I will run and walk for a long period of time in my Bataan Death March 102km ultra. Roughly 18 hours or less.
Key therefore is proper hydration and adequate energy supply. For my fuel supply I will be relying significantly on energy gels which are designed to replenish carbohydrate stores that are depleted when running.
Fortunately for me, I have received a generous support from my favorite Bicolano blogger, the Wandering Jouster. WJ has given me more a dozen High 5 gels of assorted flavors for my BDM adventures.
Thank you very much, WJ.