How Much Sodium Do Endurance Athletes Actually Need?

Most endurance athletes assume progress comes from one thing:

Going longer in training.

More miles. More grit. More suffering.

But endurance doesn’t actually work that way.

What you’re really training is:

And after coaching hundreds of athletes through half Ironman, Ironman, and ultramarathon builds, I’ve seen one issue show up again and again:

Sodium is almost always underestimated.

This confusion is one reason so many endurance fuels end up overcomplicated - or underpowered.

→ Why most endurance fuels are over-processed

Athletes tend to focus on calories first.
Carbs get all the attention.

Electrolytes, especially sodium, are usually an afterthought.

That’s a problem.

Sodium is the primary electrolyte lost through sweat. When intake doesn’t keep up, a few predictable things happen:

None of this means an athlete is “out of shape.”
It usually means hydration and electrolytes aren’t aligned with the work being done.

I once worked with an athlete training for his first 70.3 who insisted on doing all his weekday sessions fasted.

No food.
No electrolytes.
No water.
Just willpower.

Every session felt like a grind.

Paces were hard to hit.
Recovery was poor.
Progress stalled.

The first adjustment wasn’t complicated.

We didn’t overhaul his diet.
We didn’t add supplements.

We added water and sodium.

For many athletes, the simplest improvement happens before training even starts.

The goal isn’t heavy fueling.
It’s hydration, electrolytes, and just enough energy to support the session.

A clean, practical baseline:

For many athletes, that looks like:

This amount is enough to:

Especially for:

You’re not fueling a race here.
You’re setting the conditions for the workout to feel easier than expected.

There isn’t one universal number, but there is a useful framework.

For sessions longer than 60 minutes, many athletes land in the range of:

That range comes from coaching experience, sweat-rate testing, and what athletes can realistically execute in training.

Heat, humidity, sweat rate, and intensity all influence the exact number, but this gives athletes a grounded place to start.

The issue is that many endurance fuels contain plenty of sugar and very little sodium, which leads to imbalance rather than support.

Sodium targets only matter if you know how to apply them in training. Here’s how I help athletes actually execute this without overthinking it:

→ How to fuel endurance training without bonking

Many athletes sense this and try to fuel with real food instead.

I’ve done it:

The carbohydrate side usually works.

The sodium side doesn’t.

Most real food contains almost no sodium. That leads to clean calories but poor fluid balance.

Clean fuel without electrolytes is like fueling your car with premium gas and forgetting the engine oil.

Technically clean.
Functionally incomplete.

Once sodium is accounted for, fueling becomes much simpler.

A well-designed endurance fuel should provide:

This combination helps athletes:

For most sessions under an hour, the goal isn’t maximum calories.

It’s hydration and electrolytes.

A simple approach:

For many athletes, a single 80-cal serving with ~217 mg sodium before or during the session is enough, especially:

You’re not fueling a race.
You’re removing unnecessary friction.

Once training extends past an hour, sodium requirements rise quickly.

A practical target:

Examples:

This keeps fluid balance steady, energy predictable, and digestion calm. Athletes can adjust up or down based on conditions, but this creates a clear execution framework.

Maple syrup works well as an endurance carbohydrate because it provides a natural mix of glucose and fructose that’s easy to digest and quick to absorb.

When paired with adequate sodium, it becomes a fuel that:

That combination is what eventually led to Maple Boost.

Not as a business idea, but as a cleaner, more complete way to fuel training.

Recovery doesn’t begin after the workout ends.

It begins with how well hydration and electrolytes are managed before and during training.

When sodium intake is too low, the body has to dig deeper to finish the session, which extends recovery time and makes consistency harder.

Fueling well supports:

Consistency beats hero workouts every time.

Like pacing, fueling improves with practice.

When sodium and hydration are aligned with training demands:

Endurance training stops feeling like punishment and starts feeling sustainable.

If you want a clean endurance fuel built around real carbohydrates and the sodium athletes actually need, you can learn more here:

→ Get Maple Boost

Related Guides

→ Why most endurance fuels are over-processed
→ How much sodium endurance athletes actually need
→ How to fuel endurance training without bonking