Cardiorespiratory adaptations to high-intensity interval training in young boxers: A randomized controlled study

Background: – High-intensity interval training (HIIT) has been recognized for its effectiveness in enhancing cardiorespiratory fitness. However, the application of HIIT within boxing training remains underexplored. This study aimed to investigate the physiological adaptations induced by a structured 4-week HIIT-boxing regimen, with a specific focus on pulmonary function (PF), aerobic capacity, and autonomic cardiovascular regulation, assessed by heart rate recovery (HRR). Methods: – Sixteen trained young individuals were randomly assigned to either the HIIT-boxing group or the control group. Comprehensive assessments, including PF tests, peak oxygen uptake, and HRR at the 1st, 3rd, and 5th minutes postexercise, were conducted pre- and post-intervention. Results: – Significant improvements were observed in maximal voluntary ventilation, forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and peak expiratory flow over time (P < .01), while the FEV1/FVC ratio remained unchanged (P = .244). Time-by-group interactions revealed greater improvements in maximal voluntary ventilation (ηp2 = 0.817), FVC (ηp2 = 0.618), and FEV1 (ηp2 = 0.283) in the HIIT group than in the control group. Although estimated estimated maximal oxygen uptake improved significantly over time (P < .001), no significant group effect or time-by-group interaction was observed. HRR improved significantly over time in both groups (P < .001), with no significant time-by-group interaction observed at any measured interval (P > .05). Conclusion: – Supplementing conventional boxing training with HIIT may serve as a useful strategy for enhancing selected PF parameters in combat sports athletes. However, because the HIIT group performed a greater total training volume, the observed improvements cannot be definitively attributed to HIIT independently of the increased training stimulus.