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Maximizing muscle deoxygenation during interval training in middle-distance runners
Phillip Bellinger1, Will Morris2, Llion Roberts2
1Griffith Sport Science, Griffith University, Southport, QLD, 4215, Australia. p.bellinger@griffith.edu.au.
European Journal of Applied Physiology
|July 24, 2025
Summary
Shorter 400m running intervals increase muscle deoxygenation more than longer 1km intervals in trained runners. However, 1km intervals elevate heart rate for longer, suggesting different physiological impacts.
Area of Science:
- Exercise Physiology
- Sports Science
- Middle-Distance Running Performance
Background:
- Understanding the physiological demands of different interval training protocols is crucial for optimizing middle-distance runner performance.
- Muscle deoxygenation and heart rate response are key indicators of physiological stress during exercise.
- Previous research has not directly compared the muscle deoxygenation and cardiovascular responses between 1km and 400m interval sessions in trained runners.
Purpose of the Study:
- To compare the magnitude and duration of muscle deoxygenation between 6x1km and 15x400m interval running sessions.
- To investigate the time spent with elevated heart rate during these two distinct interval training protocols.
- To determine which interval session elicits greater peripheral and central physiological responses in trained middle-distance runners.
Main Methods:
- Thirteen trained middle-distance runners completed a field-based incremental running test and two interval sessions (6x1km and 15x400m) with 1-minute passive recovery.
- Maximal sustainable pace was aimed for each repetition.
- Measurements included mean speed, heart rate, rating of perceived exertion (RPE), blood lactate concentration, and muscle deoxygenation.
Main Results:
- Mean speed was significantly higher during the 400m intervals compared to the 1km intervals.
- The 400m intervals resulted in a significantly greater peak magnitude and duration of muscle deoxygenation.
- The 1km intervals led to a significantly longer duration of heart rate above 90% of peak heart rate, with no differences in RPE or blood lactate.
Conclusions:
- 400m interval sessions appear to elicit greater peripheral physiological responses, indicated by higher muscle deoxygenation, in trained middle-distance runners.
- 1km interval sessions may preferentially stimulate central physiological responses, evidenced by a prolonged elevated heart rate.
- The choice of interval distance can be tailored to target specific physiological adaptations for middle-distance running training.
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