To explore agonist and antagonist muscle characteristics, depression and physical functioning of patients with Fibromyalgia Syndrome (FMS).[Agonist muscle causes movement in a joint by contracting (e.g., biceps). Antagonist muscle is responsible for returning the joint to its initial position (e.g., triceps).
Method: 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.
Measures: 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. [Surface electromyography is computer-analyzed measurement of muscle/muscle group electrical activity. Used to evaluate the functional status of muscles for neuromuscular training and rehab.]
Results: 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.
Conclusion: 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.
Source: NeuroRehabilitation. Issue 3, 2008; 23(3):217-30. PMID: 18560138, by Jegede AB, Gilbert C, Tulkin SR. Alliant International University, San Francisco; Kaiser Permanente Chronic Pain Clinic, San Francisco, USA.