Cardiorespiratory Responses to Constant and Varied-Load Interval Training Sessions

Purpose: To compare the cardiorespiratory responses of a traditional session of high-intensity interval training session with that of a session of similar duration and average load, but with decreasing workload within each bout in cyclists and runners. Methods: A total of 15 cyclists (maximal oxygen uptake [(V)over dotO(2)max] 62 [6] mL.kg(-1).min(-1)) and 15 runners ((V)over dotO(2)max 58 [4] mL.kg(-1).min(-1)) performed both sessions at the maximal common tolerable load on different days. The sessions consisted of four 4-minute intervals interspersed with 3 minutes of active recovery. Power output was held constant for each bout within the traditional day, whereas power started 40 W (2 km.h(-1)) higher and finished 40 W (2 km.h(-1)) lower than average within each bout of the decremental session. Results: Average oxygen uptake during the high-intensity intervals was higher in the decremental session in cycling (89 [4]% vs 86 [5]% of (V)over dotO(2)max, P= .002) but not in running (91 [4]% vs 90 [4]% of (V)over dotO(2)max, P = .38), as was the time spent >90% of (V)over dotO(2)max and the time spent >90% of peak heart rate. Average heart rate (P < .001), pulmonary ventilation (P < .001), and blood lactate concentration (P < .001) were higher during the decremental sessions in both cycling and running. Conclusions: Higher levels of physiological perturbations were achieved during decremental sessions in both cycling and running. These differences were, however, more prominent in cycling, thus making cycling a more attractive modality for testing the effects of a training intervention.

Automated summary

This study aimed to compare the cardiorespiratory responses of traditional high-intensity interval training and decremental training in cyclists and runners. Results showed that decremental training led to higher levels of physiological perturbations in both cycling and running, with more prominent differences observed in cycling.