let’s say you are a 1:25 half marathoner, which kind of equates to 3 hour marathon ability. Basically these two races largely use similar energy systems one with a slightly lower intensity than another. Either way, you start both after breakfast and finish both long before lunch time.
Now say you are a 5 hour half Ironman guy, so logic might suggest that you have the capability of going 11 hours. Problem is that a half Ironman is still done between breakfast and lunch. You can largely survive this race on “last night’s pasta” plus a bar, 3 gels and 4 bottles of gatorade. Pretty easy to digest. In fact, the energy systems used in a half Ironman are very similar to marathon. You can “hammer all the way”.
Now let’s talk about the 11 hour Ironman. First of all, you eat breakfast at 5 am and even if you were doing nothing on that day, you’d need to eat lunch well before noon and even if you were doing nothing on the same day, you need to eat supper early, but hopefully after 6 pm when you would finish your Ironman (assuming a 7 am start). So to paraphrase things, the others are truly races. Ironman is a swim-bike-run-eat event. Somehow you gotta get 300-600 calories per hour in your body to keep going without bonking. This is not an event you can survive on “last night’s pasta”. To top it off, you have to balance your electrolytes (Na and K) or cramp badly at some point or become hyponatremic.
To put it into perspective, 300 calories per hour is a bar and a bottle of gatorade, or 3 gels and a gatorade, so at the low end of the scale, for 11 hours you need 33 gels and 11 bottle of Gatorade, not including any additional hydration liquid. For the 600 cal per hour plan, 66 plus 22. Now that looks pretty tough to ingest without slowing down, barfing, or just plain giving up and trying to do on a deficit (i.e. bonk)
I’m not trying to be pessimistic, but just trying to alert you to the fast that half marathon, marathon and half Ironman are all races and use the same energy systems. Ironman is an event about the guy who can slow down the least and manage nutrition well. Make sure you plan and execute on that aspect of your Ironman and you will do great. The Ironman training is easy. Everyone shows up to the race well trained, but very very very few (myself included) can execute well on race day. Most inadequate performances can be directly related to poor nutritional execution rather than fitness, even pacing or improper taper.
Mark Allen described it best, “Treat the entire swim, bike and first half marathon as a long training day. Don’t even get tempted to race. If you feel great, the real RACE starts 13.1 miles into the run”. Personally, I consider the 2.4-112-13.1 miles as the first HALF of the race. The final 13.1 miles is the last HALF of the race. Save your energy (mainly emotional and psychological) for the final 13.1 and you will have a great experience.
