New Delhi : The same thing that lets high performance athletes “feel the burn” makes people with chronic fatigue syndrome feel exhausted by the most common daily activities, even a walk across the room.
New research suggests that the neural pathways that transmit feelings of fatigue to the brain might be doing their job a little too well in some people. The findings also provide evidence that peripheral tissues such as muscles contribute to feelings of fatigue. Researchers say figuring out the origins of fatigue could help develop therapies for people with the disease.
Chronic fatigue syndrome, which the Institute of Medicine recently renamed systemic exertion intolerance disease, or SEID, is characterized by extreme chronic fatigue. Because its chief symptom—fatigue—is often associated with many other diseases, it can be difficult to diagnose for the more than one million people who actually have it, the Centers for Disease Control and Prevention says.
The disease has no root medical cause, and researchers don’t know what triggers it. But they are studying aspects of the disease to figure out ways to treat it.
The new study focuses on the role of muscle metabolites, including lactic acid and adenosine triphosphate, or ATP, in the disease. It demonstrated for the first time that these substances, released when a person exercises muscles, seem to activate these neural pathways. Also, the pathways seem to be much more sensitive in patients with chronic fatigue syndrome than in patients without the disease, something that hasn’t been studied before.
“What we have shown now, that has never been shown before in humans, is that muscle metabolites can induce fatigue in healthy people as well as patients who already have fatigue,” says Roland Staud, professor of rheumatology and clinical immunology at University of Florida College of Medicine and lead author of a paper in the journal Pain.
During exercise, muscles produce metabolites, which are sensed by metaboreceptors that transmit information via fatigue pathways to the brain, according to the researchers. But in patients with SEID, these fatigue pathways have become highly sensitive to metabolites and can trigger excessive feelings of fatigue.
