After running for 24 hours, elite runners have extremely high levels of a blood marker that signals their muscles are breaking down, and those levels stay high the next day.
Scientific Claim
Creatine kinase levels rise to an average of 53,239 U/L immediately after a 24-hour ultramarathon in elite athletes, remaining significantly elevated 24 hours later, indicating substantial skeletal muscle damage.
Original Statement
“We observed high CK activity (53 239 ± 63 608 U/L, p < 0.001) immediately after the race, and it remained elevated 24h after (p < 0.01)”
Evidence Quality Assessment
Claim Status
appropriately stated
Study Design Support
Design cannot support claim
Appropriate Language Strength
association
Can only show association/correlation
Assessment Explanation
The claim reports observed biomarker levels without implying causation. Language is descriptive and matches the observational nature of the study.
Evidence from Studies
Supporting (1)
Unknown Title
The study found that after a 24-hour race, elite runners had extremely high levels of a muscle damage marker called creatine kinase—and those levels stayed high the next day, proving their muscles were badly damaged.