Cortisol: its role and the limits of testing
Cortisol is a glucocorticoid hormone involved in energy regulation, cardiovascular function, immune signalling and the stress response. Its concentration varies with time and context.
Physiology and measurement
Cortisol follows a circadian pattern and responds to waking, exercise, psychological stress, illness, food and other factors. Blood, saliva and urine measurements represent different windows and depend on sampling time and method. A rise after hard exercise is not automatically harmful, and one value cannot distinguish productive training from maladaptation.
Exercise and cortisol-awakening response review · Athlete blood-biomarker monitoring review
Use in athletes
Reviews report variable cortisol-awakening responses with exercise and major methodological differences. Athlete biomarkers are most useful with repeated, standardised measurements and contextual data rather than a universal cutoff or testosterone-to-cortisol diagnosis. Symptoms, performance, sleep and load still require interpretation. This page does not support supplements claimed to “lower cortisol” or guarantee recovery.
Exercise and cortisol-awakening response review · Athlete blood-biomarker monitoring review
FAQ
Is cortisol always bad?
No. It has essential normal functions and changes with context.
Can one test diagnose overtraining?
No. A single cortisol value is insufficient for that diagnosis.
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