Introduction
If you’re training for Hyrox and not doing Zone 2 cardio, you’re leaving performance on the table. Most athletes show up to race day having trained too hard, too often — and they blow up in the back half. Zone 2 is the fix.
Here’s what Zone 2 actually is, why it matters for Hyrox specifically, and the best ways to build it into your training week.
What Is Zone 2 Cardio?
Zone 2 is a specific heart rate range where your body burns primarily fat for fuel and builds your aerobic base. It feels easy — almost too easy. You should be able to hold a full conversation without gasping.
To find your Zone 2 using heart rate reserve:
- Subtract your resting heart rate from your max heart rate
- Multiply that number by 0.6 and 0.7
- Add your resting heart rate back to each number
That range is your Zone 2.
For example: Max HR 186, Resting HR 46. Zone 2 = 131–144 BPM.
Why Zone 2 Matters for Hyrox
Hyrox is an 8-station race preceded by 8 x 1km runs. The athletes who fall apart aren’t always the weakest — they’re the ones who ran too hot early and had nothing left by station 5.
A strong aerobic base lets you:
- Run the 1km segments at a sustainable pace
- Recover faster between stations
- Stay in control of your heart rate under load
- Finish strong instead of surviving
Zone 2 builds the engine. Everything else is fuel.
The Best Zone 2 Cardio Options for Hyrox Athletes
1. Treadmill Running
The most sport-specific option. Running is the majority of a Hyrox race, so training your aerobic base on the treadmill directly transfers. Keep the pace easy — if your HR is creeping above your Zone 2 ceiling, slow down. Ego has no place in Zone 2 work.
Aim for 45–75 minutes per session.
2. Rowing
Rowing is a full-body Zone 2 option that also builds pulling strength and work capacity. It’s low-impact, easy to control intensity, and directly relevant to the Hyrox SkiErg and row stations.
Keep your stroke rate moderate and focus on maintaining a steady HR.
3. Bike Erg or Assault Bike
The bike erg is ideal for Zone 2 because you can dial in the exact resistance needed to stay in your target HR range without the impact of running. It’s also a great recovery tool after heavy training days.
The Assault Bike is harder to keep in Zone 2 — use the bike erg if you have access.
4. Ski Erg
If you have access to a SkiErg, low-intensity work on it pulls double duty — Zone 2 cardio plus sport-specific upper body endurance. Keep the pace controlled and the strokes smooth.
How to Structure Zone 2 in Your Hyrox Training Week
Zone 2 should be kept separate from your high-intensity work. Don’t combine it with intervals on the same day — you’ll compromise both sessions.
A simple structure:
- 2 Zone 2 sessions per week — 45 to 75 minutes each
- Keep intensity honest — use a HR monitor, not perceived effort
- Be consistent — Zone 2 adaptations take weeks to show up, not days
The temptation is to push harder. Resist it. The whole point is to stay aerobic.
The Bottom Line
Zone 2 cardio is the most underutilized tool in Hyrox training. It’s not glamorous, it doesn’t feel hard, and the results take time — which is exactly why most people skip it. Don’t be most people.
Build your aerobic base now. Your race-day self will thank you.