Journal of applied physiology最新文献

{"title":"An acute bout of 4 × 4-min or 10 × 1-min HIIT improves β cell glucose sensitivity in postmenopausal females with type 2 diabetes: a secondary analysis.","authors":"J L Low, A Marcotte-Chénard, R Tremblay, H Islam, K Falkenhain, W M Mampuya, A Mari, A M McManus, E Riesco, J P Little","doi":"10.1152/japplphysiol.00777.2024","DOIUrl":"10.1152/japplphysiol.00777.2024","url":null,"abstract":"<p><p>Improvements in glycemic control following acute exercise are typically attributed to improved postexercise insulin sensitivity (IS) with comparatively little known about how acute exercise impacts β cell function, especially in postmenopausal females. We determined how two high-intensity interval training (HIIT) protocols, matched for total estimated energy expenditure, impact β cell function in postmenopausal females with type 2 diabetes. Thirteen postmenopausal females (70 ± 5 yr; 12 ± 7 yr since diagnosis, 80.9 ± 13.8 kg, 32.4 ± 5.6 kg·m²; HbA1c-49.8 ± 10.3 mmol/mol [6.7 ± 1.0]) living with type 2 diabetes were included in this semirandomized crossover trial. The trial involved an initial resting control condition followed by two HIIT conditions [4 × 4-min HIIT (HIIT4) and 10 × 1-min HIIT (HIIT10)] completed in a randomized order 2-4 days apart. β cell function (glucose sensitivity) and insulin sensitivity were determined from a 2-h mixed-meal tolerance test performed 2 h after rest or HIIT. Both HIIT4 and HIIT10 significantly improved β cell glucose sensitivity compared with control (15 pmol/min/m²/[mmol/L], [95% confidence interval (CI) 6, 23]; <i>P</i> = 0.002 and 16 pmol/min/m²/[mmol/L], [95% CI 7, 25]; <i>P</i> = 0.002, respectively), with no difference between HIIT protocols (1 [-8, 10], <i>P</i> = 0.79). There were no significant differences in IS metrics (Matsuda index, OGIS, Stumvoli, and QUICKI) between the conditions. An acute bout of 4 × 4-min or 10 × 1-min HIIT improves β cell glucose sensitivity in postmenopausal females living with type 2 diabetes. ClinicalTrials.gov: NCT04986345.<b>NEW & NOTEWORTHY</b> This is the first study to explore the effects of acute high-intensity interval training (HIIT) on β cell function in postmenopausal women with type 2 diabetes. Our crossover trial compares two HIIT protocols, matched for total estimated energy expenditure, examining their impacts on β cell function and insulin sensitivity. Despite the absence of an insulin-sensitizing effect, we show robust effects of HIIT on β-cell function, including an improvement in β-cell glucose sensitivity.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"311-317"},"PeriodicalIF":3.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142853862","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":"Flow-mediated dilation decreases in women, but not men, following mild acute intermittent hypoxia.","authors":"Sara E Mascone, Jacqueline K Limberg, Emily F Blake, Cynthia M Weiner, Lauren E Eagan, Shannon E Khan, Sushant M Ranadive","doi":"10.1152/japplphysiol.00513.2024","DOIUrl":"10.1152/japplphysiol.00513.2024","url":null,"abstract":"<p><p>Acute, intermittent exposure to mild hypoxia increases sympathetic nervous system activity, decreases arterial shear rate, and increases blood pressure (BP) in young men. Given that the BP-raising effects of intermittent hypoxia (IH) are less evident in young women, we sought to examine the influence of sex on macro- and microvascular function following IH. BP, macrovascular function [brachial artery flow-mediated dilation (FMD)], microvascular function [reactive hyperemia area under the curve (RHAUC)], and brachial artery shear rate [shear rate area under the curve (SRAUC)] were measured before and following 30 min of IH in 18 young adults (8 women, 23 ± 5 yr). IH elicited an average nadir blood oxygen saturation ([Formula: see text]) of 92 ± 3% (<i>P</i> < 0.0001 vs. baseline). In men, brachial systolic (bSBP; 116 ± 6 to 122 ± 7 mmHg, <i>P</i> = 0.001) and diastolic (bDBP; 116 ± 6 to 122 ± 7 mmHg, <i>P</i> = 0.001) BPs increased from baseline following IH. bSBP (110 ± 8 to 111 ± 7 mmHg, <i>P</i> = 0.67) and bDBP (64 ± 7 to 68 ± 7 mmHg, <i>P</i> = 0.12) were unchanged in women after IH. Men maintained macrovascular function after IH (ΔFMD: 0.75 ± 2.44%), whereas women exhibited a decline (ΔFMD: -3.09 ± 2.64%, <i>P</i> = 0.006 vs. men). Microvascular function and shear rate declined following IH independent of sex (RHAUC: 597 ± 306 to 467 ± 205 mL/min, <i>P</i> = 0.049; SRAUC: 1772 ± 907 to 1439 ± 596 s^-1, <i>P</i> = 0.040). Acute mild IH increases BP in healthy men but not women. In women, both micro- and macrovascular functions are lower following acute mild IH; in contrast, only microvascular function is lower in men. The sex-specific effects of IH on BP and macrovascular function may have important implications for the potential beneficial effects of IH.<b>NEW & NOTEWORTHY</b> The present study aimed to investigate the influence of sex on vascular responses to 30 min of acute, mild intermittent hypoxia. Men and women exhibited similar decreases in arterial shear rate and microvascular function after intermittent hypoxia. Although men exhibited increases in blood pressure but no changes in macrovascular function, women exhibited significant decreases in macrovascular function despite no changes in blood pressure. Sex may influence the potential hormetic effects of intermittent hypoxia.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"99-106"},"PeriodicalIF":3.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11918295/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142828540","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":"Multidimensional assessment of exertional dyspnea in young healthy males and females who select unsatisfied inspiration at peak exercise.","authors":"Reid A Mitchell, Alanna S Hind, Olivia N Ferguson, Morgan Flynn, Jem I Arnold, Satvir S Dhillon, Neil D Eves, A William Sheel, Jordan A Guenette","doi":"10.1152/japplphysiol.00420.2024","DOIUrl":"10.1152/japplphysiol.00420.2024","url":null,"abstract":"<p><p>Historically, it was thought that healthy humans predominantly described their breathing as a sense of increased work or effort (W/E) during maximal exercise. However, emerging data show that many healthy adults select unpleasant dyspnea descriptors such as \"unsatisfied inspiration\" (UI), with relatively more females selecting UI than males. We hypothesized that males and females who select UI would report higher dyspnea intensity ratings during exercise, select more distressing dyspnea qualities post exercise, and have greater inspiratory constraints than those who do not. Sixty-four healthy, nonsmokers (32 males:32 females; 23 ± 5 yr) completed questionnaires, pulmonary function tests, and maximal incremental cycling with detailed dyspnea evaluation. Males in UI and non-UI subgroups reported similar Borg 0-10 dyspnea intensity ratings of W/E, UI, and unsatisfied expiration (UE) (all <i>P</i> > 0.05). Females in the UI subgroup reported significantly higher UI and UE ratings than females in the non-UI subgroup (both <i>P</i> < 0.01). Both UI subgroups reported greater air hunger, chest tightness, and mental breathing effort than non-UI participants (all <i>P</i> < 0.05). In males only, masculine gender was negatively correlated (ρ = -0.402, <i>P</i> = 0.02) and anxiety positively correlated (ρ = 0.363, <i>P</i> = 0.04) with submaximal UI ratings. Females with UI had smaller peak tidal volume (Vt) [1.74 (0.32) vs. 2.06 (0.33) L, <i>P</i> = 0.03] than non-UI females; and Vt was negatively correlated with submaximal (ρ = -0.496, <i>P</i> = 0.004) and peak (ρ = -0.495, <i>P</i> = 0.004) UI ratings in all females. There were no differences in Vt or correlations between Vt and dyspnea in male subgroups. Absolute lung volumes and psychosocial factors appear important in understanding sex differences in the perception of UI during exercise.<b>NEW & NOTEWORTHY</b> The mechanisms of sex-based differences in the sensation of unsatisfied inspiration (UI) in healthy humans during exercise are poorly understood. We found that females who selected UI at peak exercise had worse dyspnea intensity ratings throughout exercise. Both sexes who selected UI at peak exercise also reported more distressing dyspnea qualities post exercise. Psychosocial factors appeared to influence male dyspnea perception, whereas smaller absolute lung volumes correlated with worse UI ratings in females.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"73-88"},"PeriodicalIF":3.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142769267","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":"Myonuclear and satellite cell content of the vastus lateralis and soleus with 70 days of simulated microgravity and the NASA SPRINT exercise program.","authors":"Chad M Skiles, Gerard Boyd, Aaron Gouw, Ethan Robbins, Kiril Minchev, Jeffrey Ryder, Lori Ploutz-Snyder, Todd A Trappe, Scott Trappe","doi":"10.1152/japplphysiol.00468.2024","DOIUrl":"10.1152/japplphysiol.00468.2024","url":null,"abstract":"<p><p>We previously observed a range of whole muscle and individual slow and fast myofiber size responses (mean: +4 to -24%) in quadriceps (vastus lateralis) and triceps surae (soleus) muscles of individuals undergoing 70 days of simulated microgravity with or without the NASA SPRINT exercise countermeasures program. The purpose of the current investigation was to further explore, in these same individuals, the content of myonuclei and satellite cells, both of which are key regulators of skeletal muscle mass. Individuals completed 6° head-down-tilt bedrest (BR, <i>n</i> = 9), bedrest with resistance and aerobic exercise (BRE, <i>n</i> = 9), or bedrest with resistance and aerobic exercise and low-dose testosterone (BRE + T, <i>n</i> = 8). The number of myonuclei and satellite cells associated with each slow [myosin heavy chain (MHC) I] and fast (MHC IIa) myofiber in the vastus lateralis was not changed (<i>P</i> > 0.05) pre- to postbedrest within the BR, BRE, or BRE + T groups. Similarly, in the soleus, the number of myonuclei associated with each slow and fast myofiber, and the number of satellite cells associated with each slow myofiber were not changed (<i>P</i> > 0.05) pre- to postbedrest within the BR, BRE, or BRE + T groups. It appears that even with relatively large perturbations in muscle mass over a few months of simulated microgravity, or with partially or completely effective exercise countermeasures, human skeletal muscle tightly regulates the abundance of myonuclei and satellite cells. Thus, exercise countermeasures efficacy for skeletal muscle atrophy appears to be independent of myonuclei and satellite cell abundance.<b>NEW & NOTEWORTHY</b> This study showed that after 70 days of simulated microgravity, human skeletal muscle does not alter the number of nuclei or satellite cells associated with slow or fast myofibers in the two muscle groups most negatively influenced by microgravity exposure [i.e., quadriceps (vastus lateralis) and triceps surae (soleus)]. Furthermore, the efficacy of exercise countermeasures for maintaining the mass of these muscles does not appear to be related to the myocellular content of nuclei or satellite cells.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"195-202"},"PeriodicalIF":3.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142800875","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":"An IL-6 promoter variant (-174 G/C) augments IL-6 production and alters skeletal muscle transcription in response to exercise in mice.","authors":"L E Watson, C L MacRae, P Kallingappa, Y Cao, X Li, C P Hedges, R F D'Souza, N Fleming, K M Mellor, T L Merry","doi":"10.1152/japplphysiol.00391.2024","DOIUrl":"10.1152/japplphysiol.00391.2024","url":null,"abstract":"<p><p>Interleukin-6 (IL-6) is produced and secreted by skeletal muscle cells during exercise and plays an important role in mediating metabolic responses to exercise. The promoter region of the IL-6 gene contains a common genetic variant (-174 G/C, rs1800795), which may alter responses to exercise training. To isolate the impact of this gene variant on exercise-induced IL-6 expression and skeletal muscle transcription responses following exercise, we generated knock-in mice with a GG or variant CC genotype for the murine homolog of rs1800795. The overall gross metabolic phenotype of resting mice was similar between genotypes; however, following acute treadmill running, the variant CC genotype was associated with a greater increase in skeletal muscle <i>Il6</i> mRNA and circulating IL-6. Furthermore, we observed that mice with the variant CC genotype exhibited sex-specific differences in skeletal muscle master metabolism regulatory genes and had greater increases in genes controlling mitochondrial biogenesis in skeletal muscle post exercise. However, there was no effect of genotype on exercise-induced skeletal muscle glycogen depletion, circulating free fatty acids, blood glucose and lactate production, or exercise-responsive gene expression in subcutaneous fat. These findings suggest that the IL-6 promoter variant -174 G/C may result in enhanced skeletal muscle adaptations in response to exercise training and could mean that individuals with the \"C\" allele may more readily gain improvements in metabolic health in response to exercise training.<b>NEW & NOTEWORTHY</b> Interleukin-6 (IL-6) is produced and secreted by skeletal muscle during exercise and mediates metabolic responses to exercise. A common variant in the IL-6 promoter region (-174G/C) may alter responses to exercise training. Mice with the variant \"CC\" genotype exhibited higher skeletal muscle IL-6 mRNA and circulating IL-6 levels post exercise, as well as altered skeletal muscle gene transcription. This suggests that this variant might enhance muscle adaptations to exercise, potentially benefiting metabolic health.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"213-225"},"PeriodicalIF":3.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142813285","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":"Quantification of the pulmonary vasculature in mice under chronic hypoxia with contrast-free pulmonary angiography in vivo imaging.","authors":"Samar Farha, Evan Madden, Dylan Trotter, Violetta Zlojutro, Jason P Kirkness, Andreas Fouras, Serpil Erzurum, Kewal Asosingh","doi":"10.1152/japplphysiol.00279.2024","DOIUrl":"10.1152/japplphysiol.00279.2024","url":null,"abstract":"<p><p>Innovative advancements in preclinical imaging have led to the development of cone-beam computed tomography (CBCT) combined with contrast-free pulmonary angiography (CFPA), a novel lung scanning technology capable of assessing lung function and pulmonary vascular morphology. This cutting-edge approach integrates CBCT to provide detailed quantification of the pulmonary vascular tree. The application of this technique to image and quantify changes in the pulmonary vascular tree of mice exposed to chronic hypoxia has not been investigated. In this study, we investigated the feasibility of utilizing CFPA for imaging changes in the murine lung vascular bed under chronic hypoxia and assessed whether vascular metrics correlate with hematologic parameters and/or right ventricular pressure and mass. Our results revealed a significant increase in hemoglobin and total pulmonary vascular blood volume, as well as total pulmonary vessel length following exposure to chronic hypoxia. The pulmonary vascular blood volume and total vessel length strongly correlated with hemoglobin. There was also an increase in pulmonary arterial pressure and right ventricular mass under hypoxia that was linked to the hematological response and the changes in the pulmonary vascular bed. These findings highlight the application of preclinical CBCT and CFPA imaging as a valuable tool for visual and quantitative analysis of the pulmonary vasculature in preclinical models of chronic hypoxia and its potential use in investigating other pulmonary vasculopathies.<b>NEW & NOTEWORTHY</b> Cone-beam computed tomography (CBCT) combined with contrast-free pulmonary angiography (CFPA) is a novel lung scanning technology capable of assessing pulmonary vascular morphology in vivo in murine models.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"318-325"},"PeriodicalIF":3.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142882059","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":"Sex-related hypothalamic-pituitary-gonadal and hypothalamic-pituitary-adrenal axis adaptation during military training.","authors":"Robert M Gifford, Thomas J O'Leary, Rebecca L Knight, Sophie L Wardle, Craig L Doig, Richard A Anderson, Julie P Greeves, Rebecca M Reynolds, David R Woods","doi":"10.1152/japplphysiol.00691.2024","DOIUrl":"10.1152/japplphysiol.00691.2024","url":null,"abstract":"<p><p>Reproductive endocrine function adapts to psychological, environmental, and energy-associated stressors. Multistressor environments upregulate hypothalamic-pituitary-adrenal (HPA) axis, causing suppression of the hypothalamic-pituitary-gonadal (HPG) axis, but it is not known if this pattern or its magnitude is sex biased. We compared HPG and HPA axis activity in 9 men and 34 women undergoing Army training. One-hour low-dose gonadorelin and Synacthen tests were conducted at 1 and 29 wk, measuring gonadotrophins and cortisol. Cortisol was measured from hair every 3 mo. Morning and evening salivary cortisol and psychometric questionnaires were measured at six timepoints. Sexes were compared over time by two-way ANOVA. Gonadotrophin responses were significantly higher in women than men in <i>week 1</i>, but no sex difference was seen at <i>week 29</i> (no significant sex × time interaction). <i>Week 1</i> cortisol response was higher among men, but <i>week 29</i> cortisol response was higher among women (sex × time <i>F</i>_(1,44) = 18.0, <i>P</i> < 0.001). Hair cortisol was higher among women than men beforehand, not different between sexes during the first 3 mo, and significantly higher among women during training <i>months 5</i>-<i>11</i> (<i>F</i>_(3,15) = 3.25, <i>P</i> = 0.024). Morning salivary cortisol was higher among women in <i>weeks 8</i> and <i>14</i>, but higher among men in <i>week 29</i> (<i>F</i>_(4,76) = 4.0, <i>P</i> = 0.005). No differences were seen in evening salivary cortisol. Psychometrics did not change or differ between sexes. HPA axis responses to military training were greater among women than men. HPG axis responses suggest greater downregulation among women. These findings will enable equitable and individualized management of people undergoing periods of intensive physical stress.<b>NEW & NOTEWORTHY</b> We conducted a comprehensive comparison of adrenal and reproductive function in men and women undergoing 11-mo military training. We found progressively elevated cortisol levels and dynamic cortisol response to stress among women, but not men, and suppression of reproductive function among women. The physiological impact of stressful military training was greater among women than men; this could not be explained by energy balance, and sex-specific effects of sleep, socio-ethnographic, or other stressors may be responsible.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"13-21"},"PeriodicalIF":3.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142728905","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":"Quantifying the time course of changes in maximal skin wettedness with 7 days of heat acclimation.","authors":"Grant P Lynch, Yorgi Mavros, Ollie Jay","doi":"10.1152/japplphysiol.00919.2023","DOIUrl":"10.1152/japplphysiol.00919.2023","url":null,"abstract":"<p><p>The aim of the present study was to quantify the time course of changes in maximum skin wettedness (ω_max)-that is, the proportion of skin surface area covered in sweat at the point of uncompensable heat stress, throughout seven consecutive days of heat acclimation. Nine adults (6 M, 3 F) completed a humidity-ramp protocol (RAMP) on <i>days 1</i>, <i>3</i>, <i>5</i>, and <i>7</i> of seven consecutive days of heat acclimation. In each RAMP trial, participants cycled continuously at 275 W·m^-2 for 120 min at 37°C: 60 min at a vapor pressure of 2.05 kPa followed by 60 min with vapor pressure increased by 0.045 kPa·min^-1. An upward inflection in esophageal temperature (T_eso) signaled a transition to uncompensable heat stress with the critical water vapor pressure at that point used to calculate ω_max. In days between RAMP assessments, participants cycled for 90 min at 75% HR_max at 37°C, 60% RH. T_eso, whole body sweat rate (WBSR), local sweat rates on the back and forearm (LSR_back and LSR_arm, respectively), and activated sweat gland density (ASGD) were measured throughout. ω_max was progressively and significantly greater from <i>day 1</i> (0.68 ± 0.10) to <i>day 3</i> (0.75 ± 0.10; <i>P</i> = 0.002), to <i>day 5</i> (0.79 ± 0.10; <i>P</i> = 0.004), and to <i>day 7</i> (0.87 ± 0.06; <i>P</i> = 0.009). WBSR was higher on <i>days 5</i> (1.11 ± 0.30 L·h^-1; <i>P</i> = 0.01) and <i>7</i> (1.12 ± 0.19 L·h^-1; <i>P</i> < 0.001) compared with <i>day 1</i> (0.94 ± 0.21 L·h^-1). ASGD was higher on <i>day 5</i> (78 ± 15 glands·cm^-2; <i>P</i> < 0.001) and <i>day</i> 7 (81 ± 17 glands·cm^-2; <i>P</i> = 0.001) compared with <i>day 1</i> (65 ± 12 glands·cm^-2). There were no observed differences in sweat gland output (<i>P</i> = 0.21). In conclusion, ω_max significantly increased throughout 7 days of heat acclimation. These progressive increases in ω_max were predominantly mediated by an increase in the number of active sweat glands, not the output per gland.<b>NEW & NOTEWORTHY</b> Significant increases in ω_max were observed as early as 3 days into a 7-day heat acclimation protocol. These data are the first to report dynamic changes in ω_max with progressive heat acclimation and provide new information about ω_max levels between the standard \"unacclimated\" and \"acclimated\" states in existing heat stress models.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"136-143"},"PeriodicalIF":3.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142667989","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":"Decreased cardio-respiratory information transfer is associated with deterioration and a poor prognosis in critically ill patients with sepsis.","authors":"Cecilia Morandotti, Matthew Wikner, Qijun Li, Emily Ito, Tope Oyelade, Calix Tan, Pin-Yu Chen, Anika Cawthorn, Watjana Lilaonitkul, Ali R Mani","doi":"10.1152/japplphysiol.00642.2024","DOIUrl":"10.1152/japplphysiol.00642.2024","url":null,"abstract":"<p><p>Assessing illness severity in the intensive care unit (ICU) is crucial for early prediction of deterioration and prognosis. Traditional prognostic scores often treat organ systems separately, overlooking the body's interconnected nature. Network physiology offers a new approach to understanding these complex interactions. This study used the concept of transfer entropy (TE) to measure information flow between heart rate (HR), respiratory rate (RR), and capillary oxygen saturation ([Formula: see text]) in critically ill patients with sepsis, hypothesizing that TE between these signals would correlate with disease outcome. The retrospective cohort study utilized the Medical Information Mart for Intensive Care III Clinical Database, including patients who met Sepsis-3 criteria on admission and had 30 min of continuous HR, RR, and [Formula: see text] data. TE between the signals was calculated to create physiological network maps. Cox regression assessed the relationship between cardiorespiratory network indices and both deterioration [Sequential Organ Failure Assessment (SOFA) score increase of ≥2 points at 48 h] and 30-day mortality. Among 164 patients, higher information flow from [Formula: see text] to HR [TE ([Formula: see text] → HR)] and reciprocal flow between HR and RR [TE (RR → HR) and TE (HR → RR)] were linked to reduced mortality, independent of age, mechanical ventilation, SOFA score, and comorbidity. Reductions in TE (HR → RR), TE (RR → HR), TE ([Formula: see text] → RR), and TE ([Formula: see text] → HR) were associated with an increased risk of 48-h deterioration. After adjustment for potential confounders, only TE (HR → RR) and TE (RR → HR) remained statistically significant. The study confirmed that physiological network mapping using routine signals in patients with sepsis could indicate illness severity and that higher TE values were generally associated with improved outcomes.<b>NEW & NOTEWORTHY</b> This study adopts an integrative approach through physiological network analysis to investigate sepsis, with the goal of identifying differences in information transfer between physiological signals in sepsis survivors versus nonsurvivors. We found that greater information flow between heart rate, respiratory rate, and capillary oxygen saturation was associated with reduced mortality, independent of age, disease severity, and comorbidities. In addition, reduced information transfer was linked to an increased risk of 48-h deterioration in patients with sepsis.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"289-300"},"PeriodicalIF":3.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142828500","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":"Detection and perception of inspiratory resistive loads in older adults with and without chronic obstructive pulmonary disease.","authors":"Isabella Epiu, David A T Nguyen, Claire L Boswell-Ruys, Simon C Gandevia, Jane E Butler, Anna L Hudson","doi":"10.1152/japplphysiol.00398.2024","DOIUrl":"10.1152/japplphysiol.00398.2024","url":null,"abstract":"<p><p>Impairments in the detection and perception of resistive loads in healthy aging and chronic obstructive pulmonary disease (COPD) have implications for airway protection and breathlessness. This study investigated load detection and perception in 18 participants with COPD, 17 older adults [i.e., age-matched controls (AMCs)] and 23 young adults [i.e., young controls (YCs)]. Load detection was assessed as the minimal change in airway resistance that could be detected and load perception as the perceived level of effort to breathe through a series of suprathreshold resistive loads, rated on a modified Borg scale. Young and older adults, with and without COPD, could detect similar changes in resistance (∼0.7 cmH₂O/L/s) and inspiratory pressure (∼0.5 cmH₂O), although this equated to a smaller proportion of predicted maximal inspiratory pressure (MIPpred) for young adults (∼0.5% MIPpred) compared with older adults with and without COPD (∼1.0% MIPpred; <i>P</i> < 0.001). For load perception, the relationship between Borg ratings and resistance was steeper in older adult controls compared with both young adults (<i>P</i> < 0.001) and older adults with COPD (<i>P</i> < 0.01). Borg rating slopes were comparable across all participant groups with changes in inspiratory pressure. There was no correlation between load detection threshold and load perception. In older adults, heightened perception of loaded breaths with large changes in breathing resistance may be due to an increased effort to breathe at these loads.<b>NEW & NOTEWORTHY</b> We demonstrated that young adults could detect a smaller change in pressure (as a proportion of predicted maximal inspiratory pressure) than older adults. The perceived effort to breathe with increases in the resistance of breathing was heightened in older, compared with young adults. There was no further impairment in chronic obstructive pulmonary disease. Heightened dyspnea perception related to the effort to breathe was not associated with load detection thresholds in older adults.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"250-258"},"PeriodicalIF":3.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142807150","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}