This study investigates the effects of different levels of acute normobaric hypoxia on cognitive function and cerebral oxygenation in healthy young adults. Twenty-four participants aged 18–30 years were exposed to hypoxia with an inspired oxygen fraction (FiO2) equivalent to 20.9

High-altitude chronic hypoxia can induce excessive erythrocytosis (EE, defined as a haemoglobin concentration of ≥21 g/dL in men), leading to hyperviscosity and promoting endothelial dysfunction. We aimed to assess whether EE affects the retinal vascular phenotype and the ophthalmological vascular response to CO2. We conducted an ophthalmological cross-sectional study among highlanders permanently living at 5100 m (La Rinconada, Peru). The central retinal artery equivalent (CRAE), central retinal vein equivalent (CRVE) and retinal vessel tortuosity were measured using semi-automatic imaging software (VAMPIRE) from the diameters of the six largest arteries and veins on fundus images. Choroidal blood flow was assessed using laser Doppler flowmetry. Measurements were performed at rest and during a hypercapnic challenge (+10.1 ± 1.4 mmHg end-tidal CO2). Among the 62 included highlanders, 38 (61%) had EE. Compared with non-EE, highlanders with EE exhibited higher CRVE (278 ± 25 vs. 249 ± 24 µm, P < 0.001), with no other significant ophthalmological differences. Resting CRVE was significantly correlated (all P-values < 0.001) with haematocrit (r = 0.56), haemoglobin concentration (r = 0.65), blood volume (r = 0.55) and the arterial partial pressure of carbon dioxide (r = 0.46). Hypercapnia led to a moderate overall decrease in CRVE (-8.6 ± 22.0 µm, P = 0.02), without a specific effect of EE, and induced no other retinal vascular or choroidal blood flow changes in either group. We observed larger retinal vein diameters in EE highlanders compared with non-EE. Although hypercapnia is known to increase retinal vessel diameter in healthy lowlanders, it selectively decreased CRVE in highlanders, irrespective of EE status. These findings suggest a retinal vascular dysfunction in highlanders, probably induced by chronic exposure to severe hypoxia.

This study investigated whether implementing heat training during the final week of a 3-week altitude training camp affects the hematological adaptations and variables monitored during chronic hypoxia. Twenty-three well-trained triathletes (19 males, 4 females) underwent 21 days of altitude training camp in spring (Live-High-Train-High, 1850 m). From day 14 to day 21, participants were split into two groups: a control group (HYPOXIA), which remained in the same condition, while the second group (COMBINED) had a ~1 h cycling session per day conducted in the heat (36°C ± 1°C, 40% ± 5% RH). Training load was the same for both groups. Hematological responses (including hemoglobin mass (Hbmass) and plasma volume (PV)) were assessed. Monitoring included physiological responses at rest (nocturnal oxygen saturation (SpO2) and heart rate, Hooper and Spiegel questionnaires, hydration status) and during exercise (incl. power, SpO2 through 45 min cycling at fixed heart rate). Both Hbmass (3.2% ± 3.1% for HYPOXIA, 3.7% ± 2.9% for COMBINED, p < 0.001) and PV (p = 0.003) increased during the camp, without interaction between groups (p ≥ 0.266). Exercise SpO2 decreased between the end of the second and the third week (p = 0.034, d = 0.583) in the COMBINED group. No difference between groups was detected for the other physiological or perceptual parameters. Adding heat training during the third week of an altitude training camp did not affect the increase in Hbmass or monitoring variables at rest. However, it did not confer any additional PV expansion and was associated with a reduced exercise SpO2.

Abstract The erythrocyte sedimentation rate (ESR) is one of the most widely used laboratory diagnostic parameters in the preliminary assessment of inflammation; indeed, every reader of this work has likely received an ESR assessment in their lifetime. A rapid ESR is a non-specific parameter that provides information about the inflammatory process. Although the origins of this methodology date back to antiquity, the prevailing view that ESR simply reflected particle settling of erythrocytes has recently undergone a paradigm shift: once cell aggregates form a system-spanning network, gravitational collapse of a weak and percolating gel reveals a more complex process reflecting the failure. The apparent non-specific nature of the cells and proteins involved also called into question the medical utility of ESR, at least in well-resourced environments. Here we show a new experimentally derived and physically modelled approach (“supraESR”) that enhances the value and accuracy of ESR for a variety of conditions that exhibit abnormally slow ESR (e.g., sickle cell disease, neuroacanthocytosis syndromes, chronic mountain sickness). We introduce a completely new diagnostic parameter that is based on an established and easily automated measurement method that promises low-cost screening for neuroacanthocytosis syndrome, a group of rare neurodegenerative diseases that are currently detectable only through integration of complex multimodal findings.

Hypoxia research has significantly advanced our understanding of how the human body responds to low-oxygen environments, yet women are still frequently studied without adequate consideration of hormonal status or reproductive life-course stage. This review examines the complex interactions between hormonal status across the female life course and the specific physiological responses of women to acute and chronic hypoxia, focusing on the menstrual cycle, hormonal contraception, pregnancy, menopausal status, hormone replacement therapy, gender-affirming hormone therapy, and reproductive health in high-altitude environments. Estrogen and progesterone significantly modulate ventilatory, cardiovascular, hematological, vascular, and muscular/metabolic responses to hypoxia, with distinct effects across different menstrual cycle phases, contraceptive regimens, and life-course states. Menopause introduces additional complexities, as declining hormone levels alter the body’s ability to acclimatize to low-oxygen conditions. Additionally, we examine how chronic and lifelong hypoxia impacts reproductive health, including fertility and pregnancy outcomes, in women living at high altitudes, highlighting both physiological adaptations and contextual factors. While current research has made progress, further studies are needed to better understand these sex-specific responses. We propose that future research should integrate stratified approaches, accounting for hormonal status (cycle phase, contraceptive use, pregnancy, HRT, GAHT) and reproductive status, to optimize health and performance recommendations for women exposed to hypoxic environments. Hormonal status and reproductive life-course stage may modulate women’s physiological responses to hypoxia. Hypoxic exposure models differ in dose, duration, mechanisms, and physiological interpretation. Menstrual cycle phase, hormonal contraception, pregnancy, menopause, hormone replacement therapy, and gender-affirming hormone therapy represent distinct hormonal contexts. Hormonal modulation may affect ventilatory, cardiovascular, vascular, hematological, metabolic, and placental responses. Stratified study designs should report hormonal status, hypoxic dose, oxygen saturation response, exposure duration, and rest, exercise, or sleep context.

Aging is associated with reduced cerebrovascular reactivity and impaired neurovascular coupling, limiting the brain’s ability to maintain adequate oxygen delivery during physiological stressors such as hypoxia. These vascular changes may heighten middle-aged adults’ vulnerability to hypoxia-induced neural and cognitive impairments, yet dose–response data integrating cerebral oxygenation and cognition remain scarce. In a single-blind, randomized crossover trial, 16 participants completed four normobaric sessions (45–65 min each) at different FiO2 levels (20.9

A number of indigenous populations have resided at high-altitude for generations, resulting in various phenotypical adaptations promoting successful high-altitude adaptation. Although many of these adaptations have been investigated in adults, little is known regarding how children residing at high-altitudes adapt, particularly with regards to the cerebrovasculature. Under hypoxic environments, compensatory changes in cerebral blood flow (CBF) are necessary to couple oxygen delivery to metabolic demand in the face of reduced oxygen availability. In this study, we aimed to evaluate regional and global cerebral blood flow (CBF) in Andean children and adolescents living in the highest city in the world at 5,100 m. Eighteen Andeans (ages 6-17 yr) living in La Rinconada, Peru (5,100 m) were compared with sex-, age-, size-, and maturity-matched high-altitude Sherpa (3,800 m) living in the Khumbu valley of Nepal (n = 18) and lowlanders (44 m) living at sea-level in Cardiff, Wales (n = 18). Volumetric measurements of CBF were assessed using duplex ultrasound of the internal carotid and vertebral arteries to assess regional and global CBF. End-tidal gases and oxygen saturation were measured in all groups, while hemoglobin concentration was assessed in Andeans. Despite Andeans living under a more severe hypoxic environment, global CBF was similar between Andeans (687.01 ± 138.49 mL/min), Sherpa (711.27 ± 110.27 mL/min), and lowlanders (704.88 ± 59.23 mL/min). In contrast, vertebral artery blood flow was 24% lower in Andeans (72.93 ± 31.60 mL/min) compared with lowlanders (96.09 ± 19.23 mL/min). The similar global CBF in Andean children might be achieved through elevated hemoglobin concentration. However, lower posterior perfusion in Andeans requires further investigation to determine whether it represents an adaptive or maladaptive response.NEW & NOTEWORTHY We have, for the first time, quantified volumetric regional and global cerebral blood flow in indigenous Andean children and adolescents living above 5,000 m in the highest city in the world. Compared with Sherpa living at moderate altitude (3,800 m), and lowlanders residing at sea level, Andeans present with similar global cerebral blood flow, but lower posterior flow despite being more hypoxemic. Similar to adults, differences in high hemoglobin concentration may drive this pattern of cerebral blood flow.

Anemia, a global health challenge affecting a quarter of the global population, results from diverse causes such as nutritional deficiencies, chronic diseases, and genetic factors. It disproportionately impacts women of reproductive age and children, leading to significant morbidity and mortality. While high-altitude populations face unique diagnostic challenges due to natural hemoglobin increases, the current World Health Organization cutoffs often overestimate anemia in these regions. Altitude corrections significantly alter prevalence rates, particularly in South American children, leading to misdiagnosis. Proposed solutions include population-specific thresholds and iron status markers like serum hepcidin, though economic constraints and limited test availability remain challenges. Tailored strategies informed by genetic research highlight adaptations in Tibetan and Ethiopian highlanders, demonstrating the need for region-specific approaches. Socioeconomic factors exacerbate anemia in high-altitude areas. Addressing anemia requires updated diagnostic criteria, personalized strategies, and increased awareness to ensure accurate assessments and interventions in diverse populations, especially those residing at high altitudes.

Purpose:The aim of this study was to characterize changes in retinal vessel diameters and choroidal blood flow in healthy lowlanders during a high-altitude expedition. Methods:Ocular examination, fundus images acquired using a handheld camera, and laser Doppler flowmetry (LDF) measurements within the subfoveal choroid (blood flow = ChBF, blood velocity = ChVel, and blood volume = ChVol) were carried out at 200 m and after 9 days at 5100 m in 11 healthy participants. Fundus images were analyzed with the semi-automatic software Vessel Assessment and Measurement Platform for Images of the Retina (VAMPIRE) version 3.2 to quantify retinal vessel parameters: the central retinal artery equivalent (CRAE), the central retinal vein equivalent (CRVE), and arterial and venular tortuosity. Hematocrit and hemoglobin concentrations were also measured at both altitudes. Results:Corneal thickness increased slightly at altitude (median = 536 µm, interquartile range = 25-75%: [521-571] at 200 m vs. 561 µm [540-574] at 5100 m, P = 0.004). No participant was affected by high-altitude retinopathy. From 200 m to 5100 m, ChVol and ChBF decreased significantly (-31% [43-22], P = 0.003 and -13% [22-8], P = 0.01, respectively), ChVel increased (+17% [10-44], P = 0.003), and CRVE (+10% [3-14], P = 0.04) and venular tortuosity (+142% [71-168], P = 0.04) increased significantly. The altitude-induced increase in hematocrit correlated negatively with the decrease in ChBF (r = -0.88, P < 0.001) and positively with the increase in CRVE (r = 0.88, P = 0.01). Conclusions:Acute high-altitude exposure leads to a decrease of ChBF (partly related to a decrease in blood volume) and an increase in retinal vein diameter and tortuosity. The physiological consequences of these changes on retinal blood flow and retinal function remain to be explored.

A number of indigenous populations have resided at high-altitude for generations, resulting in various phenotypical adaptations promoting successful high-altitude adaptation. While many of these adaptations have been investigated in adults, little is known regarding how children residing at high-altitudes adapt, particularly with regards to the cerebrovasculature. Under hypoxic environments, compensatory changes in cerebral blood flow (CBF) are necessary to couple oxygen delivery to metabolic demand in the face of reduced oxygen availability. In this study, we aimed to evaluate regional and global cerebral blood flow (CBF) in Andean children and adolescents living in the highest city in the world at 5100m. Eighteen Andeans (ages 6-17years) living in La Rinconada, Peru (5100m) were compared to sex, age, size, and maturity matched high-altitude Sherpa (3800m) living in the Khumbu valley of Nepal (n=18) and lowlanders (44m) living at sea-level in Cardiff, Wales (n=18). Volumetric measurements of CBF were assessed using duplex ultrasound of the internal carotid, and vertebral arteries to assess regional and global CBF. End-tidal gases and oxygen saturation were measured in all groups while hemoglobin concentration was assessed in Andeans. Despite Andeans living under a more severe hypoxic environment, global CBF was similar between Andeans (687.01±138.49ml/min), Sherpa (711.27±110.27ml/min) and lowlanders (704.88±59.23ml/min). In contrast, vertebral artery blood flow was 24% lower in Andeans (72.93±31.60ml/min) compared to lowlanders (96.09±19.23ml/min). The similar global CBF in Andean children might be achieved through elevated hemoglobin concentration. However, lower posterior perfusion in Andeans requires further investigation to determine whether it represents an adaptive or maladaptive response.

Intermittent hypoxia (IH) has emerged as a promising strategy to enhance physical performance by eliciting adaptive responses across cardiovascular, respiratory, and muscular systems. Various IH protocols have been applied in both trained and untrained individuals to improve aerobic capacity, strength, and repeated sprint ability. However, the growing number of systematic reviews and meta-analyses (SRs/MAs) has led to heterogeneous conclusions due to variability in populations, protocols, and outcome measures. This umbrella review aimed to synthesize and critically appraise the available SRs/MAs on the effects of IH protocols on physical performance across different fitness levels. A systematic search, aligned with the PRIOR (Preferred Reporting Items for Overviews of Reviews) guidelines, was conducted across seven electronic databases (PubMed/MEDLINE, Web of Science, Cochrane Database of Systematic Reviews, Scopus, Embase, PsycINFO, and SciELO) from inception to June 2025. Eligible studies included systematic reviews (SRs) with or without meta-analyses (MAs) or network meta-analyses (NMAs) evaluating the effects of intermittent hypoxia protocols on physical performance. Methodological quality was assessed using the AMSTAR-2 tool. A total of 22 systematic reviews (14 with meta-analyses, 3 with network meta-analyses) analyzing 487 primary studies and 5,333 participants were included. Intermittent hypoxia (IH) protocols improved both aerobic and anaerobic performance, as well as muscular strength. Live high–train low (LHTL) and live low–train high (LLTH) protocols consistently enhanced V̇O₂max, especially when combined with sea-level training. Anaerobic-focused strategies like repeated sprint training in hypoxia (RSH) and RSH induced by voluntary hypoventilation at low lung volume (RSH-VHL) led to improvements in sprint-fatigue resistance and glycolytic capacity. Intermittent hypoxic interval training (IHIT) and high-intensity interval training (HIIT) under hypoxia showed robust aerobic benefits. However, the magnitude of these effects varied depending on the type of protocol, training status, and hypoxic dose. IH is an effective and adaptable strategy to improve aerobic and anaerobic performance, as well as to enhance muscle strength and hypertrophy. These benefits often occur without consistent hematological changes. Future studies should focus on individualized approaches, standardization of terminology, and precise quantification of both hypoxic exposure and training load to optimize outcomes and ensure reproducibility. Review registration: This overview was registered on the International Database of Systematic Review Protocols (PROSPERO ID: CRD42024465481).

Carbon monoxide (CO) rebreathing is frequently used to determine hemoglobin mass (Hbmass) during hypoxic or heat training and high-altitude research. Accurate and reliable carboxyhemoglobin (HbCO) determination is crucial for reliable Hbmass measurements. The aim was therefore to explore the stability of HbCO and interchangeability of two Radiometer analyzers in the determination of Hbmass. Twelve subjects performed a CO rebreathing test. Five capillary blood samples were taken before and after the CO rebreathing test and either analyzed immediately on site (three capillary tubes, Day 1, ABL 90) or stored at room temperature and sent to another laboratory for analysis 4-8 days later (two capillary tubes, ABL 825). Intraclass correlation coefficient (ICC) and relative typical error (TE) were calculated to compare both measurements. A paired sample t test was performed to detect potential differences between Day 1 (ABL 90) and Days 4-8 (ABL 825). A trivial mean difference was observed between the two measurements for ΔHbCO (0.05%, p = 0.01, d = -0.12) and Hbmass (7.7 g, p = 0.01, d = 0.10). High reliability (ICC > 0.98) and low TE (< 0.91%) were found for ΔHbCO and Hbmass. Immediate analysis with the same analyzer remains recommended despite trivial differences between measurements. However, when logistical issues (analyzer breakdown, extreme, and/or remote locations) do not allow optimal procedures, delayed analysis, potentially with a different analyzer, might be used as a viable alternative.

Background Since vascular responses to hypoxia in both healthy high-altitude natives and chronic mountain sickness (a maladaptive high-altitude pathology characterised by excessive erythrocytosis and the presence of symptoms-CMS) remain unclear, the role of inflammation and oxidative/nitrosative stress on the endothelium-dependent and -independent responses in both the micro- and macrocirculation, in healthy Andeans at different altitudes and in CMS patients, was examined. Methods 94 men were included: 18 lowlanders (LL), 38 healthy highlanders permanently living at 3800 m (n = 21-HL-3800) or in La Rinconada, the highest city in the world (5100-5300 m) (n = 17-HL-5100/No CMS). Moreover, 14 participants with mild (Mild CMS) and 24 with moderate to severe CMS (Mod/Sev CMS) were recruited. All undertook two reactivity tests: i) local thermal hyperaemia (microcirculation) and ii) flow-mediated dilation (macrocirculation). Endothelium-independent function (glyceryl trinitrate) was also assessed only in La Rinconada. Findings Conductance and skin blood flow velocity during the microcirculation test, as well as macrocirculation progressively decreased with altitude (LL > HL-3800 > HL-5100/No CMS). CMS also induced a decrease in macrocirculation (HL-5100/No CMS > Mild CMS = Mod/Sev CMS), while glyceryl trinitrate restored vascular function. Both oxidative stress and nitric oxide metabolites increased with altitude only. Principal component analysis revealed that increasing inflammation with altitude was associated with a progressive decline in both micro- and macrovascular function in healthy highlanders. Interpretation Both micro and macrovascular function are affected by chronic exposure to hypoxia, the latter being further compounded by CMS.

Background: 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. Objective: This review evaluates IH protocols’ benefits on cognition and brain health in older adults, regardless of cognitive status. Methods: 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. Results: 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. Conclusions: 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.

AbstractChronic mountain sickness is a maladaptive syndrome that affects individuals living permanently at high altitude and is characterized primarily by excessive erythrocytosis (EE). Recent results concerning the impact of EE in Andean highlanders on clotting and the possible promotion of hypercoagulability, which can lead to thrombosis, were contradictory. We assessed the coagulation profiles of Andeans highlanders with and without excessive erythrocytosis (EE+ and EE−). Blood samples were collected from 30 EE+ and 15 EE− in La Rinconada (Peru, 5100–5300 m a.s.l.), with special attention given to the sampling pre‐analytical variables. Rotational thromboelastometry tests were performed at both native and normalized (40%) haematocrit using autologous platelet‐poor plasma. Thrombin generation, dosages of clotting factors and inhibitors were measured in plasma samples. Data were compared between groups and with measurements performed at native haematocrit in 10 lowlanders (LL) at sea level. At native haematocrit, in all rotational thromboelastometry assays, EE+ exhibited hypocoagulable profiles (prolonged clotting time and weaker clot strength) compared with EE− and LL (all P < 0.01). At normalized haematocrit, clotting times were normalized in most individuals. Conversely, maximal clot firmness was normalized only in FIBTEM and not in EXTEM/INTEM assays, suggesting abnormal platelet activity. Thrombin generation, levels of plasma clotting factors and inhibitors, and standard coagulation assays were mostly normal in all groups. No highlanders reported a history of venous thromboembolism based on the dedicated survey. Collectively, these results indicate that EE+ do not present a hypercoagulable profile potentially favouring thrombosis.

The erythrocyte sedimentation rate (ESR) is one of the oldest diagnostic tools already known by the ancient Greeks. When blood is placed in a tube, a phase separation between blood plasma and the remaining part of the blood containing the cells appears. The distance between the top of the liquid and the phase boundary determines the sedimentation height. Fast sedimentation, typically the height measured after one hour, is an unspecific parameter indicating inflammation. However, there is more to ESR than a single value for the sedimentation height. We investigated the physical dynamics of the cell aggregation occurring during erythrocyte sedimentation and devised a novel explanation. The formation of rouleaux actually extends to the formation of a percolating gel. Therefore, it is not the aggregate size that determines ESR but the permeability of this gel. The collapse of this gel is the base of the ESR. Hence the process of erythrocyte sedimentation can be described by a set of parameters determined by this gel. In addition to differences in height, the delay time, the maximal sedimentation speed and the final compaction resemble the most important ones. In contrast to common clinical practice, where only a fast ESR is associated with pathologic conditions, we identified diseases and circumstances when the ESR is significantly slower. This includes the ESR of Sickle Cell Disease (SCD) patients, Chronic Mountain Sickness (CMS) patients, patients suffering from the Neuroacanthocytosis Syndromes (NAS) on the one hand and endurance elite athletes and highlanders on the other hand. Significant differences can be detected between healthy controls and the patients listed using the aforementioned parameters. However, diagnostic value is only given if a clear discrimination between patients and healthy controls is possible. We found such discrimination for NAS patients with 8% false negative and 11% false positive among healthy controls. For differential diagnosis, we also tested patients with neurodegenerative diseases different from NAS, namely Parkinson's disease patients, Huntington's disease patients and amyotrophic lateral sclerosis patients. None of them showed a difference in the ESR compared to healthy controls, but all of them presented a significant difference to NAS patients. Considering the low expenses required for ESR measurements and that they are automated in many central laboratories on the one hand and the difficulty and often very late diagnosis of NAS (sometimes years after the onset of symptoms), we recommend an ESR screening for NAS (slow sedimentation) as a routine in the frame of ordinary health checks of adults.

PurposeTo investigate the effects of a repeated-sprint training in hypoxia induced by voluntary hypoventilation at low lung volume (RSH-VHL) including end-expiratory breath holding (EEBH) of maximal duration.MethodsOver a 4-week period, twenty elite judo athletes (10 women and 10 men) were randomly split into two groups to perform 8 sessions of rowing repeated-sprint exercise either with RSH-VHL (each sprint with maximal EEBH) or with unrestricted breathing (RSN, 10-s sprints). Before (Pre-), 5 days after (Post-1) and 12 days after (Post-2) the last training session, participants completed a repeated-sprint ability (RSA) test on a rowing ergometer (8 × 25-s “all-out” repetitions interspersed with 25 s of passive recovery). Power output (PO), oxygen uptake, perceptual-motor capacity (turning off a traffic light with a predetermined code), cerebral (Δ[Hbdiff]) and muscle (Δ[Hb/Mb]diff) oxygenation, cerebral total haemoglobin concentration (Δ[THb]) and muscle total haemoglobin/myoglobin concentration (Δ[THb/Mb]) were measured during each RSA repetition and/or recovery period.ResultsFrom Pre-to Post-1 and Post-2, maximal PO, mean PO (MPO) of the first half of the test (repetitions 1–4), oxygen uptake, end-repetition cerebral Δ[Hbdiff] and Δ[THb], end-repetition muscle Δ[Hb/Mb]diff and Δ[THb/Mb] and perceptual-motor capacity remained unchanged in both groups. Conversely, MPO of the second half of the test (repetitions 5–8) was higher at Post-1 than at Pre-in RSH-VHL only (p < 0.01), resulting in a lower percentage decrement score over the entire RSA test (20.4% ± 6.5% vs. 23.9% ± 7.0%, p = 0.01). Furthermore, MPO (5–8) was greater in RSH-VHL than in RSN at Post-1 (p = 0.04). These performance results were accompanied by an increase in muscle Δ[THb/Mb] (p < 0.01) and a concomitant decrease in cerebral Δ[THb] (p < 0.01) during the recovery periods of the RSA test at Post-1 in RSH-VHL.ConclusionFour weeks of RSH-VHL including maximal EEBH improved the ability of elite judo athletes to repeat high-intensity efforts. The performance improvement, observed 5 days but not 12 days after training, may be due to enhanced muscle perfusion. The unchanged oxygen uptake and the decrease in cerebral regional blood volume observed at the same time suggest that a blood volume redistribution occurred after the RSH-VHL intervention to meet the increase in muscle perfusion.

We investigated highlanders, permanently living at an altitude of 5100 m and compared Chronic Mountain Sickness (CMS) patients with control volunteers. While we found differences in systemic parameters such as blood oxygen content, hematocrit, hemoglobin concentration, and blood viscosity, the mechanical and rheological properties of single red blood cells did not differ between the two investigated groups.