Protocol Dependence and Evidence Divergence in the Effects of Simulated Hypoxic Training on Cardiorespiratory Fitness in Healthy College Students: A Narrative Review

DOI: https://doi.org/10.62517/jmpe.202618507

Author(s)

Song Shuailong1, Cao Leyi1, Shi Bing2

Affiliation(s)

1School of Physical Education, Qinghai Normal University, Xining, Qinghai, China 2School of Physical Education, Shaanxi Normal University, Xi'an, Shaanxi, China

Abstract

Background: Simulated hypoxic training has been increasingly studied in healthy college students, but evidence remains inconsistent regarding whether hypoxia confers additional benefits over intensity-matched normoxic training. Objective: This narrative review examines the sources of divergence in the literature on simulated hypoxic training and cardiorespiratory fitness in healthy college students. Approach: We juxtapose Chinese college-student intervention studies with international synthesis evidence and propose an analytical framework for interpreting divergent effect estimates. Argument: Divergence is not simply a matter of "insufficient evidence." It arises from differences across five domains: the level of comparison, hypoxic dose, intensity anchoring, simulation modality, and outcome temporal window. Chinese college-student studies report signals in cardiac pumping function, hemorheology, antioxidant defense, and some aerobic performance indicators, but these signals are based on small samples, heterogeneous protocols, and incomplete reporting of dose and safety parameters. International synthesis evidence answers different questions at different levels: network meta-analysis ranks hypoxic paradigms within hypoxic training; meta-regression stratifies athletes and non-athletes; and strict meta-analysis directly compares hypoxia with matched normoxia. These answers can coexist logically, but they cannot be compressed into a single claim that "hypoxic training is effective." Conclusions: Future research should move from overall effect testing toward cumulative conditional-effect propositions: under what hypoxic dose, intensity-anchoring method, simulation modality, outcome dimension, and time window does hypoxia produce reproducible and practically meaningful differences relative to matched normoxic training.

Keywords

Simulated Hypoxic Training; Healthy College Students; Cardiorespiratory Fitness; Maximal Oxygen Uptake; Evidence Synthesis

References

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