Evaluation of critical rest interval determined from repeated sprint ability testing

Area of Science:

• Exercise Physiology
• Sports Science
• Performance Analysis

Background:

• The critical power (CP) concept is established for predicting endurance exercise.
• Its application in determining the critical rest interval (CRI) for intermittent exercise, like repeated sprint ability (RSA), remains less explored.

Purpose of the Study:

• To investigate if the CP concept can be adapted to determine the CRI using RSA protocols with varied work-to-rest ratios.
• To assess the physiological validity of the determined CRI in distinguishing exercise intensity domains.

Main Methods:

• Twelve recreationally trained men underwent graded exercise and RSA tests with 6-second sprints and 12-36s rest intervals.
• Intermittent critical power (ICP) was calculated, and CRI was estimated using average work per sprint and ICP.
• Validation trials above and below the estimated CRI were performed, measuring blood lactate, oxygen uptake (V̇O2), and heart rate (HR).

Main Results:

• Physiological markers including blood lactate, V̇O2, and HR were significantly higher below the determined CRI compared to above it.
• Significant interactions for V̇O2 and HR responses confirmed distinctions between exercise domains.
• These findings align with the expected physiological responses within heavy and severe exercise intensity domains.

Conclusions:

• The work-time relationship derived from RSA testing with varied rest intervals effectively determines CRI.
• This approach can differentiate physiological responses associated with distinct exercise intensity domains.
• RSA testing offers a viable method for establishing critical rest intervals in intermittent exercise.