Elvira Lange1, Kaisa Mannerkorpi1, Asa Cider1, Trevor Archer2 and Kerstin Wentz3*
Objective: To compare the heart rate variability (HRV) before and after a sub-maximal exercise test in women with fibromyalgia (FM) and to compare the result to matched controls. Additionally, to compare heart rate (HR) before, during and after the sub-maximal exercise test. Methods: Twenty-four women with FM and 26 controls performed a sub-maximal exercise test. HRV was registered for 5 minutes at rest before and after the exercise test. HR was registered at baseline, during the exercise test and at recovery. Results: The HRV of the healthy group was statistically different from the exercise test but the women with FM showed no such difference. HR was significantly higher among the women with FM than in the healthy group at baseline and up to 75W but lower at peak (138/152 bpm, p<0.008). In women with FM HR during exercise (HR2) was predicted by heart rate recovery (HRR20) and physical exertion (RPE2). HRR20 and RPE2 accounted for 0.465 of the variance (p=0.006) in HR2. In healthy women HR2 correlated with HRR20 and negatively with physical activity (PhA). In the reference group HRR20 and PhA accounted for 0.448 (p=0.002) of the variance HR. Conclusion:The HRV in women with FM show less adjustment of the ANS while not being significantly affected by submaximal exercise as healthy women. In healthy women heart rate during the test was negatively related to PhA. In women with FM exertion seems to replace an effect from exercise on physiological adaptation. FM may entail imperceptible extraction of power from PhA while under load. Links to FM pain will be discussed. Women with FM seem to rate exertion “Very hard” on lower workload and HR than healthy women. The physiotherapeutic methodology for measuring HRV with basic HR monitors should be improved before it can be recommended for clinical use.