If you experience sore muscles days after completing a tough training session, you have probably overworked your muscle fibers beyond their tolerance levels. Delayed-onset muscle soreness (DOMS) or post-exercise muscle soreness (PEMS) is a common yet peculiar type of pain. Unlike the acute variety, DOMS doesn’t occur during or immediately following exercise. Like its name implies, DOMS is delayed.
Exercise guru Covert Bailey adds the distinctiveness of the DOMS phenomena is there is no pain at the time of injury. Trainees don’t feel the stiffness, tenderness and soreness until a day or so later with the most intense pain worsening over the first few days. It isn’t uncommon for some trainees to suffer DOMS for up to a week.
Possible Causes Of Achy Muscles
Trainees shouldn’t count on eliminating DOMS entirely because most exercisers will experience this annoying form of muscle pain at some point in their training regimens. Furthermore, this form of muscle pain affects both novice and advanced trainees alike—especially when performing unfamiliar exercises. That’s why it’s beneficial to ease into new training routines slowly rather than to overdo it. Minimizing bouts of DOMS by taking preventative measures is key.
Prolonged or intense exercise is most often noted to cause delayed-onset muscle soreness. Muscle lengthening actions (eccentric movements) are also sited as a main cause. For instance, the descending/lowering phase of an all-out set of leg curls could potentially subject the hamstrings (rear upper legs) to delayed muscle pain if worked too hard.
DOMS or post-exercise muscle soreness can be very painful. But for balanced muscular development and improved fitness it isn’t advisable to avoid eccentric muscle actions. Eccentric motions contribute to growth, greater strength and potentially fewer subsequent bouts with DOMS for up to several weeks.
Theory Of Delayed Muscle Soreness
There are competing theories as to the physiological mechanism that causes DOMS. But scientists don’t fully understand the phenomena. Generally, it’s proposed that eccentric movements cause greatest damage due to excessive, injurious forces generated by fewer muscle fibers eccentrically contracting while attempting to control resistance.
After injury, damaged muscle fibers go through a process of losing essential internal components via leakage. Molecules normally external to muscle fibers osmotically enter damaged cells setting off demolition or cell death. This process is part of an immune response.
Debris at the site of injury attracts phagocytes for damage control. This chain of events causes inflammation, swelling, edema and a host of additional healing events. Sensations of pain, stiffness and tenderness is due in part to irritated nerve endings occurring about 12 – 48 hours after the occurrence of injury. Ironically, the pain initially gets worse as the muscle heals resulting from accelerated immunologic responses at the site of injury.
It’s conjectured the best way to alleviate DOMS is by performing milder versions of the exercise that originally damaged the muscle. However, discretion and commonsense must apply to prevent further damage, overreaching or overtraining syndrome. There is a thin line between mild stimulation and overdoing it.
When unsure, it is best to allow the pain to subside before training the affected muscle again. If the pain lasts longer than a week, there may be a more serious problem and medical attention should be sought. For more comprehensive information on the causes, prevention and treatment of DOMS see Delayed Onset Muscle Soreness.
Bailey, C. (1994). Delayed Muscle Soreness. Smart Exercise: Burning Fat, Getting Fit, 163 – 165.
Mackinnon, L.T. (2002). Neuromuscular System Response to Exercise. Exercise Physiology, 34 – 37.