Heart Rate Zones for Hyrox Training

The 5-Zone Model and Why It Fits HYROX^® Perfectly

Heart rate zones are not a new idea. Exercise physiologists have divided the aerobic and anaerobic spectrum into discrete intensity bands for decades, calibrated against physiological thresholds rather than arbitrary percentages. What makes the five-zone model particularly useful for HYROX^® is that the sport maps cleanly onto almost every zone simultaneously — within a single race.

A recreational runner might spend an entire hour-long training run inside Zone 2. A powerlifter might never train in Zone 4 at all. A HYROX^® athlete, over 60 to 90 minutes of racing, touches Zone 2 during recovery moments, Zone 3 on the opening runs, Zone 4 through most of the middle race, and Zone 5 during the peak of the Sled Push and Burpee Broad Jumps. Understanding which zone you are in, and why, is the difference between racing with a plan and reacting to how bad you feel.

The five zones are defined relative to your maximum heart rate (HRmax), which can be estimated using the formula 220 minus your age, but is more accurately determined by a field test — a flat-out 400–800 metre effort following a proper warm-up.^[1] Using an estimated HRmax is acceptable for general training structure; using a tested value gives you sharper zone boundaries that better reflect your physiology.

Zone breakdowns:

• Zone 1: Below 60% HRmax — active recovery, very light movement
• Zone 2: 60–70% HRmax — aerobic base, conversational pace
• Zone 3: 70–80% HRmax — tempo, aerobic threshold, comfortable-hard
• Zone 4: 80–90% HRmax — lactate threshold, race pace
• Zone 5: Above 90% HRmax — VO2max territory, unsustainable for more than a few minutes

For the HYROX^® training structure to work as intended, you need to be spending time deliberately in each zone — not just in the zones that feel comfortable.

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How the Zones Map to HYROX^® Race Physiology

The standard HYROX^® race structure is eight 1 km runs alternating with eight functional stations. That structure creates a specific and repeating physiological demand: a run phase that keeps heart rate elevated in Zone 3–4, followed by a station that spikes heart rate toward Zone 4–5 through a combination of muscular loading and cardiovascular stress, followed immediately by another run.

This is fundamentally different from continuous running or circuit training in isolation. The transitions are the hard part. When you leave a SkiErg at heart rate 175 and immediately start the next kilometre run, your cardiovascular system does not reset. You are running into oxygen debt, not from a recovered state. Athletes who train only in steady-state conditions — running or gym work, never both together — are poorly prepared for this demand, regardless of how fit they are in their preferred discipline.^[2]

The physiological cascade across a race looks like this: the first two runs and stations are manageable at Zone 3–4 because glycogen stores are full, core temperature is moderate, and lactate clearance is functioning close to capacity. From station three or four onward, that balance starts to shift. Lactate production begins to outpace clearance. Core temperature continues rising. Heart rate at a fixed pace begins to creep upward — a phenomenon called cardiovascular drift — which means that maintaining Zone 3 output in km 1 requires Zone 4 effort by km 6.^[3]

Knowing this changes how you approach pacing. The zone you target at the start of the race is not the zone you will be working in at the end, even if your pace is identical.

For a detailed breakdown of pacing across the full race structure, see HYROX^® pacing strategy.

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HYROX^® Heart Rate Zone Table: Station-by-Station Targets

The table below maps target heart rate zones to each segment of a HYROX^® race. These are not maximums — they are sustainable targets for an athlete racing competitively across the full course. Spiking beyond the upper end of these ranges on early stations costs more than it gains.

Segment	Target Zone	% HRmax	Notes
Run 1 (km 1)	Zone 3	70–78%	Start deliberately slower than it feels. Adrenaline inflates effort.
Run 2–4 (early)	Zone 3–4	75–82%	Settling into race pace. Should feel controlled and rhythmic.
Run 5–7 (mid-race)	Zone 4	82–88%	Fatigue drift is active. Maintain pace, expect higher HR.
Run 8 (final km)	Zone 4–5	85–92%	Earned push. Only sustainable if earlier runs were managed.
SkiErg	Zone 4	80–87%	Full-body pull. HR spikes then stabilises within 20 seconds.
Sled Push	Zone 4–5	85–92%	Short duration, max mechanical effort. Brief Zone 5 spike acceptable.
Sled Pull	Zone 4–5	83–91%	Grip and hip hinge dominant. Duration is short — hold intensity.
Burpee Broad Jumps	Zone 4	80–88%	Rhythm over explosion. Zone 5 on BBJ destroys the next run.
Rowing	Zone 4	80–87%	Match target split. Do not under-row — the time loss is real.
Farmers Carry	Zone 3–4	78–85%	HR lower than perceived effort due to isometric grip demand.
Sandbag Lunges	Zone 4	82–88%	Quad-dominant. Consistent step cadence matters more than speed.
Wall Balls	Zone 4	82–88%	Final station. No need to sandbag — leave everything here.

The Sled Push and Sled Pull are the two segments where brief Zone 5 excursions are acceptable and expected. Both are short, load-limited, and do not produce the same sustained lactate accumulation as a long Zone 5 running interval. For every other station and all eight runs, Zone 4 is the ceiling during competitive racing.

Athletes targeting sub-60 minute times will run at the upper end of Zone 4 throughout, with station peaks touching Zone 5. Athletes targeting 75–90 minute completion times should keep runs in Zone 3 and allow natural Zone 4 peaks only during stations.

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Zone 2: The Most Undervalued Part of HYROX^® Training

The 80/20 training distribution — 80% of weekly volume in Zone 1–2, 20% in Zone 3–5 — is not a suggestion for beginners. It is the physiologically validated training prescription that produces the best outcomes for athletes competing at sustained aerobic efforts lasting 60 minutes or longer.^[4]

HYROX^® athletes, particularly those from a strength or CrossFit background, routinely violate this ratio. They train at Zone 3–4 across the majority of their sessions because it feels productive. It does feel harder. But sustained tempo-and-above training without a developed aerobic base produces athletes who are fit at race pace but cannot sustain it — their ceiling is the same as their floor.

Zone 2 specifically develops mitochondrial density in slow-twitch muscle fibres, increases fat oxidation capacity, and improves the lactate clearance system that becomes critical in runs 4 through 8. Without a substantial Zone 2 base, your lactate threshold sits relatively low, your cardiovascular drift accelerates faster, and your heart rate in the second half of the race climbs into ranges that are not sustainable.

The diagnostic question is simple: can you run for 45–60 minutes while maintaining a fully conversational pace and keeping heart rate below 70% of HRmax? If the answer is no — if your heart rate creeps to 75–80% even at an easy run pace — your aerobic base is underdeveloped relative to your race demands. See Zone 2 training for HYROX^® for a structured approach to building it.

Zone 1 is not wasted training, either. Active recovery sessions at below 60% HRmax — easy walking, light cycling, gentle rowing — accelerate clearance of metabolic byproducts between hard days and reduce the sympathetic nervous system load that accumulates across a hard training block.

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Zone 4 Training: Building Race-Pace Fitness

If Zone 2 is the engine, Zone 4 is the race. Lactate threshold work — sustained efforts at 80–90% HRmax — directly raises the percentage of maximum capacity you can sustain before glycolytic fatigue overtakes aerobic energy production. In practical HYROX^® terms, it is what allows you to run your fourth kilometre at the same pace as your first.

Zone 4 training for HYROX^® takes two forms:

Continuous threshold runs: 20–40 minutes at a steady Zone 4 effort — comfortably hard, speaking in short phrases only. These develop tolerance to lactate accumulation and train the cardiovascular system to maintain output at elevated heart rate for extended periods. This is your primary race-specificity work.

Station-to-run intervals: The HYROX^®-specific Zone 4 session. Perform a functional station (SkiErg, row, sled variant, or kettlebell work) at race-target load, then immediately transition to a 400–800 metre run at Zone 4. Repeat 4–8 times. This trains the cardiovascular transition from loaded muscular effort to sustained running — the exact demand of the race — and builds comfort with elevated heart rate at the start of a run.^[5]

The common mistake in Zone 4 training is allowing intensity to creep into Zone 5. Zone 5 efforts are valuable for VO2max development, but they are not Zone 4 work — they produce a different physiological stimulus, have longer recovery requirements, and, if overdone, erode the base that Zone 4 depends on. Keep a heart rate monitor visible during threshold sessions and enforce the ceiling.

A key metric for Zone 4 development is how quickly your heart rate stabilises after a station transition. In a well-trained athlete, heart rate peaks within 30–45 seconds of starting the post-station run and then stabilises or slowly declines. In an under-trained athlete, it continues rising for 90+ seconds. Training this transition is a direct HYROX^® performance lever.

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Heart Rate Drift and What It Means for Your Race

Cardiovascular drift is the progressive rise in heart rate at a fixed workload over time, driven by dehydration, rising core temperature, and accumulated glycolytic debt. In a HYROX^® race, this is not a hypothetical — it is a guaranteed occurrence that changes how every zone feels from kilometre three onward.

The practical consequence: Zone 3 at km 1 feels easy. Zone 3 at km 6 requires conscious effort to hold. If you are targeting a fixed pace across the race without accounting for this drift, you are effectively running in Zone 4 by the middle of the race when you think you are in Zone 3. The result is a second half that becomes progressively harder to sustain, not because your fitness is insufficient, but because your pacing did not account for the physiological reality.

Data from ROXBASE's 700,000+ athlete profiles shows this pattern clearly: athletes who hold a pace target rather than a heart rate or RPE target in the first three kilometres typically see heart rate climb 8–12 beats per minute above their intended ceiling by km 5–6. At that point, the effort required to maintain pace has crossed the anaerobic threshold — and unlike Zone 4, which can be sustained for extended periods in a trained athlete, work done above lactate threshold produces a debt that must be repaid.^[6]

The practical adjustment is not complicated: start the race by heart rate, not pace. Establish your Zone 3 ceiling in the opening kilometre and let your pace float down slightly rather than fighting to hold a pace number while heart rate climbs. Athletes who execute this typically negative-split the second half of the race — not because they are fitter, but because they have managed their physiology rather than ignored it.

For a deeper look at how heart rate recovery speed affects your second-half capacity, see how to improve heart rate recovery.

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Training the Transitions: Zone 4-5 Spikes and Recovery

The zone transitions between stations and runs are where HYROX^® races are won and lost at every ability level. The challenge is that Zone 5 spike during a station — which is often unavoidable and physiologically appropriate — takes time to decay. If your heart rate does not return toward Zone 4 within the first 200–300 metres of the following run, you are carrying the spike into a segment that demands sustained effort.

Training this capacity — the speed at which your cardiovascular system recovers from an intensity spike — is a specific adaptation that most HYROX^® athletes under-develop because it requires deliberate training structure rather than incidental fitness.

A structured approach to transition training:

Hard-easy intervals: 30–60 seconds at Zone 5 (max effort on a ski erg, burpees, or loaded carry), immediately followed by 3–4 minutes of Zone 3 running. The goal is not the hard interval — it is the recovery. Monitor how many metres of Zone 3 running it takes for heart rate to drop below 85% HRmax. Train to reduce that number over weeks.

Station complexes: String three to four HYROX^®-style stations with 1 km runs between each, executed at race target zones. This directly replicates race structure and gives you real data on where your heart rate stabilises between efforts and where it does not.

Morning HRV tracking: Because cardiovascular recovery quality is heavily influenced by overall fatigue state, tracking HRV daily allows you to time your hardest transition sessions for days when recovery capacity is high. For a complete guide to integrating HRV into training decisions, see HRV for HYROX^®.

The long-term adaptation you are building is a lower resting heart rate and a faster return from peak heart rate to sustainable racing zones. Both improvements translate directly to a HYROX^® race: more heart rate headroom means more room to push when it matters, and faster recovery means less zone-bleeding into the subsequent run.

For the full training structure that brings Zones 2, 4, and race-specific transitions together into a periodised block, see the HYROX^® Training Plan guide.

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Building Your HYROX^® Heart Rate Training Plan

The practical challenge for most HYROX^® athletes is not understanding zone theory — it is implementing it consistently across a week that also includes life, work, and the functional station work that the sport demands.

A simple weekly zone distribution for intermediate HYROX^® athletes (three to five sessions per week):

Session	Primary Zone	Duration	Example
Long aerobic run	Zone 2	50–70 min	Easy run, fully conversational
Zone 4 threshold	Zone 4	30–40 min	Sustained tempo run or 4–6 × 8 min at threshold
Station-to-run	Zone 3–4	45–60 min	4–6 rounds of station + 600m run
Recovery / Zone 1	Zone 1	30–45 min	Easy walk, light bike, or swim
Race-specific	Zone 4–5	45–60 min	Race simulation or mini HYROX®

The key is protecting the Zone 2 session. It is the session most likely to be sacrificed when time is short, and it is the one that builds the base the other sessions depend on. If you can only do three sessions in a week, make one of them Zone 2.

Monitor your actual zone distribution across a training block using your heart rate data. Most athletes who believe they are training 80/20 are actually training 50/50 or worse — spending far too much time in Zone 3 "grey zone" that is neither easy enough to be true base work nor hard enough to be effective threshold stimulus. The grey zone produces fatigue without proportional adaptation. Zone discipline — genuinely easy Zone 2 and genuinely hard Zone 4 — produces better outcomes in less time.

For athletes preparing for their first race or following a structured plan, the HYROX^® race day guide covers how to taper zone distribution in the final two weeks before competition.

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Frequently Asked Questions

Q: How do I find my maximum heart rate for accurate zone calculation? The 220-minus-age formula is a reasonable starting estimate but can be off by 10–20 beats per minute in either direction. For accurate zone calculation, perform a field test: after a full 10–15 minute warm-up, run 400–800 metres at absolute maximum effort. The highest heart rate recorded during or immediately after this effort is your working HRmax. Retest every 6–12 months as fitness evolves.

Q: Is it normal to be in Zone 4–5 for most of a HYROX^® race? Yes, for competitive athletes. Elite athletes race primarily in Zone 4 with Zone 5 spikes at the Sled Push, Sled Pull, and final wall balls. Recreational athletes competing in the 80–90 minute range typically spend most of the race at Zone 3–4. Zone 5 for extended periods is not sustainable at any ability level — if you are in Zone 5 on your third run, your opening pace was too aggressive.

Q: Why does my heart rate spike so high during the Sled Push even though it is only 50 metres? The Sled Push recruits very large muscle groups — quads, glutes, and upper body simultaneously — against high resistance in a near-isometric pattern. This creates a large cardiovascular demand in a short window. Additionally, the heavy breathing restriction during a maximum push effort compresses venous return, briefly elevating heart rate above what the aerobic output alone would produce. The spike is expected and manageable as long as it decays quickly into the following run.

Q: How much of my weekly training should be in Zone 2? For athletes training four or more sessions per week, at least two sessions should be primarily Zone 2, representing 60–70% of total training volume by time. For athletes training three sessions per week, one dedicated Zone 2 session plus easy warm-up and cool-down minutes in other sessions is a workable minimum. If your Zone 2 base is underdeveloped — heart rate creeps above 70% HRmax at conversational run pace — prioritise it over everything else for 4–6 weeks before adding Zone 4 work.

Q: What should I do if my heart rate is higher than expected at the start of a HYROX^® race? A pre-race heart rate elevation of 10–20 beats above your normal training resting rate is normal due to adrenaline and caffeine. Do not try to wait it out — start the first run by pace or RPE rather than heart rate, and let your heart rate settle within the first two minutes. If heart rate remains unusually elevated through km 2 at a conservative pace, reduce effort rather than chasing a pace target. Racing through a high heart rate baseline costs far more in the second half than the time you save in the first.

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Sources

1. Laboratory-derived HRmax from incremental treadmill tests to volitional exhaustion is the gold standard, but field tests produce sufficiently accurate values for training zone calibration in applied settings. Estimated formulas introduce error because HRmax variability between individuals of the same age can exceed 20–25 beats per minute. ↩

2. Concurrent training — combining endurance and resistance work — produces different physiological adaptations than either modality in isolation. The interference effect is minimised when training is structured appropriately, but athletes who train exclusively in one modality are physiologically unprepared for the demands of the other when combined under race conditions. ↩

3. Cardiovascular drift is primarily driven by two mechanisms: progressive dehydration reducing plasma volume (increasing heart rate at fixed cardiac output) and rising core temperature increasing cutaneous blood flow demand. Glycolytic debt compounds both effects from station three onward in a HYROX^® race. ↩

4. The polarised training model (80% low intensity, 20% high intensity) has consistent support in endurance sports research as producing superior outcomes compared to threshold-dominant training distribution for events lasting 45 minutes or longer, across ability levels from recreational to elite. ↩

5. Station-to-run interval training is not widely documented in general exercise physiology literature, but the physiological rationale is grounded in specificity of adaptation — training the cardiovascular system to transition between loaded functional movement and sustained running effort at target intensity directly prepares athletes for the primary demand structure of HYROX^®. ↩

6. Excess post-oxygen consumption (EPOC) following efforts above the lactate threshold is substantially larger than EPOC from Zone 3 work. In a race with eight station-run cycles, repeated unmanaged excursions above lactate threshold produce cumulative oxygen debt that manifests as progressive cardiovascular and muscular fatigue in the second half. ↩