By Sebastian Madlangbayan, founder of Cleonse: the world's cleanest 3-ingredient organic electrolyte.
For marathon training, the best electrolyte pairs real sodium with real carbohydrate, because on long runs you lose a lot of both. Aim to take in roughly 300 to 700mg of sodium and 30 to 60g of carbs per hour once you're past 90 minutes. Cleonse covers the sodium and part of the carbs cleanly.
I'm a lifelong competitive athlete and I run an electrolyte brand, so this is squarely in my wheelhouse, but I'll keep the advice honest and useful whether or not you ever buy my product. Marathon training is where hydration and fueling stop being optional and start deciding whether your long runs feel strong or fall apart at mile 18. Here's how to think about it.
Why long-distance running is different
A 30-minute jog and a three-hour long run are completely different physiological events. On a short run, water is usually fine and your body handles the rest. On a long run, two things stack up: you sweat continuously for hours, and you steadily burn through your stored carbohydrate (glycogen). Neglect either and you'll feel it.
The sweat side means losing fluid and, critically, sodium over a long stretch. The fuel side means your glycogen tank, which is only good for roughly 90 to 120 minutes of hard running, runs low. That's the famous "wall" — it's largely running out of accessible carbohydrate. Marathon training teaches your body to handle both better, but it doesn't remove the need to take fluid, sodium, and carbs in during the effort.
How much sodium and carbohydrate you actually need
Let's put numbers on it, with the honest caveat that individual needs vary a lot. General endurance-sports guidance lands in these ranges for runs longer than about 90 minutes.
| Per hour (runs over ~90 min) | General guidance |
|---|---|
| Fluid | ~400–800 ml, adjusted to thirst and heat |
| Sodium | ~300–700 mg (more for heavy/salty sweaters) |
| Carbohydrate | ~30–60 g (up to ~90 g for trained guts on race day) |
On the sweat side, remember that a runner can lose anywhere from a few hundred milligrams to well over 1,500mg of sodium per hour depending on sweat rate and saltiness. That's why a single stick of Cleonse at 500mg of sodium fits neatly into an hourly plan: it's a meaningful, real dose rather than a token amount. If you want the deeper dive, I wrote a whole guide on how much sodium athletes need.
Where the sugar in Cleonse actually helps
Most "clean" electrolyte brands are proud of having zero sugar. For marathon training, that's often a disadvantage, not a selling point, and here's why I built Cleonse the other way.
On a long run you need carbohydrate, full stop. The 24g of organic cane sugar in a stick isn't empty calories in this context — it's fuel that helps stave off the wall and also helps your body absorb the fluid and sodium alongside it. A mix of fluid, sodium, and carbohydrate is close to the classic definition of a good endurance drink. You'll likely still want additional carbs from gels, chews, or real food on very long runs to hit the higher end of the carb range, but the drink is pulling real weight, not just flavoring your water. The full breakdown is on our facts page, and I compared it to the cleanest options in my cleanest electrolyte guide.
An honest look at the tradeoffs
I want to be straight about where a drink like mine is not the whole answer, because marathon fueling deserves honesty.
Cleonse is sodium-forward. It doesn't add potassium or magnesium beyond the trace amounts in the sea salt, so if you're chasing a specific potassium or magnesium target, you'll get those from food or other sources. And 24g of sugar per serving won't suit a runner who is deliberately doing fasted or very-low-carb training; on those runs, a zero-sugar option or plain water makes more sense. Finally, for a full marathon's carbohydrate demand you'll almost certainly need more than a drink provides. Think of Cleonse as your clean sodium-plus-some-fuel base, layered with gels or chews for the rest. That's the honest picture.
A sample long-run hydration plan
Here's a simple template you can adapt. Test everything in training — never try something new on race day.
Before the run, start hydrated: drink water with your pre-run meal, and if you're a salty or early-morning runner, take in some sodium beforehand. During runs under about 60 to 75 minutes, water is usually enough. For anything longer, begin taking fluid with sodium and some carbohydrate early rather than waiting until you feel bad — a stick of an electrolyte drink mixed into 16 oz of water per hour is a solid anchor, supplemented with a gel or chews to reach your carb target. After the run, rehydrate with fluid and sodium, and eat a carb-and-protein meal to kick off recovery.
The single biggest mistake I see is under-doing sodium on hot long runs and then wondering why the legs feel dead. Match your intake to your sweat rate and the weather, and dial it in over your training block so race day feels automatic.
Signs you're getting your hydration wrong
Your body gives you feedback on long runs if you know what to look for. Learning to read it is half the battle, and it's free.
Under-hydrating or under-doing sodium on a hot run often shows up as legs that feel heavy and flat well before you're truly tired, a heart rate that drifts higher than the pace should warrant, or the sloshing, queasy feeling of fluid sitting in your stomach because there isn't enough sodium to help it absorb. Muscle cramps late in a run can have several causes, but a salty sweater who cramps repeatedly on long efforts is often someone whose sodium intake isn't keeping up.
On the flip side, you can overdo fluid. Drinking far more plain water than you're sweating, with little or no sodium, can dilute your blood sodium and leave you feeling worse, not better. The fix isn't to drink less water blindly — it's to pair your fluid with sodium so the balance stays right. That balance is the entire reason electrolyte drinks exist.
How the drink fits with gels, chews, and salt tablets
Marathoners rarely rely on a single product, and you shouldn't feel like you have to either. Think of your fueling as a stack. A sodium-plus-carb drink like Cleonse is a clean base layer that handles your fluid, a real dose of sodium, and some carbohydrate at once. Gels and chews sit on top to push your carbohydrate intake toward the higher end on very long runs. Some heavy sweaters add plain salt capsules on especially hot days when their sodium losses outrun what the drink provides.
The advantage of starting from a clean, real-ingredient drink is that your base layer isn't full of dyes and artificial sweeteners you didn't ask for. You add exactly the extra fuel you need on top, and nothing else. Simple, honest, and adjustable to the day in front of you.
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Shop CleonseFrequently asked questions
How much sodium should I take per hour on a long run?
A common range is about 300 to 700mg per hour for runs over 90 minutes, with heavy or salty sweaters needing more. A stick of Cleonse provides 500mg, which fits neatly into that plan.
Do I need carbs during marathon training runs?
Yes, once runs pass roughly 90 minutes. Aim for about 30 to 60g of carbohydrate per hour. The cane sugar in Cleonse contributes some of that; gels, chews, or food usually make up the rest.
Is sugar in an electrolyte drink bad for runners?
Not during long runs — it's fuel that helps prevent the wall and aids fluid absorption. It's less useful on short, easy, or fasted runs, where water or a zero-sugar option may be preferable.
Can I just use water on long runs?
For runs under about an hour, often yes. Beyond that, water alone doesn't replace the sodium you're sweating out or the carbohydrate you're burning, and performance and comfort tend to suffer.
Should I practice my hydration in training?
Absolutely. Your gut adapts to taking in fluid and carbs on the run. Rehearse your exact race-day plan during long training runs so nothing is a surprise on the day.
Keep reading
- Best Electrolytes for Runners
- How Much Sodium Do Athletes Actually Need?
- Do Electrolytes Need Sugar?
Editor's note: Endurance fueling ranges (sodium ~300–700mg/hr, up to 1,500+ mg/hr lost by heavy sweaters; carbohydrate ~30–60g/hr, up to ~90g/hr on race day for trained athletes) reflect general sports-science guidance summarized by Precision Hydration and endurance-nutrition sources, verified September 2026. Cleonse figures reflect the current product label. This article is general information, not medical or dietary advice; consult a professional for a personalized plan.