Muscle pain: from myalgia to delayed-onset muscle soreness


When we talk about muscle pain, we may be referring to a variety of conditions, from chronic myalgia to delayed-onset muscle soreness (DOMS).

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What does myalgia mean? Myalgia is a medical term used to refer to what is more commonly known as “muscle pain”. The word originates from the Greek: mys muscle and algìa pain, and hence muscle pain.

Myalgia is a symptom of many illnesses or particular conditions, and can be classified as:

  • Acute myalgia
  • Chronic myalgia
  • Local myalgia
  • Diffuse myalgia

The most common cause of acute myalgia is an overload on a muscle or group of muscles; another probable cause is viral infection, above all if the pain occurs without trauma. Long term myalgia, on the other hand, may be caused by metabolic myopathy, rheumatic diseases but also by nutrient deficiencies and by chronic fatigue syndrome, where the patient suffers from diffuse muscle pain. We will look at this in more detail in the next few paragraphs.

Causes of Myalgia

Myalgia can be a side effect of some medicinal products. Among these, worth noting are statins (cholesterol medicine), known to cause muscle pain; there are also glucocorticoids, immunological medication and anti-microbial drugs that cause myalgia, in other words illnesses that impact the muscle tissue. Sudden interruptions to taking high doses of these medicines, or opioids, benzodiazepine, caffeine or alcohol can also be the cause of myalgia.

However, the most common causes of myalgia are muscle overload, due, for example, to excessive physical activity leading to DOMS, injury and tension. These factors often cause acute myalgia. Meanwhile, chronic myalgia can be caused by a series of diseases or in response to specific trigger factors such as trauma or vaccinations.

Acute myalgia is the main symptom of many acute conditions, such as:

        Trauma or overload: this type of muscle pain is localised and affects just a few muscles or a small area of the body.

        Influenza: when tackling flu, it is quite common to have muscle pain while the body fights off this virus during the flu season.

        Lyme Disease: at the start, this disease (caught from ticks) causes flu-like symptoms, including muscle pain.

        Vitamin and mineral deficiencies: various vitamin and mineral deficiencies cause muscle pain, including low levels of vitamin D and potassium.


Chronic myalgia is often the main symptom of musculo-skeletal conditions and autoimmune diseases, including:

        Fibromyalgia: this condition causes diffuse muscle pain that may be throbbing and/or stabbing.

        Rheumatoid arthritis: the same processes that cause inflammation of the joints can also cause muscle pain.

        Multiple Sclerosis (MS): muscle pain and stiffness and involuntary muscle spasms are common symptoms of MS.

        Depression: depression can also manifest physical symptoms, such as muscle pain.


It is important to note that myalgia is a symptom, not a diagnosis. The diagnosis of an underlying condition usually involves an investigation into the potential causes of muscle pain associated with other illnesses, especially those in which muscle pain and/or inflammation are the main problems.

Seeking medical attention from your doctor is useful to identify an underlying condition that may trigger muscle pain. Reaching a diagnosis can involve a number of steps:

–        The clinical history of the patient is the first step when a person complains of muscle pain. This process envisages a complete chronology of injuries, illnesses and medication previously and currently taken.

        A physical examination enables the doctor to locate the pain, the presence of any stiffness or muscle weakness and an observation of posture.

        Blood tests are useful to detect damage to muscles, tendons or ligaments, or inflammation, and are used to exclude other underlying conditions.

        Imaging, including X-rays and MRI, can be used to diagnose and exclude various causes of myalgia.


Physiotherapy is the most common treatment for acute and chronic myalgia. It can increase flexibility in contracted, painful muscles and strengthen the surrounding tissues. Physical therapy such as TECAR can also be useful.

The therapist can also help you find ways to manage stress and focus on ergonomics at work and at home.

As well as physiotherapy, there are some medicines that can help with pain management. Myalgia caused by an overload of physical activity or excessive effort usually responds well to painkillers.

There is a large variety of cases attributable to Fibromyalgia and therefore to rheumatic diseases and their treatment. This disease needs a multidisciplinary approach and special medication that needs to be prescribed by a specialist doctor.

Delayed-onset muscle soreness (DOMS)

DOMS, Delayed Onset Muscle Soreness or post-training muscle soreness, is a feeling of soreness, discomfort and aching in the muscles after intense exercise that we are not used to. It is thought that DOMS is due to temporary muscle damage or inflammation, in which the most common trigger seems to be an eccentric muscle contraction in exercises (when the muscle contracts while it is lengthening).

Why does DOMS happen?

As mentioned above, DOMS is often connected to a type of eccentric exercise, such as running downhill, plyometric exercises (dynamic exercises for explosive force), and traditional overload exercises (such as weight lifting). These exercises lead to microdamage of the membrane of muscle cells, with a consequent inflammatory response. This inflammation acts directly on the nerve endings causing a sensation of pain. Free radicals are also generated, which can cause further damage to the cell membrane.

It is therefore important to differentiate DOMS from other injuries, such as muscle strains. In fact with DOMS, you can still carry on with physical exercise without the risk of muscular damage, while in the case of muscle strain this wouldn’t be recommended as it could seriously worsen the injury.

When does DOMS happen?

The muscle soreness is felt a few hours after exercise, and more precisely 8-10 hours after physical exercise, reaching a peak between 24 and 48/72 hours. It usually only goes away after 5-7 days, even though there are some tricks that help reduce this time frame.

DOMS and Lactic Acid: a common mistake

It often happens that the day after intense training, a sports enthusiast will say “my legs really ache – they must be full of lactic acid”. This is a mistake: the level of lactic acid actually increases significantly during intense physical exercise and causes those feelings of burning and/or aching during or immediately after physical exercise.  Then the body dispels it completely within 60 minutes. On the other hand, as we have seen, DOMS peaks after 24-48 hours, when the blood levels of lactic acid are perfectly normal.

Can I train while I have muscle pain?

It would be normal to think that since DOMS is caused by micro-damage to the muscles, it would be better to avoid intense training until all symptoms go away. However, recent studies reject this theory. While it is confirmed that in the first 48 hours the muscles affected by DOMS suffer a loss of strength, research also shows that intense workouts at least two days after the previous session, despite the presence of DOMS, does not worsen performance.


Therefore it is recommended to wait 48 hours after the intense training that caused the muscle pain before doing another session of the same intensity, even if DOMS is still around.

Remedies: how to alleviate sore muscles after training

As previously explained, DOMS after workouts tend to go away only after a maximum of 5-7 days since the training that caused it. However, there are some tricks we can use to speed up the recovery process:

–        Do some low intensity aerobic work the day after the training that caused the muscle pain (for example, cycling, light running, swimming)

        Soak for a few minutes in a cold bath (even better in a bath of ice cubes) or have a crio-sauna after the workout. In the case of localised pain in the legs, you can just immerse these in cold water/ice.

–        The day after training, carry out a long stretching session with diaphragm breathing.

–        In the few days after training, have a recovery massage with a sports physiotherapist.

–        Immediately after, or on the day after training, arrange for a recovery massage with TECAR with a suitably trained sports physiotherapist. The powerful stimulus of this instrument on the circulation system really helps in recovery.

–        Never completely rest until the pain subsides; get back to training, even intense, after 2-3 days.

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