Why muscles hurt after exercise (even when they're not broken)
Neurochemical mechanism of muscular pain: Insight from the study on delayed onset muscle soreness
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
When muscles feel sore after exercise, it's not because they're damaged—it's because the nerves in the muscle get extra sensitive. In rats, this soreness comes from chemicals in the muscle turning up the 'pain volume' in nerves.
Surprising Findings
DOMS can occur without any muscle damage at all.
Contradicts the long-held belief that soreness comes from microtears in muscle fibers. The study found histological damage only at extreme intensities, not during typical DOMS-inducing workouts.
Practical Takeaways
Don’t use soreness as a measure of workout quality — you can build muscle without being sore.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
When muscles feel sore after exercise, it's not because they're damaged—it's because the nerves in the muscle get extra sensitive. In rats, this soreness comes from chemicals in the muscle turning up the 'pain volume' in nerves.
Surprising Findings
DOMS can occur without any muscle damage at all.
Contradicts the long-held belief that soreness comes from microtears in muscle fibers. The study found histological damage only at extreme intensities, not during typical DOMS-inducing workouts.
Practical Takeaways
Don’t use soreness as a measure of workout quality — you can build muscle without being sore.
Publication
Journal
The Journal of Physiological Sciences : JPS
Year
2024
Authors
K. Mizumura, T. Taguchi
Related Content
Claims (6)
Feeling sore after a workout doesn’t mean you’re building muscle or that your workout was effective — DOMS isn’t a good way to measure progress.
Even if a rat's muscles aren't actually torn or damaged, it can still feel sore after exercise — this soreness seems to come from nerve sensitivity, not from physical damage, especially when the exercise isn't too intense.
In rats, sore muscles after unusual exercise seem to start with a specific pain signal (called bradykinin) turning on right when the exercise happens. If you block that signal before exercise, the rats don’t get sore — but only if you block it early.
In rats with muscle soreness after exercise, two brain-chemical pathways team up to make muscles extra sensitive to pain, especially when certain pain-related proteins are present at low levels — and they both work through specific pain sensors in the nerves.
When rats do certain muscle exercises, they get sore deep in their muscles—not on the skin—starting a day later, peaking after 2–3 days, and going away by day 4. This soreness is due to increased sensitivity in the muscles themselves.