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  • Writer's pictureCrucial Rehab Team

Is it muscle soreness or a muscle strain?

Experiencing muscle soreness or more specifically delayed-onset muscle soreness (DOMS) is common especially among those who tend to work out after a long ‘break’. A seemingly light and easy weighted workout is capable of causing DOMS if the previous training was months ago. If one pushes too hard during the session, it may even cause a strain, where muscle fibres tear. Both situations would present themselves as being painful with the latter being an actual injury. Hence, how are we to differentiate between a common DOMS occurrence or a more serious muscle strain?

What happens in DOMS?

Four popular theories on the causes of DOMS were previously mentioned: lactic acid accumulation, spasms, torn tissue and connective tissue damage. However, according to current research, there is still a lack of conclusive evidence on the exact mechanism of DOMS. Despite the fact that most people would blame muscle soreness on lactic acid accumulation, these two are in fact not causal of one another. Rather, an inflammatory mediator known as bradykinin was found to have significant effects on the occurrence of DOMS which may explain symptoms like pain, swelling and warmth that are similar to those of inflammation. Though not as obvious as those of an acute injury, most people complain of ‘heat in the body’ or ‘feeling of swollen muscles’ when muscles are sore.

What happens in a muscle strain?

Muscle strains are muscle fibre tears that ranges from mild to severe. They are mainly classified into 3 grades (Grade I, II, III) based on the extent of muscle damage. With the presence of an injury, inflammatory symptoms such as pain, swelling, warmth and redness will most likely occur. Some other common symptoms of a strain include:

- A pop heard or felt in the muscle during the injury

- Muscle discoloration (eg. bruising)

- A decrease of complete loss of muscle strength (Grade III strains)

- A gap or dent felt as a result of the separation of muscle fibres in the presence of a major tear

The Differences

With similar symptoms presented in both muscle soreness and muscle strains, telling them apart can often be confusing and misleading. Thinking of your pain as a strain and resting the muscle may still be safe but stretching it out thinking it is just soreness when it is an actual strain may lead to further tearing of the muscle.

Here are some important points that differentiate the two conditions:

If pain persists for more than 5-7 days, do consult a professional to seek confirmation on the type of injury you have experienced and advice on the next step of treatment.


1. Cheung, K., Hume, P. A., & Maxwell, L. (February 01, 2003). Delayed Onset Muscle Soreness: Treatment Strategies and Performance Factors. Sports Medicine, 33, 2, 145-164.

2. Schwane, J. A., Watrous, B. G., Johnson, S. R., & Armstrong, R. B. (January 01, 1983). Is Lactic Acid Related to Delayed-Onset Muscle Soreness?. The Physician and Sportsmedicine, 11, 3, 124-31.

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