Pushing the Limits of Carbs and Hydration at the Javelina 100 Mile

Ultras come down to a science problem:

How can you fuel enough to push hard enough to do something that might feel impossible?

My entire training approach is designed to help solve that problem. From a fitness perspective, I want to build top-end speed early in a training cycle before channeling that running economy into fast paces at the top end of aerobic threshold, or Zone 2. The reason that velocity at aerobic threshold is key is because that’s the fastest I can reasonably go while replacing the glycogen I’m burning – likely around 500 calories per hour.

Given those astronomical calorie needs, there’s no margin for error in this science problem. Go too hard, and I bonk no matter how many calories I take in. Go too easy while doing high-carb fueling, and the offset will probably result in a GI explosion after 6 hours. The fire needs to be burning hot so most of the fuel will burn, without burning so hot that it flames out.

After consuming 120-140 grams of carbs per hour at Leadville, I desperately wanted more data to validate the science experiment. Was it just a dream day for my GI system? We are seeing similar high-carb approaches across endurance sports, but one personal data point makes for weak science. And I hate weak science.

So, 10 weeks later, I raced the Javelina 100 mile – a Golden Ticket race to the Western States 100. Every neuron in my coaching brain was screaming, “Too soon!” Every nerd impulse in my science brain was screaming, “Just right!”

And now, we’d have a fun new variable to test. There was record heat on the forecast approaching 100 degrees Fahrenheit... in the desert, with no shade. And oh... I have an extremely high sweat rate. It was time to science the crap out of this problem.

When I announced this new science experiment, I heard some skepticism. The headline narrative of the doubters was that high carb fueling wouldn’t work in the heat. Athletes like me were going to learn the hard lesson that overloading a beaker and putting it on a flame would result in making a gooey mess all over the lab walls.

That’s not what happened. I consumed more carbs than Leadville and pushed the frontiers of hydration. Here’s how I solved the science problem:

The first big element was gut training. When I told my dad what I did before the two 100 milers, he said I should keep this secret to myself. Trick, please. No secrets here.

I only did long runs with race ratios of carbs and fluid once before each race, though I kept my gut transporters primed with plenty of high-carb fueling in high-intensity training sessions (though not low intensity ones). I don’t think that practicing race ratios simulates mile 60, in the same way that a 10-mile marathon pace tempo doesn’t simulate mile 24 of a marathon. Sometimes, you need to go harder.

Instead, I concentrated my efforts on taking in all of my hourly needs at once, at least once per week. That meant 32+ oz of fluid within 5 minutes, channeling research on competitive eater training. I worked up to this approach over multiple years, and only did it when I needed the carbs and fluid—please be careful.

Given the heat, I worked up to even more fluid (only in situations where I was already dehydrated, and with proper electrolyte ratios), channeling studies on gut tolerance.

The reason my dad wanted me to take my gut training to the grave was that it’s not a common practice, so it may be one of my only advantages in a sport that is just starting to probe the limits of human physiology. We’ll see – there need to be more studies. I volunteer as tribute.

I combined that gut training with focused heat training, since excessively elevated core temperature would probably undercut my GI system no matter what I did on race day.

During the race, I started with my Leadville approach when it was less hot in the early AM: generally consisting of a Science in Sport Beta Fuel Gel (40g carbs) every 20 minutes, with every third gel being a Precision CAF gel (30g carbs), plus Skratch Sports Drink mixed with a Precision 1000mg sodium tab.

That was my security blanket fueling approach. When the temps were scorching, I had to throw the blanket out the window.

I settled into this hourly routine routine:

Science in Sport Beta Fuel Gel (40g carb) every 30 min 48-56 oz (1.5+ L) of Gu Roctane (!!!), with 1-2 Precision 1000 tabs per hour mixed in

Assuming each 16 oz had 20-30ish grams of carbs… you can do the math. I’m actually scared to put the potential numbers on paper. I felt good all day other than some cramps, and I feel mostly recovered a week later. I was even able to pee for drug testing right after finishing, which is remarkable with my sweat rate in that heat.

Starting the race, I was nervous about just one thing: could my stomach handle the amount of fluid needs on top of the carb intake when it got hot? My hypothesis a week before the race was “no,” and that I’d be spewing lab fluids like the critics asserted. By race morning, I had gaslit myself into believing in GI magic.

Maybe I didn’t need magic all along, I just needed advanced fuel sources and gut training. As Arthur C. Clarke said: “Any sufficiently advanced technology is indistinguishable from magic.”

We have the technology.

And the result isn’t magic.

It’s science: High carb fueling is here to stay, in all conditions.

Photo Credits: Cody Bare (Bare Photography)