Delayed Onset Muscle Soreness

The feeling of pain or discomfort in muscles in the hours and days following a strenuous or unaccustomed activity is called delayed onset muscle soreness or “DOMS” for short. Anything that’s intense enough or that you are not used to doing will cause DOMS if you do it long enough. This can be anything from shoveling snow from your driveway to going out and running around the block one time. The pain usually occurs 24 to 72 hours following exercise. The soreness usually subsides within 7 to 10 days of the soreness-initiating event. Muscles during this time are said to be stiff and there is often a decreased range of motion. During this time, people report a lowered ability to produce force in the affected muscles. Thus, people may not be able to lift as much when they experience DOMS. Research has shown that this is the result of both a decreased ability of the muscle to produce force and an unwillingness on the part of the person to use the DOMS-affected muscles.115 Interestingly, DOMS is not felt when the muscle is at rest; rather, we only feel the pain when the muscles in question are worked or when the muscles are touched.116 This fact can sometimes help fitness trainers to differentiate between DOMS and some other more serious types of pain (e.g., tendonitis). In other words, failure to experience pain when not moving may be a tip off that the person is experiencing DOMS.

DOMS does not result in any long-term damage to muscles. However, there is evidence of short-term damage. Muscle biopsies during DOMS reveal damage to key areas of muscle structure.117 For example studies show physical damage to sarcomeres as well as to their associated connective tissues and elevations in various enzymes associated with tissue injury.

There are several theories to explain why DOMS occurs. All theories have merit; but, no theory fully explains the process. The most common theories are the torn tissue theory, connective tissue theory and inflammation theory.


Theories of DOMS

Theory Main Details
Torn Tissue Theory Damage to muscles is cause of DOMS
Connective Tissue Theory Damage to connective tissue is cause of DOMS
Inflammation Theory White blood cells release chemicals that sensitize pain receptors

The theories aside, what everyone agrees upon is that eccentric activities (e.g., walking downhill or lowering a dumbbell.) or “negatives” as they are often called, result in far more DOMS than concentric movements.119

Some may take various drugs like aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs) to alleviate DOMS. While this practice can help reduce pain it may not be the best practice for elite athletes. There is evidence that NSAIDs reduce protein synthesis following eccentric exercise.120 This, in theory, might prolong DOMS and reduce athletic performance. For most people, however, this effect is probably not significant.

One common misconception about DOMS involves lactic acid. There is no proof that lactic acid causes DOMS. People who say this probably confuse muscle burning during exercise with muscle pain (DOMS) the next day. They are not the same thing.

Another common misconception about DOMS involves stretching. To date there is not much evidence that stretching sore muscles alleviates DOMS. In fact, there is evidence that stretching can cause DOMS, if you are not used to stretching.118 Stretching between sets however may speed recovery during subsequent sets. Likewise, the impact of various nutritional supplements (e.g., antioxidants) to protect against DOMS or speed relief has, at best, mixed results and is not fully accepted.212 As for so-called sports creams, these mask pain with either sensations of heat or cold. They do not speed recovery from DOMS. Currently, the only accepted therapy for reducing DOMS is performing a submaximal bout of the exercise before the actual workout.122 In other words, do one set of an exercise a day or so before doing 3 sets. In practical terms, novices who perform one set and gradually build upon this over time are less likely to experience DOMS or more serious injuries than those who partake in more aggressive exercise routines.


Types of Muscle Fibers

There are basically three types of muscle tissue in the body: smooth muscle (in blood vessels), cardiac muscle (in the heart) and skeletal muscle (biceps, triceps, etc.). This section will deal only with skeletal muscle.

Skeletal muscle is called skeletal because, for the most part, it’s attached to the skeleton. Skeletal muscle is also called voluntary muscle because we voluntarily cause it to move. For example, the biceps muscle can’t automatically lift a dumbbell; we must first think, “Lift that dumbbell,” before it happens.


What About Heart Muscle?

Skeletal muscle and cardiac (heart) muscle have similarities; however, one important difference is that cardiac muscle is involuntary. In other words, we don't have to think to make it contract. Imagine the problems we would have if we always had to concentrate on keeping our heart beating!


Skeletal muscle can be further divided into type I muscle fibers and type II muscle fibers and various subtypes of each. The type I and type II fibers are also sometimes called slow twitch and fast twitch muscle fibers respectively, where the “twitch” refers to contraction speed (in other words slow twitch fibers twitch or contract slower than fast twitch fibers). The type II fibers can be further subdivided into different subtypes. Usually we discuss type IIa fibers and type IIb fibers. Let’s explain each in more detail now.

Type I muscle fibers are small fibers that produce low amounts of force, but they can produce that force for long periods of time. Thus, type I fibers are hard to fatigue. This is because they are aerobic fibers that contain an abundance of myoglobin (an oxygen-carrying molecule similar to hemoglobin), mitochondria and capillaries which allow them to burn fat and glucose for energy. They are purely aerobic fibers and generally do not have the ability to work anaerobically. With respect to exercise, type I fibers do not show as much hypotrophy as other fiber types and are used during activities that are not overly difficult.