Poor hydration can cost you 5 to 10% of performance in a HYROX race. Here's a simple protocol, based on your bodyweight, for the 24h before, the morning and during the race.
HYROX Hydration: why a few sips can earn you minutes
A 2% body water loss is enough to drop performance by about 10%. On a 90 minute HYROX, that's 9 minutes. More than what you can gain with an extra month of training. Yet hydration is what most amateur athletes neglect the most.
It's not about drinking a lot. It's about drinking at the right time, with the right content, in the right amount. Here's a simple protocol based on your bodyweight, to apply starting in the 24 hours before your race.
What happens when you dehydrate during a race
- Your blood volume drops, your heart has to pump more to deliver the same oxygen to your muscles.
- Your core temperature rises faster, degrading your neuromuscular performance.
- Your muscles get stiffer, increasing the risk of cramps (the famous calves that lock up on the sled push).
- Your focus drops, and it shows first on wall balls and burpee broad jumps.
24 hours before: prep the ground
The base calculation
Aim for a total water intake equal to 40 ml per kilogram of bodyweight over the day. For a 75 kg athlete, that's 3 litres spread out. For 60 kg, 2.4 litres. For 90 kg, 3.6 litres. That's your baseline, slightly adjusted upward if you train the day before or if it's hot.
Spread it across the day
Stagger the intake: 500 ml on waking, 500 ml in the morning, 500 ml in the afternoon, 500 ml in the evening, and the rest with meals. Never drink 1 litre at once, it's pointless and you'll just urinate it all out.
The urine colour test works well: aim for pale yellow, not transparent (excess) or dark yellow (deficit). It's the fastest feedback to adjust.
Sodium and electrolytes the night before
At your evening meal, salt a bit more than usual. This is not the time to eat bland. Sodium helps retain water in muscle cells, and you'll lose plenty during the race through sweat. A solid pinch of salt on a pasta dish is exactly what you need.
Race morning
On waking
500 ml of water immediately, with a pinch of salt or a dose of electrolytes. Your body lost water during the night, this is the first refill.
With breakfast (3h before the start)
300 to 400 ml alongside the meal. No more. If you drown your breakfast in 1 litre of water, you'll slow your digestion and end up with stomach weight on the first station.
In the 90 minutes before the start
Drink in small sips: 100 ml every 15 minutes. You absorb better, you eliminate less, and you arrive at the start line hydrated without needing to use the bathroom during the first race section.
15 minutes before the gun
One last sip of 100 to 150 ml. Then nothing. That's enough to wet your mouth and trigger the salivation reflex without overloading the stomach.
During the 8 km and 8 stations
The HYROX format naturally limits intake
Unlike a marathon, you can't drink every 5 minutes. Official aid is limited, and carrying a flask is hard with sled push and wall balls. Most amateur athletes drink nothing during the race. For a sub-90 minute race, that's manageable if your prep was solid.
If you're going beyond 1h30
Place a 500 ml electrolyte bottle in the transition area, and drink 100 ml between station 4 and station 5 (right after the rower, the lowest risk window). No more, or you'll get reflux on the burpees.
Plain water or electrolytes?
Before the race: electrolytes for the last 6 hours
Over the prior 24h, mix it: pure water for most of the day, and at least one full electrolyte dose in the 4 to 6 hours before the start. Look for a product with at least 500 mg sodium, 200 mg potassium and 50 mg magnesium per dose.
During the race: electrolytes only if you're used to them
Absolute rule: nothing new on race day. If you've never tested an electrolyte drink during your training races, don't drink one on race day. You risk digestive issues with no measurable benefit.
Classic mistakes to avoid
Drinking 2 litres at once in the morning
This is the stressed athlete's mistake, trying to "feel safe". You'll urinate for 90 minutes, lose electrolytes, and arrive at the start line paradoxically dehydrated.
Ignoring salt
Plain water in large quantities, without sodium, can cause hyponatremia (blood sodium too low). It's rare but serious. Sodium in your food and hydration drinks is not optional.
Following the advice of a buddy faster than you
An athlete who finishes in 1h05 has very different needs than one who finishes in 1h45. The duration of effort changes everything. Tune your protocol to your own race, not someone else's.
Drinking too much right before the wave
The timing of the last sip is critical. If you drink 200 ml in the holding area 5 minutes before the start, you'll feel it on the first burpees. Cut intake at least 15 minutes before the gun.
Post-race recovery
In the 30 minutes after your race, target 500 to 750 ml of a drink containing carbs, sodium and a bit of protein. You speed up muscle recovery and compensate for accumulated sweat loss. Keep drinking normally for the rest of the day, adjusting to your morning bodyweight.
Hydration is also during training
The best fluid prep starts weeks before the race, in your training sessions. Test what you'll drink on race day. Measure what works for you. Note what doesn't sit well. On race day, you experiment with nothing, you execute.
Once your race is done, you can review your splits and see if hydration held up: a progressive collapse on the final runs is often a sign of accumulated dehydration. Analyse your HYROX splits here.
And if those splits deserve to be displayed at home because you closed out the race cleanly, we've got you covered. Build your ROXWALL HYROX frame.
Where's your patch?
You crossed the finish line, now display it. Create your custom hexagonal frame and turn your HYROX achievement into wall art.
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