Performance
A Brazilian endocrinologist synthesizes diagnosis, hormones, immunity, metabolism, burnout, RED-S, treatment, and prevention in overtraining syndrome.
Overtraining is defined as an accumulation of training and non-training stress, including physical, biochemical, and mental-emotional strain. Pressures outside sport count toward the total, so training load alone cannot explain who breaks down.
What marks the syndrome is not a bad week but a long-term fall in performance that takes several weeks or months to resolve. The defining paradox is that sustained hard training leads to getting worse rather than fitter.
The author argues that overtraining syndrome is better understood as burnout showing up in athletes than as the simple result of training too much. On this view the cause is a whole-life imbalance, not just excess mileage or load.
Overtraining, low-energy syndromes such as the female athlete triad and RED-S, and athlete burnout have been studied separately. The author proposes they may be different faces of one condition, or a closely related family of conditions. All are triggered by chronic deprivation of some kind.
When energy and the body's repair capacity are chronically depleted, the body makes dysfunctional forced adjustments to cope. The author calls these 'maladaptive' changes and says they cause dysfunction across several systems at once, rather than simple tiredness.
There is no single laboratory test for overtraining, and no standardized diagnostic criteria or reliable biomarkers. Diagnosis therefore depends on piecing together the clinical picture rather than reading off one number.
Exercise adaptations of the heart and muscles are well documented, but the endocrine system's long-term adaptations are much less understood. Normal hormone ranges for athletes have not yet been set, which makes abnormal results hard to judge.
One framing treats overtraining as a three-stage spectrum disorder modeled on the classic stress response. Athletes slide progressively from adaptation toward breakdown, rather than flipping suddenly from healthy to ill.