Carbs, Fluid, Sodium: Andy Blow on How to Actually Fuel a Race

I tested at 1,310 milligrams of sodium per liter of sweat.

If that number means something to you, you're already wincing on my behalf. If it doesn't, here's the short version: I lose a lot of salt, I ignored that fact for years, and it took sitting down with Andy Blow to finally take it seriously.

Andy is the founder of Precision Fuel & Hydration. Before that, he was a triathlete who kept falling apart in the heat and waking up in the medical tent with hyponatremia. His whole company didn't start as a product. It started as a question he couldn't stop asking himself: why does this keep happening to me?

A friend who was a medic ran him through a sweat test in a hospital, showed him he was dumping enormous amounts of sodium, and that one data point rearranged everything. The first version of the business wasn't a gel or a drink mix. It was just the sweat test, added on to the sports science lab he was already running. The products came later, once the testing caught on.

The single most useful idea in the whole conversation is also the simplest. There are three numbers you need to hit every hour: carbs, fluid, and sodium. And your three numbers are not my three numbers.

That's the entire reason PF&H separates fueling from hydration instead of shipping one do-it-all gel. If everything you need is baked into a single product, and you happen to need twice the sodium I do, you can't chase that sodium without also doubling your carbs and your fluid. So Andy built the range around what he calls the three levers, and the point is that you get to pull each one independently.

That framing stuck with me, because the mystification is usually the point. Confuse an athlete a little and you can sell them a magic formula. Andy's whole pitch is the opposite: here's the toolkit, here's how to assemble it, go test it.

(For the record, I'm on the carb and electrolyte mix plus two gels an hour and still not hitting a gram of sodium. Andy offered to put me on the early test list for an electrolyte gel. I said yes before he finished the sentence.)

I brought up Tim Noakes, because you can't talk fueling dogma without him. His line to me, when I pushed back on low-carb, was that I'm addicted to sugar. Andy's response was more interesting than a simple rebuttal.

His argument: the Tour de France is the best fueling experiment that exists. Three weeks of all-out racing, dozens of teams with sports scientists, no room for things that don't work. If low-carb were genuinely faster, the peloton would already be doing it. Instead the carb numbers keep climbing, and the results follow. He called it a Darwinian filter on ideas.

But he gave Noakes his due, too, which I respected. Most of us are not elites. If the average athlete decides they should be slamming 150 grams of carb and 1,500 milligrams of sodium an hour on every easy run, that's neither healthy nor helpful. Sometimes a contrarian exists to keep the pendulum from swinging too far.

Where the science gets real is in the field. PF&H has a lab now, but most of their data comes from crewing elite athletes at races and measuring what actually goes in. Their case study database is open to anyone. They have Caleb Olson's numbers from top-ten to champion, Chris Myers going from tenth to second, and Rachel Entriken taking down a 250-mile course record on 60 grams an hour over 56 hours. Andy was careful not to over-claim any of it. His line was that good fueling was a brick in the wall, not the whole wall.

The biggest mistake amateurs make isn't picking the wrong gel. It's not having a plan at all. Not recording what they eat on long runs. Not weighing themselves before and after to see what they're actually losing. We obsess over marginal gains while ignoring the thing that decides the day.

Which is the natural moment to mention the free fuel and hydration planner. It started as a literal Excel algorithm Andy and his co-founder Johnny built to help athletes at expo booths, and it's now a free tool on their site that takes your inputs and hands you a ballpark for carbs, fluid, and sodium per hour. That's the starting line. From there you test and refine. It beats walking out the door with no idea which way to turn.

We spent the back half on the business, and this is where I got a little selfish, because PF&H has sponsored this show since February and I wanted to understand how they actually think about partnerships.

The answer, over and over, was authenticity, to the point where Andy apologized for over-laboring the word. Every relationship they have, from Ironman down to this podcast, grew organically. He remembered chatting with me two years ago, off the back of Hayden Hawks handing me gels and telling me to try them. The Ironman story was even better, though: PF&H once rented a house at the World Championships in Nice, marketed themselves so aggressively from it that Ironman's legal team paid them a visit, and a few months later Ironman called asking them to be the partner.

The through-line is a filter, and it's the same one I use. Andy signs athletes who genuinely want the product and want the sports science support. Those are the two non-negotiables. He'd rather sign someone on the way up and grow the deal over time than pay top dollar for a name with no real relationship. His athlete manager Brad, a former pro triathlete, is the prototype:

The stated goal with every athlete is to be the last nutrition company they ever sign with. That's a wild thing to aim for in a category built on churn, and it maps almost exactly onto how I think about the brands I choose to work with. My rule has always been that I won't partner with a brand I wouldn't recommend for free. The deliverables are what you pay for. The recommendation was always going to be there.

That's why this one is easy.

Listen to the full episode with Andy Blow, and if you've never actually built a fueling plan, go run your numbers through the free fuel and hydration planner before your next long one. Then test it, tweak it, and stop leaving your race in the medical tent. And as a sponsor of For The Long Run, you can use the code LONGRUN26 for 15% off your first purchase on their site!