Myofascial pain and fibromyalgia: Cardiorespiratory and perceptual responses to steady-state exercise in patients with chronic fatigue syndrome and co-morbid fibromyalgia

Abstract

We have previously reported that Chronic Fatigue Syndrome (CFS) patients diagnosed with fibromyalgia (CFS+FM) were less fit, less efficient and reported more pain and effort compared to CFS only and controls (CON) during maximal exercise. These results underscored the importance of co-morbid illness in CFS and suggested that inconsistencies in previous studies could have been due to a failure to account for FM. However, limitations inherent in incremental maximal exercise such as differences in volitional effort, disproportionate exercise times and demand characteristics could have accounted for our previous observations. The purpose of the present investigation was to determine the cardiorespiratory and perceptual responses to steady-state exercise in CFS, CFS+FM and CON. Nine CFS patients, 12 CFS+FM and 14 CON completed maximal and submaximal exercise tests separated by two weeks. Maximal exercise testing determined individual submaximal workloads. Steady-state exercise was performed at ∼40% of peak oxygen consumption for 25 minutes. Cardiorespiratory variables were measured continuously. Perceptions of leg muscle pain and exertion were measured during the last 15 sec of each minute. There were no group differences in average oxygen consumption during exercise (CFS=45%; CFS+FM=47%; CON=43%: p=0.2). There were no significant differences (p>0.05) among groups for absolute measures of oxygen consumption, carbon dioxide production, breathing frequency, ventilation, respiratory exchange ratio or heart rate during either exercise or recovery. Significant main effects were found for ventilatory equivalents of oxygen and carbon dioxide [VeO2:exercise:F2,32=5.2,p=0.01; recovery:F2,32=5.1,p=0.01; VeCO2:exercise:F2,32=4.9,p=0.01; recovery:F2,32=5.8,p=0.007]. Post-hoc analyses indicated that only the CFS+FM group was significantly different than CON (p<0.05). There were also significant main effects for pain (F2,32=3.9,p=0.03) and exertion (F2,32=6.6,p=0.004). Only the CFS+FM group rated greater pain and effort (p<0.05) compared to CON. We conclude that only CFS patients with co-morbid FM exhibit altered cardiorespiratory and perceptual responses to steady-state exercise compared to healthy, sedentary controls. Support: NIH AI-32247.