Ironman Changed Its On-Course Hydration — How to Rebuild Your Race Nutrition Plan

If you've raced an Ironman or 70.3 in the last few years, your on-course nutrition just changed underneath you. Ironman has replaced traditional sports drinks with PH1000 — a low-calorie electrolyte formula delivering 1,000mg of sodium per litre — and shifted all carbohydrate delivery to Maurten products. Globally.

That's not a minor tweak. It's a fundamental redesign of what's waiting for you at the aid station.

Here's what that means, why it matters more than you think, and how to rebuild your race nutrition plan from the ground up.

What Actually Changed

For years, Ironman courses served a carbohydrate-rich sports drink — Gatorade Endurance in North America, similar formulas elsewhere. Athletes could grab a cup at every aid station and get both fluid and fuel in one go.

That model is gone.

The new on-course setup separates hydration and fueling into two distinct streams:

Hydration: PH1000, an electrolyte drink with minimal calories. Its job is to replace sodium and fluid — roughly 1,000mg of sodium per litre, which is close to the average athlete's sweat sodium concentration. It is not a fuel source.

Fueling: Maurten gels and drink mix, available separately. These deliver carbohydrates through a hydrogel matrix designed to pass through the stomach faster than traditional gels.

The key shift: hydration and carbohydrate delivery are now completely decoupled. If your previous plan assumed you were getting 30–40g of carbs per hour from the on-course drink, that math no longer works.

Why This Breaks Most Race Plans

The average Ironman athlete needs 60–90g of carbohydrates per hour on the bike and 30–60g per hour on the run. Previously, a chunk of that came "free" from the sports drink at every aid station. Athletes could plan around it — carry fewer gels, rely on course support.

Now the on-course drink gives you sodium and fluid, not carbs. If you don't adjust, you'll end up with a carbohydrate deficit that compounds hour after hour. By the time you hit the run, the shortfall catches up. You bonk — and you have no idea why, because you drank at every station and still took your gels.

This isn't hypothetical. It's the mistake thousands of athletes will make at their next race if they don't rebuild their plan.

The Bigger Lesson: Stop Outsourcing Your Nutrition

Here's the thing most athletes miss: this problem isn't unique to Ironman.

Every race can change its on-course products. Marathons switch from one gel brand to another between years. Aid station spacing varies by event. Some races serve flat cola at mile 20; others don't. The weather on race morning might be 10 degrees hotter than any forecast predicted.

If your nutrition plan depends on what someone else puts on a table at mile 14, it's not really a plan. It's a hope.

The athletes who consistently execute on race day are the ones who own their fueling from start to finish. They carry what they need, they've tested it in training, and anything they grab on course is a bonus — not a lifeline.

How to Rebuild Your Plan in 5 Steps

Step 1 — Calculate your actual carbohydrate target per hour

Forget the generic "30–60g" range. Your target depends on your body weight, your exercise intensity, your finishing time, and how well you've trained your gut.

A 60kg athlete racing a 5:30 bike split has different needs than an 85kg athlete racing 4:45. Start with a baseline of 1g of carbohydrate per kilogram of body weight per hour, then adjust up or down based on your training data.

If you've been practising gut training on your long sessions — and you should be — you may tolerate 80–90g per hour or more. If you haven't, start conservative at 40–50g and build from there over the next training block.

Step 2 — Map your carb sources

With hydration and fueling separated, you need to know exactly where every gram of carbohydrate is coming from.

Write it out: gels, chews, bars, drink mix in your bottles, and whatever you plan to take from the course. Account for each item's carb content. If you're using Maurten gels (25g carbs each) and your target is 80g per hour on the bike, you need roughly three gels per hour plus a carb drink mix in your bottles — or you need to supplement from another source.

Don't rely on mental maths at hour four of a race. Plan it on paper first.

Step 3 — Separate your hydration plan

Now that the course drink is electrolytes-only, your hydration plan is actually simpler — but you need to be deliberate about it.

Your fluid target depends on your sweat rate, which varies with temperature, humidity, and intensity. Most athletes lose between 500ml and 1,500ml of sweat per hour. If you've never measured yours, do a weigh-in test on your next long ride or run: weigh yourself before and after, add back any fluid you consumed, and divide by hours.

On race day, aim to replace 60–80% of your sweat losses. The PH1000 on course handles sodium replacement well — 1,000mg per litre is close to the average sweat sodium concentration. Drink to your plan, not to thirst. Thirst lags behind actual fluid needs, especially in the heat.

Step 4 — Test everything in training — now

You have weeks, not months. Every long session between now and race day is a dress rehearsal for your nutrition plan.

Use the exact products you'll race with. Practise the timing. Practise taking gels at race intensity, not easy-run intensity — your gut behaves differently when blood flow is redirected to working muscles.

If a product doesn't sit well, you want to find out on a Saturday long ride, not at the Ironman aid station at kilometre 130.

Step 5 — Build a backup plan

What if you drop a gel? What if the Maurten on course is gone by the time you reach the aid station? What if your stomach turns at hour three?

A good race nutrition plan has a Plan B. Carry one or two extra gels beyond what your plan requires. Know which on-course items you can tolerate as backup. And know your minimum viable carb intake — the floor below which you'll start losing performance.

What Your Watch Data Already Tells You

Here's what most athletes don't realise: you already have the data to build a better plan. Your Garmin, Apple Watch, or Strava history contains your heart rate across different intensities, your training load trends, and (on newer Garmin models) estimated sweat loss per session.

The problem isn't data. It's translation. Knowing your average heart rate on a three-hour ride doesn't automatically tell you how many gels to carry. Seeing that your Garmin estimated 1.8 litres of sweat loss doesn't tell you how much sodium you need to replace.

That's the gap — and it's exactly why Sweatr exists. Sweatr pulls your wearable data, factors in your body weight and training history, and builds a personalised fueling plan you can actually follow on race day. Not a range. Not a guess. A specific plan: what to take, when to take it, and how much.

If Ironman's hydration change has you rethinking your nutrition strategy, that's a good thing. It means you're taking race fueling seriously. The next step is building a plan that's yours — not one that depends on what's on the table at the next aid station.

The Bottom Line

Ironman's move to PH1000 and Maurten is the biggest on-course nutrition change in years. It's a wake-up call: the era of "grab a cup and hope for the best" is over.

But the principle has always been true. The best race nutrition plan is one you own, one you've tested, and one that's built from your data — not from generic averages or whatever the race happens to be serving this year.

Build it now. Test it in training. Execute it on race day.

Sweatr calculates your personalised race-day fueling plan using your Apple Watch, Garmin, and Strava data — so you know exactly what to drink and eat, mile by mile. Try it free.