The effects of a 15-week physical exercise intervention on pain modulation in fibromyalgia: Increased pain-related processing... 2023 Löfgren et al

Full title: The effects of a 15-week physical exercise intervention on pain modulation in fibromyalgia: Increased pain-related processing within the cortico-striatal- occipital networks, but no improvement of exercise-induced hypoalgesia

Highlights

• Fibromyalgia (FM) patients had reduced exercise induced hypoalgesia (EIH).
• A 15-week physical exercise intervention improved pain but not EIH in FM patients.
• Exercise increased pain-related activations in cortico-striatal brain networks.
• fMRI revealed no effect of exercise on descending pain modulatory networks.

Abstract

Dysfunctional top-down pain modulation is a hallmark of fibromyalgia (FM) and physical exercise is a cornerstone in FM treatment. The aim of this study was to explore the effects of a 15-week intervention of strengthening exercises, twice per week, supervised by a physiotherapist, on exercise-induced hypoalgesia (EIH) and cerebral pain processing in FM patients and healthy controls (HC).

FM patients (n = 59) and HC (n = 39) who completed the exercise intervention as part of a multicenter study were examined at baseline and following the intervention. Following the exercise intervention, FM patients reported a reduction of pain intensity, fibromyalgia severity and depression. Reduced EIH was seen in FM patients compared to HC at baseline and no improvement of EIH was seen following the 15-week resistance exercise intervention in either group.

Furthermore, a subsample (Stockholm site: FM n = 18; HC n = 19) was also examined with functional magnetic resonance imaging (fMRI) during subjectively calibrated thumbnail pressure pain stimulations at baseline and following intervention. A significant main effect of exercise (post > pre) was observed both in FM patients and HC, in pain-related brain activation within left dorsolateral prefrontal cortex and caudate, as well as increased functional connectivity between caudate and occipital lobe bordering cerebellum (driven by the FM patients).

In conclusion, the results indicate that 15-week resistance exercise affect pain-related processing within the cortico-striatal-occipital networks (involved in motor control and cognition), rather than directly influencing top-down descending pain inhibition. In alignment with this, exercise-induced hypoalgesia remained unaltered.

Open access, https://www.sciencedirect.com/science/article/pii/S2452073X23000016

 

Conclusion of abstract:

". In conclusion, the results indicate that 15-week resistance exercise affect pain-related processing within the cortico-striatal-occipital networks (involved in motor control cognition), rather than directly influencing top-down descending pain inhibition. In alignment with this, exercise-induced hypoalgesia remained unaltered."

Amateur copyediting of the verb 'affect.'

I am not sure that their thumbnail pressure testing for the fMRIs (P50) represents the chronic pain of FM in the brain. The pressure testing is an acute pain test, I would think, not the chronic aching that FM patients experience. I'll have to read the references section and explore that.

The complete Limitations Section with my boldings:

Limitations

The current study lacks a non-exercising control group, which hinders us from controlling for time-related effects on pressure pain response. However, our previous studies using the very same method indicate that P50 normally remains stable over time (Jensen et al., 2012a, Jensen et al., 2014). The current fMRI results were corrected for multiple comparisons (PFWE = 0.05 on an initial cluster-forming threshold of p < 0.001 uncorrected), yet the relatively small sample size of the fMRI cohort (FM n = 18; HC n = 19) implies that the brain imaging results should be interpreted with caution and need to be reproduced in a larger cohort. Finally, all participants in the current study volunteered to participate in a randomized exercise/relaxation study. Hence, the patient recruitment may be biased towards less severely affected FM patients and may not be generalizable to more severely affected patients with FM.