Renata Fast

Second wind is a phenomenon in endurance sports, such as marathons or road running, whereby an athlete who is out of breath and too tired to continue (known as "hitting the wall"), finds the strength to press on at top performance with less exertion. The feeling may be similar to that of a "runner's high", the most obvious difference being that the runner's high occurs after the race is over. In muscle glycogenoses (muscle GSDs), an inborn error of carbohydrate metabolism impairs either the formation or utilization of muscle glycogen.