AUSTIN — Decreased pain inhibition is associated with a greater percentage of proinflammatory monocytes, and a higher percentage of that phenotype is associated with less vigorous activity, suggesting a potential mechanism to intervene with the patient with chronic pain associated with fibromyalgia, according to a presentation at the 35th Annual Scientific Meeting of the American Pain Society.

Ericka N.  Merriwether, PhD, PT, a postdoctoral research fellow with University of Iowa, explained during the society’s “Clinical and Basic Science Data Blitz” that previous data from her group suggested that in women with fibromyalgia, a link has been shown between physical activity and reduced release of proinflammatory cytokines by monocytes .

Dr Merriwether’s group assessed physical activity using an Actigraph accelerometer, and pain measures through the Numeric Rating Scale, the Brief Pain Inventory, pressure pain thresholds, and the conditional pain modulation test in 33 women. The women are enrolled in a larger, ongoing randomized control intervention that is looking at nonpharmacological treatments of movement-evoked pain. As part of that larger study, blood samples were taken, which enabled the researchers to study their monocyte phenotypes.   

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According to the data, there were no significant differences in pain measures between physically active and physically inactive women, however, classical monocytes seemed to be associated with descending pain inhibition, and less vigorous physical activity. This interaction in turn, may effect how the patient processes pain, Dr Merriwether explained. 

Since fibromyalgia is characterized by elevated levels of circulating proinflammatory cytokines, looking at measures to reduce these variables is key to treating patients with this condition, Dr Merriwether explained. 

She said in an interview with Clinical Pain Advisor that here are strong data to support physical activity for chronic pain relief, and noted that her team’s data seem to support the hypothesis that “if you are more vigorously active, you are less likely to have this proinflammatory monocyte phentoype, subsequently if you got a lower percentage of that monocyte phenotype spitting out this nociceptive irritant, you are less inclined to be more physically active.” 

Dr Merriwether said the next phase of their research will focus on the cytokine release profile.


Merriwether E, Rakel BA, Dailey DL, et al . Monocyte phenotype, physical activity, and pain outcomes in women with fibromyalgia. Presented at: APS 2016. May 11-14, 2016; Austin, Tx.