How to Fuel for HYROX: A Race-Day Guide | Everyday Athlete

I've completed five HYROX races. In those five, I hit the wall in one, cramped in another, had gut issues in a third, and felt great in the others.

That mixed scorecard sent me down the research rabbit hole. How do you fuel to minimize hitting the wall, cramping, and an upset stomach, while maximizing feeling great?

Here's what I learned, organized into one guide you can use for your next race.

Why HYROX fueling is different

HYROX uniquely challenges both of your body's energy systems: aerobic and anaerobic. Aerobic powers the runs and endurance. Anaerobic powers the strength stations — sled push, burpee broad jumps, wall balls.

That combination depletes glycogen — the energy stored in your muscle and liver — faster than a marathon or a CrossFit workout. Without consuming fuel carbs, you will hit the wall. I did, in my first race.

This is why most generic running-gel advice undershoots HYROX athletes. The runs are only half the equation. The stations burn glycogen at a rate closer to a strength session, and there is no time to recover. Your fueling strategy has to do two things at once:

1. Maximize stored energy (glycogen reserves) before the race.
2. Maintain usable energy (blood glucose) during the race.

Everything below works toward those two goals.

The 48-hour race-day timeline

Here's the full fueling and hydration timeline from 48 hours out to 10 minutes after the finish line.

The sections below explain the why behind each row.

Pre-race fueling: carb-loading + the 10-minute gel

The 48-hour carb-load

To store as much glycogen in your muscles as possible, increase carb consumption for the 48 hours leading into race day. The research-backed target is roughly 9g of carbs per kg of bodyweight per day, about 4g per lb.

What that actually looks like:

• 150 lb athlete: ~600g carbs/day
• 175 lb athlete: ~700g carbs/day
• 200 lb athlete: ~800g carbs/day

That's a lot more than most people think. A sample day for a 175 lb athlete might include: a large bowl of oats with banana and honey for breakfast (~120g), a turkey sandwich on a baguette with fruit (~150g), pasta with chicken and a roll for dinner (~200g), plus snacks and a sports drink. Track it once or twice. Most athletes are under-fueling by 30–40% without realizing it.

Combined with reduced training volume in the days before the race, this loads your muscles with glycogen. Each gram of glycogen also binds to roughly 3 grams of water, so carb-loading doubles as hydration-loading.

Your final meal should be about 3 hours before your start time, high in easily digestible carbs (rice, pasta, potatoes, white bread), moderate protein, low fat and fiber.

The 10-minute pre-race gel

The final pre-race fuel, taken 10 minutes before the start, is where most athletes go wrong. The type of carb matters as much as the timing.

Glucose and maltodextrin have high glycemic scores, meaning they spike blood glucose fast. That's ideal mid-race when you need energy quickly. Pre-race, it's a trap. The process goes: high-glycemic carbs → blood sugar spike → high insulin response → glucose pushed into cells → blood sugar crash. You feel shaky, lightheaded, and weak, right when the gun goes off.

There are two ways to avoid this:

1. Low-glycemic carbs don't spike blood sugar. Palatinose — a glucose-fructose chain naturally derived from beets — has a glycemic score of 32, compared to glucose at 100 and maltodextrin between 85 and 136. It's absorbed steadily in the small intestine. Low blood sugar response, stable insulin, steady energy.
2. Adrenaline suppresses insulin. When adrenaline is released at the start of exercise, it temporarily mutes insulin secretion. This is why athletes can take high-glycemic carbs mid-race without crashing. The catch: if you take fast carbs too early, before adrenaline kicks in, you crash anyway.

The ideal pre-race gel benefits from both: low-glycemic palatinose blended with a smaller amount of fast-acting carbs, taken 10 minutes before the start. That's how we built our Energy gel.

Intra-race fueling: how often, how much, what kind

The unique physical demands of HYROX mean you have to fuel during the race.

Research suggests 30–60g of fuel carbs per hour, ideally split into smaller doses. For most athletes that's one gel every 20–30 minutes.

Take gels in transition moments. Avoid taking one right before a high-intensity station. You don't want to be swallowing a gel mid-sled push. In Doubles, the timing is easier because you're resting while your partner works. In Singles, here's the timing I use:

Dual-carb fueling: glucose + fructose

The goal is to maximize absorption in your gut while minimizing GI distress.

Your gut absorbs carbs through two pathways: glucose through one transporter (SGLT1) and fructose through another (GLUT5). Traditional gels optimize for glucose only, but glucose transporters are limited. They can absorb about 60g/hr at most. Excess glucose sits in your gut unabsorbed and causes the cramping, bloating, and nausea every endurance athlete has experienced.

Newer research shows you can absorb more total carbs with less GI risk if you target both pathways at once. That's dual-carb fueling.

Palatinose is a natural glucose-fructose chain, which is why we use it as the primary carb in our gels. It hits both transporters and releases steadily.

Hydration and electrolytes

Hydration is the other half of fueling. HYROX's intensity and duration produces high sweat rates and significant sodium loss.

Proper hydration ensures your blood pumps oxygen and nutrients efficiently to your muscles, prevents cramps, and helps your body manage its temperature. If you lose too much water and electrolytes, your performance drops or you crash entirely.

Muscle cramps are common in HYROX. I've experienced this, it sucks. They're driven by depleted sodium, potassium, and magnesium. Sodium in particular helps your body retain water and avoid cramping. These same electrolytes are also required for neuromuscular signaling, how your brain tells your muscles to fire for the strength stations.

Pre-race hydration: water + electrolytes

The bulk of hydration happens in the 48 hours before the race, not during it. The goal is to expand your blood plasma volume and store extra water in your cells.

• 2 days out: 2–3L of water per day with 1,500–3,000mg sodium
• 3 hours out: ½ liter with electrolytes
• 30 min out: A glass of water with sodium electrolytes

Sweat rate varies a lot. Typical losses are between 500 and 1,500mg of sodium per liter of sweat. If you're a heavy sweater (visible salt stains on your training shirts), aim for the higher end of the sodium range.

Intra-race hydration: optional

If you've pre-loaded properly, minimal hydration is needed during the race. Too much water mid-race can actually increase GI distress and slow you down.

There are hydration stations in the Roxzone with small cups of water. A couple of sips throughout the race is enough. Some gels, including ours, have electrolytes built in, which covers the gap.

The general rule: carb intake intra-race matters far more than water intake.

Caffeine strategy

Caffeine is one of the most widely studied and reliable performance supplements. It's particularly well-suited to HYROX because it improves both endurance (the runs) and sprint power (the strength stations).

That said, caffeine is highly individual. Test it in training before you trust it on race day.

Research generally supports 100–200mg as an effective dose with minimal jitters or GI risk. Adjust based on body weight and sensitivity.

The timing: 30 minutes before the start, with an optional smaller dose (75–100mg) mid-race for a strategic boost. Our Energy gel contains 75mg caffeine. Most of our athletes use one pre-race and a second mid-race.

Training your gut

Your gut also needs training. Don't take 60g of carbs per hour for the first time on race day.

Start lower and build over 3–4 weeks. Aim to train your gut above your target race intake, so you have a buffer.

If you plan to take 60g/hr on race day, your gut should be able to handle 80g/hr comfortably. That buffer is what keeps GI distress out of your race.

Race-day mistakes to avoid

Five mistakes I've made or watched others make. Each one is easy to skip.

1. Trying a new gel for the first time on race day

Whatever you race with, you should have used at least 5 times in training. Different formulations sit differently in your gut. Race morning is the worst time to find out.

2. Carb-loading with high-fiber foods

Whole grain bread, beans, kale, raw vegetables — all great in normal training nutrition, all wrong for the 24 hours before HYROX. They sit in your gut and cause cramps mid-race. Go with white rice, white pasta, white bread, potatoes, bananas. Boring is the goal.

3. Front-loading caffeine before adrenaline kicks in

Taking 200mg of caffeine 2 hours before your start can leave you peaking before the gun goes off and crashing during the runs. Time it to peak when your adrenaline is highest, 30 minutes before start.

4. Skipping the post-race refuel window

The 10–30 minute post-race window is the highest-return recovery period of the entire race. Replenishing glycogen and starting protein synthesis in that window measurably reduces next-day soreness. A Refuel gel right after you cross the line covers it, but anything (chocolate milk, a protein shake plus banana) is better than nothing.

5. Hydrating with water only

Drinking liters of plain water before a race can actually dilute your sodium levels and increase cramping risk. Water is half the equation. Electrolytes, especially sodium, are the other half.

FAQ

How long should I carb-load before HYROX?

48 hours is enough for most athletes. Target around 4g of carbs per pound of bodyweight per day (roughly 9g per kg). Reduce training volume in those 48 hours so the carbs go to glycogen storage instead of getting burned in workouts.

What should I eat the morning of a HYROX race?

A high-carb, low-fat, low-fiber meal eaten about 3 hours before your start time. Oatmeal with banana and honey, a bagel with jam, or rice with a small portion of lean protein all work. Avoid anything new, anything greasy, and anything high in fiber.

How many gels should I take during a HYROX?

Most athletes do well with one gel 10 minutes before the start and 2–3 gels during the race — one every 20–30 minutes. That puts total race-day intake at 3–4 gels, depending on your finish time. Take them during transitions, not before high-intensity stations.

Can I do HYROX without taking any gels?

You can finish a HYROX without fueling. You will almost certainly not perform at your best. Glycogen depletion is the single biggest reason athletes hit the wall in the back half. Even a single pre-race gel and one mid-race gel will make a noticeable difference.

What's the best gel for HYROX?

Look for three things: dual-carb (glucose + fructose, or palatinose), low-glycemic for pre-race, and electrolytes built in. Our Energy gel is built specifically around these requirements for hybrid athletes. There are other good options — what matters is that you've trained with whatever you use.

How much caffeine should I take before HYROX?

100–200mg total, ideally split between 30 minutes pre-race and an optional mid-race dose. Test in training first. If you're sensitive to caffeine or racing late in the day, skip it.

What should I eat after a HYROX race?

Within 10–30 minutes: carbs and protein together. A Refuel gel gives you 20g of protein, dual-carbs, and creatine in one shot. If you don't have one, chocolate milk plus a banana works. Within 2 hours, eat a full meal.

How do I avoid cramping during HYROX?

Cramping is mostly about sodium status, not water. Pre-load with electrolytes for 48 hours, take in 1,500–3,000mg of sodium daily, and choose gels that include electrolytes. Heavy sweaters need more.

Is carb-loading worth it for a sub-90-minute race?

Yes. HYROX depletes glycogen faster than equivalent-duration steady-state endurance because of the strength stations. Even at 70 minutes, a carb-loaded athlete will outperform an under-fueled version of themselves.

What's the difference between an energy gel and a recovery gel?

An energy gel is built for performance — fast-absorbing carbs, optional caffeine, electrolytes. A recovery gel is built for what comes after — protein, carbs to replenish glycogen, and often creatine to support next-session readiness. Our Fuel System pairs one of each.

Fuel to feel strong

The goal is simple: maximize feeling great, minimize hitting the wall, cramping, and gut issues. The system that gets you there:

• Carb-load and hydrate with electrolytes for 48 hours
• Use dual-carb, low-glycemic gels 10 minutes before the race and every 20–30 minutes mid-race
• Train your gut in advance
• Find your ideal caffeine dose
• Refuel within 10 minutes of finishing

That's the playbook. Run it.