Validity of 2-Day Cardiopulmonary Exercise Testing in Female Patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract

Introduction: Among the main characteristics of patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/ CFS) are effort in tolerance along with a prolong ed reco very from exercis e and post-exertional exacerbation of ME/CFS symptoms. The gold standard for measuring the severity of physical activity intolerance is cardiopulmonary exercise testing (CPET). Multiple studies have shown that peak oxygen consumption is reduced in the majo rity of ME/CFS patients . A consecutive day CPET protocol has shown a difference on day 2 in ME/CFS patients in contrast to sedentary controls. Because the studied numbers of female ME/CFS patients in the published literature, are not very extensive, the aim of this study was to examine whether the response to a 2-day CPET protocol in a larger sample of female ME/CFS patients was similar to that studied in other research teams. Methods: From 102 female patients, 70 female ME/CFS patients fulfilled the criteria of a 2-day CPET protocol for analysis. Measures of oxygenconsumption (VO2), heart rate (HR), systolic and di astolic blood pressure, workload (Work), and respiratory exchange ratio (RER)w ere made at maximal (peak) and ventilatory threshold (VT) intensities. Data were analysed using a paired t-test. Results: Baseline characteristics of the group were as follows. Mean age was 44 (12) years, median BMI was 27.1(4.4)kg/m2. Median disease duration was 10 years (IQR 7-13). Heart rate, systolic and diastolic blood pressure at rest and the RERdid not differ significantly between CPET 1 and CPET 2. All other CPET parameters at the ventilatory threshold and maximum exercise differed significantly (p-value between <0.005 and <0.0001). All patients experienced a deterioration of performance on CPET2 as measured by the predicted and actual VO2 and workload at peak exercise and ventilatory th reshold. Conclusion: This study confirms that female ME/ CFS patients have a reduction in exercise capacity in response to a consecutive day CPET. These results are similar to published results in female ME/CFS populations.