I was first turned on to e-Gel at the Rock and Roll Seattle expo. I used it for the half marathon and it seemed to work. However, I wanted to give it a true test. I started training for the Rock and Roll San Antonio marathon, and I used nothing but e-Gel during training. I have never felt so good after a run. Even running in 90+ heat I never cramped up. I have used many other products and have never gotten the results that I did with e-Gel. I just completed the marathon in a personal best time. I actually beat my old best by 15 minutes. And I owe it all to e-Gel. I was able to get all the energy and electrolytes that I neeeded all in one pack. I will be using nothing but e-Gel for my next marathon too.