Muscle pain also can be a sign of conditions affecting the whole body. For example, some infections such as the flu and disorders that affect connective tissues can lead to muscle pain. Other causes include tension, stress, injury, using a muscle too much or fibromyalgia, which can then lead to sleep difficulties, fatigue or headaches.

Characteristically, there is increased ‘muscle tone’ and mild to severe pain. There are also tender areas of hypersensitivity to mechanical stimulation.

However, the mechanisms by which acute muscle pain becomes pathological are yet to be understood. One idea relies on changes in muscle spindles, which are highly sensitive stretch receptors located in skeletal muscles throughout the body. Changes in muscle spindles can influence their capacity to encode changes in muscle length and provide sensory feedback.

Systemic muscle pain is different to common muscle pain in that it is felt throughout the body and is often the result of an infection, an illness or a side effect of a medication.

Our research approaches

We have also explored the efficacy of muscle relaxants, including non-benzodiazepine antispasmodics. As part of their investigation, our researchers reviewed the evidence from 31 randomised controlled trials involving over 6,500 participants.

Our research discoveries

We also found that the effects of long-term muscle relaxant use remain unknown. Despite scientific uncertainty, muscle relaxants are the third most frequently prescribed drugs for low back pain. As a result, our research suggests clinicians should discuss the uncertainty in the efficacy and safety of muscle relaxants with patients, including the possible reduction in pain, but also increased risk of experiencing a non-serious adverse event, to allow them to make informed treatment decisions.