SynthesisBMC sports science, medicine & rehabilitation2026
Effects of hypoxic high-intensity interval training on cardiorespiratory fitness, body composition, and cardiometabolic outcomes in non-clinical populations: a systematic review and meta-analysis with an age-related evidence distribution assessment.
Synthesis in BMC sports science, medicine & rehabilitation, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
0 citing papers in PubMed.
No citing paper in PubMed yet.
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
6 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Hypoxic high-intensity interval training (HHIIT) has been proposed as a time-efficient strategy for enhancing physiological adaptations. However, its efficacy in non-clinical populations remains inconsistent. This systematic review and three-level meta-analysis followed the PRISMA 2020 guidelines. PubMed, Web of Science, Scopus, and Embase were searched from database inception to 20 December 2025. Fourteen randomized controlled trials, including 534 participants, met the eligibility criteria. HHIIT produced a significant, small positive effect on overall cardiorespiratory fitness outcomes (Hedges' g = 0.369, 95% CI [0.186, 0.552], P < 0.001), and the results remained robust following CR2 small-sample correction. For relative oxygen uptake, HHIIT showed a moderate beneficial effect (g = 0.553, 95% CI [0.308, 0.797], P < 0.001). Subgroup analyses indicated that the effects of HHIIT were larger when compared with non-exercise controls than with exercise controls. n contrast, HHIIT had no significant overall effect on body composition or cardiometabolic outcomes (g = - 0.018, 95% CI [- 0.133, 0.097]) or on hematological outcomes (g = 0.122, 95% CI [- 0.292, 0.535]). The current evidence base is concentrated mainly in young adults, with limited representation of females, middle-aged adults, and older adults. In conclusion, low-to-moderate certainty evidence suggests that HHIIT may provide limited, modality-specific improvements in cardiopulmonary adaptations in non-clinical populations, particularly in relative oxygen uptake. However, substantial intervention heterogeneity warrants cautious interpretation of these findings. Its effects on body composition, cardiometabolic health, and hematological parameters remain unclear. Future trials should standardize hypoxic dose and training prescriptions, while addressing existing age- and sex-related evidence gaps. These efforts are needed to clarify the generalizability and practical value of HHIIT across broader populations.
Indexed as
Identifiers
What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.