Journal of applied physiology最新文献

{"title":"Leg blood flow during exercise with blood flow restriction: evidence for and implications of compensatory cardiovascular mechanisms.","authors":"Stuart P S Mladen, Stacey P A Forbes, Abby K Zedic, Vaughn S England, Patrick J Drouin, Michael E Tschakovsky","doi":"10.1152/japplphysiol.00772.2024","DOIUrl":"10.1152/japplphysiol.00772.2024","url":null,"abstract":"<p><p>Proximal limb cuff inflation to 40% arterial occlusion pressure (AOP) is assumed to reduce exercising leg perfusion, creating \"blood flow restriction\" (BFR). However, no study has validated this assumption. Eighteen healthy young participants (9 F) performed two-legged knee flexion/extension exercise at 25% WR_peak with bilateral cuffs applied to the proximal thigh at 0% AOP (CTL), 20% AOP, and 40% AOP. Leg blood flow (LBF; Doppler and echo ultrasound) and cardiac output (CO; finger photoplethysmography) were measured during rest and exercise. LBF values were doubled to account for both exercising legs. AOP (20% and 40%) reduced exercising LBF in a dose-response manner (<i>P</i> < 0.01). However, the magnitude of the leg blood flow restriction by 40% AOP was progressively attenuated across the exercise bout (5-15 s: 37%, 50-70 s: 20%, 240-300 s: 16%; <i>P</i> < 0.01) due to compensatory increases in leg vascular conductance (LVC) (<i>P</i> < 0.01). Between 5 and 15 s of exercise, 40% AOP significantly reduced CO compared with CTL and 20% AOP (8.0 ± 1.3 vs. 8.4 ± 1.5 L/min, <i>P</i> < 0.001 and 8.5 ± 1.5, <i>P</i> < 0.001). By 240-300 s, there were no significant differences in CO between cuff pressures (all <i>P</i> > 0.13). Pneumatic cuff inflation at 20% and 40% AOP reduces LBF in a dose-response manner, but this impairment was progressively attenuated across the exercise bout by an increase in LVC. Importantly, this compensatory response differed across participants, which may have implications for the degree of adaptations following BFR training. Furthermore, restoration of normal CO during BFR despite compromised limb perfusion suggests that other tissue perfusion is increased as part of the response.<b>NEW & NOTEWORTHY</b> It remained to be determined whether BFR set below 60% AOP impairs leg blood flow during continuous exercise. We showed that BFR at 20% and 40% AOP impairs exercising leg blood flow in a dose-response manner. However, the leg blood flow impairment was progressively attenuated across the exercise bout. Both initial compromise and partial restoration varied across participants, which may have implications for the degree of muscle adaptations following BFR training.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"492-507"},"PeriodicalIF":3.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143006008","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":"Spirometry estimation of central airway dysanapsis on computed tomography in healthy subjects without active lung diseases.","authors":"Takafumi Shimada, Naoya Tanabe, Fumi Mochizuki, Hiroaki Iijima, Kaoruko Shimizu, Shotaro Chubachi, Kazuya Tanimura, Susumu Sato, Toyohiro Hirai, Nobuyuki Hizawa","doi":"10.1152/japplphysiol.00765.2024","DOIUrl":"10.1152/japplphysiol.00765.2024","url":null,"abstract":"<p><p>The original concept of the airway-to-lung size mismatch, termed dysanapsis, was introduced on spirometry and was extended by computed tomography (CT) evaluation of the central airways. CT-assessed dysanapsis allows a risk estimation of lung disease development in healthy subjects, although radiation exposure limits its use, particularly for younger subjects. This study investigated which spirometry indices can be used to estimate CT-assessed central airway dysanapsis in healthy subjects. In consecutive lung cancer screening subjects without active lung diseases, the dysanapsis ratio (DR), forced mid-expiratory flow/forced vital capacity (FEF_25-75/FVC), forced expiratory volume in 1 s/FVC (FEV₁/FVC), and peak expiratory flow/FVC (PEF/FVC) were obtained via spirometry. The airway-to-lung size ratio for four locations, including the trachea, both main bronchi, and bronchus intermedius (ALR4), and for 14 locations, including the same four airways and 10 segmental and subsegmental airways (ALR14), were obtained via CT. According to the quartiles of the ALR14 or ALR4, 163 male and 190 female subjects were divided into four groups. CT-assessed dysanapsis was defined as the lowest quartile of the ALR14 (or ALR4). Among the spirometry indices, the area under the curve (AUC) for detecting the lowest ALR14 group was the highest for DR (0.80 and 0.78 for males and females, respectively). In contrast, the AUC for detecting the lowest ALR4 group was the highest for PEF/FVC (0.67 and 0.77 for males and females, respectively). DR and PEF/FVC on spirometry could be associated with CT-assessed dysanapsis, but the associations varied depending on the airway locations used for the ALR calculation.<b>NEW & NOTEWORTHY</b> The airway-to-lung size discrepancy on computed tomography (CT-assessed dysanapsis) highlights a lifelong risk for developing lung diseases. This study demonstrated that the spirometric index of the dysanapsis ratio can be used for estimating CT-assessed dysanapsis of the entire central airway tree from the trachea to subsegmental airways, whereas a novel index, peak expiratory flow/forced vital capacity (PEF/FVC), can be used for estimating CT-assessed dysanapsis of the extrapulmonary airways (the trachea, main bronchus, and bronchus intermedius).</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"483-491"},"PeriodicalIF":3.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143006024","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 differences in the maximal metabolic steady state of fitness-matched women and men.","authors":"Brad W Wilkins, Kathleen G Fisher, Emma F Flood, Logan J Heenan, Ian R Matthews","doi":"10.1152/japplphysiol.00655.2024","DOIUrl":"10.1152/japplphysiol.00655.2024","url":null,"abstract":"<p><p>We tested the hypothesis that power at maximal metabolic steady state is similar between fitness-matched men and women. Eighteen participants (9 men and 9 women) performed a cycling graded exercise test for maximal oxygen consumption (V̇o_2max). Men and women were matched for V̇o_2max normalized to fat-free mass (FFM), which was 50.4 ± 4.7 mL·min^-1·kg·FFM^-1 and 52.1 ± 8.2 mL·min^-1·kg·FFM^-1, respectively (<i>P</i> = 0.62). Participants completed a muscle oxygenation (%SmO₂) zero-slope prediction trial and a 3-min all-out trial (3MT). The %SmO₂ zero-slope trials included three, 5-min cycling bouts (30-s rest) spanning intensity domains. Linear regression of trial work rate and %SmO₂ slope over the final 3 min established the work rate occurring at the predicted zero slope in %SmO₂. The 3MT required cycling all-out until the word \"stop\" without providing time elapsed. End test power (ETP) was calculated as the mean power output over the last 30 s and work above end test power (WEP) as the power-time integral above ETP. Independent of method, means ± SD absolute power at the maximal metabolic steady state was similar between fitness-matched women and men (<i>P</i> = 0.72), yet became higher in women when expressed relative to FFM (<i>P</i> = 0.02). Furthermore, V̇o₂ at the power associated with %SmO₂ zero-slope represented a significantly higher fraction of V̇o_2max for women compared with men (<i>P</i> = 0.03). Normalized WEP (W/kg·FFM) remained higher in men (<i>P</i> < 0.01). Although highly correlated (<i>r</i> = 0.88, <i>P</i> < 0.01), ETP was ∼8% higher than %SmO₂ zero-slope power (<i>P</i> = 0.03). Compared with fitness-matched men, women displayed higher FFM normalized power associated with the heavy-severe exercise domain boundary. When matched for fitness, women have a higher power associated with the heavy-severe domain boundary compared with men, when expressed relative to FFM. This exercise intensity also represents a higher fraction of maximal oxygen uptake for women; suggesting women can sustain a higher relative V̇o₂ compared with men. Power at the heavy-severe domain boundary, in both sexes, was lower using muscle oxygenation-derived slope methods compared with 3-min all-out determinations.<b>NEW & NOTEWORTHY</b> When matched for fitness, women have a higher power associated with the heavy-severe domain boundary compared with men, when expressed relative to FFM. This exercise intensity also represents a higher fraction of maximal oxygen uptake for women; suggesting women can sustain a higher relative V̇o₂ compared with men. Power at the heavy-severe domain boundary, in both sexes, was lower using muscle oxygenation derived slope methods compared with 3-min all-out determinations.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"612-622"},"PeriodicalIF":3.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143006020","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":"Timing of resistance exercise and cardiometabolic outcomes in adults with prediabetes: a secondary analysis.","authors":"Jason V Thomas, Brenda M Davy, Richard A Winett, Christopher M Depner, Micah J Drummond, Paul A Estabrooks, Sheetal Hardikar, Zhining Ou, Jincheng Shen, Tanya M Halliday","doi":"10.1152/japplphysiol.00507.2024","DOIUrl":"10.1152/japplphysiol.00507.2024","url":null,"abstract":"<p><p>The objective of this study was to explore whether the time of day (AM vs. PM) resistance exercise is performed influences glucose and insulin concentrations, body composition, and muscular strength in adults with prediabetes. A secondary data analysis was conducted using data from the \"Resist Diabetes\" study, a phase II exercise intervention. Participants (age: 59.9 ± 5.4 yr; BMI: 33 ± 3.7 kg/m²) with prediabetes and overweight or obesity were categorized into AM (<i>n</i> = 73) or PM (<i>n</i> = 80) exercisers based on when they completed all of their supervised exercise sessions during a 12-wk, 2×/wk resistance exercise intervention. Blood glucose and insulin derived from oral glucose tolerance tests, body composition, and muscular strength were assessed pre- and post resistance exercise training. Inverse propensity score weighting approach was used to estimate the efficacy of AM versus PM exercise on the change of clinical responses. Paired samples <i>t</i> test was used to compare pre-/post-outcomes within AM and PM groups. No differences between AM and PM exercisers were detected in the change in glucose or insulin area under the curve (AUC), body composition, or muscular strength. When exploring within-group changes, PM exercisers reduced glucose AUC (change: -800.6 mg/dL·120 min; <i>P</i> = 0.01), whereas no significant change was detected for AM exercisers (change: -426.9 mg/dL·120 min; <i>P</i> = 0.26). Only AM exercisers increased fat-free mass (change: 0.6 kg; <i>P</i> = 0.001). The time of day resistance exercise is performed may have some impact on glucose concentrations and body composition response. Future randomized clinical trials are needed to understand how exercise timing influences cardiometabolic outcomes in at-risk adults.<b>NEW & NOTEWORTHY</b> In this secondary analysis, there was no difference between AM and PM exercisers in blood glucose, insulin, body composition, or muscular strength following 12 wk of supervised exercise. However, examining within-group changes, glucose area under the curve (AUC) was significantly reduced in PM exercisers, but not in AM exercisers.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"439-449"},"PeriodicalIF":3.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142949329","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":"Oxidative stress suppresses internal carotid artery dilation to hypercapnia in healthy older adults.","authors":"Kaitlin A Freeberg, Narissa P McCarty, Michel Chonchol, Douglas R Seals, Daniel H Craighead","doi":"10.1152/japplphysiol.00322.2024","DOIUrl":"10.1152/japplphysiol.00322.2024","url":null,"abstract":"<p><p>Cerebrovascular disease and dementia risk increases with age, and lifetime risk is greater in women. Cerebrovascular dysfunction likely precedes cerebrovascular disease and dementia but the mechanisms are incompletely understood. We hypothesized that oxidative stress mediates cerebrovascular dysfunction with human aging. Internal carotid artery dilation (ICA_CO2 dilation) and middle cerebral artery cerebrovascular reactivity (MCA CVR_CO2) in response to hypercapnia (5% CO₂) were measured in 20 young [10 F/10 M; age 23 ± 3 yr (means ± SD)] and 21 older (11 F/10 M; age 69 ± 9 yr) adults during intravenous infusions of saline (control) and vitamin C (acutely reduced oxidative stress condition). ICA_CO2 dilation increased in response to vitamin C infusion in older adults (saline = 4.3 ± 2.4%; vitamin C = 6.7 ± 3.3%) but was unchanged in young adults (saline = 6.1 ± 2.7%; vitamin C = 5.5 ± 1.9%) (group × condition: <i>P</i> = 0.004). MCA CVR_CO2 was not different in response to vitamin C in either group (group × condition: <i>P</i> = 0.341). However, when separated by sex, older female participants exhibited increased MCA CVR_CO2 with vitamin C (saline = 0.85 ± 0.79 cm/s/mmHg; vitamin C = 1.33 ± 1.01 cm/s/mmHg) compared with older male participants (saline = 1.21 ± 0.57 cm/s/mmHg; vitamin C = 0.99 ± 0.47 cm/s/mmHg) (sex × condition: <i>P</i> = 0.011). Oxidative stress selectively impairs cerebrovascular function in older adults in an artery- and sex-specific manner.<b>NEW & NOTEWORTHY</b> This study is the first to report oxidative stress-mediated suppression of cerebrovascular reactivity to hypercapnia in the internal carotid artery in older compared with young adults. Overall, these in vivo findings identify oxidative stress as an important pathophysiological contributor to cerebrovascular aging in humans, highlighting the need to identify novel interventions that can reduce oxidative stress in the aging population.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"536-545"},"PeriodicalIF":3.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143006014","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":"Running in the heat similarly reduces lipid oxidation and peak oxygen consumption in trained runners and inactive individuals.","authors":"Loïs Mougin, Heather Z Macrae, Alisha Henderson, Thomas G Cable, Lee Taylor, Lewis J James, Stephen A Mears","doi":"10.1152/japplphysiol.00710.2024","DOIUrl":"10.1152/japplphysiol.00710.2024","url":null,"abstract":"<p><p>This study compared oxygen consumption and substrate oxidation while exercising in hot and temperate conditions in individuals with different physical activity statuses (i.e., inactive individuals vs. trained runners). Ten inactive individuals (IA: 26 ± 6 yr; 79.1 ± 14.1 kg; 40.7 ± 5.1 mL·kg^-1·min^-1) and 10 trained runners (TR: 25 ± 6 yr; 69.5 ± 9.1 kg; 63.1 ± 5.1 mL·kg^-1·min^-1) completed two incremental exercise tests (4-min stages) until exhaustion in temperate (TEMP: 18.7 ± 0.1°C; 43.2 ± 4.1% relative humidity) and hot (HOT: 34.4 ± 0.2°C and 42.6 ± 1.6% relative humidity) conditions. Expired gas and blood lactate concentrations were measured at the end of each stage. Peak oxygen consumption similarly decreased in HOT compared with TEMP for IA and TR [-13.2 ± 4.5% vs. -15.2 ± 7%; <i>P</i> = 0.571; effect size (ES) = 0.25]. In HOT compared with TEMP, lipid oxidation, from 30% to 70% of peak oxygen consumption (V̇o_2peak), was reduced for both groups (IA: <i>P</i> = 0.023, ES = 0.43; TR: <i>P</i> < 0.001, ES = 0.72), whereas carbohydrate oxidation was increased for TR (<i>P</i> = 0.011; ES = 0.45) but not for IA (<i>P</i> = 0.268; ES = 0.21). Core temperature was different between conditions for TR (higher in HOT, <i>P</i> = 0.017; ES = 0.66) but not for IA (<i>P</i> = 0.901; ES = 0.25). Despite reduced physiological capacities in IA, both populations demonstrated reductions in lipid utilization and peak oxygen consumption in hot compared with temperate conditions. However, the increased carbohydrate oxidation in HOT for TR was not observed in IA, potentially explained by lower thermal strain. <b>NEW & NOTEWORTHY</b> This study shows that lipid oxidation and oxygen consumption are similarly affected by heat exposure in trained runners and inactive individuals. Carbohydrate oxidation and core temperature are greater in hot conditions in trained runners but not in inactive individuals. A lower metabolic heat production in inactive individuals for a similar relative intensity compared with trained runners could explain these differences in core temperature.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"508-517"},"PeriodicalIF":3.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143039005","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":"Changes in H-reflex, V-wave, and contractile properties of the plantar flexors following concurrent exercise sessions-the acute interference effect.","authors":"Miguel Gomes, André D Gonçalves, Pedro Pezarat-Correia, Goncalo V Mendonca","doi":"10.1152/japplphysiol.00680.2024","DOIUrl":"10.1152/japplphysiol.00680.2024","url":null,"abstract":"<p><p>The interaction between muscle strength and endurance impacts athletic performance. Integrating both modalities into concurrent exercise (CE) is challenging due to the interference effect. This study explored the acute effects of resistance-only (R), endurance-only (E), and CE sessions on voluntary muscle strength, evoked neurophysiological parameters, and contractile properties of the plantar flexors. We also explored whether the sequence of CE (E-R vs. R-E) affects these parameters. Ten males (23.5 ± 2.4 yr) experienced in resistance and endurance training underwent neuromuscular baseline assessments, including plantarflexion maximal voluntary isometric contraction (MVIC) and soleus evoked responses (M-wave, H-wave, V-wave, evoked octet, and twitch contractile properties). Then, participants completed four different exercise sessions in a randomized manner (e.g., E, R, E-R, and R-E), separated by 72 h. Exercise sessions were immediately followed by the same assessments completed at baseline. MVIC and the rate of torque development (RTD) were reduced after all sessions. The E session induced a greater decrease in RTD compared with R. Although the V-wave amplitude decreased after all sessions, the electromyographic activity of the soleus muscle remained unchanged during MVIC. The normalized amplitude of the H-reflex was reduced after E and both CE sessions. The gain of the H-reflex ascending limb (H_slope) exhibited a larger decrease after CE, irrespectively of exercise sequence. The twitch contractile properties were similarly impaired after all sessions. The E session induced a larger reduction of the evoked octet response. These findings provide new insights into the neuromuscular etiology of the acute interference effect resulting from CE.<b>NEW & NOTEWORTHY</b> All exercise modalities reduced maximal isometric strength; however, endurance exercise led to greater decreases in the rate of torque development. Resistance exercise negatively impacted supraspinal central neural drive, whereas both endurance and concurrent exercise significantly impaired spinal motoneuron responsiveness. Endurance and concurrent exercise also significantly reduced twitch contractile properties and evoked octet responses, with the most pronounced impairments observed following endurance-only exercise.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"327-341"},"PeriodicalIF":3.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142894689","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: toward 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":"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 <i>P</i> < 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 <i>P</i> < 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.<b>NEW & NOTEWORTHY</b> This is the first model of inert gas transport based on the physiology of respiratory gas. It was built for O₂ delivery and validated against literature data; it was then transposed to N₂ exchanges. The transposition procedure was checked by transposing the N₂ model to CO₂ (and validated against literature data). This model opens the possibility to integrate physiological and morphological inputs in a personalized decompression procedure in SCUBA diving.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"342-357"},"PeriodicalIF":3.3,"publicationDate":"2025-02-01","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":"Ketone monoester ingestion improves cardiac function in adults with type 2 diabetes: a double-blind, placebo-controlled, randomized, crossover trial.","authors":"M Perissiou, Z L Saynor, K Feka, C Edwards, T J James, J Corbett, H Mayes, J Shute, M Cummings, M I Black, W D Strain, J P Little, A I Shepherd","doi":"10.1152/japplphysiol.00800.2024","DOIUrl":"10.1152/japplphysiol.00800.2024","url":null,"abstract":"<p><p>Type 2 diabetes (T2D) is a metabolic disease associated with cardiovascular dysfunction. The myocardium preferentially uses ketones over free fatty acids as a more energy-efficient substrate. The primary aim was to assess the effects of ketone monoester (K_me) ingestion on cardiac output index ([Formula: see text]i). The secondary aims were to assess the effects of K_me ingestion on markers of cardiac hemodynamics, muscle oxygenation, and vascular function at rest, during and following step-incremental cycling. We undertook a double-blind, randomized, crossover design study in 13 adults [age, 66 ± 10 yr; body mass index (BMI), 31.3 ± 7.0 kg·m^-2] with T2D. Participants completed two conditions, where they ingested a K_me (0.115 g·kg^-1) or a placebo taste-matched drink. Cardiac function was measured using thoracic impedance cardiography, and muscle oxygenation of the calf was determined via near-infrared spectroscopy. Macrovascular endothelial function was measured by flow-mediated dilation (FMD), and microvascular endothelial function was measured via transdermal delivery of acetylcholine (ACh) and insulin. Circulating β-hydroxybutyrate [β-Hb] was measured throughout. K_me ingestion raised circulating β-Hb throughout the protocol (peak 1.9 mM; <i>P</i> = 0.001 vs. placebo). K_me ingestion increased [Formula: see text]i by 0.75 ± 0.5 L·min^-1·m^-2 (<i>P</i> = 0.003), stroke volume index by 7.2 ± 4.5 mL·m^-2 (<i>P</i> = 0.001), and peripheral muscle oxygenation by 9.9 ± 7.1% (<i>P</i> = 0.001) and reduced systemic vascular resistance index by -420 ± -225 dyn·s^-1·cm^-5·m^-2 (<i>P</i> = 0.031) compared with the placebo condition. There were no differences between K_me and placebo in heart rate (<i>P</i> = 0.995), FMD (<i>P</i> = 0.542), ACh max (<i>P</i> = 0.800), and insulin max (<i>P</i> = 0.242). Ingestion of K_me improved [Formula: see text], stroke volume index, and peripheral muscle oxygenation but did not alter macro- or microvascular endothelial function in people with T2D.<b>NEW & NOTEWORTHY</b> For the first time, we show that acute ketone monoester ingestion (K_me) can increase cardiac output and stroke volume and reduce systemic vascular resistance at rest and during exercise in sodium glucose transporter inhibitors naïve (i.e. no drug-induced ketosis) people with type 2 diabetes. Acute K_me ingestion improves peripheral skeletal muscle oxygenation during moderate intensity and maximal exercise. K_me has no effect on macro- or microvascular endothelial function in people with type 2 diabetes.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"546-558"},"PeriodicalIF":3.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143006006","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":"Dilatory responsiveness of the internal carotid artery to shear stimulus is constant under different levels of transient hypercapnia.","authors":"Rintaro Sakamoto, Tatsuki Kamoda, Shigehiko Ogoh, Kohei Sato, Masaki Katayose, Toru Neki, Erika Iwamoto","doi":"10.1152/japplphysiol.00774.2024","DOIUrl":"10.1152/japplphysiol.00774.2024","url":null,"abstract":"<p><p>Peripheral endothelial function, which accounts for the variability in shear stimulus, can be assessed using shear-mediated dilation normalized to the increased shear stimulus. Similarly, shear-mediated dilation of the internal carotid artery (ICA), an index of cerebrovascular endothelial function, should be normalized to increased shear stimulus. However, this approach has not yet been validated. Thus, the shear-mediated dilation of the ICA was assessed in 14 young adults during three levels of transient hypercapnia, induced by elevating the partial pressure of end-tidal carbon dioxide for 30 s by 6, 9, and 12 mmHg. The ICA shear rate (SR) was calculated using the ICA diameter and velocity, both measured by Doppler ultrasound. The total vasodilator stimulus was quantified as the SR area under the curve from the onset of hypercapnia to peak dilation, including and excluding baseline values [(SR_AUC) and delta SR_AUC (_DSR_AUC), respectively]. Shear-mediated dilation was calculated as the percent increase in diameter from baselines. ICA dilation was positively associated with _DSR_AUC [r_(rm) = 0.47, <i>P</i> < 0.01] but not with SR_AUC [r_(rm) = 0.32, <i>P</i> = 0.09]. Consequently, ICA dilation normalized to _DSR_AUC did not differ among trials (main effect of rial, <i>P</i> = 0.77). Contrarily, the difference in ICA dilation among trials remained significant when normalized to SR_AUC (main effect of trial, <i>P</i> = 0.02). Therefore, normalized shear-mediated dilation using _DSR_AUC can reduce variability associated with increased shear stimulus during ICA dilation assessment, thereby enhancing the validity of evaluating cerebrovascular endothelial function.<b>NEW & NOTEWORTHY</b> This study demonstrated that shear-mediated dilation of the internal carotid artery (ICA), an index of cerebrovascular endothelial function, increased with the increase of shear stimulus induced by different degrees of transient hypercapnia. However, when ICA dilation was normalized to the total increased shear stimulus above baseline, the vasodilation became comparable across different hypercapnia levels. Thus, normalizing ICA dilation to the total shear stimulus increased from baseline may enhance the validity of assessing cerebrovascular endothelial function.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"397-403"},"PeriodicalIF":3.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142894704","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}