Muscle characteristics of persons with Fibromyalgia Syndrome

A study has shown that Fibromyalgia Syndrome patients and patients with other chronic pain conditions have unusual muscle activity when compared to healthy controls.¹

The study aimed to explore the muscle characteristics, depression and physical functioning of patients with Fibromyalgia Syndrome (Fibro).

Thirty-four individuals with Fibro and 36 individuals with chronic pain were recruited for the study from a chronic pain management program. Thirty-seven healthy controls were recruited from the general community.

Demographic data (age, gender, marital status, ethnicity, and employment status) was collected for each study participant. The participants were asked to self-report on their physical and psychological functioning, current level of pain and level of depression. Agonist (positive action) and antagonist (negative action) muscle activity was measured with sEMG (surface Electromyogram, a test of muscle activity) for the Sternocleidomastoid muscle(SCM), the Biceps/triceps, the Forearm flexor/extensor muscles and the Lower leg tibialis anterior/Gastrocnemius muscles.

It was found that there was a significant difference in upper arm muscle contra-activation between the Fibro patients and the healthy controls but not between the non-Fibro chronic pain patients and the healthy controls.¹

When compared to the healthy controls, the Fibro group reported more depression and a higher level of physical functioning problems, but it was not significantly different from the mean score for the non-Fibro chronic pain group.v

The researchers also found that problems with physical functioning and depression did not predict strength of contra-activation in the upper arm muscle.¹

The researchers concluded that:

"These findings suggest presence of unusual muscle activity occurring in the bicep muscle of FMS and non-FMS chronic pain patients, which establishes a possible link between muscle dysfunction, mood and pain."¹

It is not mentioned whether the study participants were assessed for myofascial trigger points in the muscles measured. Myofascial trigger points, as well as causing pain and other symptoms, can affect muscle function. They are also likely to be more common in people with a chronic pain condition.²

References:

1. Jegede AB, Gilbert C, Tulkin SR. Muscle characteristics of persons with fibromyalgia syndrome. NeuroRehabilitation. 2008;23(3):217-30.
2. Wolfe F, et al. The fibromyalgia and myofascial pain syndromes: a preliminary study of tender points and trigger points in persons with fibromyalgia, myofascial pain syndrome and no disease. J Rheumatol. 1992 Jun;19(6):944-51.