There is no consistent physiological, hormonal, or biochemical marker that correlates with overtraining; therefore, the primary diagnostic criterion for overtraining is determined by the duration of performance recovery rather than the presence of ancillary symptoms.

Study: Overtraining in Resistance Exercise: An Exploratory Systematic Review and Methodological Appraisal of the Literature

The study looked at overtraining in weightlifting and found that no blood test or hormone level reliably shows when someone is overtrained. Instead, the best sign is how long it takes their performance to bounce back.

Study: Overtraining Syndrome as a Risk Factor for Bone Stress Injuries among Paralympic Athletes

The study says doctors can’t rely on blood tests or hormones to diagnose overtraining, which matches the claim that recovery time is more important for diagnosis.

Study: Diagnosing Overtraining Syndrome: A Scoping Review

The study found that certain body signals like hormones and heart patterns can help diagnose overtraining when used together, which goes against the idea that no such reliable signs exist.

Study: Diagnosis of Overtraining Syndrome: Results of the Endocrine and Metabolic Responses on Overtraining Syndrome Study: EROS-DIAGNOSIS

The claim says we can’t use body markers to diagnose overtraining and should instead wait to see how long it takes athletes to recover. But this study found a set of blood and hormone tests that can diagnose overtraining perfectly, which goes against that idea.