Delayed-onset muscle soreness (DOMS)

Delayed-onset muscle soreness (DOMS) is the diffuse ache, stiffness, and tenderness that shows up 24 to 72 hours after unfamiliar or eccentric-heavy exercise. It peaks around 48 hours and fades within 5 to 7 days. Eccentric contractions (where the muscle lengthens under load) create high tension per fiber. That causes tiny structural damage to the sarcomeres, makes membranes leaky, and sets off an inflammatory wave of neutrophils and macrophages that sensitizes your pain nerves. One persistent myth: lactate does not cause it. Blood lactate clears within an hour of exercise, long before the soreness starts (Cheung et al. 2003). A single eccentric workout buys you the 'repeated-bout effect'. Do a similar session 1 to 6 weeks later, and you get far less soreness, strength loss, and CK rise, thanks to mechanical reinforcement and neuromuscular tweaks. The inflammation from this microtrauma is actually hormesis: a brief stressor that drives tissue remodeling, mitochondrial biogenesis, and satellite-cell activation. Some molecular details (like a proposed role for titin breakdown) come partly from lab and animal models and are still being studied (Sonkodi 2022).

Last reviewed: June 22, 2026

This definition is educational and is not medical advice, a diagnosis, or treatment. Talk to a doctor about any health decisions. Read our full medical disclaimer