Many, many problems in ultras are linked to fueling. TRR coach Ryan Sheehy gives three proactive strategies for being your best on race day, and in training.

A friend of mine kept cramping in ultras. Full-body, seize-up, day-ending cramps that DNF’d him race after race. He blamed his electrolytes and tinkered: more salt, extra magnesium, a new drink mix. The cramps kept coming. Then he stopped fiddling with electrolytes and just ate more carbs. More gels, more often. The cramping vanished, and he’s finished every ultra since. He’d spent three DNFs treating a fueling problem as a hydration problem.

That’s the trap. When something breaks late in a race, be it a cramp, a bonk, a stomach in revolt; we blame the nearest suspect and miss the real one. The real culprit is usually simple: you’re not fueling enough, and the systems that let you absorb that fuel aren’t dialed in. Fix that and your body stops falling apart at mile 80. Here’s how, across the three levers that matter: train the gut, hydrate properly, mitigate heat.

Train Your Gut

Your gut is a muscle, and like any muscle, it adapts to the load you hand it. Feed it 30 grams of carbs an hour in training and it will revolt when you demand 80 on race day. So train high. I target 90 g/hr in races and push 110 g/hr on my long runs and hard workouts, deliberately above what the race will ask for, so race day feels like a downshift. Build up to it though. Start about 12 weeks out and add roughly 10 g/hr a week rather than lurching to triple digits. Past roughly 60 g/hr, switch to multiple transportable carbs (a glucose-fructose blend), or your gut won’t be able to absorb effectively. Then get weird with it: pound a liter-plus of electrolyte fluid and head out for moderate work. Teach the gut to perform while it’s full and cranky. After a few weeks, “cranky” quietly becomes “unremarkable.”

And notice what I left out: real food. Through the marathon, and most of an ultra, fast carbs are the entire toolkit. Real food doesn’t need to enter your world until you’re running into the night, 100K and up, and even then it’s a pivot, not an upgrade. Make the switch when your body demands it (nausea, hunger) or you’ve got a specific job for it. At 2 a.m. I want something hot and salty, so ramen earns its spot.

Hydrate Properly

This is the one runners butcher, and it’s the hidden hand behind most “gel problems.” Under-salt your fluids and you don’t just risk cramps, you choke off carb absorption at the source. Sodium and glucose ride the same doorway into your bloodstream (a transporter called SGLT1); no sodium, no open door, and those carbs sit in your gut fermenting into nausea and worse. That “gel gut” you blamed? Usually an electrolyte deficit wearing a costume. So drink to a plan, not just to thirst, and pair every bottle with real sodium, think 500 to 1,000 mg an hour, more if you’re a heavy or salty sweater, plus potassium and magnesium to keep the whole system in balance. This holds from the marathon to the 100-miler; the longer you’re out there, the more a small hourly deficit compounds.

Mitigate Heat

You can nail every gram of carb and milligram of sodium and still detonate if you let your core cook. Once core temperature creeps past about 39°C (102°F), your gut lining literally goes leaky: blood shunts to your skin to shed heat, your intestines get starved, and everything you swallow turns against you. Acclimation and pacing help, but the most underrated tool once you’re running is embarrassingly simple: get wet and apply ice. Ice in the hat, down the shorts, clenched in each fist. Douse yourself at every aid station, before you feel like you need it. Keeping your core temp down keeps your gut intact, and an intact gut keeps your fuel moving. Cooling isn’t comfort, it’s fueling strategy.

Takeaway

Stop blaming the gels. That’s not your failing. In fact, they are your saving grace to a strong marathon or longer. But you have to set your body up to truly optimize them for your race. Work with a coach who has experience dialing in race-day nutrition and can get you set up for success in training.

Ryan is a coach with Team RunRun. To learn more about him or to work with him, check out his coach profile.