This randomized controlled trial aimed to investigate the effects of a 12-week Whole-Body High-Intensity Interval Training (WB-HIIT) program compared with Moderate-Intensity Continuous Training (MICT) on immune function in recreationally active young adults. Participants were randomly assigned to either WB-HIIT or MICT groups. Immune-related biomarkers and performance outcomes were assessed before and after the intervention. The study sought to determine whether different exercise modalities produce distinct adaptations in immune function.