The mechanism that causes high-performance athletes to “feel the burn” turns out to be the culprit in what makes people with chronic fatigue syndrome feel exhausted by the most common daily activities, new research from University of Florida Health shows.
Published in the February issue of the journal Pain, the study shows that the neural pathways that transmit feelings of fatigue to the brain might be to blame. In those with chronic fatigue syndrome, the pathways do their job too well.
The findings also provide evidence for the first time that peripheral tissues such as muscles contribute to feelings of fatigue. Determining the origins of fatigue could help researchers develop therapies or identify targets for those therapies.
Dr. Roland Staud, a professor of rheumatology and clinical immunology in the College of Medicine, and Dr. Michael E. Robinson, a professor in the department of clinical and health psychology in the College of Public Health and Health Professions, focused on the role of muscle metabolites, including lactic acid and adenosine triphosphate, or ATP, in the disease. The study has demonstrated for the first time that these substances, released when a person exercises his or her muscles, seem to activate these neural pathways. Also, UF Health researchers have shown that these 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,” said Dr. Staud, the paper’s lead author.
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.
“For most of us, at the end of strenuous exertion we feel exhausted and need to stop — but we will recover rapidly,” Dr. Staud said. “However, these individuals tire much more rapidly and sometimes just after moving across a room, they are fully exhausted. This takes a toll on their lives.”