Published in 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.
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," 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."