Carb loading for Hyrox: how much and when

Most Hyrox athletes either overthink carb loading or ignore it completely. Both cost you time on race day.

A Hyrox race runs 60 to 90+ minutes for most competitors, past the point where your glycogen stores alone can carry you through eight stations and 8km of running. Get the carbs wrong and you'll feel it on the last two runs: legs empty, pace dropping, sled feeling heavier than it should. Get it right and that fade doesn't happen, or it happens much later.

Here's what the research actually says, and what it means for your race.

What "carb loading" means for a Hyrox-length race

Carb loading, in the classic sense, is a marathon strategy: three days of high-carb eating to max out muscle glycogen before a 3+ hour effort. Most Hyrox racers don't need it. Your race is shorter and glycogen depletion isn't usually the limiting factor the way it is in an Ironman marathon leg.

What matters more for Hyrox is the 24 to 48 hours before the race, and what you take in during it.

Pre-race (24-48h): Shift your carb intake up and fat intake down slightly. You're not eating double your normal volume, you're prioritising rice, pasta, oats and fruit over fried food and heavy fats that sit in your gut. The goal is topped-up glycogen stores and a settled stomach, not a food challenge.

Race morning: Eat 1-4g of carbs per kg of bodyweight, 1-4 hours before the start. For a 75kg athlete, that's roughly 75-300g depending on how close to the start you're eating and how your gut handles food pre-race. Closer to the start, lean toward the lower end and simpler carbs (banana, white toast, a sports drink) over anything high in fibre or fat.

During the race: the number that matters

The International Society of Sports Nutrition's position on carbohydrate intake during extended, high-intensity exercise (over 60 minutes at above 70% VO2 max) is 30-60g of carbs per hour, ideally from a 6-8% carbohydrate-electrolyte solution taken in small amounts every 10-15 minutes (ISSN position stand on nutrient timing).

For events pushing past 2.5 hours, more recent guidance goes higher: up to 90g/hour using multiple transportable carbohydrate sources (glucose plus fructose, since they use separate gut absorption pathways and stack better than glucose alone). Most competitive Hyrox athletes fall in the 60-90 minute range, so the 30-60g/hour range is the practical target for most people reading this. Elite-level or slower age-group athletes racing closer to 75-90 minutes can lean toward the higher end of that range.

In practice: that's one gel (roughly 20-25g carbs) every 20-25 minutes, or sipping an electrolyte drink with carbs mixed in throughout. Don't wait until you feel the fade to start fuelling. By the time you notice it, you're already behind.

Why electrolytes matter alongside the carbs

Carbs without sodium is half the equation. You're sweating out electrolytes across an hour-plus effort in a warm venue, and sodium is what helps your body actually hold onto the fluid you're drinking instead of running straight through you. This is the whole logic behind a carbohydrate-electrolyte solution rather than plain water or a straight sugar hit.

If you've read our piece on isotonic vs electrolyte drinks for Hyrox, this is the same principle applied to race day itself: concentration matters as much as the ingredient list.

A simple pre-race and race-day plan

• T-minus 48h: Increase rice, pasta, oats, fruit. Ease off fried food and heavy fats.
• T-minus 2-3h: Main pre-race meal, carb-heavy, moderate protein, low fat and fibre.
• T-minus 30-60 min: Small, simple carb top-up if needed (banana, a few dates, a sip of an electrolyte drink).
• During the race: 30-60g carbs/hour, small and often, alongside sodium. Don't experiment with something new on race day, test it in training first.

Mistakes that wreck race-day fuelling

Trying something new on race morning. The gel, the drink, the pre-race meal, all of it should be tested in training first. Your gut has an opinion on new foods under stress, and Hyrox is not the place to find out what it is.

Waiting until you feel the fade. By the time low energy is noticeable, you're already 10-15 minutes behind on carbs. Set a timer or fuel on a schedule instead of waiting for a signal from your body.

Under-fuelling because you're worried about feeling sluggish mid-race. A few too many carbs cause mild stomach discomfort. Too few cause a hard fade in the last three stations. The second is the worse trade.

Ignoring sodium and only thinking about sugar. A carb source without electrolytes doesn't hold fluid as well. If your drink or gel is pure sugar, you're missing half of what actually keeps you hydrated through a long effort.

Don't guess this in training either

The same logic applies to any session over an hour: long Zone 2 rides, back-to-back conditioning blocks, or a full Hyrox simulation. If you've never practised fuelling mid-session, race day is the wrong place to find out your gut doesn't like a particular gel. Test your carb and electrolyte strategy on a training day that mimics race intensity and duration.

Electrolyte+ is built around this: 20 servings per pack, calcium-heavy formula designed to support hydration during longer efforts, £19.99. Worth trialling in training before you rely on it in a race.

Get the fuelling dialled in before race day and the last two stations stop being a lottery. That's the whole point.