A HYROX race sits in a brutal middle ground. It is too long to survive on stored energy alone and too intense to fuel casually like a slow marathon. Most athletes who blow up in the back half of a race did not fail on fitness. They failed on fuel. The good news is that fueling is one of the few race variables you can completely control, and the work starts days before you toe the line.

This guide walks through exactly how to eat, supplement and fuel from race week through to the final wall balls.

Why fueling matters more in HYROX than almost any other event

HYROX lives at or above your threshold for 60 to 100 minutes. Your body has two main fuel tanks: fat, which is nearly unlimited but slow to burn, and carbohydrate (stored as glycogen in your muscles and liver), which is fast burning but strictly limited.

Here is the problem. A trained athlete stores roughly 400 to 600 grams of glycogen, which sounds like a lot until you understand the burn rate. At HYROX intensity you can be churning through 3 to 4 grams of carbohydrate per minute. That is 180 to 240 grams per hour.

When glycogen runs low, your body does not politely ask you to slow down. Your running pace collapses, sled pushes feel like moving a house, your grip disappears on the farmers carry, and your brain gets foggy because your liver can no longer keep blood glucose stable. This is the wall, and in HYROX it usually arrives somewhere between the sled pull and the lunges.

The entire fueling strategy below exists to do two things: start the race with your tanks completely full, and keep drip feeding fuel in so you never hit empty.

The days leading in: how to lean into carbs

72 to 48 hours out: begin the carb load

Forget the single giant pasta dinner the night before. Real carb loading happens over two to three days, not one meal. The target is 8 to 10 grams of carbohydrate per kilogram of body weight per day. For a 75 kg athlete, that is 600 to 750 grams of carbs daily. It is more food than most people expect, and it takes intention.

Practical ways to hit the number:

• Build every meal around a carb anchor: rice, potatoes, oats, pasta, sourdough, fruit
• Add liquid carbs between meals. Juice, smoothies with banana and dates, and sports drinks all count and are easier to stomach than another plate of rice
• Drop your fat and protein slightly to make room. You do not need extra protein this week, you need glycogen
• Keep training volume low. Carb loading only works when you are not burning it off. Your taper and your carb load work together

24 hours out: same carbs, less fibre

The day before the race, keep the carbs high but shift to lower fibre sources. Swap brown rice for white rice, wholegrain bread for white bread, and go easy on big salads, legumes and cruciferous veg. Fibre is fantastic 51 weeks of the year. The day before a race, it just adds gut weight and risk.

Eat your biggest meal at lunch, not dinner. A moderate dinner around 6 to 7 pm gives your gut time to process everything overnight so you wake up light but loaded. Hydrate steadily all day and include sodium with your meals. You are storing water with that glycogen, and electrolytes help you hold it where you want it.

The supplement stack: what actually works

Four ergogenic aids have genuine evidence behind them for an event like HYROX. Here is how each works and how to time it.

Beta alanine: the long game

Beta alanine raises muscle carnosine, your internal buffer against the acidity that builds during hard efforts. More carnosine means you can hold higher intensities for longer before the burn forces you to back off. This matters enormously in HYROX, where the sleds, burpees and wall balls generate exactly the kind of acid load carnosine buffers.

The catch: beta alanine is a chronic supplement, not an acute one. It takes 4 to 6 weeks of consistent daily dosing at 3.2 to 6.4 grams to saturate your muscles. Taking it on race morning does essentially nothing. If your race is next week and you have not been loading, skip it and plan better for the next block. If your race is 6 or more weeks out, start today.

Sodium bicarbonate: the acute buffer

Where beta alanine buffers inside the muscle, bicarb buffers in the blood. It raises your blood pH slightly, creating a bigger gradient for acid to leave working muscle. The research on high intensity efforts in the 1 to 10 minute range is strong, and HYROX is essentially eight of those efforts stitched together with running.

Dosing: 0.2 to 0.3 grams per kilogram of body weight, taken 90 to 150 minutes before the start. For a 75 kg athlete that is 15 to 22 grams.

The warning label: bicarb is famous for gut distress. Never, ever try it for the first time on race day. Trial it in training at least three or four times. Strategies that reduce gut issues include splitting the dose over 30 to 60 minutes, taking it with a small carb rich meal, and using enteric coated capsule or lozenge formats rather than raw powder in water. If your gut simply will not tolerate it, leave it out. A working gut beats a marginal buffer every time.

Beetroot and dietary nitrate: cheaper oxygen

Beetroot is rich in nitrate, which your body converts to nitric oxide. Nitric oxide improves blood flow and, critically, reduces the oxygen cost of exercise. You produce the same power for less oxygen, which at HYROX intensity translates to a slightly lower heart rate at the same pace, or a slightly faster pace at the same effort.

The target is 6 to 12 mmol of nitrate (roughly 400 to 800 mg), taken 2 to 3 hours before the race. Even better, load daily for the final 3 to 5 days leading in, then take a final dose on race morning. Concentrated beetroot shots or a quality nitrate containing formula make the dose practical, because eating enough whole beetroot to hit 12 mmol is a genuine chore.

Athletic Energy: the stimulant free way to stack it

If managing three separate supplements with three separate timing windows sounds like a headache, this is exactly the problem a well built performance formula solves. Athletic Energy was formulated around the same evidence base above: nitric oxide support for blood flow and oxygen efficiency, buffering support for the acid load of stations, and steady energy without stimulants.

The stimulant free part matters more than people realise for HYROX. Many races run morning heats where a big caffeine hit wrecks pacing and gut comfort, and plenty of athletes race afternoon or evening heats where caffeine destroys that night's sleep and the recovery that follows. A stimulant free formula gives you the performance chemistry without the crash, the jitters on the start line, or the 2 am ceiling stare.

Timing: take it 30 to 45 minutes before your start, exactly as you have practised in training. Which brings us to the golden rule: nothing new on race day. Every supplement above should have been rehearsed in hard training sessions weeks before you race it.

Race morning: topping off the tank

Your glycogen is loaded from the days before. Race morning is about topping off liver glycogen (which drains overnight) and settling your gut.

3 to 4 hours before: eat your main meal, 2 to 3 grams of carbohydrate per kilogram. Think oats with banana and maple syrup, white toast with jam, or rice with a small amount of protein. Low fibre, low fat, familiar.

60 to 90 minutes before: a small top up of 30 to 60 grams of easy carbs. A banana, a few dates, white bread with honey, or a sports drink.

30 to 45 minutes before: your Athletic Energy or chosen formula, plus small sips of fluid. Stop drinking large volumes now so you are not racing with a sloshing stomach.

Fueling during the race: the part almost everyone skips

Here is the mistake: athletes assume a 60 to 90 minute event does not need fuel during. The research says otherwise, and the reason is depletion speed.

At the intensity HYROX demands, carbohydrate use runs at 3 to 4 grams per minute. Your liver glycogen, the store responsible for keeping your blood glucose and your brain online, holds only about 80 to 100 grams and was already partly drained overnight. Muscle glycogen in the specific muscles doing the work (quads on sleds and lunges, shoulders on wall balls) depletes locally and fast. You can hit the wall in one muscle group while the rest of you feels fine, and in HYROX that usually means legs that stop responding somewhere around station six.

There is also a second mechanism most athletes never hear about: carbohydrate signals directly to the brain. Even carbs that have not been fully absorbed yet reduce perceived effort and protect your pacing. Fuel taken at the halfway point is not just for the muscles, it is for the head.

The strategy:

• Races over 60 minutes need fuel during. Full stop. Target 30 to 60 grams of carbohydrate across the race
• Front half, not back half. Fuel taken at station seven is too late to help. Take your first hit early, around the 20 to 30 minute mark, ideally on a run leg where your breathing lets you swallow
• Format matters. Gels and liquid carbs beat anything you have to chew. Practical pattern: one gel around run 3 or 4, another around run 6, small sips of water or sports drink where the course allows
• Train your gut. The gut is trainable like any muscle. Practise taking your race fuel during hard interval sessions and simulations for at least 3 to 4 weeks before race day. An untrained gut rejects fuel exactly when you need it most

The complete timeline at a glance

The bottom line

Fitness gets you to the start line. Fuel decides what happens after station five. Load your carbs over days rather than hours, build your supplement stack on evidence and rehearse every piece of it in training, and never let a race longer than an hour run on an emptying tank. The athletes flying through the wall balls at the end are not always the fittest in the field. They are the ones who never ran out of fuel.

Train smart, fuel smarter.