Effects of Non-Wingate-based High-intensity Interval Training on Cardiorespiratory Fitness and Aerobic-based Exercise Capacity in Sedentary Subjects: A Preliminary Study

This study examined two hypotheses: (1) a non-Wingate-based high-intensity interval training protocol of 20×30-second cycle exercise at 120% of peak aerobic power interspersed with 60-second recovery per session, 3 sessions per week for 6 weeks, can enhance cardiorespiratory fitness and aerobic-based exercise capacity; and (2) proportional-assist ventilation (PAV) can augment interval training intensity, and, in turn, enhance the adaptations to the training in sedentary and mild obese individuals. Sixteen subjects were paired up and assigned into an interval training (IT) group or IT plus PAV (IT + PAV) group. During the 6-week interval training program, the increase in training intensity was not different between the IT and IT + PAV groups (p > 0.05). Nevertheless, significant improvements were found in the peak work rate and peak O₂ during the post-training incremental cycling test in both groups. Moreover, the limit of tolerance during the post-training constant-load cycling test (70% of pre-training peak aerobic power) was enhanced, while blood lactate accumulation, heart rate, ratings of breathing discomfort, and perceived exertion at the iso-time point of the pre-training test at exhaustion were reduced (p < 0.05). The interaction effect on the change in each variable between the two groups was not significant (p > 0.05). In conclusion, the 6-week non-Wingate-based high-intensity interval training protocol was preliminarily found to enhance cardiorespiratory fitness and aerobic-based exercise capacity in sedentary and mild obese subjects. The provision of PAV during the interval training did not augment training intensity and subsequent aerobic adaptations.