Hi
What’s is the rough average of calories that need to be consumed per hour for a 9.30 ironman
Athlete weight 65 kg
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If you google “Portman calculator”, you’ll get a very good estimate using that.
It’s not perfect by any means, as everybody is different to an extent. But its at least as good as estimates that you’ll get here. It also gives advice on how to distribute the eating of those calories out through the race
75kg.
On the bike I planned by aid station – 10 miles is about 1/2 hour – 1 bottle of Gatorade plus 1 90-120kcal energy bar.
Make sure the calories you put on your bike are ones that you will consume even when nauseous. I see more bikes come into T2 with bars/gels left. Why transport an energy bar 112 miles?
Portman calculator came up with 38 oz/381 cal TOTAL for 4 hr marathon (175 lbs male) - seems very low, no?
For a stand alone marathon? That seems about right.
You have to remember that you have 300-400g of carbs stored in your body when you begin, so you’re well ahead when you start fuelling.
Its a different ball game to fuelling the run leg of an IM for example.
I’ve never done an ironman but have found this to be useful:
This “portman caclulator” is really way off … it gives me 260 cal during the bike segment of an ironman (170 pounds, about 5hr bike, about 9:45 total).
There is no reason, why consuming less than 400cals per hour would have any benefit.
That’s for IM marathon. I thought that as a rule you want to replace 150-200 cal/hr in the run.
In total the table has me expending 11,000 calories while replacing 1,700. Even assuming I store 3,000 cals before I start - I’m still short 6,000 calories for the day.
260kcal total for the ride? Or per hour?
Although I suppose either would be way off base.
I’ve always found it to be a useful tool, and it’s certainly never given me any whacky numbers.
I think it provides a good baseline that you can start with, while you learn your own tolerance.
OK that seems a bit low than for an IM marathon where you are pretty depleted
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260kcal total for the ride? Or per hour?
Although I suppose either would be way off base.
I’ve always found it to be a useful tool, and it’s certainly never given me any whacky numbers.
I think it provides a good baseline that you can start with, while you learn your own tolerance.
Per hour. And only 0,5l of fluid.
Thats about half of what makes sense. (400 cal /hr and a litre of fluid is my guideline)
Hi
What’s is the rough average of calories that need to be consumed per hour for a 9.30 ironman
Athlete weight 65 kg
it really depends - very individual. I test a lot of athletes with a very specific Ironman metabolic test protocol. For argument’s sake, let’s use my own personal numbers but adjust my weight from 75kg to 65kg (this reduces the amount of calories burned), and use my numbers from IMAZ where I went 9:11. That should give you a good idea.
Now, in addition to that, let’s just focus on the bike, since on the run you’re usually limited by what you can take in due to the discomfort/motion of running (let’s say 300 calories per hour on the run which is reasonable for many people, probably on the upper end). Here are some of the numbers:
Starting glycogen: your muscles can only use glycogen that is stored in them i.e. your legs cannot use glycogen stored in your arms. My legs have a lean muscle mass (wet) of 21.3 kg, which fully “loaded” could hold ±400g-500g glycogen depending on the loading protocol. Let’s just estimate 1200 calories for a 65kg athlete.
So, here are the actual numbers:
Assumed watts: 250 (could be less but let’s be optimistic)
Start: 1200 calories (glycogen in muscles, number depends on lean muscle mass of legs and loading protocol). For me it’s a fair amount more but I use an unorthodox loading protocol.
Bike: 4:45, 250w, 780 kCal/hour total (435 carbohydrate, 345 fat, assuming 65kg athlete) - so for calculation purposes ignore the fat, you only need to care about lost CHO.
Run: 3:15 - I burn 350 carb calories per hour at 7:30 pace (75kg), just reduce that a bit for a 65kg athlete.
Based on those assumptions, if I weighed 65kg I would be ok taking in 350 carb calories per hour on the bike and 250 carb calories per hour on the run. For my own weight of 75kg it would be 400 calories per hour on the bike and 250 on the run.
Big caveat: the numbers above are very specific to me, and are kind of consistent with athletes similar to me that I’ve tested. If the athlete is planning on a 9:30 let’s assume they have a solid history of endurance sports that may (or may not) be similar to mine. If you want to be sure, let me know and I could possibly put you in touch with someone local who can do a test.