Delayed-onset muscle soreness (DOMS)

Delayed-onset muscle soreness (DOMS) is the diffuse muscular pain, stiffness, and tenderness that develops 24–72 hours after unaccustomed or eccentric-heavy exercise, peaking around 48 hours and resolving within five to seven days. Eccentric contractions generate high mechanical tension per active cross-bridge, causing ultrastructural sarcomere disruption, increased membrane permeability, and an inflammatory cascade of neutrophils and macrophages that sensitizes peripheral nociceptors. Contrary to a persistent misconception, lactate accumulation is not a cause: blood lactate clears within an hour of exercise, well before soreness onset (Cheung et al. 2003). A single eccentric bout confers the repeated-bout effect: a second comparable session one to six weeks later produces markedly less soreness, strength loss, and creatine kinase (CK) elevation, attributed to sarcomere mechanical reinforcement and neuromuscular adjustments. The inflammatory signaling from exercise-induced microtrauma represents hormesis — a transient stressor that drives tissue remodeling, mitochondrial biogenesis, and satellite-cell activation. Molecular details such as the proposed role of titin degradation derive partly from in vitro and animal models and remain under active investigation (Sonkodi 2022).