gas partial pressures under normobaric and hyperbaric conditions. However, the lack of reference values prevents direct validation of this new model. Therefore, the N₂ model has been transferred to CO₂. The resulting CO₂ model has been validated by comparing it with physiological reference values (Spearman correlation tests p<0.01). The validity of the CO₂ model constructed from the N₂ model demonstrates the plausibility of this physiological model of inert gas exchanges. In the context of personalized decompression procedures, the proposed model is of significant interest as it enables the integration of physiological and morphological parameters (blood and respiratory flows, alveolo-capillary diffusion, respiratory and blood volumes, oxygen consumption rate, fat mass, etc.) into a model of nitrogen saturation/desaturation, in which oxygen and CO₂ partial pressures can also be incorporated.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142728893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Clinical and physiological effects of high-intensity aerobic training on metabolic syndrome: understanding the individual exercise response variability.","authors":"Alfonso Moreno-Cabañas, Felix Morales-Palomo, Laura Alvarez-Jimenez, Diego Mora-Gonzalez, Eva Garcia-Camacho, Belen Martinez-Mulero, Ricardo Mora-Rodriguez","doi":"10.1152/japplphysiol.00501.2024","DOIUrl":"https://doi.org/10.1152/japplphysiol.00501.2024","url":null,"abstract":"<p><p>We analyzed the interindividual heterogeneity in health responses to a supervised high-intensity interval training (HIIT) program in individuals with metabolic syndrome (MetS). Two-hundred and sixty-four adults with overweight/obesity (56.3±7.3 y, body mass index, 32.3±4.7 kg·m^-2), and MetS were randomized to a standard health care non-exercise group (CONT group, N=58) or standard health care plus HIIT (EXER group, N=206). HIIT intervention was performed on a cycloergometer thrice a week (43 min·session^-1). The change in MetS components (i.e., MetS <i>z</i> score), cardiorespiratory fitness (VO_2PEAK), maximal cycling power (W_PEAK), and body weight/composition was assessed in both groups before (0 weeks) and after the intervention (16 weeks). Individual responses in the EXER group were considered attributable to HIIT when the improvements were larger than twice the typical error (>2 TE). TE was calculated using pre- and post-intervention data from the time-matched CONT group. The percent of participants that improved MetS <i>z</i> score beyond 2TE was 51% driven by reductions in blood pressure (45%) and waist circumference (48%). Blood lipids and glucose response were only 21% and 16% (participants improving beyond 2TE). Sixty percent of individuals that improved MetS <i>z</i> score, also improved VO_2PEAK (r=-0.013; P=0.86) while 85% of individuals improving MetS <i>z</i> score also improved W_PEAK (r=0.151; P=0.03). In summary, health providers can expect that a 16- week HIIT program would indisputably improve MetS in approximately 50% of individuals completing the program. Lastly, W_PEAK better predicts which individuals would improve MetS than VO_2PEAK when the direct assessment of the five MetS factors is not feasible.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142716127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}