PHYS-44 · Principle

My HRV crashed and my CK is high. Am I overtrained?

Not from those alone. Each marker has its own causes and noise (alcohol, a late session, a race), and none diagnoses overtraining. Read trends beside how you feel and perform.

How the body works, agreed across the reviews below; a study entry shows what one experiment measured.

established physiologyApplies to every blood, heart-rate and device markerEstablished — no single marker diagnoses fatigue or overtraining, which stays a diagnosis of exclusion (ECSS/ACSM consensus, REF-206; a monitoring review, REF-367); well supported — self-reported well-being tracked…

Practical Application

My HRV crashed and my CK is high. Am I overtrained? Not from those alone. Each marker has its own causes and noise (alcohol, a late session, a race), and none diagnoses overtraining. Read trends beside how you feel and perform.

What it means for training: read a marker within the person, on the same device and protocol, as a multi-day trend, and next to self-report (SYNTH-30); a lone low reading is context (SYNTH-29).

What it does not mean: that markers are useless (a standardised submaximal test does reflect overreaching, REF-207), or that self-report is infallible: it is open to social-desirability bias (REF-368).

Mechanism

No marker meets the criteria for routine diagnosis of overtraining (REF-206); there is no definitive fatigue marker, and hormonal markers are not currently justified for routine use (REF-367, full text).

Each marker has its own drivers: resting CK moves with age, sex, ethnicity, muscle mass and climate (REF-1349, PHYS-25); inflammation raises ferritin (PHYS-36); overnight HRV falls with alcohol (REF-1011) and after a late hard session (REF-1193); single-day HRV is noise until averaged (REF-361).

A change counts only when it exceeds the marker's own noise (PHYS-43).

Common misreading

"HRV down, so overtrained"; "CK normal, so recovered"; "low lactate, so it was easy"; "my testosterone-to-cortisol ratio shows my training state".

Backs

SYNTH-29 "Do not cut the week on one bad morning or on HRV alone" · SYNTH-30 "Do not let a device number overrule what the athlete tells you" · SYNTH-89 "blood lactate (a metabolic marker, not a fatigue measure)" · SYNTH-34 "lab markers are the wrong judge" · SYNTH-70 "Blood markers are not a return signal"