Symptom variability following acute exercise in myalgic encephalomyelitis/chronic fatigue syndrome: a perspective on measuring post-exertion malaise

ABSTRACT

Background: Consensus for an operational definition of post-exertion malaise (PEM) and which symptoms best characterize PEM has not been established and may be due to variability within and between studies.

Purpose: Determine the magnitude of the effect of maximal and submaximal physical exertion on multiple myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) symptoms that are associated with PEM and explore variability among two studies in which mood, fatigue, and pain symptoms were measured before and after exercise.

Methods: Symptoms were measured before, and 48 and 72 hours after exercise in study 1 (ME/CFS = 13; Controls = 11) and before and 24 hours after exercise in study 2 (ME/CFS = 15, Controls = 15). Between-study variability was examined by comparing Hedges d effect sizes (95% CI) from studies 1 and 2. Within-patient group variability was examined via inspection of dot density plots.

Results: In study 1, large increases in general fatigue (Δ = 1.05), reduced motivation (Δ = 0.93), feelings of fatigue (Δ = 0.90), feelings of confusion (Δ = 0.93), and total mood disturbance (Δ = 0.90) were found at 72 hours. In study 2, a large increase in affective/sensory pain (Δ = 0.79) was found at 24 hours. Dot density plots in both studies revealed substantial variability among people with ME/CFS relative to healthy control participants.

Conclusions: PEM symptoms are variable among people with ME/CFS and several gaps in the literature need to be addressed before guidelines for measuring PEM in the clinical or research setting can be established.

KEYWORDS:

• Chronic fatigue
• exercise
• post-exertion malaise
• symptoms
• variability

Acknowledgements

The contents do not represent the views of the Department of Veterans Affairs or the United States Government.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Both studies were supported by the Solve ME/CFS Initiative. Jacob Meyer was supported by a National Research Service Award from the Health Resources and Services Administration T32HP10010 to the University of Wisconsin Department of Family Medicine and Community Health.

Notes on contributors

Jacob B. Lindheimer

Jacob Lindheimer is a postdoctoral fellow with the War Related Illness and Injury Study Center of the VA New Jersey Healthcare System.

Jacob D. Meyer

Jacob D. Meyer is a postdoctoral researcher with the Department of Family Medicine and Community Health at the University of Wisconsin-Madison.

Aaron J. Stegner

Aaron J. Stegner is a research scientist with the William S. Middleton Memorial Veterans Hospital and University of Wisconsin-Madison.

Ryan J. Dougherty

Ryan J. Dougherty is a graduate student in Exercise Psychology at the University of Wisconsin-Madison.

Stephanie M. Van Riper

Stephanie M. Van Riper is a graduate student in Exercise Psychology at the University of Wisconsin-Madison.

Morgan Shields

Morgan Shields is a faculty associate at the University of Wisconsin-Madison.

Amanda Reisner

Amanda Reisner is an undergraduate student at the University of Wisconsin-Madison.

Sanjay K. Shukla

Sanjay K. Shukla is a research scientist at the Marshfield Clinic Research Foundation.

Alan R. Light

Alan R. Light is a research professor of Anesthesiology at the University of Utah.

Steven Yale

Steven Yale is the director of the Clinical Research Center at the Marshfield Clinic Research Foundation.

Dane B. Cook

Dane B. Cook is a research physiologist/health science specialist at the William S. Middleton Memorial Veterans Hospital and is a full professor at the University of Wisconsin-Madison.