Sun River Energy Gels have proven themselves to be very effective in providing an immediate source of fueling. I have used an energy gel just prior to running an indoor track race and it provided energy without any stomach discomfort. I only consumed a sports drink prior to racing in the afternoon without consuming any food up until that point. The Sun River Energy Gel provided me with the lift that I needed prior to the race. My brother ingested a Sun River gel about a half hour prior to a Boxing match. It also provided immediate energy without the worry of any stomach issues. Competing in our 50's we are wary about what we ingest prior to competing because we cannot tolerate anything that can potentially cause GI issues! I have yet to try the gels during endurance training but I know that they will work very well. Thanks Sun River for fueling our athletic pursuits.