After a 24-hour race, the blood of elite runners shows massive spikes in six tiny molecules that come from muscle tissue—some up to over 100,000 times higher than normal.

Scientific Claim

Circulating levels of six muscle-specific microRNAs (miR-1-3p, miR-133a-3p, miR-133b, miR-208a-3p, miR-208b-3p, and miR-499a-5p) increase 18- to 124,723-fold immediately after a 24-hour ultramarathon in elite athletes.

Original Statement

“Circulating myomiR levels (miR-1-3p, miR-133a-3p, miR-133b, miR-208a-3p, miR-208b-3p, and miR-499a-5p) were elevated immediately after the 24-h run (fold changes: 18-124,723, p<0.001)”

From study:Unknown Title

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 uses precise, observed data without implying causation or diagnostic utility. Language is conservative and aligned with observational design.

Evidence from Studies

Supporting (1)

Unknown Title

Cross-Sectional Study

Human

After running 24 hours straight, elite runners had huge spikes in six specific tiny molecules in their blood that come from damaged muscles — exactly as the claim says.

Contradicting (0)

No contradicting evidence found

Source Study

Unknown Title

Score: 31

DOI: 10.1111/sms.14000

Similar Assertions

These tiny molecules in the blood might help doctors tell how badly a runner’s muscles are damaged after an ultra-race—better than current tests.

81%

After a 24-hour race, the levels of certain tiny muscle molecules in the blood match up better with how weak the runners still feel the next day than the usual muscle damage markers do.

80%