The Acute Effect of Sprint Interval Training on the Immune System: A Systematic Review and Meta-Regression

Weibao Liang¹Yu Hou²Shuting Xu³Lyu Zikun²Yasong Zhang^4*Wenbai Huang^1*

• ¹Guangdong Provincial Key Laboratory of Speed Capability Research, Su Bingtian Center for Speed Research and Training, School of Physical Education, Jinan University, Guangzhou, China
• ²Department of Physical Education, Kunsan National University, Gunsan-si, Republic of Korea
• ³The First Affiliated Hospital of Jinan University, Guangzhou, China
• ⁴Department of Basic Medicine, Langfang Health Vocational College, Langfang, China

Background: Sprint Interval Training (SIT) is an increasingly popular time-efficient training paradigm, yet its acute impact on the immune system remains ambiguous due to inconsistent findings across studies. This systematic review and meta-analysis aims to quantitatively evaluate the acute effects of a single SIT session on key immunological markers in healthy individuals. Methods: We systematically searched PubMed, Web of Science, SPORTDiscus, Cochrane Library, Embase, and Scopus for experimental studies assessing acute immunological changes following a single bout of SIT in healthy participants. Pooled Standardized Mean Differences (SMDs) and 95% confidence intervals (CIs) were calculated using a random-effects model. Non-linear meta-regression and subgroup analyses were performed to investigate sources of heterogeneity, and the certainty of evidence was evaluated using the GRADE methodology. Results: Twenty-one studies involving participants were included. The meta-analysis revealed that a single session of SIT induced a robust and significant increase in total leukocyte count (SMD = 2.68, 95% CI [1.79, 3.57]), neutrophil count This is a provisional file, not the final typeset article (SMD = 1.04, 95% CI [0.75, 1.34]), with the latter exhibiting zero heterogeneity (I² = 0%). Lymphocyte count (SMD = 3.83, 95% CI [1.07, 6.59]) also increased significantly, showing a U-shaped dose-response relationship with repetition duration. Interleukin-6 (IL-6) increased significantly (SMD = 1.10, 95% CI [0.49, 1.71]), with subgroup analysis revealing a twofold greater response in trained athletes compared to untrained individuals. In contrast, salivary IgA (sIgA) remained stable in trained athletes (SMD = 0.07, 95% CI [-0.31, 0.45]) but showed high variability in untrained groups. Plasma interleukin-10 (IL-10) concentration exhibited a small, non-significant increasing trend (SMD = 0.18, 95% CI [-0.06, 0.43]). Conclusion: A single session of SIT elicits a potent acute systemic immune response, characterized by a highly conserved mobilization of circulating leukocytes, particularly neutrophils. This response is significantly modulated by individual training status: athletes exhibit a distinct immunometabolic profile characterized by a robust IL-6 release and stable mucosal immunity (sIgA), whereas untrained individuals show more variable responses. These findings provide critical evidence for understanding the physiological stress of SIT and can inform training and recovery practices to safeguard immune health.