Rehabilitation effects of high-intensity interval training on asthma: a systematic review and meta-analysis of randomized controlled trials

Background: High-intensity interval training (HIIT) has demonstrated benefits in cardiometabolic health, but its efficacy and safety in asthma rehabilitation remain controversial due to inconsistent findings from existing randomized controlled trials (RCTs). This systematic review and meta-analysis aims to synthesize the latest evidence. Methods: Following PRISMA 2020 guidelines, we systematically searched PubMed, Embase, Web of Science, and the Cochrane Library up to June 2025 for RCTs comparing HIIT against control conditions (including passive controls and active interventions like moderate-intensity continuous training) in individuals with asthma. Primary outcomes were the Asthma Control Questionnaire (5-item version) (ACQ-5), peak oxygen uptake (VO2peak), forced expiratory volume in 1 second as percentage of the predicted value (FEV1%), fractional exhaled nitric oxide (FeNO), and the Mini Asthma Quality of Life Questionnaire (MiniAQLQ). Standardized mean differences (SMDs) with 95% confidence intervals (CIs) were pooled using a random-effects model. Heterogeneity was quantified using the I2 statistic, and the risk of bias was assessed with the Cochrane RoB 2.0 tool. Results: Seven RCTs (n=518 participants) were included. The meta-analysis demonstrated no statistically significant benefits of HIIT over control conditions for ACQ-5 (SMD: −1.19; 95% CI: −2.69 to 0.32; P=0.12), VO2peak (SMD: 1.41; 95% CI: −0.25 to 3.08; P=0.10), MiniAQLQ (SMD: 1.44; 95% CI: −0.71 to 3.60; P=0.19), FeNO (SMD: 0.15; 95% CI: −0.46 to 0.76; P=0.63), or FEV1% (SMD: 0.45; 95% CI: −0.09 to 0.98; P=0.10). However, extreme statistical heterogeneity was observed across all outcomes (I2>90%). Sensitivity analysis indicated that the point estimate was not driven by any single study. However, Pitzner-Fabricius 2023 is the primary source of heterogeneity. Egger’s test showed no significant publication bias (P>0.05). The included studies generally had a high risk of performance bias due to the challenge of blinding participants and personnel. Conclusions: Current evidence does not conclusively establish the superior efficacy of HIIT over conventional rehabilitation or control conditions for asthma management. The pooled effect estimates are highly uncertain due to extreme clinical and methodological heterogeneity stemming from varied HIIT protocols, diverse control groups, and heterogeneous patient populations. Therefore, the findings should be interpreted with caution. Future high-quality RCTs with standardized interventions, rigorous safety monitoring, and phenotypic stratification are needed to define the role of HIIT in asthma rehabilitation.