Research
Hormonal
Acute exercise (45 min at 70% VO2max) causes a transient ~1.2-fold increase in plasma irisin immediately post-exercise, which returns to baseline within 2 hours.
If you measure irisin right after a hard workout, it will be slightly higher. However, this spike is short-lived and does not persist, suggesting it is not a primary driver of long-term metabolic adaptation via this specific hormone.
GoodSupportsHIGH confidence
Circulating irisin was reduced in response to 12 weeks of training, and was increased acutely (~1.2-fold) just after acute exercise.
Why this rating
Consistent findings across two groups and confirmed with a second antibody kit.
Source
The effects of acute and chronic exercise on <scp>PGC</scp>‐1α, irisin and browning of subcutaneous adipose tissue in humans
Frode Norheim et al. · FEBS Journal · 2013
DOI 10.1111/febs.12619
rct · n=26Cited 559×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
More from this paper
- Twelve weeks of combined endurance and strength training in humans does not increase circulating irisin levels and may actually reduce them, despite increasing muscle FNDC5 mRNA expression.Good
- Chronic exercise training increases muscle PGC1A and FNDC5 mRNA expression in humans, but this transcriptional increase does not correlate with plasma irisin levels or subcutaneous fat browning (UCP1).Good
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