Muscle characteristics of persons with fibromyalgia syndrome

To explore agonist and antagonist muscle characteristics, depression and physical functioning of patients with Fibromyalgia Syndrome (FMS).

Individuals with FMS (N=34) and chronic pain (N=36) were recruited from a chronic pain program. Normal controls (N=37) were recruited from the general community.

Demographic data (age, gender, marital status, ethnicity, and employment status), self-report physical and psychological functioning, current level of pain, level of depression, and agonist and antagonist muscle activity (SCM, Biceps/triceps, Forearm flexor/extensor, Lower leg tibialis anterior/gastrocnemius) were measured with sEMG.

There was a significant difference in upper arm muscle contra-activation between the FMS patients and normal controls but not between the non-FMS chronic pain patients and normal controls. When compared to normal controls, the FMS 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-FMS chronic pain group. Problems with physical functioning and depression did not predict strength of contra-activation in the upper arm muscle.

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.