Comparative and dose-response effects of supplementary exercise training on VO2max in trained athletes: a Systematic Review and Bayesian network meta-analysis.

Background

Maximal oxygen uptake (VO2max) is a critical determinant of endurance performance in athletes, yet the comparative effectiveness and dose-response profiles of different supplementary exercise training modalities remain incompletely characterized. This systematic review and Bayesian network meta-analysis aimed to compare 11 exercise training modalities for improving VO2max in healthy athletes, examine dose-response relationships, explore effect modification by sport type, and evaluate study-level moderators using network meta-regression.

Methods

Four databases were searched for randomized controlled trials. Bayesian network meta-analysis (NMA), Bayesian network meta-regression, and dose-response NMA were conducted. Confidence in the evidence was assessed using the Confidence in Network Meta-Analysis framework.

Results

Sixty-one studies were included in the systematic review; 60 contributed to the main NMA and 31 to the dose-response NMA. Five exercise modalities were significantly superior to the active control condition, which consisted of maintaining regular sport-specific training without additional supplementary intervention: blood flow restriction training, high-intensity interval training (HIIT), intermittent hypoxic training, sprint interval training (SIT), and small-sided games (SSG). HIIT and SIT showed the most consistent overall support, although sparse subgroup findings remained exploratory. The dose-response analysis suggested that the modelled significant regions extended across the observed supplementary exercise dose ranges for HIIT, SIT, and SSG. Bayesian network meta-regression showed no clear effect modification by age, baseline VO2max, or intervention duration.

Conclusions

Given the predominantly low to very low certainty of evidence, the findings should be interpreted cautiously. HIIT and SIT appeared to be the most consistently supported supplementary modalities for improving VO2max in trained athletes, but these model-based findings require confirmation in larger, higher-quality head-to-head trials with common active control groups and standardized VO2max methodology.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/view/CRD420261360986, identifier CRD420261360986.