- Last Updated: 25 November 2015 25 November 2015
Measuring the effects of post-exertional malaise in CFS patients
As patients, we know what often happens after “we do too much.” We “crash”, we have to go to bed for one or more days, we’re sick, in pain, and have no energy whatsoever. Would it ever be possible to compare effects in the body after exertion between healthy people who don’t suffer any substantial effects and CFS patients who do? Could one measure substantial physiological changes in CFS patients that confirm a pathological biological response to the exertion?
Dr. Komaroff reported, in fact, that a major study has found just such physiological changes in CFS patients that do not occur in healthy individuals. The importance of this study and its further confirmation cannot be overestimated. The study was conducted by Alan Light, et al. and published in the journal Pain in 2009.
The human body contains molecules that can sense fatigue and pain. These molecules occur as ion channel receptors, adrenalin receptors, and immune system molecules. The study, by means of a blood assay, measured these groups of molecules in both CFS patients and healthy controls before and after exercise—beginning 25 minutes after exercise, and then 8 hours, 24 hours, and 48 hours afterward. The exercise consisted of 25 minutes on a combined arm-leg cycle ergometer.
The difference between patients and healthy controls post-exercise was absolutely striking, if not amazing—see slide, Fatigue & Pain Sensing Molecules: Normals vs. CFS, Post-Exercise.
Before exercise—“at baseline”—there was actually not much difference between the molecular profile of patients and “normals”. Following exercise, the study measured “fold increases” in the molecular profiles of both patients and controls at each interval period.
In controls, the highest changes occurred at about 8 hours, but were less than 2 ½ times base line, and these were mostly in adrenergic and immune groups of molecules.
But in CFS patients, changes in specific sensory, adrenergic, and immune measures substantially exceeded the control group. At 30 minutes, two pain measures and one adrenergic measure had increased over four-fold. At 8 hours, an adrenergic measure had increased six-fold, and at 24 hours, almost nine-fold. Sensory measures at 24 hours and 48 hours remained extremely high—as well as the adrenergic measures. Most immune measures exceeded those of healthy controls from 80-100% throughout the post-exercise period.
Dr. Komaroff pointed out that while this study brings to light further objective biomarkers of CFS, it does not prove that these biomarkers, these molecules, are the cause of post-exertional malaise. The association is one of correlation, not necessarily causation.