A new research paper, published in Frontiers of Physiology, seems to suggest that CPET tests may not be a reliable measure of Post-Exertional Malaise. The paper, titled ‘Cardiopulmonary Exercise Test Results Do Not Change Over Two Sequential Days in Patients with Chronic Fatigue Syndrome,' was carried out Prof Benjamin Natelson and colleagues with a grant from the NIH in America. Dr Charles Shepherd, MEA Hon. Medical Advisor, provides comment below.
Summary
- In a study where 58 people with ME/CFS and 25 matched sedentary controls completed two maximal cycling exercise tests (CPETs) on consecutive days, there was no drop in measured physical performance (e.g., oxygen use or endurance) from Day 1 to Day 2 or between groups.
- However, people with ME/CFS felt significantly more exertion during exercise and had a lower peak heart rate than controls, despite similar measured performance.
- Overall, the results suggest that 2-day CPET testing may not be a reliable way to identify post-exertional malaise (PEM) or disability in ME/CFS patients.
Extracts
Abstract
Background: Two consecutive cardiopulmonary exercise tests (CPETs) performed 24 hours apart is increasingly used to determine post-exertional malaise (PEM) and disability in patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Declines in functional capacity on Day 2 reflect impaired recovery and PEM. However, reports have variably described a reduction in peak oxygen consumption (VO2) and/or VO2 at the anaerobic ventilatory threshold (VT). Given the inconsistent findings, we sought to replicate the studies performing sequential 2-day CPETs in ME/CFS and age and sex matched sedentary controls
Methods: Accordingly, we performed maximal bicycle ergometer CPETs on 2 consecutive days in 58 patients with ME/CFS (mean age 38.6 ± 9.6 yrs, BMI 24.1 ±3 .3 kg/m2, 11 men and 47 women ) and 25 age-matched sedentary control (CON) subjects (age 38.2 ± 9.9 yrs, BMI 24.2 ± 3.4 kg/m2, 5 men, 20 women). Peak VO2 was reported as the highest 30-sec average, VT was selected as the nadir of the VE/VO2 and PETCO2 curves, and VE/VCO2 as the slope throughout exercise.
Findings: For ME/CFS and CON subjects there were no significant changes in Peak VO2 between Day 1 and 2 studies (ME/CFS Day 1: 22.3 ± 5.4; Day 2: 22.5 ± 5.4 ml/kg/min; CON: Day 1: 23.4 ± 3.5; Day 2: 22.8 ± 3.6 ml/kg/min; NS). Similarly, VO2VT and VE/VCO2 slopes were not significantly different between the ME/CFS patients and CON and on day 2 did not show any differences within or between groups. Peak heart rate was significantly higher in CON versus ME/CFS. The level of perceived exertion was significantly greater at all levels of exercise on the Day 1 and 2 tests for ME/CFS patients versus CON.
Interpretation: Our data indicate that 2-day CPET provides exercise-related results that are the same in ME/CFS patients and in CON subjects. ME/CFS patients have greater perception of exertion throughout exercise and a lower maximum heart rate than CON. The data do not support using the 2 day CPET protocol to define PEM or disability.
MEA Comment
Question and Answer on cardiopulmonary exercise testing from the MEA Medical Matters Library:
Please note that at the time this answer was prepared all the research evidence indicated that abnormal CPET results in people with ME/CFS provided objective evidence of post exertional malaise (PEM).
This new research, which appears to have been well conducted, has now cast doubt on these previous findings and conclusions.
Which is why it's so important to try and make sure that abnormal findings are replicated by other independent research groups.
Dr Charles Shepherd,
Trustee and Hon. Medical Adviser to the ME Association,
Member of the 2018-2021 NICE guideline on ME/CFS committee,
Member of the 2002 Chief Medical Officer's Working Group on ME/CFS
