The Study
MR measurements of muscle damage and adaptation after eccentric exercise
This study watched 6 guys closely after they did a tough arm exercise, taking pictures and blood tests over 8 weeks. It shows what happened to them, but because there was no comparison group and so few people, we can't say for sure that the exercise caused the changes or that it would happen to everyone.
Analysis score
Maximum 72 for a cohort study.
Where the score came from
When young men do a tough arm exercise, their muscles swell and show changes on MRI that last for weeks. Doing the same exercise again 8 weeks later causes less damage, showing muscles adapt and protect themselves.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 530 / 100
Quality score
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Key takeaways
Summary
Based on the study abstract and findings.
- 1The muscle changes show real damage and long-term remodeling, but the reduced response the second time means the body learns to protect itself from similar stress.
- 2T2 signal went up by 8 ms right after exercise, peaked at 47 ms after 7 days the first time, and 37 ms after 2–4 days the second time.
- 3Muscle swelled over 40%, then shrank to 10% smaller than normal.
- 4Soreness and damage markers were much lower the second time.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of Applied Physiology
Year
1999
Authors
Jeanne M. Foley, Roop C. Jayaraman, Barry M. Prior, James M. Pivarnik, Ronald A. Meyer
Related Content
Claims (8)
Your muscles get used to tough workouts over time, so they hurt less and recover faster the more you do them.
When young guys do a specific arm exercise, their muscle response right after is about the same the first and second time, even though their body adapts later on.
When young guys do super intense bicep curls they're not used to, their muscle scans show changes that start right away, get worse over a week, and can still be seen two months later.
After a tough bicep workout, guys' arm muscles swell up a lot in just two days, then shrink below normal size and stay that way for over two months.
When young guys do a tough arm workout a second time, their muscles aren't as sore, swollen, or damaged as they were the first time — their bodies seem to adapt after the first go-around.
If you suddenly do really intense stretching-type workouts that your muscles aren't used to, it can seriously damage them — so much that the muscles actually get smaller for a few weeks.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.