You may take all the carbs of the world -gels, sports drinks, etc.- and you will not see any improve in your performance. You may take all the caffeine in a single cup and all you will get is nervous. What you put in your mouth is just a minimum part of all the energy you can get. What feeds a runner is the whole universe if he is connected to it, to its light, sounds, smells. I run barefoot as much as I can and that´s the only way that I feel I am doing something good for me and our planet. Barefoot, I can feel the energy going through the center of the earth to the center of my being. I am not tired anymore; I am just sweating, breathing and feeling graceful for the immense gift of life.