Association of cardiorespiratory fitness with pressure pain sensitivity and clinical pain in women with fibromyalgia.

The aim of the present study was to assess the association of cardiorespiratory fitness (CRF) with pressure pain sensitivity and clinical pain in women with fibromyalgia (FM). Thirty-one women with FM were included in the study. Pressure pain sensitivity was assessed with an electronic pressure dolorimeter. The average pressure pain threshold (PPT) from the 18 FM-related tender points and the tender points count (TPC) were recorded. Clinical pain was assessed on a 10-cm visual analog scale (VAS; from the FM impact questionnaire). The patients performed an incremental treadmill test, which consisted in six increasing workloads. Gas exchange was continuously monitored, and peak oxygen uptake (as measure of CRF) was recorded. Pairwise correlation and multiple linear regression were used to examine the association of CRF with PPT and VAS, and binary logistic regression assessed the odds of having <18 positive tender points as a function of CRF. The correlations of CRF with the average PPT and VAS were 0.355, (P < 0.001) and 0.058 (P > 0.05), respectively. Regression analyses revealed that CRF was associated with the PPT (B = 0.093; 95 % CI 0.064-0.122; P < 0.001; R (2) = 0.306) and TPC (OR 1.51; 95 % CI 1.30-1.75; P < 0.001) but not with VAS (B = 0.068; 95 % CI -0.061-0.197; P > 0.05). The findings of this study suggest that CRF is associated with pressure pain sensitivity but not with clinical pain in women with FM. Further longitudinal and intervention studies are needed to determine whether CRF could be involved in some mechanisms of pain processing.