High-intensity interval training in cancer patients: a bayesian meta-analysis of effects on VO₂max, dose-response,...

Cancer treatment impairs cardiorespiratory fitness (CRF), an independent prognostic indicator in cancer populations. High-intensity interval training (HIIT) improves maximal oxygen uptake (VO₂max), but existing meta-analyses have relied on frequentist approaches without probabilistic expression of clinical relevance and have analyzed dose-response and adherence in isolation.

Four databases were searched through 1 April 2026 for randomized controlled trials (RCTs) of HIIT versus non-exercise controls reporting VO₂max. Mean differences (MDs) were pooled using a Bayesian three-level random-effects model, with the posterior median, 95% credible interval (CrI), probability of direction (pd), Bayes factor (BF10), and the posterior probability of exceeding a prespecified threshold of 1.0 mL·kg⁻1·min⁻1 reported. Functional-form comparison was applied to 14 dose moderators, and certainty of evidence was rated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach.

Sixteen RCTs contributing 35 effect sizes were included. HIIT increased VO₂max by 2.61 mL·kg⁻1·min⁻1 versus non-exercise controls (95% CrI: 1.68 to 3.51), with pd = 1.00 and a 99.96% posterior probability of exceeding the threshold. The primary effect remained stable across all subgroup and sensitivity analyses. Dose-response curves showed minimal variation, and only the number of intervals reached pd = 0.95 among the 14 moderators. Mean adherence was 85.7%, with no prescription parameter showing a statistically significant association. Certainty of evidence was rated moderate.

HIIT reliably improves VO₂max in cancer patients, with near-certain posterior probability of exceeding clinical relevance. Dose-response and adherence analyses were exploratory and underpowered and do not support dose equivalence. Interval number was the only directional signal and may warrant further investigation.