The Ultimate HYROX Fuelling & Hydration Guide

HYROX is a unique test of strength, endurance, pacing, and mental grit. Eight 1 km runs, each followed by a functional workout station, means your energy systems are under constant strain, oscillating between high aerobic loads and explosive anaerobic bursts.

Whether you're a first timer, an experienced hybrid athlete, or transitioning from CrossFit, triathlon, or obstacle course racing, proper fuelling and hydration can make or break your performance.

In this guide, we’ll break down the science of how to fuel and hydrate before, during, and after your HYROX event in a simplistic, easy to follow guide, which you can use to guide your fuelling and hydration strategies going forward.

Why Fuelling and Hydration Matter in HYROX?

HYROX races can take anywhere from 55 minutes to over 2.5 hours depending on category and fitness level. Regardless of pace, this high-intensity format means:

• Elevated carbohydrate demand
• Significant sweat loss
• Constant muscular fatigue and cognitive load

Unlike a straight endurance event, HYROX uniquely taxes glycogen stores while also demanding fluid and electrolyte balance for neuromuscular control.

So if you want to sustain performance and avoid crashing mid-race, fuelling and hydrating smartly is essential.

Pre-Race Fuelling: What to Eat Leading Up to HYROX

The Day Before Your Race

To ensure your muscle and liver glycogen stores are topped up aim for the below:

• Carbohydrate intake: 6 - 8 g/kg of body weight over 24 hours (more if racing >2 hours)
• Focus on low-fibre, low-fat, high-carbohydrate foods: rice, potatoes, pasta, oats, bananas, sports drinks
• Don’t drastically overeat. Considering spreading your carbs across your meals and snacks. An easy way to ensure you get all your hydration, carbs and electrolytes is using a drink mix like Active Vita’s drink mix which carries enough electrolytes for even the sweatiest of sweaters and easy to dose carbohydrates.

If you're sensitive to large carb intakes you could always split your intake across 5 - 6 small meals instead of 3 big ones or again, take it in fluid form.

Race Morning

Your pre-race meal should:

• Be eaten 2 - 3 hours before start time
• Contain 1 - 2 g/kg body weight of carbs
• Be familiar, digestible, and low in fibre and fat

Example options:

• White rice with scrambled eggs
• Toast with honey or jam
• Oats with banana and a scoop of protein

30 - 60 Minutes Before Start

Just before the event you can top off with:

• 1 - 2 carb-rich snacks (banana, 2-5 dates depending on which ones you choose, concentrated drink mix, 30 g energy gel or chews)
• Small sip of an electrolyte + carb drink if desired

Pre-Race Hydration: Avoid Starting Dehydrated

Starting the race even mildly dehydrated can impair:

• Thermoregulation
• Muscle contraction
• Mental focus
• Power output

To avoid this you want to build up some reserves. Here’s a couple ways you can do just that:

The Night Before

• Drink around 500 ml of water with electrolytes (sodium-based) 60 - 90 minutes before bed

Race Morning

• Est. 500 ml electrolyte drink 90 minutes before start
• Small sips of water up until 15 minutes before go time

Why electrolytes? Sodium helps retain fluid, supports nerve transmission, and reduces the risk of cramping, which especially important for heavier sweaters or warm conditions.

Remember, hydration isn't about chugging litres of water. It’s about balancing fluid and electrolytes in the right amounts that you can both digest and use.

During the Race: What Should You Fuel With?

For most athletes, HYROX lasts 75 - 105 minutes. This duration lands in a fuelling "grey zone": long enough to benefit from in-race carbs, but short enough that too much can cause GI discomfort if you’re untrained. Especially with all the jostling up and down, athletes can become very vulnerable to GI issues.

General Guidelines:

• Consume 30 - 60 g of carbs per hour if racing over 75 mins.
• For <75 minutes, a small amount (15 - 30 g) may still be beneficial for late-race energy.
• Use gels, chews, or carb-rich drink mixes that are easy to absorb under intensity.

How to Take It:

• Consider using transitions (after ski erg, before sled push) to consume carbs.
• Chews or diluted drinks may be better tolerated than thicker gels during high breathing demand.
• Carry chews in pockets or gel flasks with gels or drink mix and absolutely practice this in training.

Hydration During HYROX: Do You Need to Drink?

Yes - but keep it simple.

• Sweat rates are high due to intensity, clothing, and indoor race environment. Unless you are lucky enough to get an air con environment but even then air cons are extremally dehydrating so while you may not be sweating you will still need to offset this.
• If your race lasts over 75 mins or you’re a heavy sweater, aim for 200 - 300 ml of fluid every 25 - 30 minutes.
• Include electrolytes (especially sodium) to avoid cramps and to retain fluids.

If aid stations are sparse, use small soft flasks in your race belt as mentioned above, or drink around 300 ml of drink mix just before entering the arena.

Caffeine: Performance Aid or Overrated?

Caffeine has been shown to enhance endurance, delay fatigue, and reduce perceived exertion.

For HYROX, you might consider:

• 3 - 6 mg/kg of body weight 45 - 60 minutes pre-race (e.g., caffeine gel or black coffee). Caffeine can take up to 60minutes to take effect so unless you want to stay perky after the event, we suggest take it before your group starts so the effects kick in near the finish line…. Just when you need it!
• Again, testing caffeine intake during training is an absolute must as it can lead to jitters, GI issues, or disrupted hydration. Ultimately, the timing and tolerance matter.

Example: A 70 kg athlete may benefit from 200 - 300 mg caffeine pre-race

Training the Gut: Use this to your advantage

If you plan to race with carbs, train with carbs.

This helps:

• Reduce risk of nausea, bloating, and cramping on event day.
• It improves carb absorption and oxidation rates.
• It also boost confidence in your fuelling plan.

Try to include your race-day drink mix or gel strategy in training sessions such as bricks, intervals, and simulations. High and low intensity and in between different activities. This will highlight areas you are most sensitive (e.e., just before burpees) to taking anything onboard and show you slots in your event where you can fuel up and blast on, such as an easy-ish run between stations.

Think of it like pacing practice but for your gut.

Post-Race Recovery: Don't Neglect the Aftermath

You’ve just completed a high-load event. Your muscles, nervous system, and glycogen stores are depleted. As much as a celebration is well-deserved and on the cards, you may want to consider getting in some quality fuelling before the celebration kicks in. This is to help you recover faster, lessen your chances of crashing later and boost your immune system after a thrashing.

Post-race priorities:

1. Rehydrate: Water + electrolytes is key to recovery when replacing lost fluids, not just water. Go for 500 - 750 ml of fluids in this instance.
2. Refuel: 1.2 g/kg of carbs + 0.3 g/kg protein within 1 hour to optimise that window of opportunity and instantly repair the hard worked muscles and depleted glycogen stores.
3. Relax: Low-intensity walking, cooldown, or active mobility can help ease the aches and pains, especially the following day. Going home and couching it will likely result in cramps and greater next day stiffness.
4. Restore: Prepare the necessary to get a good night’s sleep as this is where a lot of your recovery happens. Taking in high-protein meals, and hydration in the next 24 hours will help you return to your normal self sooner.

A carb-protein drink mix that delivers both glycogen replenishment and electrolytes can tick several boxes at once here and yes you can mix different products to get your optimal concoction.

Common HYROX Fuelling Mistakes to Avoid

• Starting under-fuelled or under-hydrated.
• Trying new foods or gels on race day.
• Overdoing fibre, fat, or caffeine before racing.
• Not practicing in-race fuelling in training.
• Assuming you don’t need to eat if your race is <90 mins.

If you’re training for your next HYROX event, try integrating your fuelling and hydration strategies in your bricks, long runs, or high-intensity circuits.

HYROX rewards athletes who can manage intensity, movement quality, and fatigue under pressure. Nutrition and hydration are not side notes, they’re performance enablers.

Whether your goal is to finish strong, podium, or simply beat your last time, dialling in your fuelling strategy is one of the most impactful and easiest upgrades you can make.

Start practicing it now. Train the way you want to race and fuel like performance depends on it because it does.