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Updated: Jul 16, 2026
10:16
Human Circadian Phenotyping and Diurnal Performance Testing in the Real World
Published on: April 7, 2020
Circadian phenotype is associated with diurnal variation in human exercise performance
Akshay Singh1, Sanjida Ahmed1, Stuart J Hesketh2
1School of Medicine and Dentistry, University of Lancashire, Victoria Street, Harrington Building, , Preston, PR1 2HE, UK.
European Journal of Applied Physiology
|July 15, 2026
Summary
Evening exercise performance is significantly better than morning exercise. Chronotype and sleep timing influence these diurnal performance differences, impacting exercise prescription and testing.
Area of Science:
- Exercise Physiology
- Chronobiology
- Sports Science
Background:
- Time-of-day significantly influences exercise performance.
- The role of individual circadian phenotypes in this variation is not fully understood.
Purpose of the Study:
- To investigate diurnal variations in aerobic exercise performance.
- To determine if chronotype and sleep timing correlate with morning-evening performance differences.
Main Methods:
- Twenty-four healthy adults completed 10-min cycling time trials in the morning and evening.
- Standardized sleep, diet, and activity preceded trials.
- Circadian phenotype assessed via questionnaires and actigraphy.
Main Results:
- Evening trials showed significantly higher mean power, peak power, and distance covered (p < 0.01).
- Chronotype (r = -0.47) and sleep midpoint (r = 0.52) significantly predicted performance differences.
- Physiological strain markers (heart rate, lactate, exertion) were similar; core temperature was higher in the evening.
Conclusions:
- Endurance exercise performance is enhanced in the evening compared to the morning.
- Circadian phenotype markers are associated with the magnitude of diurnal performance variation.
- Time-of-day and chronotype are crucial factors for optimizing exercise testing and prescription.
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