Delayed Onset Muscle Soreness: Overview

Clients often ask me about the muscle pain and tightness that occur a day or two after beginning/increasing exercise. Often the pain takes them by surprise, since they didn't notice it during the workout. This type of pain is called "delayed onset muscle soreness," or DOMS.

If you've been working out for a while, you've probably been told that DOMS results from lactic acid build-up in the muscles. That theory had a good run before researchers determined that lactic acid is merely a by-product of activity, and not the cause of pain following exercise.

Currently, several theories attempt to explain DOMS. One of the most widely accepted theories is that DOMS is caused by the inflammatory and regenerative response of the body to the microscopic damage that training causes within the muscle fibers. This damage-recovery cycle is considered a normal adaptation process that leads to greater strength and stamina. However, at times the damage will be more extreme, thus will be the recovery, leading to DOMS.

Besides the intensity of the work-out affecting the risk of DOMS, the type of activity can also create a greater chance of DOMS. Activities that focus on eccentric actions put you at greatest risk of DOMS. (Eccentric exercise lengthens the muscle, as in slow squatting, stepping down, or any activity where you have to control movement with resistance.) Isometric actions (application of force without joint movement, no change in the length of the muscle, as in a squat hold) elicits the next greatest chance of experiencing DOMS. Finally, concentric actions (i.e., shortening the muscle, as in bicep curl from arm straight to arm flexed) poses the least risk of DOMS.

DOMS can affect a professional athlete just as easily as a boot-camper or a novice. Any time you begin a new program or new intensity, be ready for the possibility of DOMS.

Next time we'll address how you can deal with DOMS when it strikes, and even better, how you and your trainer can minimize the risk of DOMS.