Repeated maximal exercise tests of peak oxygen consumption in people with myalgic encephalomyelitis/ chronic fatigue syndrome: a systematic review and meta-analysis, John Derek Franklin, Michael Graham in Fatigue: Biomedicine, Health & Behavior 16 Aug 2022

Key points:

• The techniques of synthesis and meta analysis were used to extract more information from existing exercise studies in ME/CFS.
• Evidence of limited aerobic capacity was noticed in the 24 hours following high-intensity exercise in ME/CFS, but not for controls, identified by a repeat exercise test.
• It would be useful to explore the lowest demand needed to illicit this response and assess the feasibility of repeated exercise at lower intensities.
• These findings add support to the hypothesis of a possible physiological mechanism associated with ME/CFS.

Research review abstract:

Background:

Repeated maximal exercise separated by 24 hours may be useful in identifying possible objective markers in people with ME/CFS that are not present in healthy controls.

Aim:

We aimed to synthesise studies in which the test-to-retest (24 hours) changes in VO2 and work rate have been compared between people with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and controls.

Research synthesis – It aims to generate new knowledge by combining and comparing the results of multiple studies on a given topic [Wikipedia]

Methods:

Seven databases (CINAHL, PubMed, PsycINFO, Web of Knowledge, Embase, Scopus and MEDLINE) were searched. Included studies were observational studies that assessed adults over the age of 18 years with a clinical diagnosis of ME/CFS compared to healthy controls. The methodological quality of included studies was assessed using the Systematic Appraisal of Quality for Observational Research critical appraisal framework. Data from included studies were synthesised using a random effects meta-analysis.

Results:

The pooled mean decrease in peak work rate (five studies), measured at retest, was greater in ME/CFS by −8.55 (95% CI −15.38 to -1.72) W. The pooled mean decrease in work rate at anaerobic threshold (four studies) measured at retest was greater in ME/CFS by −21 (95%CI −38 to −4, tau=9.8) W. The likelihood that a future study in a similar setting would report a difference in work rate at anaerobic threshold which would exceed a minimal clinically important difference (10 W) is 78% (95% CI 40%-91%).

Conclusion:

Synthesised data indicate that people with ME/CFS demonstrate a clinically significant test-retest reduction in work rate at the anaerobic threshold when compared to apparently healthy controls.

Comment by Dr Katrina Pearson