Cardiorespiratory Responses to Constant and Varied-Load Interval Training Sessions

Area of Science:

• Exercise Physiology
• Sports Science
• Cardiorespiratory Fitness

Background:

• High-intensity interval training (HIIT) is effective for improving cardiorespiratory fitness.
• Optimizing HIIT protocols can enhance training efficacy and testing outcomes.

Purpose of the Study:

• To compare cardiorespiratory responses between traditional HIIT and a decremental HIIT protocol in cyclists and runners.
• To assess the physiological impact of decreasing workload within exercise bouts.

Main Methods:

• 15 cyclists and 15 runners completed both traditional and decremental HIIT sessions.
• Sessions involved four 4-minute intervals with 3-minute active recovery.
• Decremental sessions featured a decreasing power output within each interval.

Main Results:

• Decremental HIIT resulted in higher average oxygen uptake and time spent above 90% of maximal oxygen uptake in cycling.
• Both cycling and running showed higher average heart rate, pulmonary ventilation, and blood lactate during decremental HIIT.
• Physiological perturbations were greater in decremental sessions, particularly in cycling.

Conclusions:

• Decremental HIIT elicits a more significant cardiorespiratory challenge compared to traditional HIIT.
• The enhanced physiological stress in decremental HIIT may offer advantages for training and testing, especially in cycling.