Heart Rate Zones
Heart rate zones are training intensity ranges defined as percentages of your maximum heart rate. The standard five-zone model provides an objective framework for pacing HYROX runs, structuring training, and developing all energy systems needed for race day.
Definition
Heart rate zones are training intensity ranges defined as percentages of your maximum heart rate (MHR). The standard five-zone model divides effort from easy recovery to all-out exertion, providing an objective framework for pacing runs, structuring workouts, and racing HYROX®. By training in the right zone at the right time, athletes develop all energy systems needed for the unique run-plus-station demands of HYROX®.
The Science
Each heart rate zone targets different metabolic pathways:
| Zone | % Max HR | Fuel Source | Physiological Adaptation |
|---|---|---|---|
| Zone 1 | 50-60 % | Fat | Active recovery, blood flow |
| Zone 2 | 60-70 % | Mostly fat | Mitochondrial density, aerobic base |
| Zone 3 | 70-80 % | Fat + carbs | Aerobic endurance, moderate lactate |
| Zone 4 | 80-90 % | Mostly carbs | Lactate threshold, race pace |
| Zone 5 | 90-100 % | Almost all carbs | VO2 max, neuromuscular power |
As intensity increases, the body shifts from fat oxidation to carbohydrate glycolysis. Zone 2 builds the aerobic engine. Zone 4 raises the anaerobic threshold. Zone 5 expands the ceiling of oxygen consumption.
Why It Matters for HYROX®
Understanding zones lets HYROX® athletes:
- Pace running segments - most athletes should hold Zone 3-4 during 1-km runs to avoid blowing up before stations.
- Control station effort - Wall Balls and SkiErg often spike HR into Zone 5; knowing this helps plan recovery.
- Structure weekly training - the 80/20 rule (80 % Zone 1-2, 20 % Zone 4-5) optimises adaptation while minimising injury risk.
- Race-day strategy - elite athletes aim to keep running in upper Zone 3 / low Zone 4 and allow stations to push into Zone 5, then recover in transitions.
How to Measure It
- Determine max heart rate - use a lab test, a field max HR test (see Max Heart Rate), or the formula 208 − (0.7 x age) as an estimate.
- Set zones - calculate each zone range from your MHR.
- Monitor in real time - use a chest strap (Polar H10, Garmin HRM-Pro) or optical watch sensor.
- Review post-session - platforms like Garmin Connect, TrainingPeaks, and Strava show time-in-zone breakdowns.
How to Improve It
Training across all zones is essential for HYROX®:
- Zone 2 runs (3-4x/week, 40-60 min) - build your aerobic base without excess fatigue.
- Zone 4 tempo work (1-2x/week) - 20-30 min at threshold pace to raise your sustainable race speed.
- Zone 5 intervals (1x/week) - 4-6 x 2-3 min with full recovery to expand VO2 max.
- HYROX® simulations - practice transitioning between zones as you move from running to stations and back.
HYROX® Benchmarks
| Race Target | Running Zone | Station Peak Zone | Avg Race HR (% MHR) |
|---|---|---|---|
| Finish (90+ min) | Zone 3 | Zone 4-5 | 75-82 % |
| Sub-75 min | Zone 3-4 | Zone 5 | 80-87 % |
| Sub-60 min | Zone 4 | Zone 5 | 85-90 % |
| Elite (sub-55) | Upper Zone 4 | Zone 5 | 88-93 % |
FAQ
Which heart rate zone should I run in during HYROX®? Most athletes should aim for Zone 3 to low Zone 4 during 1-km running segments. Going harder early will cause excessive fatigue at later stations. Elite athletes may sustain upper Zone 4.
Are wrist-based heart rate monitors accurate enough? For zone-based training they are adequate, but chest straps provide more reliable data, especially during high-movement activities like Burpee Broad Jumps.
Should I use heart rate or RPE on race day? Both. HR monitors can lag during rapid intensity changes. Use RPE as the primary gauge at stations and HR for running pacing.
Train in the right zone, race smarter - plan your HYROX® season with ROXBASE.
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