I participate in long distance cross-country Mt. bike races. I have always had trouble with muscle cramping on these hard rides, typically around the 4-hour mark. I got sweat tested by LEVELEN, and began using LEVELEN Level 3 while riding. I am confident that their products, which are tailored to your personal specific mineral and electrolyte losses, were integral to my success at the Leadville Trail 100, where I completed the 104 mile course, with 12,500 feet of elevation gain in 11:37:52 without one single cramp!