An umbrella review of 22 systematic reviews examines hypoxia and physical performance. The authors compare different exposure and training strategies, including altitude-based approaches and exercise in reduced oxygen. However, potential performance benefits coexist with substantial variation in protocols and evidence quality.
Scope and research methods
The search covered seven databases through June 2025 and followed PRIOR recommendations. The included reviews comprised 14 with meta-analysis and three with network meta-analysis, covering 487 primary studies and 5,333 participants. However, these review-level totals do not represent a newly recruited cohort. The authors assessed methodological quality with AMSTAR-2.
Hypoxia and physical performance: aerobic outcomes
Parts of the evidence base link live-high–train-low and live-low–train-high approaches to improved maximal oxygen uptake. However, the response depended on exposure dose, accompanying sea-level training and initial fitness. The review does not identify one universally effective protocol for every athlete or untrained person.
Sprinting, strength and training load
Repeated sprints in hypoxia showed associations with fatigue resistance and glycolytic adaptations. These protocols included voluntary hypoventilation at low lung volume. In addition, hypoxic interval training showed aerobic effects. Strength and hypertrophy outcomes depended on the combination of hypoxia and exercise. The training load therefore remains an essential part of the interpretation.
Important distinctions between protocols
Exercise in hypoxia and passive hypoxia–hyperoxia are different interventions. In this review, the abbreviation IHHT is used for hypoxia–hyperoxia combined with exercise, unlike its use in many clinical papers. Results from active training should therefore not be presented as direct evidence for passive clinical IHHT or for a particular device.
How confident can we be?
The methodological quality of the reviews was predominantly low or critically low. Furthermore, populations, terminology and exposure reporting varied, and evidence concerning passive hypoxia–hyperoxia was limited. Performance gains did not always coincide with persistent changes in blood measures. An erythropoietic explanation is therefore not sufficient for every response.
Conclusion
Hypoxic strategies may support aerobic and anaerobic performance, but the useful question is which protocol fits which training objective. Consistent dose reporting and better-quality studies are needed. The original paper contains the detailed comparisons; experimental breath-holding protocols are not instructions for unsupervised training.
Context and further reading
For the difference between active hypoxic training and controlled IHHT at rest, see technology. The applications page discusses sports and recovery contexts without treating these distinct interventions as interchangeable.
Related research
- Intermittent hypoxia and healthy ageing: systematic review
- How intermittent hypoxic conditioning works: adaptive mechanisms
Original publication
Ayoub Boulares, Olivier Dupuy, Nicola Luigi Bragazzi, Aurélien Pichon. Effects of Intermittent Hypoxia Protocols on Physical Performance in Trained and Untrained Individuals: An Umbrella Review of Systematic Reviews and Meta-Analyses. Sports Medicine – Open · 2025 · 11:145. DOI: 10.1186/s40798-025-00933-7.