High-intensity decreasing interval training (HIDIT) increases time above 90% O₂peak

Area of Science:

• Exercise Physiology
• Sports Science
• Cardiorespiratory Fitness

Background:

• Training at or near maximal oxygen uptake (VO2max) is key for enhancing VO2max.
• High-intensity interval training (HIIT) is an effective, time-efficient method for improving cardiorespiratory and metabolic function.
• Different HIIT protocols may differentially impact time spent at high exercise intensities and time to exhaustion (Tlim).

Purpose of the Study:

• To compare the time spent above 90% of peak oxygen uptake (VO2peak) during three distinct HIIT protocols.
• To evaluate the effectiveness of different HIIT structures in achieving high physiological intensities.

Main Methods:

• Twelve cyclists completed three HIIT protocols: long-interval (LI_HIIT), short-interval (SI_HIIT), and high-intensity decreasing interval training (HIDIT).
• All protocols maintained consistent work and recovery power ratios.
• Measurements included time above 90% VO2peak, Tlim, blood lactate ([La]), and rate of perceived exertion (RPE) at Tlim.

Main Results:

• Time above 90% VO2peak was significantly greater in HIDIT (312 ± 207 s) compared to SI_HIIT (182 ± 225 s) and LI_HIIT (179 ± 145 s).
• No significant differences were observed in Tlim, [La], or RPE at Tlim across the three protocols.
• HIDIT protocol involved decreasing work intervals and recovery periods.

Conclusions:

• The high-intensity decreasing interval training (HIDIT) protocol resulted in the longest duration above 90% VO2peak.
• HIDIT may be a more effective strategy for increasing time spent close to VO2peak compared to traditional long or short HIIT intervals.
• Despite differences in time above VO2peak, overall exercise tolerance (Tlim) and physiological markers ([La], RPE) were similar across protocols.