Muscle Soreness — Acute vs. DOMS

People who do resistance training commonly experience discomfort, soreness, stiffness, or pain. These afflictions fall into two general categories: those that occur during and immediately after exercise (which may persist for several hours), and those that usually do not appear until 24 to 48 hours later (Alter, 1996).

Acute soreness — pain felt immediately and after exercise. It can result from the accumulation of end products of exercise, such as lactic acid, and from tissue edema (fluid shifting from the blood plasma into the tissues — the "pump up" feeling).

DOMS (Delayed-Onset Muscle Soreness) — muscle soreness felt between 12 hours and 48 hours after a strenuous bout of exercise. Because the pain does not occur immediately, it is referred to as delayed-onset muscle soreness, or DOMS.

Note: some degree of soreness is often experienced by those who have not previously exercised or stretched — the penalty for being inactive. Well-trained athletes who work out at higher-than-usual difficulty can also become sore.

• Two categories: (1) during/immediately after exercise (lasts several hours); (2) appearing 24–48 hours later.
• Acute: immediate pain from end products (e.g., lactic acid) and tissue edema (plasma fluid → tissues, "pump up").
• DOMS: soreness felt 12 to 48 hours after strenuous exercise; delayed onset gives it its name.
• Affects the previously inactive and well-trained athletes working harder than usual.

• doms-three-hypotheses — the three explanations for soreness.
• eccentric-action — eccentric work as the primary instigator of DOMS.
• lactic-acid-system — lactic-acid end products in acute soreness; that module's verification_note covers the broader 2026 update on lactate and fatigue (it's not the culprit it was once thought to be).
• recovery-physiology — recovery between bouts.