Journal of applied physiology最新文献

{"title":"Cardiac dysfunction is associated with indices of brain atrophy and cognitive impairment in heart failure with reduced ejection fraction.","authors":"Cameron J Morse, Adam M S Luchkanych, Natasha G Boyes, Allen D Champagne, Michael Kelly, Michael D Nelson, Rory A Marshall, Geoffrey Karjala, Alexander Zhai, Haissam Haddad, Darcy D Marciniuk, Corey R Tomczak, T Dylan Olver","doi":"10.1152/japplphysiol.00840.2024","DOIUrl":"https://doi.org/10.1152/japplphysiol.00840.2024","url":null,"abstract":"<p><p>Cardiac dysfunction in heart failure with reduced ejection fraction (HFrEF) may contribute to brain atrophy and cognitive decline beyond that which is typical of healthy ageing. This study tested the hypothesis that HFrEF would be associated with regionally-unique brain remodelling and impaired cognitive performance independent of age. Further, that cardiac index and clinical markers of HFrEF severity would predict brain remodelling and cognition with age and HFrEF, respectively. Cardiac function and brain morphology were assessed using magnetic resonance imaging in young healthy adults (24±6y), older healthy adults (60±6y) and patients living with HFrEF (59±6y). The Montreal Cognitive Assessment was administered to assess cognition. Gray matter volume (GMV) (young: 492±24, old: 456±24, HFrEF: 433±32cm³, P≤0.05) and cortical thickness (young: 2.44±0.07, old: 2.33±0.08, HFrEF: 2.22±0.10mm, P<0.01) were lower with age and lowered further with HFrEF. Regional analysis revealed a unique pattern of atrophy with HFrEF. Whereas age had little effect on cortical curvature (P=0.60), it was greater in HFrEF (young: 0.127±0.003, old: 0.128±0.003, HFrEF: 0.136±0.005mm^-1, P<0.01). Cardiac index was the best correlate of brain atrophy and cognitive performance with age (R=0.33-0.47; P<0.05). However, EF and end systolic volume index were better correlates of brain atrophy and cognitive performance in HFrEF (R=-0.50-0.49; P≤0.05). These data indicate that lower GMV and cortical thickness in HFrEF are not merely an acceleration of age-related declines but reflect a unique pattern of brain atrophy and remodelling. Additionally, classic markers of HF severity may be better predictors of pathological brain remodelling than reduced cardiac index.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143663425","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":"Lower Calf Raise Efficiency in Obesity is Partially Related to Higher Triceps Surae MTU Passive Stiffness, Hysteresis, and Reduced Relative Strength.","authors":"Leonardo Cesanelli, Hans Degens, Cem Rifat Toper, Sigitas Kamandulis, Danguole Satkunskiene","doi":"10.1152/japplphysiol.00702.2024","DOIUrl":"https://doi.org/10.1152/japplphysiol.00702.2024","url":null,"abstract":"<p><p>The objective of this study was to assess the efficiency of calf raise exercise in individuals with obesity, and to what extent this is related to the structural and mechanical properties of the Triceps Surae muscle-tendon-unit (MTU). In 22 obese (BMI, 32.2 ± 1.5 kg/m²) and 22 non-obese (BMI, 23.3 ± 1.5 kg/²) men we measured anthropometric parameters, gas exchange, heart rate, and rating of perceived exertion in sitting, standing and during a self-paced 30-sec calf raise exercise. Maximal voluntary isometric contraction of the plantar flexor muscles and passive resistive torque of the Triceps Surae MTUs were measured using an isokinetic dynamometer. B-mode ultrasound imaging of plantar flexor muscles and Achilles tendon was also performed. Individuals with obesity exhibited a greater metabolic energy cost during standing and calf raise exercise, and a lower exercise efficiency and ankle mobility (p<0.05). Plantar flexor MTUs stiffness and hysteresis were greater, while gastrocnemius-medialis tendon strain was lower in subjects with obesity compared to controls (p<0.05). There was a negative correlation between calf raise exercise net efficiency, plantar flexor MTUs hysteresis (r=0.38; p<0.05) and the body mass by maximal voluntary isometric torque ratio (r=0.41; p<0.05). These observations indicate that increased musculotendinous stiffness and hysteresis, together with a lower strength to body mass ratio, are among the factors contributing to higher metabolic energy costs, and lower exercise efficiency in individuals with obesity.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143669952","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":"PoWeR elicits intracellular signaling, mitochondrial adaptations, and hypertrophy in multiple muscles consistent with endurance and resistance exercise training.","authors":"Christian J Elliehausen, Szczepan S Olszewski, Dennis M Minton, Audrey L Spiegelhoff, Carolyn G Shult, Wenyuan G Zhu, Troy A Hornberger, Adam R Konopka","doi":"10.1152/japplphysiol.00872.2024","DOIUrl":"https://doi.org/10.1152/japplphysiol.00872.2024","url":null,"abstract":"<p><p>Physical activity guidelines recommend both endurance and resistance exercise to improve and maintain overall health. Recently, progressive weighted wheel running (PoWeR), a voluntary, progressive, and high-volume exercise paradigm, was posited as a singular prototype of combined endurance and resistance exercise in mice as evident by enhanced capillarization and hypertrophy of select plantar flexor muscles. Despite growing interest in this model, it remains incompletely characterized if PoWeR resembles the acute and chronic responses to resistance and/or endurance exercise in humans. Therefore, the purpose of this study was to assess canonical signaling events, mitochondrial bioenergetics, and cellular adaptations across multiple extensor and flexor muscles of the fore- and hindlimbs that may be conducive for whole-body functional improvements as traditionally observed in humans. 8-weeks of PoWeR (~8km/day) improved glucose metabolism, exercise capacity, body composition, and bone mineral density as well as increased mass, myofiber CSA, and oxidative myofiber type distribution in the soleus, plantaris, and FDL. Using two <i>ex-vivo</i> high-resolution flourorespirometry protocols that model <i>in vivo</i> physiological conditions, PoWeR decreased mitochondrial ADP sensitivity which was accompanied by greater mitochondrial H₂O₂ emissions, respiration, conductance, and protein content in the vastus lateralis, gastrocnemius, and triceps in muscle-specific fashion. Three days of short-term PoWeR stimulated mTORC1 and AMPK signaling in soleus, plantaris and/or FDL in line with the hypertrophic and metabolic adaptations observed with long-term training. Collectively, these data support PoWeR as a suitable paradigm in mice to model the acute signaling and chronic adaptations associated with endurance and resistance exercise in humans.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143657397","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":"Effects of Analgesic Doses of Opioids on Cardiorespiratory Responses and Survival to Hemorrhage and Trauma in Rats.","authors":"Stephanie M Lipiec, Kathy L Ryan, Mariam L Calderon, Cassandra M Rodriguez, Brian S Connor, Carmen Hinojosa-Laborde, Harold G Klemcke","doi":"10.1152/japplphysiol.00708.2024","DOIUrl":"https://doi.org/10.1152/japplphysiol.00708.2024","url":null,"abstract":"<p><p>Opioids are used for analgesia but questions persist about their safety following traumatic hemorrhage. We investigated <i>analgesic</i> doses of three opioids (morphine, fentanyl and sufentanil) on cardiorespiratory responses and survival to moderate or severe (37 and 50% blood volume) hemorrhage after trauma. A conscious hemorrhage model with extremity trauma (fibular fracture + soft tissue injury) was used; mean arterial pressure (MAP) and heart rate (HR) were measured by telemetry while minute volume (MV) was determined by whole body plethysmography. Male rats (n=10/group) received saline, morphine (2 mg/kg), fentanyl (10 µg/kg) or sufentanil (1 µg/kg) after traumatic hemorrhage. Neither survival times (for 37% hemorrhage: P=0.209; for 50% hemorrhage: P=0.88) nor survival percentages (for 37% hemorrhage: P=0.357; for 50% hemorrhage: P=1.0) differed among groups. For 37% hemorrhage, MAP of all opioid groups was higher than the saline-treated group 10 min post-injection. By 75 min post-injection, MAP after sufentanil was higher than saline; MAP for other opioids did not differ from saline. HR did not differ across treatments. Opioid injection decreased MV within 10 min but did not vary by treatment subsequently. For 50% hemorrhage, opioid injection did not immediately alter MAP but morphine and sufentanil were lower than saline at ≥75 min post-injection, with no treatment effects on HR. Fentanyl produced an immediate (5 min) decrease in MV with no treatment effects thereafter. Opioid effects on cardiorespiratory function were therefore modest and did not alter survival during a 4 hr observation period, supporting the judicious use of analgesic doses following traumatic hemorrhage.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143648592","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":"Motor unit discharge behaviour in human muscles throughout force gradation: a systematic-review and meta-analysis with meta-regression.","authors":"J Greig Inglis, Hélio V Cabral, Caterina Cosentino, Alberto Bonardi, Francesco Negro","doi":"10.1152/japplphysiol.00863.2024","DOIUrl":"https://doi.org/10.1152/japplphysiol.00863.2024","url":null,"abstract":"<p><p>The analysis of motor unit (MU) discharge behaviour provides an effective way of assembling information about the generation and control of movement. In this systematic-review and meta-analysis we identified and summarized the literature investigating MU discharge rate and discharge rate variability (CoV-ISI) during voluntary isometric contractions at various force levels. Databases were searched up to January 7, 2025, and a total of 262 studies were included. The meta-means of MU discharge rate and CoV-ISI were estimated and compared across human muscles. The influence of contraction intensity on MU discharge behaviour was assessed through linear meta-regressions. At low-to-moderate forces (<60% MVC), the <i>first dorsal interosseous, biceps brachii</i> (<i>BB</i>) and <i>forearm extensors</i> (<i>FE</i>) had the highest discharge rate, while the <i>soleus</i> had the lowest. At high force levels (>60% MVC), the <i>tibialis anterior</i> (<i>TA</i>) had the highest mean discharge rate compared to all other muscles, with the <i>soleus</i> maintaining the lowest. Regarding CoV-ISI results at low forces (<30% MVC), the <i>TA</i> had the lowest CoV-ISI values, except in comparison to the <i>vastii</i>. Additionally, the <i>vastii</i> had lower CoV-ISI values than the <i>FE</i>, <i>gastrocnemius medialis</i>, and <i>soleus</i>. Contraction intensity was positively associated with the mean discharge rates in all muscles investigated, although some muscles showed steeper slopes than others. Similar results were observed for CoV-ISI meta-regressions, with muscle-specific differences in slope. These findings suggest potential variations in neural control strategies across muscles during force gradation, such as differences in the relative contribution of rate coding to facilitate increasing force demands.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143648606","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":"ELEVATED CIRCULATING ENDOTHELIAL CELL-DERIVED MICROVESICLES: A BIOMARKER OF ENDOTHELIAL VASOMOTOR DYSFUNCTION IN ADULTS WITH OBESITY.","authors":"Vinicius P Garcia, Hannah K Fandl, Kendra N Wegerson, Auburn R Berry, Samuel T Ruzzene, Jared J Greiner, Kelly A Stockelman, Caitlin A Dow, Andrew J Park, Brian L Stauffer, Christopher A DeSouza","doi":"10.1152/japplphysiol.00081.2025","DOIUrl":"https://doi.org/10.1152/japplphysiol.00081.2025","url":null,"abstract":"<p><p>Endothelial cell-derived extracellular microvesicles (EMVs) have emerged as a biomarker of cardiovascular disease risk, progression and severity. The aims were to determine: 1) if circulating EMV levels are elevated in adults with obesity; and 2) whether circulating EMVs are associated with obesity-related endothelial vasomotor dysfunction. Thirty-six sedentary, midlife adults (45-63 years) were studied: 18 adults with normal weight (12M/6F; age: 56±6 yr; BMI: 23.3±1.5 kg/m²) and 18 adults with obesity (12M/6F; 53±5 yr; 31.9±1.7 kg/m²). EMV (CD31⁺/42^-) concentration in plasma was determined by flow cytometry. Forearm blood flow (FBF: via plethysmography) was assessed in response to intra-arterial infusions of acetylcholine (4.0, 8.0 and 16.0 μg/100 mL tissue/min), sodium nitroprusside (1.0, 2.0 and 4.0 μg/100 mL tissue/min) and the selective endothelin (ET)-1 receptor antagonist BQ-123 (ET_A receptor blockade; 100 nmol/min; for 60 min). Circulating EMVs were ~85% higher (P<0.001) in adults with obesity (147±54 EMV/μL) than adults with normal weight (79±27 EMV/mL). FBF response to acetylcholine was significantly lower (~30%) in adults with obesity (from 4.3±0.9 to 10.5±2.3 mL/100 mL tissue/min) vs adults with normal weight (from 4.2±0.9 to 15.1±2.4 mL/100 mL tissue/min). BQ-123 elicited a significantly greater (~35%) increase in FBF in adults with obesity, indicative of higher ET-1-mediated vasoconstrictor tone. Circulating EMVs were inversely related with total FBF response to acetylcholine (r=-0.49; P=0.001) and positively associated with total FBF response to BQ-123 (r=0.46; P=0.005). In conclusion, circulating levels of EMVs are elevated in adults with obesity and are associated with reduced endothelium-dependent vasodilation and increased ET-1 mediated vasoconstrictor tone.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143624822","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":"Blood pressure in human large cerebral arteries: a feasibility study.","authors":"Leena N Shoemaker, Tyson Matern, Farah Kamar, Keith St Lawrence, Santiago Ortega-Gutierrez, Mario Zanaty, J Kevin Shoemaker","doi":"10.1152/japplphysiol.00825.2024","DOIUrl":"10.1152/japplphysiol.00825.2024","url":null,"abstract":"<p><p>The lack of direct measures of brain blood pressure (BBP) has severely restricted understanding of cerebral pressure-flow relationships and their control. We sought to evaluate the feasibility of directly measuring BBP and its pulsatility between the aorta and middle cerebral artery (MCA) during elective endovascular surgical procedures. We report five case studies (four female, 61 ± 13 yr; means ± SD) of patients undergoing cerebrovascular interventional procedures for aneurysm and stenoses, using direct BBP measures with the COMET 2 pressure guidewire system (Boston Scientific). Patients were supine, intubated, and under anesthesia. The sensor wire was inserted via the femoral artery, measuring, as feasible, blood pressure (BP) in the aorta to MCA vascular segments, referenced to the radial artery BP waveform (arterial catheter). Mean arterial pressure varied between the radial (80 ± 18 mmHg), internal carotid artery (ICA; 70 ± 25 mmHg), and MCA (62 ± 29 mmHg), and marked interindividual heterogeneity was observed. Pulse pressure was higher in the radial artery (68 ± 23 mmHg) compared with the intracranial ICA (ICAi; 43 ± 29 mmHg) and MCA (M1; 25 ± 12 mmHg) segments. Direct measures of BBP in humans are feasible in this interventional surgery model. Although limited by the small sample size, the results suggest a heterogenous pattern of change between systemic and brain measures of blood pressure and pulse pressure.<b>NEW & NOTEWORTHY</b> We explored the feasibility of making direct measures of blood pressure in the large arteries at the base of the brain in humans. Measures were made with an optical sensor positioned in the aorta, common carotid, internal carotid artery external to the cranium, internal carotid artery within the cranium, and/or middle cerebral artery (MCA), M1 segment. Measures varied across individuals, as did the pressure gradient from systemic pressures to those in the MCA.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"693-698"},"PeriodicalIF":3.3,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143364751","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":"10.1152/japplphysiol.00396.2024","url":null,"abstract":"<p><p>Impaired glycemic control increases the risk of 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 using HT in cognitively healthy older individuals at risk for AD due to existing metabolic risk factors. Participants underwent 4 wk of HT (three sessions/week) via HWI, alongside cognitive screening, self-reported sleep characterization, glucose tolerance tests, and MRI scans pre- and postintervention. A total of 18 participants (9 males, 9 females; mean age: 71.1 ± 3.9 yr), 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 postintervention 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 (<i>P</i> < 0.05), with a trend toward improved body mass index (<i>P</i> = 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 the potential to improve brain health.<b>NEW & NOTEWORTHY</b> Our pilot study demonstrated promising results for heat therapy (HT) via hot water immersion in older adults at risk for Alzheimer's disease due to metabolic factors. Despite a relatively short intervention, significant improvements in mean arterial pressure, diastolic blood pressure, and cerebral blood flow postintervention were observed. High participant adherence, overall satisfaction, and minimal adverse events suggest HT's feasibility. These findings highlight HT's potential as an effective alternative intervention for cardiometabolic dysfunction in at-risk populations.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"720-730"},"PeriodicalIF":3.3,"publicationDate":"2025-03-01","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":"Altitude-induced central sleep apnea does not affect mean sleep oxygen saturation in young healthy males.","authors":"G Heiniger, F Raemy, G Solelhac, T Imler, A Waeber, K Lambercy, B Bradley, G Lecciso, F Degache, R Heinzer","doi":"10.1152/japplphysiol.00665.2024","DOIUrl":"10.1152/japplphysiol.00665.2024","url":null,"abstract":"<p><p>At high altitudes, periodic breathing (PB) can occur during sleep in healthy individuals. PB is characterized by a cyclical ventilatory pattern that alternates between central sleep apnea and brief episodes of hyperventilation. The aim of this study was to evaluate the effect of periodic breathing on sleep blood oxygen saturation ([Formula: see text]). Thirty-six healthy male subjects (median [IQR] age: 26 [24-28] yr old, median [IQR] body mass index: 22.7 [21.1-23.8] kg/m²) underwent a polysomnography at a simulated altitude of 3,500 m ([Formula: see text]: 13%). Correlations were sought between the apnea-hypopnea index (AHI), oxygen desaturation index (ODI), percentage of sleep time spent in PB (PB), and mean [Formula: see text] throughout the entire sleep period by calculating the Spearman's rank correlation test. We identified 20 participants who had experienced at least 3 min of periodic breathing adjacent to at least 3 min of regular breathing (RB). We compared the mean [Formula: see text] between the two respiratory patterns using Wilcoxon signed-rank test. At simulated altitude, the subjects spent a median [IQR] of 43.9 [12.5-79.1]% of sleep time in PB. The median [IQR] AHI was 77.3 [31.4-127.5]/h, and the median [IQR] ODI was 82.6 [52.6-134.0]/h. Median awake and asleep [Formula: see text] were 75.4 [72.0-77.2]% and 68.5 [66.4-72.5]%, respectively. We found no within-subject difference in mean [Formula: see text] between RB and PB periods (median [IQR] RB vs. PB: 67.2% [63.8%-74.8%] vs. 67.5% [64.5%-73.9%]; <i>P</i> = 0.43). No significant correlation was found between the mean sleep [Formula: see text] and AHI (<i>n</i> = 36, <i>rs</i> = -0.19, <i>P</i> = 0.26), ODI (<i>n</i> = 36, <i>rs</i> = -0.23, <i>P</i> = 0.18) or PB (<i>n</i> = 36, <i>rs</i> = -0.07, <i>P</i> = 0.67). Awake [Formula: see text] was correlated with mean [Formula: see text] during sleep (<i>n</i> = 36, <i>rs</i> = 0.55, <i>P</i> = 0.001). Periodic breathing per se does not have a detrimental effect on mean [Formula: see text] in young healthy males. Correlation between awake [Formula: see text] and sleep [Formula: see text] suggests that sleep [Formula: see text] at high altitude is primarily determined by baseline oxygen saturation rather than the respiratory pattern developed during sleep.<b>NEW & NOTEWORTHY</b> Periodic breathing, which occurs during sleep at altitude, causes an oscillation between central apneas and periods of hyperventilation. The overall impact of this breathing pattern on blood oxygen saturation ([Formula: see text]) remains a topic of debate. We compared the mean [Formula: see text] between periods of periodic breathing and periods of regular breathing for the same individual. The results suggest that periodic breathing does not affect mean sleep [Formula: see text].</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"792-798"},"PeriodicalIF":3.3,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143416787","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":"Competing influences of arterial pressure and carbon dioxide on the dynamic cerebrovascular response to step transitions in exercise intensity.","authors":"Eric T Hedge, Richard L Hughson","doi":"10.1152/japplphysiol.00643.2024","DOIUrl":"10.1152/japplphysiol.00643.2024","url":null,"abstract":"<p><p>Recent investigations of middle cerebral artery blood velocity (MCAv) kinetics at the onset of exercise have not accounted for potential dynamic changes in arterial partial pressure of carbon dioxide ([Formula: see text]) during the transient phase of exercise transitions when modeling MCAv kinetics, despite [Formula: see text] having known effects on cerebrovascular tone. The purpose of our study was to determine the independent effects of mean arterial pressure (MAP) and estimated [Formula: see text] ([Formula: see text]) on mean MCAv during repeated moderate-intensity exercise transitions. We hypothesized that cerebral autoregulation would minimize the effect of sustained exercise-induced changes in MAP on mean MCAv and that dynamic changes in [Formula: see text] would contribute to changes in mean MCAv. Eighteen young healthy adults (7 women, age: 28 ± 5 yr) performed three exercise transitions from 25 W to 90% of the ventilatory threshold in sequence with 5-min stages. Mean MCAv increased (<i>P</i> < 0.001) from 25 W (60.5 ± 14.0 cm·s^-1) to 90% of the ventilatory threshold (68.8 ± 15.1 cm·s^-1). MAP at the level of the middle cerebral artery (MAP_MCA) (Δ = 14 ± 8 mmHg, <i>P</i> < 0.001) and [Formula: see text] (Δ = 2.7 ± 1.8 mmHg, <i>P</i> < 0.001) also increased with exercise intensity. Autoregressive moving average (ARMA) analysis isolated the independent effects of dynamic changes in MAP_MCA and [Formula: see text] on MCAv, with low prediction error (mean absolute error = 1.12 ± 0.25 cm·s^-1). Calculated steady states of the ARMA step responses were 0.13 ± 0.15 cm·s^-1·mmHg^-1 for Δmean MCAv/ΔMAP_MCA and 1.95 ± 0.83 cm·s^-1·mmHg^-1 for Δmean MCAv/Δ[Formula: see text]. These data demonstrate that the combination of dynamic changes in MAP and [Formula: see text] largely explains the MCAv response during transitions in exercise intensity.<b>NEW & NOTEWORTHY</b> Time-series analysis of moderate-intensity exercise transitions suggested that cerebral autoregulation buffered the effect of sustained changes in mean arterial pressure on middle cerebral artery blood velocity (MCAv) and that changes in estimated arterial partial pressure of carbon dioxide ([Formula: see text]) contributed to the dynamic changes in MCAv during exercise transitions. Therefore, changes in [Formula: see text] at the onset of exercise are central to modeling dynamic MCAv responses and understanding the benefits of exercise on cerebral blood flow.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"816-824"},"PeriodicalIF":3.3,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143492190","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}