The Relationship Between the Moderate-Heavy Boundary and Critical Speed in Running

Area of Science:

• Exercise Physiology
• Sports Science
• Endurance Training

Background:

• Training intensity distribution is crucial for optimizing endurance performance and adaptations.
• Training intensity zones are categorized into moderate, heavy, and severe domains.
• Estimating the critical speed (CS) is feasible from training data, but determining the first threshold (T1) requires costly testing.

Purpose of the Study:

• To review the scientific literature and determine the typical percentage at which the first threshold (T1) occurs relative to critical speed (CS).
• To provide insights into the relationship between T1 and CS for improved exercise intensity prescription.

Main Methods:

• A systematic literature search was conducted to identify relevant studies.
• Data from 26 studies involving 527 participants were analyzed.
• Participants were grouped based on their mean critical speed (CS) into low, medium, and high categories.

Main Results:

• Across all studies, the first threshold (T1) was found to occur at 82.3% of critical speed (CS).
• T1 occurred at a higher fraction of CS in medium (83.2%) and high (84.2%) CS groups compared to the low CS group (80.6%).
• A notable uncertainty exists regarding the precise fraction of T1 relative to CS, influenced by varied methodologies.

Conclusions:

• The relationship between T1 and CS is not definitively fixed and can be influenced by individual characteristics and testing protocols.
• The findings offer a basis for remote analysis and prescription of exercise intensity.
• While providing valuable estimates, direct physiological testing is recommended for precise exercise intensity prescription.