DOMSDelayed-Onset Muscle Soreness
The muscle soreness that appears a day or two after unfamiliar or hard exercise.
DOMS (Delayed-Onset Muscle Soreness) is the ache and stiffness that arrives a day after training, peaks somewhere around 24 to 72 hours, and fades over the following days. It follows unfamiliar movements and lengthening work in particular, which is why a new exercise wrecks you and the tenth session of the same exercise does not.
It matters mostly as a source of confusion. Soreness is a measure of novelty and mechanical disruption, not of whether a session built anything. A beginner is sore constantly and grows well; an experienced lifter is rarely sore and grows anyway. Chasing soreness by rotating exercises every week trades progression for sensation.
The old explanation, lactic acid, is simply wrong. Lactate clears within roughly an hour of finishing, long before the soreness arrives. The current understanding involves microscopic damage to muscle and connective tissue and the inflammatory response to it, with the nervous system's sensitivity playing a part too.
It fades fast with exposure. The repeated bout effect means the second session of a movement produces markedly less soreness than the first, even a few weeks later, which is why the answer to soreness is usually to keep doing the thing at a sensible dose rather than to avoid it.
Most remedies underperform their marketing. Stretching before or after does not reliably prevent it. Cold water immersion can dull the feeling, though after resistance training soon afterwards it may blunt some of the adaptation you trained for. Gentle movement, sleep and food are unglamorous and work about as well as anything.
Know the line between sore and injured. Soreness is diffuse, symmetrical, worst on the second day and improving. Sharp, one sided pain, pain at a joint, swelling, or pain that worsens rather than settles is a different thing and deserves attention rather than another session.
In practice, judge a programme by whether the numbers move over months, not by how much it hurt on Tuesday.
Sources
- Behm DG, et al. Acute effects of muscle stretching on physical performance, range of motion, and injury incidence in healthy active individuals: a systematic review. Appl Physiol Nutr Metab 2016;41(1):1-11
- Piñero A, et al. Throwing cold water on muscle growth: a systematic review with meta-analysis of post-exercise cold water immersion and resistance-training hypertrophy. Eur J Sport Sci 2024