Effects of Intermittent Hypoxia Protocols on Physical Performance in Trained and Untrained Individuals: An Umbrella Review of Systematic Reviews and Meta-Analyses
Bibliographic record
Abstract
BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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).
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.043 | 0.128 |
| Meta-epidemiology (narrow) | 0.003 | 0.002 |
| Meta-epidemiology (broad) | 0.018 | 0.022 |
| Bibliometrics | 0.016 | 0.016 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.004 | 0.003 |
| Open science | 0.003 | 0.003 |
| Research integrity | 0.003 | 0.002 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".