HYROX is 8 km of running split across 8 functional work stations. The specific challenge: you can't go too fast on the runs (you'll blow up at the stations) or too slow (you'll lose real time). Heart rate monitoring is the most underused tool by intermediate HYROX athletes. Here's how to use it right.
The 5 Heart Rate Zones: Definitions and Calculation
The 5 heart rate zones are defined relative to your maximum heart rate (HRmax). The most accurate calculation method is a field test (e.g., 12-minute Cooper test, all-out effort) rather than the 220-age formula (standard error of ±10-15 bpm).
Zone 1: Active Recovery (50-60% HRmax) — Easy conversation pace. HYROX use: warm-up, recovery between training blocks.
Zone 2: Aerobic Base (60-70% HRmax) — You can hold a conversation. Primarily burns fat. HYROX use: aerobic foundation — 80% of your training volume should be here based on elite athlete analysis.
Zone 3: Tempo / Aerobic Threshold (70-80% HRmax) — Conversation is hard, short phrases. HYROX use: race pace for beginner to intermediate athletes during running phases.
Zone 4: Lactate Threshold (80-90% HRmax) — You can't talk anymore. HYROX use: race pace for advanced and elite athletes during runs. Unsustainable for full 8 km for most.
Zone 5: Maximum Effort (90-100% HRmax) — Breathless, sustainable for 30-120 seconds max. HYROX use: terminal sprints, final station.
Which Zone to Target During Competition Runs?
The answer depends on your level and target time.
Beginners (target > 1h45): aim for Zone 2-3 (65-75% HRmax) during runs. Your biggest risk is going too fast on runs 1-2 and running out of fuel for stations 5-8. Practical rule: if you hit Zone 4 during a run, slow down immediately.
Intermediate (target 1h15-1h45): Zone 3 target (72-80% HRmax) on runs, with Zone 4 tolerance on the last 2km. Use HR to check after each station: if you spike to >85% HRmax during Wall Balls or Sled Push, your passive recovery between stations isn't enough — review your transitions.
Advanced (target < 1h15): Zone 4 during runs (80-88% HRmax), with Zone 5 spikes on the SkiErg and Row. Elites like Hunter McIntyre and Leonie Beck maintain an average HR of 88-92% HRmax for the entire race — reserved for years of built aerobic base.
The Station 1 trap: the opening SkiErg causes a rapid cardiac spike. If you start too hot after run 1, your HR will be at 90%+ at the start of the SkiErg, and you'll never fully recover for the rest of the race.
Zone-Based Training Program for HYROX
Ideal weekly training structure for a HYROX athlete competing in 8-12 weeks:
Monday: Zone 2 aerobic base (60 min) — 45-60 min continuous run in Zone 2. If HR climbs to Zone 3, slow down. Goal: build mitochondrial capacity and low-intensity efficiency.
Tuesday: HYROX-specific training (45-60 min) — 3-4 HYROX stations (SkiErg, Sled Push, Sled Pull, Wall Balls) in circuit format, active recovery between blocks. HR monitoring: don't let HR drop below 60% HRmax (stay in Zone 1-2 active recovery).
Wednesday: Recovery or rest
Thursday: Zone 4 intervals (45 min) — 6-8 × 3 min in Zone 4 (80-90% HRmax), 2 min Zone 1-2 active recovery. Builds lactate tolerance and ability to maintain race pace.
Friday: Partial HYROX simulation (60-90 min) — 4-6 stations + 4-6km running. Monitor inter-station HR recovery — target: return below 75% HRmax within 45-60 seconds of transition.
Saturday: Long Zone 2 run (75-90 min) — Long low-intensity run, strict Zone 2. Foundational for aerobic base.
Sunday: Full rest or mobility
Heart Rate Recovery as a Progression Indicator
An underused metric by HYROX athletes: how fast HR recovers after effort. 1-minute Heart Rate Recovery (HRR1) is one of the best markers of aerobic fitness.
How to measure: after 1 min of intense station work (e.g., SkiErg), note your HR. Wait 1 minute of active walking. The difference = HRR1. - HRR1 20 bpm: good aerobic base, competitive in your category
Application during training: in HYROX simulation, measure HRR1 after each station. If it decreases across stations (you're recovering more slowly), aerobic base is your limiting factor — increase Zone 2 volume.
Resting HR as recovery indicator: a morning resting HR 5-8 bpm above your norm signals incomplete recovery or early overtraining. Replace the planned session with Zone 1 active recovery.
For most HYROX athletes, mistake #1 is insufficient Zone 2 volume and too much intensity on early race runs. Build your aerobic base with 60-70% of volume in Zone 2, learn your actual zones from a field test, and monitor your inter-station HR recovery. Elites don't just work harder — they work smarter.