Muscle Biopsy and Plasma Study
Post-Exertional Malaise (PEM)
David Systrom MD
One of the defining characteristics of ME/CFS that sets it apart from other conditions is intolerance to exertion, known as post-exertional malaise (PEM). Even mild exertion, like a short walk, can cause ME/CFS symptoms to suddenly worsen, often feeling like the flu, usually within 1-24 hours after exertion. This worsening may last for days or weeks or longer and is often completely debilitating. Past research has identified an effective way to measure PEM, using a 2-day cardiopulmonary exercise test (CPET), where key factors are measured at baseline, during and after an exercise challenge, and then 24 hours later in a second exercise challenge.
CPET testing clearly shows the effects of exertion intolerance in ME/CFS. Earlier studies indicated that PEM may be due to metabolic (the process the body uses to change food and drink into energy) dysfunction and/or dysfunction in the way cells use oxygen.
This study will compare PEM in ME/CFS patients who’ve become ill in the past two years to patients who have had ME/CFS longer, as well to healthy controls. It will use a variety of testing methods on both muscles and blood to document what happens in the body of an ME/CFS patient during and after exercise, looking at both metabolic functions and oxygen use.
Energy production occurs inside the body’s cells in mitochondria, so this study will measure various mitochondrial functions. Red blood cells play a critical role in how the body delivers oxygen, so red blood cell function will also be examined.
The Study Goal
Previous studies have indicated possible deformities in red blood cells of those with ME/CFS. These factors are interrelated with inflammation and immune dysfunction, which are both significant factors in ME/CFS. Better understanding the causes and effects of exertion intolerance—and the differences between newly ill patients and long-term patients—can help to better understand the mechanisms behind the scenes in ME/CFS and exactly what is happening in the bodies of patients.
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