HYROX is not a running race. Eight 1 km runs between eight heavy stations means you're working hard for an hour or more, mostly on carbohydrate. Fuel it like a 10 km and your runs fall apart by the second half.

Why HYROX burns through carbohydrate

At hard effort your muscles rely mainly on stored carbohydrate (glycogen). Sled pushes, lunges, burpee broad jumps and wall balls are high-force efforts that push heart rate and lactate up, then you run straight off them. Starting with low stores means your station power and run pace drop before you feel truly out of breath (Burke et al., 2011).

The day before and race morning

  • The day before: aim for around 7–10 g of carbohydrate per kg of body weight over the 24 hours before you race. For a 75 kg athlete that's roughly 525–750 g. A full multi-day carb load isn't needed for an event this length (Thomas et al., 2016).
  • Go lighter on fibre and fat in the last 12–24 hours so you don't feel heavy on the sled.
  • 2–3 hours out: 1–2 g/kg of easy carbohydrate — white bagel with jam, rice, oats, banana — with 400–600 ml of fluid (Kerksick et al., 2017).
  • 15–45 minutes out: a small top-up of 15–30 g, such as a gel or sports drink, if it sits well for you.

During the race

  • Under about 60 minutes: with a good breakfast, you need little. A few mouthfuls of sports drink or a mouth rinse is enough.
  • 60–120 minutes (most athletes): 30–60 g of carbohydrate per hour helps hold your pace in the later stations (Thomas et al., 2016). In practice that's one or two gels, or a sports drink, across the race.
  • When to take it: in the Roxzone as you head out on a run, when breathing settles. Not just before wall balls or burpees.
  • Liquid or thin gels are easier to get down when you're breathing hard.

Fluids and sodium

Indoor venues get hot and you'll sweat a lot. Start well hydrated, sip during the race, and if you're a heavy or salty sweater, add around 300–500 mg of sodium to your pre-race drink. Practise this in training first.

Quick checklist

  • 7–10 g carbs/kg the day before; lighter on fibre and fat
  • Familiar breakfast 2–3 hours out, small top-up before your wave
  • 30–60 g carbs per hour if you'll be out there longer than an hour
  • Fuel in the Roxzone, not before high-breathing stations
  • Rehearse it all in a simulation session — nothing new on race day