Hypoxic Training Research Articles

Intermittent hypoxia training improves cerebral blood flow without cognitive impairment.

Brief exposure to intermittent hypoxia has been shown to potentially induce protective effects in the body. Animal studies suggest that intermittent hypoxia could increase cerebral blood flow and confer resistance to subsequent hypoxic-ischemic injury, yet clinical investigations are limited. This study aimed to evaluate the impact of a moderate short-term intermittent hypoxia protocol on cerebral blood flow and cognitive performance. Subjects who met the inclusion criteria were recruited to this study and randomized into the intermittent hypoxia group or the control group, which receives intermittent hypoxia training and sham-intermittent hypoxia training, respectively. Cerebral hemodynamics, cognitive performance, cerebral perfusion pressure, and oxygen saturation were assessed before and after the intervention. A total of 100 healthy participants were included in this study. Compared to the control group, the intermittent hypoxia group exhibited higher peak systolic blood flow velocity (108.64 ± 22.53 vs. 100.21 ± 19.06, p = 0.049) and cerebrovascular conduction index (0.74 ± 0.17 vs. 0.66 ± 0.21, p = 0.027), and lower cerebrovascular resistance index (1.41 ± 0.29 vs. 1.54 ± 0.36, p = 0.044) following intermittent hypoxia training. Additionally, within-group comparisons revealed that intermittent hypoxia training led to increased cerebral blood flow velocity, elevated cerebrovascular conductance index, and decreased cerebrovascular resistance index (p < 0.05). Other indicators including cognitive function, cerebral perfusion pressure, and oxygen saturation did not exhibit significant differences between groups. These findings revealed that intermittent hypoxia may represent a safe and effective strategy for improving cerebral blood flow.

Effects of a Combined Method of Normobaric Hypoxia on the Repeated Sprint Ability Performance of a Nine-Time World Champion Triathlete: A Case Report

Elite athletes are an under-represented population in scientific studies, and there are no works analysing the influence of hypoxia in elite triathletes. The aim of this study was to analyse the influence of different methods of normobaric hypoxia on repeated sprint ability (RSA) performance. This study was a case study with an elite triathlete who has won nine triathlon world championships. The study used a combination of different methods of normobaric hypoxia. The three methods combined were as follows: live high-train low interspersed; intermittent hypoxic training; and intermittent hypoxic exposure. This study analysed the influence of these methods on RSA performance in variables such as power output, saturation of muscular oxygen, heart rate and ventilatory variables (VO2 and VCO2). The triathlete was measured before the training protocol (PRE), just after (POST-D3) and 21 days after the end of the protocol (POST-D21). This type of protocol has shown that it can lead to an improvement in RSA performance in the number of sprints (PRE vs. POST-D3 vs. POST-D21: 19 vs. 24 vs. 28), power output (PRE 615 W vs. POST-D3 685 W vs. POST-D21 683W) and efficiency of the triathlete. This work may be useful in improving power output and repeated sprint ability for elite triathletes.

Repeated-sprint training in hypoxia: A review with 10 years of perspective.

Over the past decade, numerous studies have investigated an innovative "live low-train high" approach based on the repetition of short (<30 s) "all-out" sprints with incomplete recoveries in hypoxia; the so-called Repeated-Sprint training in Hypoxia (RSH). The aims of the present review are therefore threefold. First, this study summarizes the available evidence on putative additional performance enhancement after RSH comparing to the same training in normoxia (RSN). Second, a critical analysis of underpinning mechanisms discusses how advantages can be obtained through RSH for sea-level performance enhancement. An enhanced microcirculatory vasodilation leading to improved muscle perfusion and/or oxygenation and an increase in muscular phosphocreatine content may help explain the superiority of RSH vs. RSN. Third, the present review aims to provide guidelines for coaches, athletes and scientists to apply RSH interventions with regard to the interval duration, exercise-to-rest ratio and training volume. In conclusion, this review supports repeated-sprint training in hypoxia as an efficient (but not magic) training intervention with 77% of the controlled studies reporting an additional benefit with added hypoxia, mainly for team-, combat- and racket-sports athletes but also for all other sports (e.g. endurance) that require repeated accelerations with lesser fatigue.

Preconditioning with Moderate Hypoxia Increases Tolerance to Subsequent Severe Hypoxia in Rats with LPS-Induced Endotoxemia

Hyperproduction of mediators of LPS-induced inflammatory process (endotoxicosis, sepsis) initiates the development of acute respiratory failure (ARF), impaired gas exchange, progressive hypoxemia and hypercapnia, hypotension, respiratory arrest and death. Severe sepsis associated with hypoxemia remains the main cause of death, and therefore the development of methods to increase resistance to acute hypoxia in septic patients is an urgent task. The aim of the work was to study the effectiveness of preconditioning with short-term intermittent moderate hypoxia to increase tolerance to subsequent severe hypoxia in rats with LPS-induced endotoxicosis. The experiments were carried out on anesthetized and tracheostomated male Wistar rats. Endotoxicosis was modeled by administration of a lipopolysaccharide solution (Escherichia coli) in an amount of 7 mg/kg. To assess resistance to severe hypoxia, the rebreathing method of (RM) with a gradual decrease in oxygen in the rebreather from 21% to the onset of apnea was used. Hypoxic preconditioning (hypoxic training, HT) was also created by the method of RM in the mode of 3 cycles: reduction of the oxygen fraction in the rebreather to 12% – 3 min, 5 min – normoxia. 3 groups of animals were studied: I-control-NaCl, II–LPS, III–LPS+HT. The following parameters were recorded: external respiration, mean blood pressure (APm.), saturation (SpO2), fraction of inhaled O2, time of onset of apnea, the amount of spontaneous respiratory recovery (autoresuscitation) in the posthypoxic period. It was shown that the administration of LPS under normoxic conditions was accompanied by hyperventilation, hypoxemia and hypotension. The maximum deterioration in resistance to severe hypoxia was observed in rats with LPS, which was manifested by a decrease in APm, SpO2 and a decrease in the possibility of autoresuscitation after hypoxic apnea. The effect of HT prevented a decrease in blood pressure, SpO2 increased by 1.4 times, survival increased by 2 times, which is comparable to the level of normoxia before the introduction of LPS. It is assumed that the effectiveness of hypoxic preconditioning is due to the inhibition of the inflammatory response.

Effects of concurrent heat and hypoxic training on cycling anaerobic capacity in men

Physical training in heat or hypoxia can improve physical performance. The purpose of this parallel group study was to investigate the concurrent effect of training performed simultaneously in heat (31 °C) and hypoxia (FIO2 = 14.4%) on anaerobic capacity in young men. For the study, 80 non-trained men were recruited and divided into 5 groups (16 participants per group): control, non-training (CTRL); training in normoxia and thermoneutral conditions (NT: 21 °C, FIO2 = 20.95%); training in normoxia and heat (H: 31 °C, FIO2 = 20.95%); training in hypoxia and thermoneutral conditions (IHT: 21 °C, FIO2 = 14.4%), and training in hypoxia and heat (IHT + H: 31 °C, FIO2 = 14.4%). Before and after physical training, the participants performed the Wingate Test, in which peak power and mean power were measured. Physical training lasted 4 weeks and the participants exercised 3 times a week for 60 min, performing interval training. Only the IHT and IHT + H groups showed significant increases in absolute peak power (p < 0.001, ES = 0.36 and p = 0.02, ES = 0.26, respectively). There were no significant changes (p = 0.18) after training in mean power. Hypoxia appeared to be an environmental factor that significantly improved peak power, but not mean power. Heat, added to hypoxia, did not increase cycling anaerobic power. Also, training only in heat did not significantly affect anaerobic power. The inclusion of heat and/or hypoxia in training did not induce negative effects, i.e., a reduction in peak and mean power as measured in the Wingate Test.

Normobaric Hypoxia Symptom Recognition in Three Training Sessions

INTRODUCTION: Hypoxia training is mandatory for military pilots, but variability in hypoxia symptoms challenges the training. In a previous study we showed that 64% of pilots recognized hypoxia faster in their second normobaric hypoxia session conducted 2.4 yr after the first. Our aim here was to evaluate whether a third session conducted 5.0 yr after the first would provide further benefit. METHODS: This study was conducted under normobaric conditions in a tactical F/A-18C Hornet simulator in three sessions in which the pilots performed visual identification missions and breathed 21% oxygen in nitrogen. The breathing gas was changed to a hypoxic mixture containing either 8%, 7%, or 6% oxygen in nitrogen without the pilot’s knowledge. Data were collected from 102 military pilots. The primary outcome was the time taken for initial identification of hypoxia symptoms. RESULTS: Hypoxia symptoms were recognized on average in the first session in 8% oxygen in 100 s, 7% oxygen in 90 s, and 6% oxygen in 78 s; in the second in 87 s, 80 s, and 71 s, respectively; and in the third in 79 s, 67 s, and 64 s, respectively. In 2 sessions 20 pilots and in each 3 training sessions 3 pilots had slow recognition times. DISCUSSION: Hypoxia symptom recognition improved the further the repeated normobaric hypoxia training went. More emphasis should be put on the 23% group of slow hypoxia symptom recognizers and more customized hypoxia training for them should be offered. Leinonen AM, Varis NO, Kokki HJ, Leino TK. Normobaric hypoxia symptom recognition in three training sessions. Aerosp Med Hum Perform. 2024; 95(10):758–764.

Hypoxic training as a doping method - the final whistle from Norway and Italy.

Hypoxic training as a doping method - the final whistle from Norway and Italy.

Hypoxic Functional Training Improves Young Adults’ Sleep Quality And Exercise Performance When Acutely Entering High Altitude

Hypoxic Functional Training Improves Young Adults’ Sleep Quality And Exercise Performance When Acutely Entering High Altitude

Reverse periodization in ultratrail: The road to the 2023 World Mountain and Trail Running Championships of an elite female ultrarunner

Introduction and Purpose Traditionally, linear periodization has been widely applied to endurance training programs, whereas reverse periodization has been often used for shorter endurance events (Clemente-Suárez et al., 2015; Clemente-Suárez et al., 2018; Clemente-Suárez &amp; Ramos-Campo, 2019) and fitness (Prestes et al., 2009). The aim of this study was to describe the training characteristics of a Spanish high-level female ultrarunner in her preparation to the 2023 World Mountain and Trail Running Championships using a reverse linear periodization model. Methods Day-by-day data training of 1 study subject for 29 weeks (from November 2022 to June 2023) was retrospectively analyzed. Training form (endurance, strength or complementary sessions), intensity (low-, moderate-, and high-intensity training), intensity distribution, exercise endurance mode (cycling, elliptical, running or trail running) and specific exercise mode goal session (running uphill, running flat, running downhill, hiking or mixed) were considered. Specific sessions, key competitions, tapering, hypoxia period and periodization were also analyzed. Results An average training of 8 hr and 53 min per week, covering 87.2 km and 3,755 m of altitude gain, was completed. The hardest week consisted of 14 hr and 58 min, 145 km, and 7,552 m of altitude gain. Distribution percentage of the training form of total training time was ~60% of running, ~17% cross training (mainly road cycling) and ~11% of strength training. Intensity distribution varied considering specificity and characteristics of the main races, progressing from more polarized to pyramidal pattern distribution. Moreover, running volume increased during the preparation period and more specific sessions and with mixed specific exercise modes was realized close to the main races, with the longest trail run of 4 hr 18 min of duration. Training in hypoxia was also completed, and tapering started 12 days before the world championship. In addition to the World Championship, National Championship races were held during the preparation period, where a 4th and a 3rd place in the Marathon (February 2023) and Ultratrail (April 2023) National Championships, respectively, was achieved. Discussion Reverse periodization has been successfully implemented in an elite female ultrarunner, finishing 11th in the 2023 World Mountain and Trail Running Championships. Reverse periodization was planned and completed, mainly considering volume and tendency of distribution, going from a polarized pattern to a pyramidal one. Moreover, overall planning and key sessions progressed in specificity, developing more rolling-hill trail runs, longer trail runs, longer longest trail run of the week, and more specific exercise modes (i.e. more hiking and mixed sessions vs flats runs) along the macrocycle. Conclusion Training specificity in trail running, considering race intensity, exercise mode and race characteristics (i.e., elevation gain and distance) progressed during the macrocycle. Reverse periodization can be successfully implemented in ultratrail running by focusing on specific training and race demands, especially close to the main races.

Effects of 12 Weeks of Combined Exercise Training in Normobaric Hypoxia on Arterial Stiffness, Inflammatory Biomarkers, and Red Blood Cell Hemorheological Function in Obese Older Women.

The present study examined the effect of 12-week combined exercise training in normobaric hypoxia on arterial stiffness, inflammatory biomarkers, and red blood cell (RBC) hemorheological function in 24 obese older women (mean age: 67.96 ± 0.96 years). Subjects were randomly divided into two groups (normoxia (NMX; n = 12) and hypoxia (HPX; n = 12)). Both groups performed aerobic and resistance exercise training programs three times per week for 12 weeks, and the HPX group performed exercise programs in hypoxic environment chambers during the intervention period. Body composition was estimated using bioelectrical impedance analysis equipment. Arterial stiffness was measured using an automatic waveform analyzer. Biomarkers of inflammation and oxygen transport (tumor necrosis factor alpha, interleukin 6 (IL-6), erythropoietin (EPO), and vascular endothelial growth factor (VEGF)), and RBC hemorheological parameters (RBC deformability and aggregation) were analyzed. All variables showed significantly more beneficial changes in the HPX group than in the NMX group during the intervention. The combined exercise training in normobaric hypoxia significantly reduced blood pressure (systolic blood pressure: p < 0.001, diastolic blood pressure: p < 0.001, mean arterial pressure: p < 0.001, pulse pressure: p < 0.05) and brachial-ankle pulse wave velocity (p < 0.001). IL-6 was significantly lower in the HPX group than in the NMX group post-test (p < 0.001). Also, EPO (p < 0.01) and VEGF (p < 0.01) were significantly higher in the HPX group than in the NMX group post-test. Both groups showed significantly improved RBC deformability (RBC EI_3Pa) (p < 0.001) and aggregation (RBC AI_3Pa) (p < 0.001). The present study suggests that combined exercise training in normobaric hypoxia can improve inflammatory biomarkers and RBC hemorheological parameters in obese older women and may help prevent cardiovascular diseases.

Mapping ethical positions concerning a coach’s decision to organise a hypoxic training camp

ABSTRACT On the basis of qualitative literature data, the ethical value of hypoxic training in sports is subject to debate. The objective of the present empirical study was to map various ethical positions with regard to how individuals mentally combined several factors (the hypoxic training’s objective, fairness, planning/monitoring, and method) when judging the acceptability of holding a hypoxic training camp before an event. Two hundred and sixteen participants (including 126 men and 90 women, and 186 athletes and 30 non-athletes) specified their judgement of acceptability in 36 scenarios created by cross-referencing the four factors. A cluster analysis was applied to the whole dataset. Repeated-measures analyses of variance with a 2 × 3 × 3 × 2 factorial design were then applied to each cluster. Lastly, the relationship between the clusters and the participants’ characteristics was assessed in chi-squared tests. The analyses showed four ethical positions: “Moderately acceptable” for 26% of the participants, “Acceptable, depending mainly on monitoring” for 38% of the participants, “Always acceptable” for 20% of the participants, and “Never acceptable unless planned with an expert in hypoxic training and monitored by a physician” for 16% of the participants. Contrary to female participants and non-athletes, male participants and athletes tended to accept the coach’s decision to organise a hypoxic training camp easily. Our study confirmed empirically that hypoxic training does not violate the spirit of sport. Sports stakeholders might refer to our study’s findings to set up a public relations plan that highlights the ethical value of hypoxic training.

Repeated sprint training in hypoxia and repeated long sprint ability in highly trained sprint runners

Repeated sprint training in hypoxia and repeated long sprint ability in highly trained sprint runners

The impact of hypoxic training at different altitudes on human physiology, biochemistry, and cytogenetics

This study investigated the impact of dosed hypoxic normobaric exercises on the physio-biochemical parameters of blood and lymph circulation, as well as cytogenetic changes in red blood cells (RBC), using a Sprague Dawley Rat Model. Hypoxic training was conducted in an animal hypoxic chamber. The session lasted 34-35 minutes. The O2 content was 20.5% at the beginning of the session; then, it dropped to 14.8% within 4-5 minutes, corresponding to a rise to an altitude of 2,900-3,000 m, and was maintained at that level until the end of the session. The hypoxic training cycle increased the RBC count by 4.1%, the hemoglobin count by 4.2%, the blood oxygen capacity by 8.3%, the circulating blood volume by 16.7%, and interstitial metabolism and lymph circulation by 30.6%. A cytogenetic study revealed an increase in erythropoiesis-reticulocyte count by 40.3% and a slightly higher frequency of micronucleated erythrocytes. We observed economization of the heart, respiration, activation of glucose transport by 33.5%, increased lipid utilization, and increased antioxidant protection. These parameters especially changed when hypoxic training was combined with physical activity. Hypoxic training with physical activity expands the body’s compensatory and adaptive capabilities by increasing the reserves of the respiratory, cardiovascular, and lymphatic systems.

Effects of Intermittent Hypoxia Protocols on Cognitive Performance and Brain Health in Older Adults Across Cognitive States: A Systematic Literature Review.

The rise in the aging population highlights the need to address cognitive decline and neurodegenerative diseases. Intermittent hypoxia (IH) protocols show promise in enhancing cognitive abilities and brain health. This review evaluates IH protocols' benefits on cognition and brain health in older adults, regardless of cognitive status. A systematic search following PRISMA guidelines was conducted across four databases (PubMed, Scopus, Web of Science, and Cochrane Library) and two registers, covering records from inception to May 2024 (PROSPERO: CRD42023462177). Inclusion criteria were: 1) original research with quantitative details; 2) studies involving older adults, with or without cognitive impairment; 3) studies including IH protocols; 4) articles analyzing cognition and brain health in older adults. Seven studies and five registered trials met the criteria. Findings indicate that Intermittent Hypoxia Training (IHT) and Intermittent Hypoxia-Hyperoxia Training (IHHT) improved cognitive functions and brain health. Intermittent Hypoxic Exposure (IHE) improved cerebral tissue oxygen saturation, middle cerebral arterial flow velocity, and cerebral vascular conductance, particularly in cognitively impaired populations. IHT and IHHT had no significant effect on BDNF levels. There is a lack of studies on IHHE in older adults with and without cognitive impairment. IH protocols may benefit cognition regardless of cognitive status. IHT and IHE positively affect cerebral outcomes, with all protocols having limited effects on BDNF levels. Future research should standardize IH protocols, investigate long-term cognitive effects, and explore neuroprotective biomarkers. Combining these protocols with physical exercise across diverse populations could refine interventions and guide targeted therapeutic strategies.

The Effects of Normobaric Hypoxia on the Acute Physiological Responses to Resistance Training: A Narrative Review.

Allsopp, GL, Britto, FA, Wright, CR, and Deldicque, L. The effects of normobaric hypoxia on the acute physiological responses to resistance training: a narrative review. J Strength Cond Res XX(X): 000-000, 2024-Athletes have used altitude training for many years as a strategy to improve endurance performance. The use of resistance training in simulated altitude (normobaric hypoxia) is a growing strategy that aims to improve the hypertrophy and strength adaptations to training. An increasing breadth of research has characterized the acute physiological responses to resistance training in hypoxia, often with the goal to elucidate the mechanisms by which hypoxia may improve the training adaptations. There is currently no consensus on the overall effectiveness of hypoxic resistance training for strength and hypertrophy adaptations, nor the underlying biochemical pathways involved. There are, however, numerous interesting physiological responses that are amplified by performing resistance training in hypoxia. These include potential changes to the energy system contribution to exercise and alterations to the level of metabolic stress, hormone and cytokine production, autonomic regulation, and other hypoxia-induced cellular pathways. This review describes the foundational exercise physiology underpinning the acute responses to resistance training in normobaric hypoxia, potential applications to clinical populations, including training considerations for athletic populations. The review also presents a summary of the ideal training parameters to promote metabolic stress and associated training adaptations. There are currently many gaps in our understanding of the physiological responses to hypoxic resistance training, partly caused by the infancy of the research field and diversity of hypoxic and training parameters.

Combined intermittent hypoxic exposure at rest and continuous hypoxic training can maintain elevated hemoglobin mass after a hypoxic camp.

Athletes use hypoxic living and training to increase hemoglobin mass (Hbmass), but Hbmass declines rapidly upon return to sea level. We investigated whether intermittent hypoxic exposure (IHE) + continuous hypoxic training (CHT) after return to sea level maintained elevated Hbmass, and if changes in Hbmass were transferred to changes in maximal oxygen uptake (V̇o2max) and exercise performance. Hbmass was measured in 58 endurance athletes before (PRE), after (POST1), and 30 days after (POST2) a 27 ± 4-day training camp in hypoxia (n = 44, HYP) or at sea level (n = 14, SL). After returning to sea level, 22 athletes included IHE (2 h rest) + CHT (1 h training) in their training every third day for 1 mo (HYPIHE + CHT), whereas the other 22 HYP athletes were not exposed to IHE or CHT (HYPSL). Hbmass increased from PRE to POST1 in both HYPIHE + CHT (4.4 ± 0.7%, means ± SE) and HYPSL (4.1 ± 0.6%) (both P < 0.001). Compared with PRE, Hbmass at POST2 remained 4.2 ± 0.8% higher in HYPIHE + CHT (P < 0.001) and 1.9 ± 0.5% higher in HYPSL (P = 0.023), indicating a significant difference between the groups (P = 0.002). In SL, no significant changes were observed in Hbmass with mean alterations between -0.5% and 0.4%. V̇o2max and time to exhaustion during an incremental treadmill test (n = 35) were elevated from PRE to POST2 only in HYPIHE + CHT (5.8 ± 1.2% and 5.4 ± 1.4%, respectively, both P < 0.001). IHE + CHT possesses the potential to mitigate the typical decline in Hbmass commonly observed during the initial weeks after return to sea level.NEW & NOTEWORTHY Sets of 2-h intermittent hypoxic exposure + 1-h continuous hypoxic training, every third day, possess the potential to mitigate the typical decline in Hbmass that is commonly observed during the initial weeks after return to sea level from an altitude camp. Inclusion of IHE + CHT in the training regimen was also accompanied by improvements in V̇o2max and exercise performance in most but not all Tier 3-Tier 5 level endurance athletes during the training season.

Apnoea as a novel method to improve exercise performance: A current state of the literature.

Acute breath-holding (apnoea) induces a spleen contraction leading to a transient increase in haemoglobin concentration. Additionally, the apnoea-induced hypoxia has been shown to lead to an increase in erythropoietin concentration up to 5h after acute breath-holding, suggesting long-term haemoglobin enhancement. Given its potential to improve haemoglobin content, an important determinant for oxygen transport, apnoea has been suggested as a novel training method to improve aerobic performance. This review aims to provide an update on the current state of the literature on this topic. Although the apnoea-induced spleen contraction appears to be effective in improving oxygen uptake kinetics, this does not seem to transfer into immediately improved aerobic performance when apnoea is integrated into a warm-up. Furthermore, only long and intense apnoea protocols in individuals who are experienced in breath-holding show increased erythropoietin and reticulocytes. So far, studies on inexperienced individuals have failed to induce acute changes in erythropoietin concentration following apnoea. As such, apnoea training protocols fail to demonstrate longitudinal changes in haemoglobin mass and aerobic performance. The low hypoxic dose, as evidenced by minor oxygen desaturation, is likely insufficient to elicit a strong erythropoietic response. Apnoea therefore does not seem to be useful for improving aerobic performance. However, variations in apnoea, such as hypoventilation training at low lung volume and repeated-sprint training in hypoxia through short end-expiratory breath-holds, have been shown to induce metabolic adaptations and improve several physical qualities. This shows promise for application of dynamic apnoea in order to improve exercise performance. HIGHLIGHTS: What is the topic of this review? Apnoea is considered as an innovative method to improve performance. This review discusses the effectiveness of apnoea (training) on performance. What advances does it highlight? Although the apnoea-induced spleen contraction and the increase in EPO observed in freedivers seem promising to improve haematological variables both acutely and on the long term, they do not improve exercise performance in an athletic population. However, performing repeated sprints on end-expiratory breath-holds seems promising to improve repeated-sprint capacity.

Inflammation A Core Reason of Erectile Dysfunction: Intermittent Hypoxia Training A Proposed Novel Solution

Inflammation A Core Reason of Erectile Dysfunction: Intermittent Hypoxia Training A Proposed Novel Solution

Clinically-relevant reductions in oxygen partial pressure as possible contributor to cardiovascular benefits of sauna practice

The practice of sauna has been found to have both acute and long-term cardiovascular benefits, which are generally postulated to be a result of thermoregulatory physiological adaptations. Another element of sauna conditions which has been overlooked is that the extremely high absolute water content of air at sauna temperature, even at low relative humidity, results in significantly decreased partial pressure of oxygen. Using the Arden-Buck equation for water-carrying capacity of air along with the barometric formula, it is shown in this hypothesis that typical sauna conditions have an oxygen partial pressure reduction that may be equivalent to significant elevations above sea level. This effect may also be enhanced by lower air density further reducing available oxygen relative to respiratory volume.This paper presents the hypothesis that altitude adaptation may be a contributing factor in the cardiovascular benefits of sauna treatments, suggesting that sauna should be considered as an alternative in instances where intermittent hypoxic training is indicated but not available, and that clinical research into sauna treatment is merited for conditions in which intermittent hypoxic training is known to have applications. The hypothesis could be investigated through pulse oximetry of subjects under sauna conditions and by tracking blood markers of altitude adaptation compared to a control group using steam rooms.

Influence of Interval Hypoxic Training in Different Regimes on the Blood Parameters of Rats

The development of ways to increase the adaptive reserves of the body and resistance to negative factors continues to be an urgent problem for physiology, which has a significant translational potential in the fields of healthcare, sports, cosmonautics and the national economy. Long-term authors studies have proved the promise in this respect of hypoxic hypobaric conditioning in a pressure chamber. In the present study, the principles of hypobaric conditioning were transferred to the model of normobaric intermittent hypoxia/normoxia caused by the inhalation of gas mixtures, which is widely used in practice for human interval hypoxic training. A comparative experimental analysis of molecular and cellular changes in the blood of rats in response to three-day interval hypoxic training at 9, 12, or 16% O2 in the mixture was carried out using an automated setup. It was shown that the most intense and effective 3 × 9% O2 regimen, in terms of duration and amplitude, had the greatest effect on the parameters of the clinical blood test of rats, initiating an increase in the number of erythrocytes and a decrease in the variability of their volumes, and causing a shift in the balance of lymphokine and monokine effects towards a calm activation reaction. On the first day after training at 9 and 12% oxygen, the total antioxidant capacity of serum significantly decreased, followed by rapid normalization, which fits into the dynamics of the reaction of pro- and antioxidant systems to non-damaging hypoxia. The stimulating effect of all the studied regimens of interval training on the basal and stress activity of the hypothalamic-pituitary-adrenocortical system, characteristic of conditioning, was revealed. All detected post-training changes can be attributed to the basic adaptive mechanisms that increase resistance to adverse factors.