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Delayed Onset Muscle Soreness and the Reasons Why It Happens

Delayed Onset Muscle Soreness (DOMS), according to Healthline, is the increased soreness during the first 24 hours following an intense workout. This soreness typically peaks at 24 to 72 hours and then most often subsides five to seven days later. The degree of soreness is related to both the intensity of muscular contractions and the duration of an exercise session, with the intensity of muscular contractions seeming to have the greater influence.

Eccentric contractions – when the muscle produces force while it’s lengthening (as in alpine skiing or running downhill) – cause the most amount of delayed onset muscle soreness. The soreness is generally located in the distal (furthest from the mid-line of the body) section of the muscle. This delayed soreness probably results from a combination of trauma to the membrane immediately surrounding the muscle cells, in addition to damage to the connective tissue supporting the muscle.

The ‘Torn Muscle Tissue’ Hypothesis of Delayed Onset Muscle Soreness

Stronger by Science notes that delayed onset muscle soreness is often related to structural damage to the sarcolemma, a thin elastic membrane surrounding each muscle fiber. Eccentric (lengthening) contractions produce more trauma to the sarcolemma than concentric (shortening) or isometric (muscle length remaining the same) contractions, although peak force and rate of force development are critical factors.

During a workout session, considerable force is exerted over a relatively small cross-sectional area of the muscle during an eccentric or fast, high-intensity concentric or isometric contraction. As a result, there is a disruption of structural proteins within the muscle fiber. Increases in blood levels of exercise-related enzymes indicate muscle damage, because these intramuscular proteins are too large to escape the muscle cell unless the cell membrane is broken.

Interestingly, blood levels of creatine kinase in the days after running a marathon are similar to those seen in patients following a heart attack, according to Cleveland Clinic. That finding led some physicians several decades ago to suggest that chronic exercise might be harmful to the heart.

As it turns out, creatine kinase leaking from skeletal muscle is different from creatine kinase from cardiac muscle. According to the European Journal of Applied Physiology, researchers have found the time course and magnitude of the increases in these blood enzymes are correlated with delayed onset muscle soreness. That supports the “torn muscle tissue” hypothesis, as described by physical trainer Joe Cannon.

The ‘Torn Connective Tissue’ Hypothesis

Overstretching the connective tissue in and around the muscle cells also contributes to post-exercise pain. Collagen – the protein that forms inelastic fibers of tendons, ligaments, and fascia – decreases in strength with elevations in temperature and decreases in acidity, both of which occur in muscles during exercise.

Levels of hydroxyproline in the urine, a marker of connective tissue damage, is highly correlated with delayed onset muscle soreness following exercise. This “torn connective tissue” theory of delayed onset muscle soreness, according to Orthopedic Massage, is further supported by sufferers’ reports that pinpoint the greatest soreness in the tendons, which attach muscle to bone.

Related: Cardiovascular Health and Avoiding Problems with Your Heart

Delayed Onset Muscle Soreness Does Not Result from Lactic Acid Accumulation

Contrary to popular locker room myths, delayed onset muscle soreness is not the result of lactic acid accumulation within muscles, according to Performance Bodywork. Lactic acid certainly causes acute fatigue (probably because it interferes with calcium utilization during muscular contractions), but it is not elevated during times of delayed onset muscle soreness. Consequently, it should not be considered as bad as many exercisers might think.

As it turns out, lactate is actually a very important source for energy metabolism, and you probably could not walk across a room without it. Blood lactate levels about 15 minutes after completing a 26.2-mile marathon remain at normal resting levels. They are not correlated with the degree of delayed onset muscle soreness experienced following exercise.

The elevated lactate level that some athletes experience in the first few minutes after finishing an endurance event is almost entirely due to the sprint to the finish line at the end as compared to their overall exertion during the race.

Related link: Sprint Internal Training: A New Method for Physical Fitness

Aspirin Probably Does Not Help Relieve Delayed Onset Muscle Soreness and May Even Be Detrimental

IDEA Health and Fitness Association notes that aspirin is commonly taken for exercise-related inflammatory conditions such as Achilles tendinitis and plantar fasciitis. However, it cannot always help and may even be detrimental in treating delayed onset muscle soreness. Prostaglandin blockers such as aspirin may even interfere with muscle protein turnover and repair during recovery from intense exercise.

To relieve post-exercise soreness, many athletes experiment with applying heat to sore muscles through the use of topical ointments and creams containing methyl salicylate, menthol, thymol, and camphor. While muscle massage and the warmth of anti-inflammatory medications may reduce pain and provide psychological benefits from the pain relief, it is doubtful if these treatment methods facilitate the repair processes within damaged tissues. According to the American College of Sports Medicine, research on exercise-induced injury in animals indicates that the degenerative processes in delayed onset muscle soreness often do not follow the inflammatory sequences that these medications are designed to reduce.

Repeated, Low-Intensity Muscular Activity Is Best for Treating Muscle Soreness

According to Healthline, the best treatment for delayed onset muscle soreness most often focuses on simple, repeated low-intensity muscular activity. The first two times I ran the Saint George marathon in Utah, I was so tired that I could hardly move in the weeks after the race. My muscles remained extremely sore nearly up until ski season.

Simple and repeated low-intensity muscular activity is the best treatment for delayed onset muscle soreness.

The third time I ran the George marathon, I had to park my car three miles away from the finish line. As a result, it was a long walk to return to my car after the race and that low-intensity walk proved helpful after the strenuous exercise of the marathon.

I also refused to just sit around and stay stiff in the days following the marathon. I was delighted to find out that the delayed onset muscle soreness which all marathoners inevitably experience was less intense and did not last nearly as long.

During repeated, normal exercise sessions, delayed onset muscle soreness from a previous workout substantially diminishes with stretching and exercise. Afterwards, the muscle soreness will return, but to a lesser degree.

Typically, this cycle continues until the muscles become sufficiently trained and adapt to the repeated stress. The short-term relief from delayed onset muscle soreness following exercise may also be related to the release of endorphins by the central nervous system.

Sensory neurons (which carry the sensation of pain from muscles to brain) are inhibited by these endorphins, natural pain relievers that are actually more potent than morphine in blocking pain, according to Harvard Medical School. Muscular conditioning through repeated training, however, has been shown to reduce post-workout soreness after following intense exercise and is presently the best-known treatment for delayed onset muscle soreness, notes Strength and Conditioning Journal.

Daniel G. Graetzer, Ph.D., received his B.S. from Colorado State University/Fort Collins, a M.A. from the University of North Carolina/Chapel Hill and a Ph.D. from the University of Utah/Salt Lake City. He has been a faculty member in the School of Health Sciences, Department of Sports and Health Sciences, since 2015. As a regular columnist in social media blogs, encyclopedias, and popular magazines, Dr. Graetzer greatly enjoys helping bridge communication gaps between recent breakthroughs in practical application of developing scientific theories and societal well-being.

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