Running - Fuel for Thought. Running can be hard on your muscles, especially when you go out for a long haul. Working out for more than an hour can tax your system. Muscles can hold only so much fuel. Once that fuel is depleted, your muscles begin to tire, slow you down and wear you out.
Most gels contain simple sugars, as well as electrolytes and often caffeine .
These gels are absorbed directly into the bloodstream and provide energy right away. Most companies produce a pudding-like gel, which is easy to suck down while you're in motion. Bars are fine, but they don't digest as easily, and they're hard to eat while running. Bars also slow down the absorption process and tend to suck water out of your system. Drinks don't give you as many carbohydrates.