Effects of aerobic exercise teaching with different intensity on cardiopulmonary function and lower limb exercise biomechanical characteristics of college students

Background: Smoking remains a significant public health concern, particularly affecting cardiopulmonary function through various pathophysiological mechanisms. While exercise is known to improve cardiopulmonary health, the optimal exercise intensity for enhancing cardiorespiratory adaptations, especially in the context of smoking status, remains unclear. Aim: This study investigated the differential effects of exercise intensity on cardiopulmonary adaptations and lower limb biomechanical functions among university students, considering smoking status as a potential moderating factor in physiological and biomechanical responses. Methods: A randomized controlled trial was conducted with 120 university students, stratified by smoking status and randomly allocated to four groups: high-intensity interval training (HIIT, 85%–95% HRR), moderate-intensity continuous training (MICT, 65%–75% HRR), low-intensity continuous training (LICT, 45%–55% HRR), or control group. The 12-week intervention comprised three weekly sessions, with comprehensive assessment of cardiopulmonary parameters and biomechanical characteristics at baseline, week 6, and week 12. Results: The HIIT protocol elicited superior improvements in cardiopulmonary function, with a 29.6% increase in VO2max (p < 0.05, η2 = 0.78), compared to MICT (18.1%, p < 0.05) and LICT (9.7%, p < 0.05). These adaptations were consistent across smoking status categories, though smokers showed slightly attenuated responses. Heart rate variability parameters demonstrated enhanced autonomic regulation, particularly in the HIIT group (HF power increased 80.4%, p < 0.05), with smoking status moderating the magnitude of improvement. Conclusions: High-intensity interval training demonstrated superior efficacy in improving both cardiopulmonary and biomechanical parameters compared to moderate and low-intensity protocols, regardless of smoking status. These findings suggest that HIIT may be particularly beneficial for enhancing cardiorespiratory fitness in university students, though individual smoking status should be considered when prescribing exercise intensity. The implementation of structured HIIT programs in university physical education curricula may optimize physiological and biomechanical adaptations, potentially offering a time-efficient strategy for improving health outcomes in both smoking and non-smoking students.