In patients with rheumatoid arthritis (RA), a long-term health-enhancing physical activity (HEPA) support program reduces global pain but not pressure pain sensitivity or hypoalgesia, according to results published in Arthritis Research & Therapy.

The study included participants with RA, recruited from a larger intervention cohort in which participants did strength training and moderate-intensity aerobic activity (n=30). The researchers performed assessments before the HEPA intervention and at 1 and 2 years of follow-up. They assessed global pain using a visual analog scale (0-100) and pressure pain thresholds and suprathreshold pressure pain at rest corresponding to 4/10 (medium pain; SP4) and 7/10 (strong pain; SP7), respectively, on the Borg category ratio 10 scale, using algometry.

The researchers also used a subsample of participants (n=21) to assess segmental and plurisegmental hypoalgesia during standard submaximal static contraction (30% of the individual maximum) alternately at the contracting right M. quadriceps and the resting left M. deltoideus.

After 2 years of follow-up, the researchers found that global pain decreased from a median of 11 to a median of 6 (P =.040). However, pressure pain thresholds and SP4 pressure pain at rest did not change from baseline at 2 years of follow-up. SP7 decreased from a mean of 647 kPa to a mean of 560 kPa (P =.006) from baseline to 2 years.

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In the subsample, the researchers found that segmental hypoalgesia during static muscle contraction increased from the assessment before the intervention from a mean of 1.02 to a mean of 1.42 (P =.001). Plurisegmental hypoalgesia also increased from a mean of 0.87 to a mean of 1.41 (P <.001).

The results did not indicate any significant changes in segmental or plurisegmental hypoalgesia from before intervention to 2-year follow-up.

“Our findings that two years of HEPA did not influence pain sensitivity (that is, [pressure pain thresholds] or moderate suprathreshold pressure pain at rest) indicate that long-term HEPA does not reduce pain sensitivity in RA,” the researchers wrote.

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Reference

Lofgren M, Opava CH, Demmelmaier I, et al. Long-term, health-enhancing physical activity is associated with reduction of pain but not pain sensitivity or improved exercise-induced hypoalgesia in persons with rheumatoid arthritis [published online November 26, 2018]. Arthritis Res Ther. doi: 10.1186/s13075-018-1758-x