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.

For most competitors a Hyrox takes 60-90+ minutes, which is past the point where 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: empty legs, a dropping pace and a sled that feels heavier than it should. Get them right and that fade either never comes or comes much later.

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

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

Classic carb loading is a marathon strategy: three days of high-carb eating to max out muscle glycogen before a 3+ hour effort. Most Hyrox racers can skip it. Your race is shorter, and glycogen rarely runs out the way it does on the marathon leg of an Ironman.

For Hyrox, the 24-48 hours before the race matter more, along with what you take in during it.

Pre-race (24-48h): Nudge your carbs up and your fat down slightly. Keep your portions roughly normal and choose rice, pasta, oats and fruit over fried food and heavy fats that sit in your gut. You're after topped-up glycogen and a settled stomach.

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 eat and how your gut copes with food before a race. The nearer you get to the start, the more you should lean towards the lower end and simple carbs (banana, white toast, a sports drink) and away from anything high in fibre or fat.

During the race: the number that matters

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

For events past 2.5 hours, newer guidance goes higher: up to 90g an hour from mixed carb sources. Glucose and fructose use separate absorption routes in the gut, so together they stack better than glucose alone. Most competitive Hyrox athletes finish in 60-90 minutes, so 30-60g an hour is the practical target for most people reading this. If you're racing closer to 75-90 minutes, lean towards the top of that range.

In practice that's one gel (roughly 20-25g carbs) every 20-25 minutes, or sipping an electrolyte drink with carbs in it throughout. Start fuelling before you feel the fade. By the time you notice it, you're already behind.

Why electrolytes matter alongside the carbs

Carbs without sodium only cover half of it. You're sweating out electrolytes for over an hour in a warm venue, and sodium helps your body hold on to the fluid you drink. That's the whole logic behind a carbohydrate-electrolyte drink.

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

A simple pre-race and race-day plan

• T-minus 48h: Eat more rice, pasta, oats and fruit. Ease off fried food and heavy fats.
• T-minus 2-3h: Main pre-race meal: carb-heavy, moderate protein, low in fat and fibre.
• T-minus 30-60 min: A small, simple carb top-up if you need it (banana, a few dates, a sip of electrolyte drink).
• During the race: 30-60g carbs an hour, small and often, alongside sodium. Test everything in training first, and keep race day for things you've already tried.

Mistakes that wreck race-day fuelling

Trying something new on race morning. The gel, the drink and the pre-race meal should all be tested in training first. Your gut has opinions about new food under stress, and a Hyrox is a bad place to hear them.

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 and fuel on a schedule.

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

Thinking only about sugar and forgetting sodium. A carb source without electrolytes holds fluid less well. If your drink or gel is pure sugar, you're missing half of what keeps you hydrated through a long effort.

Practise it in training too

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 fuelled mid-session, race day is the wrong place to find out your gut hates a particular gel. Test your carb and electrolyte plan on a training day that matches race intensity and duration.

Electrolyte+ is £19.99 for 20 sticks, with 1500mg of electrolytes per stick. Trial it in training before you rely on it in a race.

Sort your fuelling before race day and the last two stations stop being a lottery. That's the whole point.