Although the precise cause is still unknown, the type of muscle contraction seems to be a key factor in the development of DOMS. Exercises that involve many eccentric contractions, such as downhill running, will result in the most severe DOMS. This has been shown to be the result of more muscle cell damage than is seen with typical concentric contractions, in which a muscle successfully shortens during contraction against a load.
Some research claims that DOMS is not caused by the pain from damaged muscle cells, but from the reinforcement process. The muscle responds to training by reinforcing itself up to and above its previous strength by increasing the size of muscle fibers (muscle hypertrophy). This reinforcement process causes the cells to swell in their compartment and put pressure on nerves and arteries producing pain.
Stretching before and after exercise has been suggested as a way of reducing DOMS, as has warming up before exercise, cooling down afterwards, and gently warming the area. However, there is also evidence that the effect of stretching on muscle soreness is negligible. Overstretching itself can cause DOMS. Some recommend contrast showers as a treatment, alternating between cold and hot water; it may increase circulation.