HYROX IS MOSTLY RUNNING: WHAT THE FIRST HYROX STUDY MEASURED

HYROX gets described as a strength-and-conditioning race, and the stations are what people picture: sled push, sled pull, wall balls. The first scientific study of the format timed a simulated race and found that most of the clock goes to the running. Chapter 5 of The Hybrid Athlete Protocol explains why that matters for anyone training strength at the same time.

What the Study Measured

In 2025, Brandt, Ebel, Lebahn, and Schmidt published what they describe as the first scientific study on HYROX, in Frontiers in Physiology. Eleven recreational HYROX athletes (27% women, with a median of 18 months of HYROX experience) completed a simulated race to Individual Open Division standards: eight 1-kilometer runs alternating with eight functional stations. The researchers tracked heart rate throughout and recorded blood lactate and perceived exertion after each run and each station.

The Time Split

• Median completion time: 86.5 minutes.
• Running: a median of 51.2 minutes.
• Stations: a median of 32.8 minutes.
• The difference between running time and station time was statistically significant (p = 0.003).

The authors reported that most of the event was performed at hard and very hard intensities relative to maximum heart rate.

Where It Felt Hardest

Running took more time, but the stations produced the higher peaks. Maximum blood lactate was higher during the stations (8.5 mmol/L) than during the runs (7.7 mmol/L), and so was maximum perceived exertion (18 versus 16). The highest heart rate, lactate, and exertion readings all came at the final station, wall balls. The two heaviest stations were finished fastest: a median of 128 seconds for the sled push and 155 seconds for the sled pull.

What Went With Faster Finish Times

Faster completion correlated with higher VO2max (p = 0.01), more weekly endurance training (p = 0.04), and lower body fat percentage (p = 0.03). The authors concluded that HYROX emphasizes endurance capacity, with moderate to low requirements for maximum strength, coordination, and mobility compared with other forms of high-intensity functional training.

Those are correlations in 11 people measured once. They describe who finished faster in this group, not what training would make any one athlete faster.

Why a Running-Heavy Race Matters for Hybrid Training

This is where the chapter connects HYROX to the interference research. In a 2012 meta-analysis of 21 studies in the Journal of Strength and Conditioning Research, Wilson and colleagues found that resistance training combined with running, but not with cycling, was associated with significant decrements in muscle size and strength. Higher endurance-training frequency and longer duration were also associated with larger decrements.

A broader 2026 umbrella review by Held and colleagues complicates that picture. Pooling 17 meta-analyses, it found concurrent training produced strength, power, and hypertrophy outcomes comparable to resistance training alone overall.

Brandt's study measured what a single HYROX race demands. It did not measure long-term interference from training for one. What the time split does show is that preparing for HYROX means a lot of running, which is the kind of endurance work that earlier research linked most clearly to interference. The book treats that as the reason HYROX training needs structure, not a reason to avoid it.

What I Couldn't Find

On September 16, 2026, a PubMed search for "hyrox" returned 9 records, confirming the literature is indexed and searchable. The same search combined with injury terms returned none. I could not find published injury data for HYROX. That's a gap in the research, not evidence that the format is low-risk.

The Protocol

How Chapter 5 fits HYROX into a training week:

• A HYROX-style session is its own format-specific slot. The book doesn't count it as both your strength session and your aerobic session just because it contains running and loaded work.
• In a strength-priority block, the book keeps it to one moderate session for format exposure.
• In a HYROX-priority block, it becomes central to the week and strength work moves to a maintenance dose.
• Scale loads and pace to your current fitness, and stop for sharp pain, dizziness, chest symptoms, or loss of safe running mechanics.

Chest pain or pressure, fainting, or unusual shortness of breath during training needs urgent medical attention, not a scaled workout. If you have a heart condition or haven't trained at high intensity recently, talk with your physician before attempting a race-pace simulation.

Battle Hard. — Will Power

Sources

1. Brandt T, Ebel C, Lebahn C, Schmidt A. Acute physiological responses and performance determinants in Hyrox — a new running-focused high intensity functional fitness trend. Front Physiol. 2025;16:1519240. PMID 40230601
2. Wilson JM, Marin PJ, Rhea MR, Wilson SM, Loenneke JP, Anderson JC. Concurrent training: a meta-analysis examining interference of aerobic and resistance exercises. J Strength Cond Res. 2012;26(8):2293-2307. PMID 22002517
3. Held S, Wolf L, Rappelt L, et al. Maximizing adaptations in concurrent training: an umbrella review of meta-analyses. Sports Med. 2026;56(6):1489-1512. PMID 41762427