Tired? It’s all mental.

We are constantly using our muscles. Whether we are working out, playing a sport, or just walking up stairs, our muscles will eventually get tired and it will be more difficult to use them to exert force. The ability we have to voluntarily use our muscles is dependent on will power and muscle fatigue. We hear coaches tell us that the right mindset can overcome fatigue, but to what extent is fatigue really controlled in the head? Well, researchers have recently discovered that the brain actually plays a major role in muscle fatigue. There is a mechanism in the brain the triggers a reduction in muscle performance in order to prevent the body from exceeding its physiological limits.
In a recent study, researchers from the University of Zurich and ETH Zurich found the fatigue response in a muscle to be significantly weaker when nerve signals from the muscle to the brain were interrupted. By locating the regions of the brain that show increased activity during fatigue, they concluded that fatigue is a response to prevent the body from causing itself harm by over exertion of the muscles. The researchers found that nerve communication between the brain and a muscle becomes more intense as the muscle tires, showing that the brain helps to regulate muscle activity.
With muscles being such an important part of bodily function, this is an important and beneficial discovery. Experts will be able to use the knowledge gained from the studies to help optimize muscle performance and deal with reduced muscular performance due to diseases or medications.

http://www.sciencedaily.com/releases/2011/12/111205081643.htm