How muscle fatigue originates in the head

http://www.biologynews.net/archives/2011/12/05/how_muscle_fatigue_originates_in_the_head.html

Apparently, before muscle fatigue starts in the muscles, it actually starts in the brain. Previous research in this area has only been confined to the muscle, but now scientists have begun to look at the brain. It turns out that nerve impulses from the muscle inhibit the ACH neurotransmitter. they proved this when the person could not lift a weight with his leg anymore,but then could lift more when they numbed his spinal cord. Using MRI, they were able to pinpoint the exact areas of the brain and spinal cord that were responsible for decreased muscle activity. it is the thalamus and insular cortex. Those areas have also been known to be responsible for analyzing hunger and threat.