After a strenuous workout, soreness can develop about 24 to 48 hours after a workout. This soreness is called delayed onset muscle soreness, or DOMS. According to Len Kravitz, Ph.D., DOMS is often brought on by eccentric exercise, such as resistance training, downhill running and plyometrics. There are a few hypotheses as to why muscles become sore, but nothing is universally accepted yet.
Lactic Acid Accumulation
The accumulation of lactic acid in the muscle tissues was once believed to be the major cause of delayed onset muscle soreness. However, this theory is not true. According to a study published in the "European Journal of Applied Physiology and Occupational Physiology," blood lactate levels returned to resting levels within an hour of exercise. This holds true whether a person works out at a low or high intensity.
Tissue Breakdown
Delayed onset muscle soreness may result from muscle tissue breakdown. According to a "Physician and Sports Medicine Journal" study, there was considerable cellular damage in the muscle biopsies taken from marathon runners after competition or training. Cell membranes may rupture, thus releasing the cells' contents in between other muscle fibers. The study also reported there was damage to the contractile filaments actin and myosin, which are responsible for muscle contraction.
Inflammatory Response
Strenuous exercise can often provoke an immune system response, resulting in delayed muscle soreness. White blood cell count has been shown to increase following strenuous activities, according to a study published in the "Sao Paulo Medical Journal." This has led to the hypothesis that DOMS is caused by an inflammatory response in the muscles. Researchers have been unsuccessful in reducing soreness by administering athletes with anti-inflammatory drugs.
Summary
Most researchers will agree that delayed onset muscle soreness results from strenuous eccentric muscle contraction. DOMS is still a debatable topic; none of the theories are universally accepted. Many researchers believe a chain of events, both mechanical and chemical, result in DOMS. An inflammatory response in the muscles may be caused by microscopic muscle damage brought on by strenuous exercise. This acute damage to muscle tissues is likely to cause DOMS by a chain of events over a 48-hour period that leads to cellular death. The intracellular contents and white blood cells accumulate between the muscle fibers, thus stimulating the nerve endings of the muscle, resulting in the feeling of soreness.
References
- University of New Mexico; Treating and Preventing DOMS; J.D. Maes, L. Kravitz; 2003
- "European Journal Applied Physiology Occupational Physiology"; Lactate kinetics after short strenuous exercise in man; H. Freund et al; August 1978
- "Physician and Sportsmedicine"; Muscle damage in marathon runners; F.C. Hagerman et al; 1984
- "Sao Paulo Medical Journal"; Effects of three different types of exercise on blood leukocyte count during and following exercise; V.M. Natale et al; January 2003
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