"I use Generation UCAN (full disclosure they now sponsor me) in my marathons. This carbohydrate is manipulated by heat and water so it is absorbed more slowly to avoid the spike and crash. You “feed” with it every hour of the race (one scoop/packet each hour) to provide glucose to the brain and working muscles but your blood glucose level stays at a more steady level instead of the rapid increase and decrease like with the fast acting carbohydrates. Because you feed less frequently and because it’s easier on the GI tract, you avoid the GI upset that can occur late in the race. That’s been a win-win for me and many other runners. Another big plus is that the regimen on race day is much simpler. You just get your carbohydrates once every hour and then just need to drink water and electrolytes in between. Super simple."
UCAN Fuel Strategy
Ingest a packet 30-60 minutes before the start and then another packet every hour. Mix as a liquid or make into a paste/gel and chase with water.
"Try these methods in a few long runs. See what you find works. Then once you have it dialed in on a long run, try it in a goal pace workout and see if it works in a more intense situation. Then once that is dialed in, try it in a tune up race. Then finally after learning from these experiences and tweaking your plan, you can feel very confident that you have the best strategy for you."
Greg's Favorite UCAN Products
Referenced from: https://www.mcmillanrunning.com/fueling-for-the-marathon/