Built from your own numbers and preferences
Tired of fueling advice that gives you the same gel every 30 minutes it gives a runner 40 pounds lighter and an hour faster?
CarbRate builds your plan from your weight, your goal time, your measured sweat rate, what your stomach handles today, and the weather you will be running in.
Twelve questions, about four minutes, and every question has a not-sure option.
Why generic fueling numbers leave you bloated or out of fuel, even when you follow them exactly
The advice everybody gets is a range. Sixty to ninety grams of carbohydrate an hour. Drink to thirst. Take some salt.
A range works for a population. You need one number.
Sixty grams an hour is barely a third of what a fast marathoner burns, and it is already the most a stomach that has never practiced can handle.
Fluid varies even more. between 0.5 and 2.0 litres an hour, a fourfold range, and a drink-500ml-an-hour rule cannot tell you where in that range you are.
So you follow the number exactly, and you end up bloated from too much fluid or out of fuel late in the race.
You followed the plan correctly. The number was never personalized to you.
Luckily, you can work out every one of those numbers from things you already know about yourself. CarbRate asks for them, one question at a time.
Four numbers decide your plan, and all four are yours
How much carbohydrate you need comes from how long you will be running. puts the limit for a single carbohydrate source near 60 grams an hour, rising to about 90 for the longest efforts.
What your stomach handles today limits that further, and it is usually your stomach, not your legs, that sets the limit.
How much you need to drink comes from your sweat rate, which depends on how hard you are working, the conditions, and your size.
The sodium in your plan is set as a concentration in your drink, never as a separate hourly dose.
Those numbers come from the CarbRate engine: same race, same conditions, different runners.
The same 26.2 miles takes 199 grams of carbohydrate for one runner and 393 for another, and one runner needs barely half the fluid of the other.
To work that out yourself you would need a heat-balance calculation, a glycogen model, and a set of scales.
That is why CarbRate calculates all four from twelve questions, and shows you where every number came from.
CarbRate calculates how much glycogen you burn from your own weight and goal time
Your weight is the strongest single predictor of how much glycogen each mile burns, and your goal time sets how fast you burn it.
CarbRate combines the two first, and shows you the gap between what your race burns and what your body can store.
That gap is why you hit the wall.
Every question after that helps CarbRate close that gap.
CarbRate tells you which of your numbers are measured and which are estimated
Every number in your plan has a label: you set this, or estimated.
That label tells you how much to trust each number.
CarbRate does not guess your sweat rate from questions about how much you sweat compared to your friends.
It starts you with a calculated sweat rate and shows you the range around it, which is wide at first.
Then it tells you exactly how to narrow that range.
CarbRate turns your sweat rate from an estimate into a measured number in one run
Weigh yourself before a run, run at least 45 minutes, towel off and weigh yourself again, and tell CarbRate what you drank.
That is the whole test. CarbRate does the math and adds the result to your plan.
The range around your sweat rate starts at roughly ±45% and narrows toward ±12% as you log tests, and your fluid and sodium numbers get more precise with it.
CarbRate adjusts its estimate with every test instead of replacing it, so one bad weigh-in moves your plan by about 13%.
A two-minute weigh-in before and after a run you were already doing is the single biggest improvement you can make to your fueling plan.
CarbRate shows you what changes before you commit to it
You can open every input in your plan. Change your goal time from 3:30 to 3:25 and CarbRate shows you the result before you save it.
Carbs 75 to 78 grams an hour. Projected finish 3:34 to 3:29.
CarbRate only shows the rows that changed.
You can see how every number in your plan was calculated, and nothing changes unless you approve it.
Do not know your numbers? Used a calculator before?
Your training was never generic. Your fueling should not be either
You picked your shoes for your feet and your paces off your own race times.
Your race-day fueling should be built from your own numbers too.
- Fueling plan built on your exact course
- Personalized to your sweat rate, weight, and goal
- Adjusts when the race-day forecast changes
- Week-by-week gut-training practice schedule
- One prescribed change after every rough run
- The dress-rehearsal run, scheduled early
- Live guidance through every gel and drink
- All 163 gels, chews, and mixes built in
Julie Beaudoin“This app helped me test products throughout my training for Grandmas and put together a plan with more drinking. It was the first time I’ve finished with no stomach issues.”
See how CarbRate handles the rest of your race
A page for each one: