What the Research Actually Says About Training for HYROX

HYROX has become one of the fastest-growing competitive fitness formats in the world: eight 1-kilometer runs, interspersed with eight fixed-load functional stations — sled push, sled pull, burpee broad jumps, rowing, farmers carry, sandbag lunges, wall balls, and a ski erg. It's simple to describe and brutal to execute.

Because the sport is so new, dedicated research on it is still sparse. As of 2025, there are only two published studies specific to HYROX. But a review published in the National Strength and Conditioning Association's Strength & Conditioning Journal (Davids, 2025) pulled together what does exist — synthesizing the direct HYROX data with the broader CrossFit, hybrid fitness, and endurance literature — to build a working picture of the sport's physiological demands and what training should look like in response.

Here's what it found, and what it means for how you should actually train.

The aerobic engine sets the ceiling

The clearest signal in the data comes from a simulated-race study out of the University of the Bundeswehr Munich, one of the two dedicated HYROX studies the review draws on. Researchers had 11 recreational HYROX athletes complete a full simulated race under competition-standard conditions while tracking heart rate, blood lactate, and perceived exertion throughout.

The finding: faster overall completion time correlated significantly with higher VO₂ max, along with greater endurance training volume and lower body fat percentage. Of the roughly 86-minute median completion time, running accounted for the majority — about 51 minutes, versus about 33 minutes across all eight stations combined.

The practical read: your aerobic capacity is the foundation the rest of your HYROX performance sits on. If it isn't built, technical work at the stations only buys back marginal time.

The stations are a separate physiological problem

Where it gets more interesting is what happens at the stations themselves. In that same simulated-race study, blood lactate peaked higher during the fitness stations (8.5 mmol/L) than during the runs (7.7 mmol/L), and athletes spent approximately 80% of total race time at "hard" or "very hard" heart rate intensities. The single highest readings for heart rate, lactate, and perceived exertion all occurred at the final station — wall balls, arriving after eight rounds of accumulated fatigue.

This tells you something a VO₂ max number alone can't: HYROX isn't just an endurance test wearing a strength-sport costume. The stations demand real anaerobic capacity and local muscular endurance — the ability of specific muscle groups to keep contracting under load, station after station, without full recovery in between.

Wall balls, walking lunges, and burpee broad jumps are the movements that expose this gap. An athlete with an excellent aerobic base can still blow up here if local muscular endurance hasn't been trained specifically.

Sled push and pull play by different rules

One detail the review calls out specifically: HYROX sled weights are fixed, not scaled to body mass. In most strength sports, load is relative to the athlete. Here, it isn't. That means raw absolute strength — not just aerobic fitness — buys a mechanical advantage on two of the eight stations, and that advantage compounds over the course of the race. If your programming is aerobic-only, the sled stations are where that gap shows up on the clock.

What the review recommends for training

Based on the combined evidence, the review points to three tools as the core of a HYROX training approach:

• High-intensity interval training (HIIT) as the primary conditioning method — it develops aerobic and anaerobic capacity concurrently, which matches the demand profile of the sport itself.
• Circuit training for event-specific preparation — replicating the run-to-station-to-run transition under fatigue, not just training each energy system in isolation.
• Blood flow restriction (BFR) training as a lower-fatigue-cost way to build local muscular endurance, particularly useful for athletes who are already carrying high overall training volume and can't afford to add more.

The honest caveat

It's worth being direct about the limits of this evidence. HYROX-specific research is still thin — the review itself is extrapolating from CrossFit, hybrid fitness, and endurance literature to fill in the gaps where direct HYROX data doesn't yet exist. The training framework is sound and consistent with well-established themes across the broader high-intensity functional training literature: VO₂ max as a leading performance predictor, elevated lactate at strength stations, and the challenge of training aerobic and anaerobic systems concurrently without one blunting the other. What HYROX adds to that picture isn't new physiology — it's a standardized, globally repeatable format that makes those demands measurable in a way ad hoc CrossFit workouts never were.

Where to start

If you're training for HYROX — or any hybrid event that mixes sustained aerobic output with loaded functional stations — the first number worth knowing is your VO₂ max. It tells you whether your aerobic ceiling is where it needs to be, and it's the baseline every other training decision should be built from.

At Custom Fit, VO₂ max testing is included, unlimited, with every Personal Training, Partner Training, and Tier 2 Gym membership. No separate booking, no added cost — just a clear read on where your engine stands and what to build next.

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