Heart Rate Zones for HYROX Training
Every zone. What it does. When to hit it.
You’ve finished a session, opened ROXFIT, and seen a bar chart of your time in each zone. That data works whether you just did an easy jog, a threshold run, or a full HYROX simulation. What follows explains what those five zones actually mean, how to use them in HYROX training, and how to make sure the numbers ROXFIT shows you are as accurate as they can be.
What heart rate zones actually are
Heart rate zones are bands of intensity, defined as a percentage of your maximum heart rate. Every workout you do falls into a mix of zones. The mix tells you what training effect you got. A session spent mostly in zone 2 built aerobic base. A session spent mostly in zone 4 hit your threshold. A session bouncing between zone 3 and 4 with no clear plan is the classic grey-zone trap.
One important caveat before we go any further: zones are based on an estimate of your max heart rate, and everyone’s actual max is a bit different. Two people the same age might have max HRs that differ by 20 beats or more. Zones give you a useful framework, not an exact prescription.
The five zones ROXFIT uses
ROXFIT calculates your max heart rate using the classic formula: 220 minus your age. Your birthday sets your age. The zones are then cut as percentages of that max.
| Zone | Name | % of max HR |
|---|---|---|
| 1 | Very Light / Recovery | 0–65% |
| 2 | Light / Fat Burn | 65–81% |
| 3 | Moderate / Aerobic | 81–89% |
| 4 | Hard / Anaerobic | 89–97% |
| 5 | Max Effort | 97–100% |
The 220 minus age formula is a rough guide, not a lab-measured value. For most athletes, it’s close enough to be useful. If you’ve had your max HR tested in a lab, you’ll know whether your real max is higher or lower than the formula predicts, and you can adjust how you interpret the zones accordingly.
What each zone does in HYROX training
Zone 1: Recovery
Warm-ups, cool-downs, and easy walking on rest days. If you’re breathing through your nose the whole time, you’re in zone 1. Not a training stimulus, but a recovery aid. Useful the day after a hard HYROX session to keep the blood moving without adding load.
Zone 2: Aerobic base
The zone HYROX athletes should spend most of their easy running in. Zone 2 builds the aerobic engine that lets you hold pace when the stations start biting. The pace feels almost too easy. That’s the point. Most people undertrain this zone because it feels like they’re not doing enough. See the training pillar for how zone 2 fits into a full week.
Zone 3: The grey zone
Medium-hard, kind of uncomfortable, feels productive. It usually isn’t. Time spent in zone 3 is time you can’t recover from as easily as zone 2 and can’t push as hard from as zone 4. Most HYROX training weeks accidentally live here. Most HYROX Athletes Train at the Wrong Intensity covers the diagnosis and the fix.
Zone 4: Threshold
Hard but sustainable, the effort you can hold for around an hour. This is roughly HYROX race pace for a solo Open athlete, which is why threshold sessions transfer so well. One structured zone 4 session per week is plenty for most athletes.
Zone 5: Max effort
The top of what your body can produce, sustainable for seconds to a couple of minutes at most. On race day, you’ll dip into zone 5 during Burpee Broad Jumps and the last kilometre. In training, short intervals and hard finishes get you here. Not a zone to spend a lot of time in; a zone to know how to visit and recover from.
Getting your zones accurate in ROXFIT
Because the whole zone system is calculated from your age, the single most important thing to get right is your birthday in your ROXFIT profile. If your birthday isn’t set, we default your age to 30. That’s fine if you’re 30, but it means a 45-year-old with an unset profile will see zones that are 15 years too aggressive, and a 20-year-old will see zones that are 10 years too soft.
Two minutes in your profile settings fixes this. Open the app, add your date of birth, and your zones recalculate automatically for every workout going forward.
For athletes who’ve had their real max HR tested in a lab or via a proper field test, the formula will always be a rough guide rather than a personal number. In that case, use the zones as a general framework and lean on your own knowledge of what specific efforts feel like at each intensity.
A tool to train by and race by
Heart rate zones are a tool, not a rulebook. Used well, they tell you what a session did to your body, help you avoid the grey-zone trap in training, and give you a way to manage effort on race day when pace won’t cooperate. If you’re mid-HYROX, off your target pace, and your legs are done, zones give you something else to steer by. Keep the effort under control, hit your zone, get to the finish.
That’s the difference between racing to a plan and racing to whatever the day gives you.
