There are many theories that explain the damage that happens in DOMS at the cellular level. The most known explanation is the accumulation of lactic acid, but this was rejected because it was shown to be unrelated to DOMS. There is the muscle spasm theory that indicates that resting activation of the muscles caused spasm that compressed the vessels, hindering blood flow and increased the sensation of pain. The connective tissue states that there is a predominance of type II fibers that increase susceptibility to stretch injuries. The muscle damage theory states that there is mechanical damage, especially to the Z-line, to the muscular unit due to increased tension in a given area. This has been attributed to eccentric exercise as they exhibit
