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.
No biological mechanisms were identified in this study. This may be an epidemiological, observational, or survey-based study that reports associations rather than proposing causal biological pathways.
Systematic Reviews & Meta-Analyses
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Max 90Cohort Studies
Max 72Case-Control Studies
Max 58Cross-Sectional Studies
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Evidence Score
Based on clinical experience or non-systematic literature reviews. The lowest level of evidence as they are most susceptible to bias and personal perspective.
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.
No biological mechanisms were identified in this study. This may be an epidemiological, observational, or survey-based study that reports associations rather than proposing causal biological pathways.
Systematic Reviews & Meta-Analyses
Max 100Randomized Controlled Trials
Max 90Cohort Studies
Max 72Case-Control Studies
Max 58Cross-Sectional Studies
Max 44Case Reports & Case Series
Max 30Expert Opinion & Narrative Reviews
Max 51 / 5
Evidence Score
Based on clinical experience or non-systematic literature reviews. The lowest level of evidence as they are most susceptible to bias and personal perspective.
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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.