If you’d have asked me six months ago if it was humanly possible to race a 10 to 14 hour endurance race without fuel, specifically carbohydrates, only consuming water, I’d say it might be impossible.
Yet that is what I will do this November when I race the 140.6 mile Ironman Arizona. An Ironman consists of swimming 2.4 miles, followed by a 112 mile bike race and then the final leg running a 26.2 mile marathon. To be an official finisher I have to complete the total in 17 hours or less. The pros run in about 8 hours. My fastest time ever was 13:51 at this race in 2010.
I’ve discovered that I can actually race this long without the need to consume any carbohydrate while I race. At my pace intensity