What is muscle damage?

muscle damage

What is muscle damage?

Muscle Damage

We’ve all felt the results of the first day at the gym: soreness, stiffness, inflammation, and pain. The cause of this discomfort is known as exercise induced muscle damage (EIMD), and although it’s uncomfortable, is a necessary part of growth.

Why is muscle damaged during exercise?

Intense exercise or a new workout routine typically results in placing excessive strain on muscle tissue, resulting in EIMD. This damage causes decreased power, range of motion, and endurance, inflammation, and delayed onset muscle soreness (DOMS) in the exercised muscles1.


EIMD results in soreness and discomfort in the 12-72 hours following exercise. Experts agree that eccentric contractions (movement when the muscle fiber lengthens) are mainly responsible for damage. After numerous contractions, the muscle fiber undergoes physical damage to many of its components2.

This damage affects the way the muscle works and even results in further damage due to various chemicals released into neighboring tissue. Muscle damage also leads to an inflammatory response which is associated with further reduction in muscle function, (DOMS), and release of muscle proteins into the blood2.

What happens after a muscle is damaged?

After an intense exercise session, the immune system begins to remove debris and protein fragments left over from the damage. The inflammatory response begins, allowing recovery to take place. Performance decreases during inflammation. The degree of performance loss depends largely on the magnitude of force, degree of muscle fiber lengthening, speed of movement, and volume of a workout. In other words, performance decreases are much greater when exercise intensity and duration are very high2.

The recovery process takes as little as 12-48 hours but can last as long as 1-3 weeks depending on the nature of muscle damage2.

Exercise Recovery Strategies

Recovery strategies are broken down into a few categories. These strategies reduce swelling, improve blood flow, decrease pain, and improve healing. Athletes should be more focused on the healing aspects of recovery rather than only reducing soreness2.

Pharmacological. This approach involves taking medication such as anti-inflammatory drugs to reduce soreness. Some studies have raised concerns over using anti-inflammatories when dealing with EIMD and soreness. Research suggests these products disrupt the body’s natural inflammatory response and inhibit performance gains. These medications may make you feel better now at the cost of fully realizing the benefits of intense exercise2.

Nutritional/Supplementation. This approach involves supplementing with various products to either preemptively reduce muscle damage, or aid in the recovery process. Creatine and protein supplements, as well as an adequate calorie intake are generally helpful. There is research to suggest vitamin C inhibits recovery and actually increases muscle damage2.

Exercise-Related. This approach involves stretching and low intensity exercise. There is some evidence (although mixed) that stretching and low intensity exercise enhances recovery3,4.

How is muscle damage measured?

There are a few ways researchers measure muscle damage, mainly through measuring enzymes found in the blood following intense exercise. Creatine kinase (CK) is found in muscle tissue. Increased levels in the blood rise after a heart attack, injury to the muscle, increased alcohol consumption, or EIMD5.

Lactic dehydrogenase (LDH) is an enzyme found in red blood cells, kidneys, the brain, lungs, and muscle tissue. Higher LDH levels indicate damaged or diseased tissue6. Researchers also measure subjective scores of muscle soreness, range of motion tests, or post-exercise performance as more indirect measures of how much EIMD a subject sustained.

What supplements help decrease muscle damage and soreness?

There are a number of supplements claiming to reduce muscle damage. Creatine monohydrate and branched chain amino acids (BCAAs) seem to have the most positive research backing this claim. Some argue adequate protein intake has a superior effect to only taking BCAAs. Research also shows vitamin C, which many use to decrease muscle damage, actually hinders the recovery process; avoid taking large amounts (more than what is contained in a multivitamin).

The Bottom Line

Muscle damage and soreness are normal parts of the recovery process. Exercise causes varying amounts of damage which the body repairs during rest. This repair and recovery process is what makes us stronger, faster, and bigger. There are numerous ways to improve the efficiency of the recovery process. How long it takes depends on many factors including individual genetics, exercise duration and intensity, and whether we use strategies to speed it along.


  1. Caldwell, J. T., Wardlow, G. C., Branch, P. A., Ramos, M., Black, C. D., & Ade, C. J. (2016). Effect of exercise-induced muscle damage on vascular function and skeletal muscle microvascular deoxygenationPhysiological Reports, 4(22). doi:10.14814/phy2.13032
  2. Fatouros, I., & Jamurtas, A. (2016). Insights into the molecular etiology of exercise-induced inflammation: Opportunities for optimizing performanceJournal of Inflammation Research,Volume 9, 175-186. doi:10.2147/jir.s114635
  3. Almasi, J., Jalalvand, A., & Farokhroo, N. (2014). The effect of PNF stretching and therapeutic massage combination treatment on markers of exercise induced muscle damageInternational Journal of Biosciences (IJB), 217-228. doi:10.12692/ijb/4.4.217-228
  4. Torres, R., Pinho, F., Duarte, J. A., & Cabri, J. M. (2013). Effect of single bout versus repeated bouts of stretching on muscle recovery following eccentric exercise. Journal of Science and Medicine in Sport, 16(6), 583-588. doi:10.1016/j.jsams.2013.01.002
  5. Greco, F., & Walton-Ziegler, O. (n.d.). Creatine Kinase. Retrieved from https://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=167&ContentID=creatine_kinase_blood
  6. Fraser, M., & Haldeman-Englert, C. (n.d.). Lactic Acid Dehydrogenase. Retrieved from https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=167&contentid=lactic_acid_dehydrogenase_blood

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