Decreased oxygen extraction during cardiopulmonary exercise test in patients with chronic fatigue syndrome

Abstract

BackgroundThe insufficient metabolic adaptation to exercise in Chronic Fatigue Syndrome (CFS) is still being debated and poorly understood.MethodsWe analysed the cardiopulmonary exercise tests of CFS patients, idiopathic chronic fatigue (CFI) patients and healthy visitors. Continuous non-invasive measurement of the cardiac output by Nexfin® (BMEYE B.V. Amsterdam, the Netherlands) was added to the cardiopulmonary exercise tests. The peak oxygen extraction by muscle cells and the increase of cardiac output relative to the increase of oxygen uptake (ΔQ’/ΔV’O2) were measured, calculated from the cardiac output and the oxygen uptake during incremental exercise.ResultsThe peak oxygen extraction by muscle cells was 10.83 ± 2.80 ml/100ml in 178 CFS women, 11.62 ± 2.90 ml/100 ml in 172 CFI, and 13.45 ± 2.72 ml/100 ml in 11 healthy women (ANOVA: P=0.001), 13.66 ± 3.31 ml/100 ml in 25 CFS men, 14.63 ± 4.38 ml/100 ml in 51 CFI, and 19.52 ± 6.53 ml/100 ml in 7 healthy men (ANOVA: P=0.008).The ΔQ’/ΔV’O2 was > 6 L/L (normal ΔQ’/ΔV’O2 ≈ 5 L/L) in 70% of the patients and in 22% of the healthy group.ConclusionLow oxygen uptake by muscle cells causes exercise intolerance in a majority of CFS patients, indicating insufficient metabolic adaptation to incremental exercise. The high increase of the cardiac output relative to the increase of oxygen uptake argues against deconditioning as a cause for physical impairment in these patients.

Metabolic profiling indicates impaired pyruvate dehydrogenase function in myalgic encephalopathy/chronic fatigue syndrome

“…Our data, suggesting that ME/CFS is associated with impaired efficiency of energy metabolism combined with lactate overproduction, may explain why many ME/CFS patients reach anaerobic threshold at a low workload (9)(10)(11). This is supported by an individual patient report (35) and our own observations of patients with severe ME/CFS that had lactate levels elevated to more than 8 mM from just standing upright for 10 minutes.…”

Physical activity measures in patients with myalgic encephalomyelitis/chronic fatigue syndrome: correlations between peak oxygen consumption, the physical functioning scale of the SF-36 questionnaire, and the number of steps from an activity meter

“…In comparison to values reported in other ME/CFS populations, our study participants had similar steps per day [21], and %peak VO 2 values [22,27,30]. The reported median or mean physical functioning scale of the SF-36 questionnaire vary widely between studies ranging between 17 and 59% [13][14][15][16][17][18].…”

“…Cardiopulmonary exercise testing (CPET): patients underwent a symptom-limited exercise test on a cycle ergometer (Excalibur, Lode, Groningen, The Netherlands) according to a previously described protocol [22]. A RAMP workload protocol was used varying between 10-30 Watt/min increases, depending on sex, age and expected exercise intolerance.…”

“…Objective measures of functional status and wellbeing have the potential to augment and improve the validity of questionnaire measures. Exercise intolerance can be quantified by using an activity meter [21] and by measuring peak oxygen consumption on a cardiopulmonary stress test (CPET) [22][23][24][25][26][27][28][29][30][31][32][33].…”

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

“…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 majority of ME/CFS patients (De Becker et al, 2000;Fulcher & White, 2000;Hodges et al, 2018;Jammes et al, 2005;Keller et al, 2014;Sargent et al, 2002;Sisto et al, 1996;Snell et al, 2013;Vanness et al, 2007;Vermeulen et al, 2010;Vermeulen & Vermeulen van Eck, 2014;Wallman et al, 2004). However, studies have also shown that a single CPET may show in ME/CFS patients that peak VO 2 values can be similar to or only slightly lower than those of healthy sedentary controls.…”