Journal of applied physiology最新文献

{"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":"Habitual preexercise caffeine supplementation prevents exercise training-induced attenuation of exercising systolic blood pressure and double product.","authors":"Kylee S West, Nate J Helwig, Laura E Schwager, Thomas W Hart, Anna C Zucker, Jacob S Venenga, Mark Flores, Nathaniel D M Jenkins","doi":"10.1152/japplphysiol.00874.2024","DOIUrl":"10.1152/japplphysiol.00874.2024","url":null,"abstract":"<p><p>We examined the effect of habitual preexercise caffeine supplementation on training-induced adaptations to exercising systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure (PP), heart rate (HR), and double product (DP). Young women (means ± SD; 24 ± 7 yr) were randomized to a caffeine (120 mg) supplement (CAF; <i>n</i> = 17) or placebo (PLA; <i>n</i> = 16) group, completed 6 wk of high-intensity exercise training on three nonconsecutive days per week, and supplemented with CAF or PLA 30-60 min before exercise or else upon waking. Before (PRE) and after (POST) the intervention, SBP, DBP, and HR were measured and PP and DP were calculated, at rest and during fixed-power exercise at 50 and 75 W. Statistical analyses included three-way mixed-factorial ANOVAs with post hoc comparisons as necessary. Group × intensity × time interactions were observed for SBP (<i>P</i> = 0.0105) and DP (<i>P</i> = 0.003). SBP and DP increased with increasing exercise intensity at PRE and POST in both groups. However, although SBP and DP decreased PRE to POST at 50 and 75 W in PLA, SBP and DP did not change at any intensity from PRE to POST in CAF. An intensity × time interaction was observed for DBP (<i>P</i> = 0.006) indicating no change in resting DBP, but reductions from PRE to POST at 50 and 75 W that were independent of group. Main effects of intensity (<i>P</i> < 0.0001) and time (<i>P</i> = 0.03) were observed for HR, and a main effect of intensity was observed for PP (<i>P</i> < 0.0001). Habitual caffeine supplementation blunted training-induced reductions in exercising SBP and DP. Individuals may wish to avoid preexercise supplementation if seeking to maximize the BP-lowering benefits of exercise.<b>NEW & NOTEWORTHY</b> Habitual preexercise caffeine consumption prevented reductions in exercising systolic blood pressure and double product induced by 6 wk of high-intensity exercise in women. Therefore, our findings indicate that habitual preexercise caffeine supplementation may impede beneficial hemodynamic adaptations of exercise training in healthy, young women.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"358-365"},"PeriodicalIF":3.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142894724","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":"A case report of the female world record holder 1500m to marathon in the 75+ age category.","authors":"Bas Van Hooren, Zoi Balamouti, Michele Zanini","doi":"10.1152/japplphysiol.00974.2024","DOIUrl":"https://doi.org/10.1152/japplphysiol.00974.2024","url":null,"abstract":"<p><p><b>Purpose:</b> This study assessed the cardiorespiratory fitness, running biomechanics, muscle architecture and training characteristics of a 76-year-old female runner who currently holds the world record 1500m to marathon in the women's 75-79 age category. <b>Methods:</b> maximal oxygen uptake (V̇O_2max), running economy (RE), lactate threshold (LT) and lactate turnpoint (LTP), maximal heart rate (HR_max), and running biomechanics were measured during a discontinuous treadmill protocol followed by a maximal incremental test. Muscle architecture was assessed using ultrasound. The testing was done in close proximity to her world record marathon performance in 2024. <b>Results:</b> V̇O_2max was 47.9 ml∙kg^-1∙min^-1, and HR_max was 180 beats∙min^-1. At marathon speed (11.9 km∙h^-1) her RE was 210 ml∙kg^-1.km^-1. Fractional utilisation corresponding to LT (11.1 km∙h^-1) and LTP (12.5 km∙h^-1) occurred at 83% and 92% of V̇O_2max, respectively. Fractional utilisation at marathon speed corresponded to 88% of V̇O_2max. Average weekly distance was 115 and 84 km∙w^-1 in the 6 weeks prior to the marathon world record and world-championships track (where she achieved 6 medals out of 6 events), respectively, with on average 90%, 9%, and 1% of training time performed in the moderate, heavy, and severe intensity domain, respectively. <b>Conclusion:</b> The 76-year-old female world-record holder 1500m to marathon showed the highest V̇O_2max ever recorded for a female >75 years old, a very high fractional utilization of V̇O_2max at LT, LTP, and at marathon pace, but RE was modest in comparison to other world-class master athletes and younger elite runners.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143039000","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":"Lois Mougin, Heather Z Macrae, Alisha Henderson, Thomas G Cable, Lee Taylor, Lewis J James, Stephen A Mears","doi":"10.1152/japplphysiol.00710.2024","DOIUrl":"https://doi.org/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 status (i.e., inactive individuals vs. trained runners). 10 inactive individuals (IA: 26 ± 6 y; 79.1 ± 14.1 kg; 40.7 ± 5.1 ml·kg^-1·min^-1) and 10 trained runners (TR: 25 ± 6 y; 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 to TEMP for IA and TR (-13.2 ± 4.5% vs. -15.2 ± 7%; <i>p</i>=0.571; ES=0.25). In HOT compared to TEMP, lipid oxidation, from 30 to 70% of 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) while 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 utilisation and peak oxygen consumption in hot compared to temperate conditions. However, the increased carbohydrate oxidation in HOT for TR were not observed in IA, potentially explained by lower thermal strain.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-01-24","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":"Influence of work intensity on acute kidney injury risk during simulated occupational heat stress.","authors":"Hayden W Hess, Molly E Heikkinen, Erica Tourula, M Jo Hite, Kelli Rivers, Roger S Zoh, Blair D Johnson, David Hostler, Zachary J Schlader","doi":"10.1152/japplphysiol.00590.2024","DOIUrl":"https://doi.org/10.1152/japplphysiol.00590.2024","url":null,"abstract":"<p><p>Violation of the National Institute of Occupational Safety and Health (NIOSH) heat stress recommendations by exceeding the allowable wet bulb globe temperature (WBGT) for a given work intensity and work-rest ratio augments acute kidney injury (AKI) risk. Here we tested the hypothesis that exceeding the allowable work intensity at a given WBGT and work-rest ratio would also worsen AKI risk. Twelve healthy adults completed two NIOSH recommendation compliant trials and one noncompliant trial consisting of a 4 h (half workday) exposure. Work-rest ratio was fixed at 30 min of walking and 30 min of rest each hour. Work intensity (metabolic heat production) was prescribed as a function of WBGT- 412±51 W (27.3±0.3°C; high intensity compliant [C_high]), 290±75 W (31.6±0.2°C; low intensity compliant [C_low]), and 410±61 W (31.7±0.2°C; high intensity noncompliant [NC_high]). AKI risk was quantified by the product of urinary insulin-like growth factor-binding protein 7 and tissue inhibitor of metalloproteinase 2 normalized to urine specific gravity ([IGFBP7•TIMP-2]_USG). Peak core temperature was higher in NC_high trial (38.3±0.4°C) compared to the compliant trials (C_high: 38.0±0.3°C; C_low: 37.8±0.4°C; p≤0.0095). [IGFBP7•TIMP-2]_USG increased from pre- to immediately postexposure in all trials (time effect: p=0.0454) but the peak increase was not different between trials (C_high: 0.89±1.7 [ng/mL]²/1000; C_low: 0.78±1.7 [ng/mL]²/1000; NC_high: 1.0±1.4 [ng/mL]²/1000; p=0.7811). Violating the NIOSH recommendations by exceeding either the allowable work intensity (i.e., NC_high versus C_low) or WBGT (i.e., NC_high versus C_high) resulted in a modest elevation in peak core temperature but did not modify AKI risk.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143039002","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":"Improving Glycemic Control via Heat Therapy in older adults at risk for Alzheimer's Disease (FIGHT-AD): a pilot study.","authors":"Anneka E Blankenship, Riley Kemna, Paul J Kueck, Casey John, Michelle Vitztum, Lauren Yoksh, Jonathan D Mahnken, Eric D Vidoni, Jill K Morris, Paige C Geiger","doi":"10.1152/japplphysiol.00396.2024","DOIUrl":"https://doi.org/10.1152/japplphysiol.00396.2024","url":null,"abstract":"<p><p>Impaired glycemic control increases the risk for type 2 diabetes (T2D) and Alzheimer's Disease (AD). Heat therapy (HT), via hot water immersion (HWI), has shown promise in improving shared mechanisms implicated in both T2D and AD, like blood glucose regulation, insulin sensitivity, and inflammation. The potential for HT to improve brain health in individuals at risk for AD has not been examined. This pilot study aimed to assess the feasibility and adherence of utilizing HT in cognitively healthy older individuals at risk for AD due to existing metabolic risk factors. Participants underwent four weeks of HT (three sessions/week) via HWI, alongside cognitive screening, self-reported sleep characterization, glucose tolerance tests, and MRI scans pre- and post-intervention. A total of 18 participants (9 male, 9 female; mean age: 71.1 ± 3.9 years), demonstrating metabolic risk, completed the intervention. Participant adherence for the study was 96% (8 missed sessions out of 216 total sessions), with one study related mild adverse event (mild dizziness/nausea). Overall, the research participants responded to a post-intervention survey saying they enjoyed participating in the study and it was not a burden on their schedules. Secondary outcomes of the HT intervention demonstrated significant changes in mean arterial pressure, diastolic blood pressure, and cerebral blood flow p<0.05), with a trend toward improved body mass index (p=0.06). Future studies, including longer durations and a thermoneutral control group, are needed to fully understand heat therapy's impact on glucose homeostasis and potential to improve brain health.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143006005","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, randomised, 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":"https://doi.org/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 (<i>Q̇i</i>). Secondary aims were to assess the effects of K_me ingestion on markers of cardiac haemodynamics, muscle oxygenation and vascular function at rest, during and following step-incremental cycling. We undertook a double-blind, randomised, crossover design study in 13 adults (age, 66±10 y; 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-mathced 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 <i>Q̇i</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 to 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), insulin max (<i>P</i>=0.242). Ingestion of K_me improved <i>Q̇i</i>, stroke volume index and peripheral muscle oxygenation, but did not alter macro- or microvascular endothelial function in people with T2D.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-01-17","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":"Remote Ischemic Preconditioning Attenuates Ischemia-Reperfusion Injury Induced Reductions in Vascular Function through Release of Endogenous Opioids.","authors":"Alexander J Rosenberg, Alexander Fernandez, Ayrion W Moody, Justin D Sprick","doi":"10.1152/japplphysiol.00913.2024","DOIUrl":"https://doi.org/10.1152/japplphysiol.00913.2024","url":null,"abstract":"<p><p>Remote Ischemic Preconditioning (RIPC) is a therapy characterized by repeated bouts of limb ischemia and reperfusion. RIPC protects against ischemia-reperfusion injury (IRI), and preclinical studies suggest that this is mediated through release of endogenous opioids. We aimed to interrogate the role of endogenous opioids in RIPC-signaling in humans, using an arm model of IRI. We hypothesized that RIPC would attenuate IRI-induced reductions in brachial artery flow mediated dilation (FMD), and that this would be prevented by systemic opioid receptor blockade. 11 healthy adults (8M/3F, age=28±8y) completed three experimental visits in which IRI was induced via 20-min upper arm ischemia and 20-min reperfusion achieved via upper arm cuff inflation to 250mmHg. FMD was measured at rest and again following IRI. During the control condition, RIPC was not performed. During the RIPC condition, RIPC was performed on the contralateral arm via 4 cycles of 5-min cuff inflation (250mmHg) with 5-min reperfusion. During the opioid receptor blockade condition (Naloxone), RIPC was performed in the presence of systemic opioid receptor blockade via intranasal naloxone (4mg) which was administered during the first 5-min cycle of RIPC. The change in FMD from baseline vs post-IRI were compared between visits via a two-way repeated measures ANOVA (factor 1: <i>time</i>, factor 2, <i>condition</i>) followed by Tukey post-hoc tests. IRI reduced FMD during the Control (Pre=6.1±2.4%, Post=3.5±2.8%, P<0.001) and Naloxone (Pre=6.6±2.7%, Post=3.5±1.9%, P<0.001) conditions but not during the RIPC condition (Pre=5.9±2.2%, Post=4.9±2.8%, P=0.14). These findings demonstrate that RIPC provides vascular protection from IRI in humans through an opioid-dependent mechanism.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143006016","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":"Acute selective serotonin-reuptake inhibition elevates basal ventilation, attenuates the rebreathing ventilatory response, independent of cerebral perfusion.","authors":"Jay Mjr Carr, Jodie Koep, L Madden Brewster, Ayechew Getu, Jonah C Dizon, Declan Isaak, Andrew Steele, Connor A Howe, Philip N Ainslie","doi":"10.1152/japplphysiol.00751.2024","DOIUrl":"https://doi.org/10.1152/japplphysiol.00751.2024","url":null,"abstract":"<p><p>Serotonin (5-HT) is integral to signalling in areas of the brainstem controlling ventilation and is involved in central chemoreception. Selective serotonin reuptake inhibitors (SSRIs), used to effectively increase 5-HT concentrations, are commonly prescribed for depression. The effects of SSRIs on the control of breathing and the potential influence of cerebral blood flow (CBF) have not been directly assessed. We hypothesized that a single SSRI dose in healthy adults would not impact resting ventilation, global CBF, or brainstem blood flow reactivity to CO₂, but would steepen the slope of the hypercapnic ventilatory response (HCVR). In 15 young, healthy adults (6 female, 25±5years, 70±10kg, 172±15cm, 24±4kg/cm²), using a placebo-controlled, double-blind, randomized design, we assessed baseline cardiorespiratory and CBF (duplex ultrasound) responses to SSRI (40 mg citalopram), as well as to hyperoxic hypercapnic rebreathing (as an index of central chemoreception). Baseline measures of mean arterial pressure, heart rate, minute ventilation, CBF and the pressures of end-tidal oxygen and carbon dioxide, were all not influenced by SSRI. Likewise, the sum of blood flowing through both vertebral arteries (as an index of brainstem blood flow) during hypercapnia was also unchanged. In contrast, basal ventilation (during rebreathing following hyperventilation and during hyperoxia) was elevated from 9.5±4.1 to 11.5±5.5 L/min (interaction p=0.023); and, counter to our hypothesis, the central chemoreceptor-mediated ventilatory response to CO₂ was reduced following SSRI from 7.5±5.3 to 5.1±4.1 L/min/mmHg (interaction p=0.027). The implications of these findings in health and pathology remain to be determined.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143005995","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":"Effect of condensed heat acclimation on thermophysiological adaptations, hypoxic cross-tolerance, exercise performance and de-acclimation.","authors":"Charlotte E Stevens, Joseph T Costello, Michael J Tipton, Ella F Walker, Alex A M Gould, John S Young, Ben J Lee, Thomas B Williams, Fiona A Myers, Jo Corbett","doi":"10.1152/japplphysiol.00775.2024","DOIUrl":"https://doi.org/10.1152/japplphysiol.00775.2024","url":null,"abstract":"<p><p>Short duration heat acclimation (HA) (≤5 daily heat exposures) elicits incomplete adaptation compared to longer interventions, possibly due to the lower accumulated thermal 'dose'. It is unknown if matching thermal 'dose' over a shorter timescale elicits comparable adaptation to a longer intervention. Using a parallel-groups design, we compared: i) 'condensed' HA (CHA; <i>n</i>=17 males) consisting of 4×75 min∙day^-1 heat exposures (target rectal temperature (<i>T</i>_rec)=38.5°C) for 2 consecutive days, with; ii) 'traditional' HA (THA; <i>n</i>=15 males) consisting of 1×75 min∙day^-1 heat exposure (target <i>T</i>_rec=38.5°C) for 8 consecutive days. Physiological responses to exercise heat-stress, hypoxia, and normoxic exercise performance were evaluated pre- and post-intervention. Thermal (<i>T</i>_rec over final 45 min: CHA=38.45±0.17°C, THA=38.53±0.13°C, <i>p</i>=0.126) and cardiovascular strain were not different during interventions, indicating similar thermal 'dose', although CHA had lower sweating rate, higher starting <i>T</i>_rec, and greater inflammation, gastrointestinal permeability and renal stress (<i>p</i><0.05). However, CHA elicited an array of thermophysiological adaptations that did not differ from THA (reduced indices of peak thermal [<i>e.g.</i>, Δ peak <i>T</i>_rec CHA=- 0.28±0.26°C, THA=-0.36±0.17°C, <i>p</i>=0.303] and cardiovascular strain, inflammation and renal stress; blood and plasma volume expansion; improved perceptual indices), although improvements in resting thermal strain (<i>e.g.</i>, Δ resting <i>T</i>_rec CHA=-0.14±0.21°C, THA=- 0.35±0.29°C, <i>p</i>=0.027) and sweating rate were less with CHA. Both interventions improved aspects of hypoxic tolerance, but effects on temperate normoxic exercise indices were limited. The diminished thermal strain was well-maintained over a 22-day decay period. In conclusion, CHA could represent a viable acclimation option for time-restricted young healthy-males preparing for a hot, and possibly high-altitude, environment.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143006000","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}