Effects of Intermittent Hypoxia–Hyperoxia on Performance- and Health-Related Outcomes in Humans: A Systematic Review

Abstract

Background Intermittent hypoxia applied at rest or in combination with exercise promotes multiple beneficial adaptations with regard to performance and health in humans. It was hypothesized that replacing normoxia by moderate hyperoxia can increase the adaptive response to the intermittent hypoxic stimulus. Objective Our objective was to systematically review the current state of the literature on the effects of chronic intermittent hypoxia–hyperoxia (IHH) on performance- and health-related outcomes in humans. Methods PubMed, Web of Science™, Scopus, and Cochrane Library databases were searched in accordance with PRISMA guidelines (January 2000 to September 2021) using the following inclusion criteria: (1) original research articles involving humans, (2) investigation of the chronic effect of IHH, (3) inclusion of a control group being not exposed to IHH, and (4) articles published in peer-reviewed journals written in English. Results Of 1085 articles initially found, eight studies were included. IHH was solely performed at rest in different populations including geriatric patients (n = 1), older patients with cardiovascular (n = 3) and metabolic disease (n = 2) or cognitive impairment (n = 1), and young athletes with overtraining syndrome (n = 1). The included studies confirmed the beneficial effects of chronic exposure to IHH, showing improvements in exercise tolerance, peak oxygen uptake, and global cognitive functions, as well as lowered blood glucose levels. A trend was discernible that chronic exposure to IHH can trigger a reduction in systolic and diastolic blood pressure. The evidence of whether IHH exerts beneficial effects on blood lipid levels and haematological parameters is currently inconclusive. A meta-analysis was not possible because the reviewed studies had a considerable heterogeneity concerning the investigated populations and outcome parameters. Conclusion Based on the published literature, it can be suggested that chronic exposure to IHH might be a promising non-pharmacological intervention strategy for improving peak oxygen consumption, exercise tolerance, and cognitive performance as well as reducing blood glucose levels, and systolic and diastolic blood pressure in older patients with cardiovascular and metabolic diseases or cognitive impairment. However, further randomized controlled trials with adequate sample sizes are needed to confirm and extend the evidence. This systematic review was registered on the international prospective register of systematic reviews (PROSPERO-ID: CRD42021281248) (https://www.crd.york.ac.uk/prospero/).

Effectiveness, implementation, and monitoring variables of intermittent hypoxic bicycle training in patients recovered from COVID-19: The AEROBICOVID study

“…Previous literature supports hypoxia in multiple health conditions (Millet et al, 2016a;Millet and Girard, 2017;Behrendt et al, 2022). More specifically, the safety and efficacy of physical exercises in recovering patients from severe acute respiratory syndrome (SARS) have already been identified but without a detailed description of monitoring variables (Lau et al, 2005).…”

“…Hypoxic training has been treated as a promising strategy for health ( Camacho-Cardenosa et al, 2020 ; Behrendt et al, 2022 ), even with the difficulty of establishing an optimal hypoxia dose ( Lizamore et al, 2016 ). Regarding hypoxia as an additional stimulus to exercise and the exercise workload, it is important to control the dose of exposure to hypoxia ( Millet et al, 2016b ; Soo et al, 2020 ; Behrendt et al, 2022 ).…”

“…Hypoxic training has been treated as a promising strategy for health ( Camacho-Cardenosa et al, 2020 ; Behrendt et al, 2022 ), even with the difficulty of establishing an optimal hypoxia dose ( Lizamore et al, 2016 ). Regarding hypoxia as an additional stimulus to exercise and the exercise workload, it is important to control the dose of exposure to hypoxia ( Millet et al, 2016b ; Soo et al, 2020 ; Behrendt et al, 2022 ). Several studies associated physical training and normobaric hypoxia, showing as moderate hypoxia (2,500 to 3,000 m simulated altitude) is a safe practice ( Navarrete-Opazo and Mitchell, 2014 ), which presents significant results compared to normoxic situations, like fat mass reduction ( Camacho-Cardenosa et al, 2018 ), lean mass increase ( Matsumoto et al, 1999 ), cardiorespiratory improvement ( Foster, 1998 ; Papoti et al, 2009 ; Camacho-Cardenosa et al, 2018 ).…”

Influence of acute and chronic intermittent hypoxic-hyperoxic exposure prior to aerobic exercise on cardiovascular risk factors in geriatric patients—a randomized controlled trial

“…Hence, intermittent exposure to hypoxia and hyperoxia is expected to have beneficial effects on two of the most common age-related risk factors/comorbidities (i.e., hypertension and dyslipidemia) and is well applicable in geriatric patients. Recently, the effects of IHHE on health-related outcomes have been systematically reviewed, and it has been found that 3–6 weeks of IHHE can reduce cardiovascular risk factors, particularly blood glucose concentration as well as systolic and diastolic blood pressure ( Behrendt et al, 2022b ). However, the evidence concerning the effects of IHHE on blood lipid and lipoprotein concentrations are inconclusive ( Behrendt et al, 2022b ).…”

“…Recently, the effects of IHHE on health-related outcomes have been systematically reviewed, and it has been found that 3–6 weeks of IHHE can reduce cardiovascular risk factors, particularly blood glucose concentration as well as systolic and diastolic blood pressure ( Behrendt et al, 2022b ). However, the evidence concerning the effects of IHHE on blood lipid and lipoprotein concentrations are inconclusive ( Behrendt et al, 2022b ).…”