This study aimed to investigate the cardiopulmonary responses and exercise performance during the low-intensity phase of HIIE compared to the concentric HIIE.
Nine healthy males performed two single-session exercises: CHII (concentric high intensity interval exercise) and CEA (concentric and eccentric alternate exercise) on a bicycle ergometer. Each session included a 5-minute warm-up and cool-down at 30% peak power output (PPO), and a 30-minute main exercise. There were 5 cycles for high and low intensity intervals in the main exercise, where high-intensity phases were 80% PPO, and low-intensity phases were 40% PPO, respectively. In CEA, eccentric exercise at 80% PPO replaced concentric exercise at 40% PPO during the low-intensity periods. Both sessions reached the same PPO in total. Oxygen consumption (VO2) and heart rate (HR) were detected using precise gas analyzing systems.
Both sessions showed similar trends in HR and VO2. During the high-intensity phases, the CHII reported a HR of 164±10 bpm and the VO2 value of 28.6±3 ml/kg/min, while the CEA showed 159±11 bpm in HR, and 26.6±3 ml/kg/min in VO2. During the low-intensity phases, HR and VO2 value in CHII were 153±8 bpm and 21.5±3 ml/kg/min, respectively, while HR and VO2 in CEA dropped to 145±9 bpm and 18±3 ml/kg/min. There was a significant lower VO2 observed in EAE during the recovery phase compared to the CHII (P 0.05).
CEA showed approximately one third VO2 value and HR compared to CHII, indicating that eccentric exercise during the low-intensity phase of HIIE presented lower cardiopulmonary demands. CEA could act as a recovery strategy in interval exercise training.
The combination of concentric and eccentric type of interval exercise may provide a superior option to improve aerobic fitness and diminish perceived exertion for individuals with exercise intolerance.
High intensity interval exercise
Physiological responses
