Sodium Isn't Just for Cramps: The Real Reason It's in Your Fuel

Your gut has a specific transport system that moves glucose from your stomach into your bloodstream. That system runs on sodium. Literally. The transporter (called SGLT1) grabs sodium and glucose together and pulls them both through.

No sodium, no transport.

This is why you can eat the right amount of carbs at the right time and still feel terrible. If there's not enough sodium alongside it, the fuel backs up. It sits in your stomach, sloshing around, going nowhere. Meanwhile your muscles are waiting for energy that isn't coming.

The cramping thing? That's more complicated. Some cramps are related to fluid balance and sodium does help there. But a lot of cramps come from neuromuscular fatigue — your muscles are just cooked, and no amount of salt fixes that. The science on cramps is honestly all over the place.

The science on absorption isn't. Sodium moves the carbs. That part is settled.

So when you see sodium in your gel or drink mix, don't think of it as cramp insurance. Think of it as the thing that makes the rest of your fueling plan actually work.

If your workout is under 60 minutes, you probably don't need to think about it. Your body has enough sodium on board to handle a shorter effort.

The exception is heat — if it's hot out, even a 45-minute run can leave you sweating enough that some sodium helps (more on this below).

Once you're past 60 minutes, sodium should be part of your fueling plan. Not separate from carbs, but alongside them. They're not two different systems you manage independently. They work together. Your gut uses sodium to absorb the carbs, and both get depleted the longer you're out there.

The simple rule: if you're fueling carbs, you're fueling sodium too.

Just like carbs, your sodium needs are personal. The biggest variable is how salty your sweat is — and that varies a lot from person to person.

You probably already know which camp you fall into. Think about what happens after a long or hard session:

• Low sweater (~400 mg/h) — You rarely see salt stains on your gear or skin. Your sweat is there, but it doesn't leave much behind.
• Moderate sweater (~700 mg/h) — You notice some salt marks on your hat, shirt, or skin after longer or more intense efforts. Nothing crazy, but it's visible.
• Heavy sweater (~1,000 mg/h) — There's grit on your face when you wipe it. Heavy white crust on your kit. Your eyes sting when sweat runs into them. People have probably commented on it.

Your baseline covers most situations. But two things can push your sodium needs higher.

• If you're fueling above 75g of carbs per hour, add 200 mg/h to your baseline. At higher carb intake, your gut needs more sodium to keep up with absorption. Without it, you're flooding the system with fuel that has no way to get through. A moderate sweater at 700 mg/h doing high-carb fueling becomes 900 mg/h.
• If it's hot out — above 77°F / 25°C — multiply your target by 1.25×. You're sweating more, losing more sodium per hour, and your gut is already under stress from the heat. That same 700 mg/h baseline becomes roughly 875 mg/h. If it's hot and you're fueling high carbs, both adjustments stack.

These aren't precise to the milligram. But they get you in the right range, which is what matters.

This is simpler than it sounds. Most gels and drink mixes already include sodium.

Check the label — you're probably getting 100–200mg per gel, more from a full bottle of drink mix. If your baseline is moderate and you're taking a gel every 20–30 minutes plus sipping a sports drink, you're likely in the right range without doing extra math.

If you want more control or you're a heavy sweater, add an electrolyte product to your bottle. LMNT, Nuun, Liquid IV, whatever you like. These let you dial in sodium separately from your carb source.

If you're going the DIY route with honey or maple syrup, add some sea salt to your fuel mix. Not complicated.

The point isn't to measure everything to the milligram. The point is to make sure sodium is in there somewhere. Carbs without sodium is a half-finished fueling plan.

When people hear "take more sodium," they often follow it with "drink more water."

Makes sense on the surface. But more sodium plus way more water can actually make things worse.

Here's why: if you're taking in a lot of water without enough sodium, you dilute what's already in your system. Your blood sodium drops, you feel foggy and bloated, and in extreme cases you end up worse off than if you'd done nothing. This is called hyponatremia and it's more common than people think, especially in longer races where aid stations are everywhere and nerves lead to overconsumption.

Think of it like mixing a sports drink. If the instructions say one scoop per 16 ounces, and you put in the scoop but fill it with 32 ounces of water, you've got a weak, diluted drink that doesn't do its job. Same thing happens in your body.

The fix is simple: drink to thirst, not to some arbitrary schedule. Fuel sodium based on your sweat profile. Let the ratio take care of itself.

PODIUM calculates your sodium and carb targets together because your body uses them together. They're not separate systems — sodium is what makes your fuel actually work.

You tell the app your sweat profile, your workout, and the conditions. It gives you a combined target and tells you when to fuel with tactical audio alerts. No mental math mid-run.

Sodium isn't a cramp thing. It's a fuel thing. It's the reason your carbs either work or sit in your stomach making you miserable.

Figure out your sweat type. Make sure sodium is part of your fueling plan. That's it. The rest takes care of itself.