Repeated maximal exercise tests of peak oxygen consumption in people with myalgic encephalomyelitis/chronic fatigue syndrome: a systematic review and meta-analysis

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.

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.

KEYWORDS:

• Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS)
• VO_2peak
• repeated exercise
• work rate

Acknowledgements

We would like to thank Professor Greg Atkinson and Professor Alan Batterham for their guidance and support throughout the development and completion of this review.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

All data that has been collated in the development of this review is presented in this manuscript.

Additional information

Funding

This study was a component of John Franklin’s PhD which was part funded by Teesside University.

Notes on contributors

John Derek Franklin

Dr. John Franklin is a Senior Lecturer in Research Methods at Teesside University and Fellow of the Higher Education Academy.

Michael Graham

Dr. Michael Graham is a Senior Lecturer in Sport and Exercise Science at Teesside University with a specialism in health and physical activity promotion and a Fellow of the Higher Education Academy.