PHYS-25 · Principle

My CK was high after a race. Is something wrong, or am I not recovered?

A rise after a long, hard or downhill effort is expected and falls back over days. Its size says as much about you as about the race, and not when you are ready.

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

established physiologyApplies to everyoneEstablished — the rise and the spread between people; well supported — "a poor readiness marker" (force sizes damage, blood proteins do not, REF-1351; no single marker is accepted even for overtraining, REF-206…

Practical Application

My CK was high after a race. Is something wrong, or am I not recovered? A rise after a long, hard or downhill effort is expected and falls back over days. Its size says as much about you as about the race, and not when you are ready.
What it means for training: judge readiness by function, feel and how a known session goes (SYNTH-70).
What it does not mean: low CK is not proof of readiness, high not proof of overreaching, and two athletes' values are not comparable; group gaps (REF-703, REF-235) are those studies' numbers.

Mechanism

Lengthening contractions disrupt sarcomeres and membranes (REF-704); CK and myoglobin leak out, most after ultra and downhill running (REF-1349, REF-830), peaking 24 to 120 h after, by exercise and person (REF-1350).
Resting CK moves with age, sex, ethnicity, muscle mass, activity and climate; people are low or high responders (REF-1349); the same ride, repeated on three days, split men by quadriceps size and strength, not fitness (REF-305).
After a marathon the markers recovered on different clocks (REF-762); jump height, not any marker, separated easy running from rest (REF-761); damage cut cyclists' peak power, not time trials (REF-701).

Common misreading

"CK back to normal = ready", "lower CK = faster recovery": cold water did not speed the return of strength (REF-250).
Safety: high CK after full rest with no other cause needs a medical work-up (REF-1349); very high values with dark urine or severe weakness, a doctor (inference, REF-826).

Backs

SYNTH-49 "a load signature, not a fault" · SYNTH-23 "as a durability score" · SYNTH-70 "not a return signal" · SYNTH-89 "markers that point in opposite directions"

Sources

Brancaccio, Maffulli & Limongelli 2007 REF-1349 (C+) · Paper ↗
Warren, Lowe & Armstrong 1999 REF-1351 (B+) · Paper ↗
REF-1350 (C+)
REF-1371 (B-)