Normobaric Hypoxic Conditions Research Articles

Enhanced cardiac vagal activity and mood after low-dose hypoxic gas inhalation in healthy young adults.

Developing strategies to enhance cardiac vagal activity (CVA) is essential for improving mood and managing stress. Although hypoxia inhalation may boost CVA, the optimal acute hypoxic conditions remain unclear. Therefore, we aimed to achieve a comprehensive understanding of the hypoxic conditions required to improve CVA and mood following hypoxia. Twenty-one healthy adults participated in both normobaric hypoxic (NH; FIO2: 13.5%) and normoxic (NN; FIO2: 20.9%) conditions. We monitored heart rate variability (HRV), percutaneous oxygen saturation (SpO2), and mood across pre-, hypoxia, and post-sessions and assessed psychophysiological stress using the Baevsky Stress Index (SI). Under hypoxia, SpO2 decreased to 88.1%, accompanied by reductions in vagally-mediated HRV, followed by supercompensation post-hypoxia. Additionally, mood declined during hypoxia but rapidly rebounded, correlating with CVA and SI fluctuations. These results indicate that acute low-dose hypoxic gas inhalation at FIO2: 13.5% enhances CVA and mood post-hypoxia, offering a practical method for building resilience.

The Effect of EEG Biofeedback Training Frequency and Environmental Conditions on Simple and Complex Reaction Times.

The objective of this study is to evaluate the impact of EEG biofeedback training under normoxic and normobaric hypoxic conditions on both simple and complex reaction times in judo athletes, and to identify the optimal training frequency and environmental conditions that substantially enhance reaction times in the examined athlete groups. The study comprised 20 male judo athlete members of the Polish national judo team in the middleweight and heavyweight categories. We randomly assigned participants to an experimental group and a control group. We conducted the research over four cycles, varying the frequency of EEG biofeedback sessions and environmental circumstances for both the experimental and control groups. Every research cycle had 15 training sessions. The results showed that the experimental group, following the theta/beta regimen, got significantly faster at complex reactions after a training cycle that included sessions every other day at normal oxygen levels. Following daily training sessions in normoxic circumstances, we noted enhancements in simple reaction speeds. Under normobaric hypoxia conditions, the judo athletes showed deterioration in both simple and complex reaction times. The control group showed no similar changes. Daily EEG training in normoxic settings markedly improved simple reaction time, but EEG-BF training conducted every other day greatly raised complicated reaction time. In contrast, training under normobaric hypoxia settings did not result in enhancements in basic or complicated reaction times following EEG training.

The influence of EEG-biofeedback training and Beta waves in normoxia and normobaric hypoxia on the bench press in judo athletes

The aim of this study was to assess the effect of EEG -Biofeedback training in normoxic and normobaric hypoxic conditions on bench press improving in elite judo athletes. The study included 20 male elite judo athletes. Each athlete was a member of the Polish National Team and held either an International Master Class (MM) or National Master Class (M) – purposive selection. The research was carried out over two cycles that differed in the external conditions of EEG biofeedback trainings for both the control and experimental groups. The experimental group underwent training under simulated hypoxic conditions The training sessions for the experimental group were conducted at a simulated altitude of 3000m above sea level. Each cycle of the study comprised of 15 training sessions. The control group's study followed the same frequency, and duration of EEG biofeedback training sessions, and demonstrated an identical pattern to that of the experimental group, but in normoxia conditions. In the discussed cycle conducted in hypoxia, a clear upward dynamics of Beta wave values with a growing trend from session 14 was observed. In normoxia, the variability in the EG group had a significantly less dynamic course. In hypoxia, a clear upward dynamics of the achieved PP values with a growing trend from measurement 14 was observed. In normoxia, the discussed measurement cycle conducted in the CG group showed a lesser upward dynamics of achieved PP values with a growing trend from measurement 10. The overall conclusion from these analyses suggests that EEG biofeedback training in hypoxic conditions may have a beneficial impact on brain activity and improvement in muscle strength and power. These results may be of significant importance for sports training and rehabilitation, especially for individuals engaged in sports disciplines requiring physical exertion in low oxygen environments.

Aerobic Exercise Training Under Normobaric Hypoxic Conditions to Improve Glucose and Lipid Metabolism in Overweight and Obese Individuals: A Systematic Review and Meta-Analysis.

Guo, Hai, Linjie Cheng, Dilihumaier Duolikun, and Qiaoling Yao. Aerobic exercise training under normobaric hypoxic conditions to improve glucose and lipid metabolism in overweight and obese individuals: a systematic review and meta-analysis. High Alt Med Biol. 24:312-320, 2023. Background: Obesity is a critical public health issue around the world, reaching epidemic proportions in some countries. However, only a few studies have examined the effects of hypoxic training on metabolic parameters in an obese population. This systematic review and meta-analysis aimed to determine the effects of aerobic exercise training under normobaric hypoxic conditions versus normoxic training in improving glucose and lipid metabolism in obese individuals. Methods: A systematic search of PubMed, EMBASE, Web of Science, and Wan Fang databases (up to August 2021) was performed to identify randomized controlled trials (RCTs) of overweight or obese human subjects eligible for inclusion. Main study endpoints were changes in body mass index (BMI), waist/hip (W/H) ratio, leptin, blood glucose and insulin levels, as well as blood lipids between hypoxic and normoxic conditioning. Results: Fourteen RCTs with a total of 413 subjects qualified for inclusion. Pooled analyses revealed that BMI (d = 0.38), W/H ratio (d = 0), blood glucose (d = 0.01), and triglyceride (d = -2.27) were not significantly different between aerobic exercise training under hypoxic and normoxic conditions. However, significant differences were found in heart rate at rest (d = -4.50) between aerobic exercise training under hypoxic versus normoxic conditions. Conclusions: In conclusion, no significant benefits were noted in aerobic exercise training under hypoxic conditions over normoxic conditions in overweight or obese individuals. However, the maximum training heart rate mm was significantly higher under hypoxic conditions than under normoxic conditions. Future studies with larger samples controlling for exercise-related parameters, and addressing the potential modifying effects of level of hypoxia, sex, or age on the role of hypoxic exercise training are warranted. PROSPERO registration number: CRD42020221680.

320 Oxygenated Peritoneal Perfluorodecalin Improves Response to Normobaric Hypoxic Exposure in Swine

OBJECTIVES/GOALS: Patients suffering from respiratory failure have few options to support oxygenation and carbon dioxide removal aside from mechanical ventilation. Our objective was to test a novel extrapulmonary mechanism of gas exchange via peritoneal oxygenated perfluorocarbon (PFC) in a large animal model. METHODS/STUDY POPULATION: Using two 50 kg swine, hypoxia was modeled with subatmospheric oxygen and hypercarbia induced with acute hypoventilation. Through a midline laparotomy, cannulas were placed into the peritoneal space to allow for PFC infusion and circulation. After abdominal closure, these cannulas were connected to a device capable of draining, oxygenating, and infusing PFC. One animal was subjected to acute hypoxia (12% FiO2) and another animal to acute hypoventilation (4 breaths per minute). Primary outcomes were times for SpO2 to reach 75 mmHg, respectively. Trials were performed without PFC and with PFC dwelling or circulating through the peritoneal space, during which abdominal and bladder pressures were monitored and maintained under 20 mmHg by regulation of the PFC volume contained in the animal. RESULTS/ANTICIPATED RESULTS: In the animal subjected to acute hypoxia (12% FiO2), survival time improved from 5:55 to 20:00 (min:sec) after 2.5 liters of oxygenated PFC was instilled in the peritoneal space. Oxygen percent saturation of PFC before and after dwelling in the peritoneal space was measured at 100% before and 70% after dwelling in the animal during this hypoxic period corresponding with a gas transfer of 300 mL of oxygen over the 20-minute trial (i.e., 15 mL/min). Continual PFC circulation did not further extend the survival time during hypoxic conditions over PFC dwelling in the abdomen. In the animal that was acutely hypoventilated, there were no detectable differences in the rate of CO2 accumulation as measured by EtCO2 or direct blood pCO2 measurements with PFC dwelling or circulating through the peritoneal space. DISCUSSION/SIGNIFICANCE: Oxygenated PFC dwelling in the peritoneal space increased the duration of systemic arterial blood saturation remaining greater than 50% during normobaric hypoxic (12% FiO2) conditions but did not appreciably clear blood carbon dioxide during hypoventilation. Future experiments will focus on maximizing the rate of systemic oxygen uptake.

Resistance circuit training combined with hypoxia stimulates bone system of older adults: A randomized trial

PurposeAging leads to gradual irreversible decline in bone mass. As adherence to pharmacological treatment is poor, hypoxia combined with strength training has been suggested for therapeutic benefit for clinical populations. The present study investigated the effects of normobaric cyclic hypoxic exposure combined with resistance circuit training on bone of older adults. MethodsHealthy older adults (n = 50) were randomly assigned to a (1) control group (CON; n = 20), who were instructed to continue with their normal daily activities, (2) a group that performed resistance training in normoxia (RTN; n = 17) and (3) a group that performed resistance training in hypoxia (RTH; n = 13). During 24 weeks, RTH group performed resistance training with elastic bands under normobaric hypoxic conditions (16.1 % FiO2). A session of both exercise groups included nine exercises of several body areas with a structure of 3 sets × 12–15 repetitions per exercise, with a 1-minute rest between sets. Bone mineral density (g·cm-2) was measured using dual-energy X-ray absorptiometry. Bone turnover markers of formation (N-terminal propeptide of type I procollagen; PINP) and resorption (C-terminal telopeptide of type I collagen; bCTX) were analysed with enzyme-linked immunosorbent assay (ELISA) microplate reader. ResultsValues of bCTX and bCTX/PINP significant decreased in RTN (bCTX: 47.79 %; p = 0.002; bCTX/PINP: 61.43 %; p = 0.007) and RTH (bCTX: 59.09 %; p = 0.001; bCTX/PINP: 62.61 %; p = 0.003) groups compared with CON group. Change in bone mineral density was not significantly different between groups. Based on clinically significant change, 23 % of the participants in the RTH group reached this value for femoral neck and trochanter bone mineral density (vs 0 % and 6 % of the RTN group, respectively). Conclusions24-Weeks of normobaric cyclic hypoxic exposure combined with resistance circuit training has potential to generate positive effects on bone in older adults.Trial registration number: NCT04281264 (date of registration: February 24, 2020).

Effects of Drinking Oxygenated Water on Blood Oxygen Saturation During Exercise Under Normobaric Hypoxic Conditions: A Randomized Placebo-controlled Single-blinded Trial.

This study aimed to investigate the effects of drinking oxygenated water on oxygen saturation during exercise under normobaric hypoxic conditions. A randomized placebo-controlled single-blinded trial was performed. Twenty-two healthy adults (16 men and 6 women), with a mean age (standard deviation) of 22.4 (2.73) years, participated in the study. The participants were randomly assigned to one of two groups: an OX group (drinking oxygenated mineral water) and a control group (drinking normal mineral water). Both groups performed walking exercises under normobaric hypoxic conditions. Blood oxygen saturation (SpO2), pulse rate (PR), and walking distance were measured during exercise. SpO2 decreased and PR increased during exercise in both groups. The decrease in SpO2 was smaller and the increase in PR was greater in the OX group compared with those in the control group. No significant difference was found in walking distance between the two groups. Drinking oxygenated water before exercise may inhibit SpO2 reduction under normobaric hypoxic conditions.

Dietary Nitrate Supplementation Is Not Helpful for Endurance Performance at Simulated Altitude Even When Combined With Intermittent Normobaric Hypoxic Training.

IntroductionTraining intensity and nutrition may influence adaptations to training performed in hypoxia and consequently performance outcomes at altitude. This study investigates if performance at simulated altitude is improved to a larger extent when high-intensity interval training is performed in normobaric hypoxia and if this is potentiated when combined with chronic dietary nitrate (NO3−) supplementation.MethodsThirty endurance-trained male participants were allocated to one of three groups: hypoxia (13% FiO2) + NO3−; hypoxia + placebo; and normoxia (20.9% FiO2) + placebo. All performed 12 cycling sessions (eight sessions of 2*6 × 1 min at severe intensity with 1 min recovery and four sessions of 4*6*10 s all-out with 20 s recovery) during a 4-week period (three sessions/week) with supplementation administered 3–2.5 h before each session. An incremental exhaustion test, a severe intensity exercise bout to exhaustion (Tlim) and a 3 min all-out test (3AOT) in hypoxia (FiO2 = 13%) with pulmonary oxygen uptake (O2), O2 kinetics, and changes in vastus lateralis local O2 saturation (SmO2) measured were completed by each participant before and after training.ResultsIn all tests, performance improved to the same extent in hypoxia and normoxia, except for SmO2 after Tlim (p = 0.04, d = 0.82) and 3AOT (p = 0.03, d = 1.43) which were lower in the two hypoxic groups compared with the normoxic one. Dietary NO3− supplementation did not bring any additional benefits.ConclusionPerformance at simulated altitude was not improved to a larger extent when high-intensity interval training was undertaken in normobaric hypoxic conditions, when compared with normoxic training. Additionally, dietary NO3− supplementation was ineffective in further enhancing endurance performance at simulated altitude.

Acute Physiological Response to Different Sprint Training Protocols in Normobaric Hypoxia.

Background: the purpose of this study was to examine acute physiological responses to and the performance effects of two sprint training protocols in normobaric hypoxic conditions. Methods: Healthy competitive female (n = 2) and male (n = 5) kayakers (19 ± 2.1 years) performed four sprint training sessions on a kayak ergometer over a period of two weeks. Participants performed five sets of 12 × 5 s sprints or 3 × 20 s sprints in both normobaric normoxic (NOR, FiO2 = 20.9%) or normobaric hypoxic (HYP, FiO2 = 13.6%) conditions. The peak power output (PPO), rate of perceived exertion (RPE), and heart rate (HR) of each participant were monitored continuously. Their blood lactate concentrations ([BLa+]), in addition to their blood gas (mixed-venous partial pressure (p) of carbon dioxide (pCO2), O2 (pO2), and oxygen saturations (sO2)) were collected before and after exercise. Results: A significantly greater RPE, HR, and [BLa+] response and a significant decrease in pCO2, pO2, and sO2 were observed in HYP conditions versus NOR ones, independent of the type of training session. The PPO of participants did not differ between sessions. Their RPE in HYP12 × 5 was greater compared to all other sessions. Conclusions: The HYP conditions elicited significantly greater physiological strain compared to NOR conditions and this was similar in both training sessions. Our results suggest that either sprint training protocol in HYP conditions may induce more positive training adaptations compared to sprint training in NOR conditions.

Cardiovascular-metabolic responses and oxygen uptake kinetics during kayak paddling in normobaric hypoxia in young flatwater kayakers

Background: The aim of the study was to evaluate response of cardiovascular, metabolic and oxygen consumption kinetics at kayak paddling exercise in the normoxic and normobaric environment. Material and Methods: Seven kayakers (age: 16±1.2 year; height: 165±8.3cm; body weight: 53±8kg; fat percentage: 17±4.4%; VO2max: 34.57±9.24 ml.kg-1.dk-1; Maximal La: 8.72±2.75 mM) with four years’ experience participated in the study. All subjects performed incremental maximal and sub-threshold constant load kayak paddling tests in normoxic and normobaric hypoxic conditions on different days. According to maximal tests results, the individual anaerobic threshold and VO2max values were determined. Results: VO2max, HRmax, peak power and maximal lactate values demonstrated statistical significant differences between the normobaric hypoxia and normoxic environment. The response of VO2max was found higher in the normoxic than the normobaric environment. Oxygen uptake kinetic was statistically (p<0.05) faster, and O2 values were lower (p<0.05) in the normoxic than the normobaric environment. Recovery kinetics was found to be statistically faster (p<0.05) in the hypoxia than in the normoxia environment. Conclusions: The ATP supply in an anaerobic way was higher in the normoxic environment than in the normobaric environment, and lactate tolerance increased. Having faster oxygen uptake kinetics in the normoxic environment shows that the volume of oxygen deficit is lower. Faster recovery kinetics in normobaric hypoxia shows the positive effects of altitude on recovery.

Acute Exhaustive Exercise under Normoxic and Normobaric Hypoxic Conditions Differentially Regulates Angiogenic Biomarkers in Humans.

Background and Objectives: Angiogenesis describes the outgrowth of new capillaries from already existing ones. Different biomarkers regulate this process. Physical exercise and hypoxia are key stimuli for the activation of different angiogenic molecules, such as the vascular endothelial growth factor (VEGF). matrix metalloproteases (MMPs)-2 and -9 or the extracellular matrix cleavage fragment endostatin. The present study aimed to investigate influences of short-term, intensive cycling exercise under both normoxic and normobaric hypoxic conditions on the mentioned parameters. Materials and Methods: Twelve male subjects (age: 23.3 ± 2.0 years) participated in the study. All subjects conducted four intensive cycling tests until individual exhaustion in a randomized order under the following conditions: normoxia, 2000 m, 3000 m and 4000 m above sea level. Blood samples were taken before (pre) and 10 min, 30 min, 60 min and 240 min post exercise and were analyzed by ELISA. Results: VEGF showed a significantly reduced concentration compared to the pre-value solely under 4000 m at 10 min post exercise. MMP-2 showed significantly reduced concentrations at 240 min post exercise under 4000 m. MMP-9 increased at 240 min post exercise under both 2000 m and 4000 m conditions. Endostatin was significantly increased at 10 min post exercise independently of the applied stimulus. Conclusions: The presented data show that intensive short-term exercise bouts facilitate the bioavailability of angiogenic, ECM (extracellular matrix)-related biomarkers. This finding is interesting for both health- and performance-related research as it demonstrates the positive effects of intensive short exercise interventions.

Effects of combined hot and hypoxic conditions on muscle blood flow and muscle oxygenation during repeated cycling sprints.

The purpose of the present study was to determine muscle blood flow and muscle oxygenation during repeated-sprint exercise under combined hot and hypoxic conditions. In a single-blind, cross-over research design, 11 active males performed three sets of 5 × 6-s maximal sprints with 30-s active recovery on a cycling ergometer under control (CON; 23°C, 50% rH, 20.9% FiO2), normobaric hypoxic (HYP; 23°C, 50% rH, 14.5% FiO2), or hot + normobaric hypoxic (HH; 35°C, 50% rH, 14.5% FiO2) conditions. The vastus lateralis muscle blood flow after each set and muscle oxygenation during each sprint were evaluated using near-infrared spectroscopy methods. Despite similar repeated-sprint performance among the three conditions (peak and mean power outputs, percent decrement score), HH was associated with significantly higher muscle blood flow compared with CON after the first set (CON: 0.61 ± 0.10mL/min/100g; HYP: 0.81 ± 0.13mL/min/100g; HH: 0.99 ± 0.16mL/min/100g; P < 0.05). The tissue saturation index was significantly lower in HYP than in CON during the latter phase of the exercise (P < 0.05), but it did not differ between HH and CON. These findings suggest that a combination of normobaric hypoxia and heat stress partially facilitated the exercise-induced increase in local blood flow, but it did not enhance tissue desaturation.

Effects of normobaric hypoxic endurance training on fatigue in patients with multiple sclerosis: a randomized prospective pilot study

BackgroundFatigue is one of the most frequent symptoms in patients with multiple sclerosis (MS), causing a major impact on quality-of-life. Non-pharmacological intervention strategies involve physical activity, which has been shown to reduce fatigue. Training under normobaric hypoxic conditions is thought to improve the response to endurance training and may, therefore, have an additional benefit over normoxic training conditions in MS patients.ObjectiveTo compare the effects of endurance training under hypoxic and normoxic conditions on fatigue, mobility and spasticity in patients with MS during inpatient rehabilitation.MethodsThirty-nine patients with MS were assigned within a randomized prospective longitudinal pilot study to (1) a routine clinical rehabilitation program, (2) a routine clinical rehabilitation program + normoxic endurance training and (3) a routine clinical rehabilitation program + hypoxic endurance training for 14 days. Fatigue (WEIMuS and MFIS), spasticity (MSSS-88) and walking endurance (6MinWT) were assessed at days 0, 7 and 14.ResultsFatigue scores improved significantly in all groups, but these improvements were reached faster in the groups which additionally received endurance training (normoxic p = 0.004; hypoxic p = 0.002). Spasticity scores were significantly lower in endurance training groups at the end of the study compared to baseline (normoxic p = 0.048, hypoxic p = 0.012), while only the hypoxic group increased significantly in 6MinWT (p = 0.001).ConclusionsOur findings demonstrate that endurance training provides substantial benefit to neurological rehabilitation programs. Endurance training under hypoxic conditions could positively influence walking endurance within a 2-week training intervention and warrants further investigations.

Reliability and validity of the Hypoxico Everest Summit II altitude generator

The Hypoxico Everest Summit II Altitude Generator produces normobaric hypoxic conditions, which are commonly used in altitude acclimation. Despite being used routinely within applied sport science, this system is yet to be independently validated. Thus, the aim of this study was to explore within- and between-day inter- and intra-machine reliability and validity. Two Hypoxico Everest Summit II Altitude Generators were investigated for six altitude settings in a randomised order (0.5, 3.0, 5.5, 8.0, 10.5, 12.0). Following institutional ethics approval, Hypoxico generated air was sequentially pumped into three Douglas bags, each with a 1-min collection period. Samples were collected on eight occasions, measuring inter- and intra-machine reliability, both within-day (9 AM–2 PM) and between-day (48-h) with samples analysed to determine FiO2 (%) and volume (L·min−1). Coefficient of variation (CV) was calculated for FiO2 and volume for each altitude setting. Mean CV for FiO2 did not exceed 0.42% within-day, 0.49% between-day and 0.81% inter-machine. Volume mean CV did not exceed 0.85% within-day, 0.91% between-day and 1.17% inter-machine. One-sampled t-tests were conducted comparing Hypoxico reference values with collected samples using equivalent FiO2 for each altitude setting with a Bonferroni corrected significance set at p &lt; 0.004. Settings 3.0, 5.5, 8.0, 10.5 and 12.0 all produced significantly different ( p &lt; 0.001) FiO2 concentrations than the reference values stated (−0.51, −0.97, −0.72, +0.41 and +0.40%, respectively). Altitude setting and 1-min volume had an inverse relationship. All settings produced a significantly lower ( p &lt; 0.001) volume by 21.80 to 35.40 L·min−1 as compared to the company’s claim of 126.6 L·min−1. The Hypoxico Everest Summit II produced a reliable and consistent air feed; however, the manufacturer’s reference values demonstrated poor agreement with machine produced FiO2 and volume. Therefore, it is recommended that athletes, practitioners and researchers self-validate the altitude generator post-warm-up using an accurate oxygen sensor for accuracy and safety purposes.

Effects of six weeks of aerobic training on the resting levels of VEGF, Body Composition and VO2max within normobaric hypoxic conditions in overweight/obesity women

هدف: با توجه به رشد فزایندۀ چاقی و اضافه وزن در سال‌های اخیر، این پژوهش با هدف بررسی تأثیر تمرین هوازی در شرایط هایپوکسی نورموباریک و نورموکسی بر سطوح استراحتی VEGF و VO2max زنان دارای اضافه وزن / چاق انجام گرفت. روش‌ها: بدین‌منظور 24 زن دارای اضافه وزن (میانگین و انحراف استاندارد سن، قد و وزن به‌ترتیب 7/3 ±25/28 سال، 01/3±8/161 سانتی‌متر و 18/7±64/78 کیلوگرم) در گروه تمرین هایپوکسی نورموباریک به مدت 6 هفته و هر هفته 3 جلسه تمرین هوازی در چادر هایپوکسی را انجام دادند و گروه نورموکسی در زمانی معادل با زمان تمرین گروه هایپوکسی نورموباریک تمرین هوازی در شرایط نورموباریک داشتند. برنامۀ تمرین شامل 5 دقیقه گرم کردن، 20 دقیقه فعالیت با 60 درصد ضربان قلب بیشینه در هفتۀ اول بود و سپس هر هفته 5 دقیقه به مدت زمان فعالیت افزوده شد.نتایج: تغییرات وزن (165/0p=) و BMI (191/0p=) گروه هایپوکسی نورموباریک در مقایسه با نورموکسی معنادار نبود. ولی تغییرات درصد چربی (022/0p=) و دور کمر (031/0p) هنگام مقایسۀ دو گروه معنادار بود. تغییرات اکسیژن مصرفی بیشینه (008/0p=) و VEGF (001/0p <) تفاوت معناداری نشان داد. نتیجه‌گیری: افزایش بیشتر و معنادار سطوح استراحتی VEGF در شرایط هایپوکسی نورموباریک نشان‌دهندۀ اهمیت فعالیت بدنی در کاهش خطر بیماری‌های قلبی- عروقی و عملکرد اندوتلیال عروق در افراد دارای اضافه وزن است.

Alterations in acid\u2013base balance and high-intensity exercise performance after short-term and long-term exposure to acute normobaric hypoxic conditions

This investigation assessed the course of renal compensation of hypoxia-induced respiratory alkalosis by elimination of bicarbonate ions and impairments in anaerobic exercise after different durations of hypoxic exposure. Study A: 16 participants underwent a resting 12-h exposure to normobaric hypoxia (3,000 m). Blood gas analysis was assessed hourly. While blood pH was significantly increased, PO2, PCO2, and SaO2 were decreased within the first hour of hypoxia, and changes remained consistent. A substantial reduction in [HCO3−] levels was observed after 12 h of hypoxic exposure (− 1.35 ± 0.29 mmol/L, p ≤ 0.05). Study B: 24 participants performed in a randomized, cross-over trial portable tethered sprint running (PTSR) tests under normoxia and after either 1 h (n = 12) or 12 h (n = 12) of normobaric hypoxia (3,000 m). No differences occurred for PTSR-related performance parameters, but the reduction in blood lactate levels was greater after 12 h compared with 1 h (− 1.9 ± 2.2 vs 0.0 ± 2.3 mmol/L, p ≤ 0.05). These results indicate uncompensated respiratory alkalosis after 12 h of hypoxia and similar impairment of high-intensity exercise after 1 and 12 h of hypoxic exposure, despite a greater reduction in blood lactate responses after 12 h compared with 1 h of hypoxic exposure.

Magnesium Supplementation Combined With Hypoxic Training In Improving Hepatic Lipid Metabolism In Obese Mice

PURPOSE: To explore the effect of hypoxic training on magnesium level, investigate the mechanism of magnesium supplementation combined with hypoxia training on hepatic lipid metabolism in obese mice. METHODS: Forty high-fat diet induced C57BL/6J mice were assigned into four groups (n=10 each): Diet-induced obesity (DIO); hypoxia training (HT), living and training in normobaric hypoxic conditions; magnesium supplementation (Mg), the 100mg/kg/d dose of magnesium chloride added to drinking water; hypoxia training+magnesium supplementation (HT+Mg). And set up a chow diet control group (CON). The intervention lasted for 4 weeks. All comparisons were made using two-way ANOVA analysis. RESULTS: 1) Serum magnesium in HT group (63.17±0.86 ppm vs 71.85±3.06 ppm) was decreased; femur magnesium in Mg group (2287.71±88.48 ppm vs 2106.89±41.68 ppm) were significant increased after 4 weeks intervention. And the femur magnesium was significantly negatively correlated with body weight (p<0.01, r=-0.645). 2) Compared with DIO group (1.80±0.32 g),liver weight of HT group(1.32±0.17 g),HT+Mg group (1.38±0.23 g) were significantly decreased; 3) Compared with DIO group (19.10±1.82 ng/ml,8.58±0.41 U/L),serum ATGL level in Mg group (25.43±1.71 ng/ml), HT+Mg group (31.56±2.46 ng/ml) and serum CPT-1 level in HT+Mg group (17.46±1.56 U/L vs) were significantly increased. 4) Compared with DIO group(1.01±0.19),liver PPARα mRNA expression in HT group (1.30±0.28), HT+Mg group (2.32±0.75) were significantly increased; liver ATGL (3.68±2.20 vs 1.04±0.31), LPL (7.72±3.14 vs 1.02±0.21), CPT-1 (6.85±3.89 vs 1.03±0.30) mRNA expression in HT+Mg group were significantly higher than DIO group. Moreover, the PPARα, CPT-1 mRNA expression level was significantly higher than HT group (1.43±0.46). CONCLUSIONS: 1) Hypoxic training can significantly reduce femur magnesium,increase the loss of magnesium while effectively losing weight. 2) 4 weeks of hypoxic training combined with magnesium supplementation intervention can effectively reduce the liver weight and hepatic free fatty acid in obese mice; 3) Hypoxic training combined with magnesium supplementation may promote liver lipolysis and fatty acid beta oxidation by activating liver PPARα and its downstream factors, improve liver lipid metabolism in obese mice.

CrossTalk opposing view: Barometric pressure, independent of , is not the forgotten parameter in altitude physiology and mountain medicine.

CrossTalk opposing view: Barometric pressure, independent of , is not the forgotten parameter in altitude physiology and mountain medicine.

Acute environmental hypoxia potentiates satellite cell-dependent myogenesis in response to resistance exercise through the inflammation pathway in human.

Acute environmental hypoxia may potentiate muscle hypertrophy in response to resistance training but the mechanisms are still unknown. To this end, twenty subjects performed a 1-leg knee extension session (8 sets of 8 repetitions at 80% 1 repetition maximum, 2-min rest between sets) in normoxic or normobaric hypoxic conditions (FiO2 14%). Muscle biopsies were taken 15 min and 4 hours after exercise in the vastus lateralis of the exercised and the non-exercised legs. Blood samples were taken immediately, 2h and 4h after exercise. In vivo, hypoxic exercise fostered acute inflammation mediated by the TNFα/NF-κB/IL-6/STAT3 (+333%, +194%, + 163% and +50% respectively) pathway, which has been shown to contribute to satellite cells myogenesis. Inflammation activation was followed by skeletal muscle invasion by CD68 (+63%) and CD197 (+152%) positive immune cells, both known to regulate muscle regeneration. The role of hypoxia-induced activation of inflammation in myogenesis was confirmed in vitro. Acute hypoxia promoted myogenesis through increased Myf5 (+300%), MyoD (+88%), myogenin (+1816%) and MRF4 (+489%) mRNA levels in primary myotubes and this response was blunted by siRNA targeting STAT3. In conclusion, our results suggest that hypoxia could improve muscle hypertrophic response following resistance exercise through IL-6/STAT3-dependent myogenesis and immune cells-dependent muscle regeneration.

Serum Autofluorescence and Biochemical Markers in Athlete's Response to Strength Effort in Normobaric Hypoxia: A Preliminary Study.

The human organism has the ability to adapt to hypoxia conditions. Training in hypoxia is used in sport to improve the efficiency of athletes; however, type of training affects the direction and scope of this process. Therefore, in this study, the usefulness of serum fluorescence spectroscopy to study the assessment of athlete's response to strength effort in hypoxia is considered in comparison with biochemical assay. Six resistance-trained male subjects took part in a research experiment. They performed barbell squats in simulated normobaric hypoxic conditions with deficiency of oxygen 11.3%, 13% 14.3% compared to 21% in normoxic conditions. Fluorescence intensity of tyrosine revealed high sensitivity on strength effort whereas tryptophan was more dependent on high altitude. Changes in emission in the visible region are associated with altering cell metabolism dependent on high altitude as well as strength training and endurance training. Significant changes in serum fluorescence intensity with relatively weak modifications in biochemical assay at 3000 m above sea level (ASL) were observed. Training at 5000 m ASL caused changes in fluorescence parameters towards the normobaric specific values, and pronounced decreases of lactate level and kinase creatine activity were observed. Such modifications of fluorescence and biochemical assay indicate increased adaptation of the organism to effort in oxygen-deficient conditions at 5000 m ASL, unlike 3000 m ASL. Fluorescence spectroscopy study of serum accompanied by biochemical assay can contribute to the understanding of metabolic regulation and the physiological response to hypoxia. The results of serum autofluorescence during various concepts of altitude training may be a useful method to analyze individual response to acute and chronic hypoxia. An endogenous tryptophan could be exploited as intrinsic biomarker in autofluorescence studies. However, these issues require further research.