Delayed Onset Muscle Soreness: What It Is, and What It Isn't

Delayed onset muscle soreness, often shortened to DOMS, is the dull, diffuse soreness that tends to appear 24–48 hours after unfamiliar or unusually intense exercise. It's extremely common, especially after returning to activity after a break, or trying a new type of movement your body isn't used to.

A common misconception is that DOMS is caused by lactic acid buildup. Lactic acid clears from the muscles fairly quickly after exercise, well before the soreness typically peaks, so it isn't the primary explanation. The more widely accepted view is that it relates to small-scale structural stress in the muscle fibers, particularly from movements that lengthen a muscle under load.

Another common belief is that soreness is a required sign of an effective workout. It isn't. Soreness tends to reflect how unfamiliar a movement was to your body more than how beneficial it was — a well-trained person can get a thorough, effective workout with very little resulting soreness.

Gentle movement, light activity, and adequate hydration tend to help people feel more comfortable while sore, though none of these dramatically speed up the underlying recovery process. Mostly, DOMS resolves on its own within a few days.

Pain that is sharp, localized to a joint, or doesn't follow this general pattern is a different matter, and is worth having assessed rather than assumed to be ordinary post-exercise soreness.