Most HYROX Athletes Train at the Wrong Intensity
The problem isn’t that you’re not working hard enough. It’s that you’re working at the same intensity almost every session. Medium-hard. Harder than easy, not as hard as a proper threshold effort. It feels productive. It isn’t.
That middle ground, sometimes called the grey zone or Zone 3, generates enough fatigue to leave you tired but not enough intensity to drive the adaptations you’d get from real high-intensity work. Session after session in that range and you accumulate stress without the training return to show for it.
What Zone 2 actually is
Zone 2 sits below your first lactate threshold. In practice, your breathing is elevated but not laboured, and you can hold a full conversation without gasping between words. Most athletes find their Zone 2 pace is slower than expected. Sometimes significantly slower. That feeling that you’re not working hard enough is almost exactly the right signal.
At this intensity, your body uses fat as its primary fuel source. Your mitochondria, the energy-producing structures inside your muscle cells, adapt and multiply. Stroke volume improves. Your aerobic engine gets larger. None of that happens quickly. The adaptation requires volume over months, not weeks, and it only comes if you stay genuinely below the threshold rather than drifting above it.
Why the middle is a trap
Training just above Zone 2 is hard enough to generate significant fatigue but not hard enough to drive the adaptations of true high-intensity work. You pay the recovery cost without cashing in the adaptation.
Do that repeatedly and your hard sessions suffer too. They feel hard because you’re already carrying fatigue, not because the intensity is producing the right stimulus. The whole week becomes medium-hard, with one session that’s slightly harder than the rest. The aerobic base doesn’t build. The high-end doesn’t sharpen.
What the right distribution looks like
The model that works is a large volume of genuine Zone 2 work and one genuinely hard session per week. One. Not one hard session per week plus three sessions that drift above easy. One session that’s hard, with everything else kept below the threshold.
The reason one hard session can be genuinely hard is that the rest of the week hasn’t accumulated the fatigue that would dilute the stimulus. You arrive at that session recovered enough to actually respond to it.
Hidde Weersma, the Dutch S&C coach and Elite 15 HYROX athlete, runs roughly 70km a week with most of it at Zone 2 pace. He adds six to eight hours of cycling on top, also mostly easy. The total aerobic volume is high. The intensity distribution is what makes that volume sustainable. He trains 18 to 23 hours a week. He doesn’t break down. That’s not because he’s exceptional. It’s because the workload is structured correctly.
Why cycling and the StairMaster count
One of the most practical adjustments you can make is doing your Zone 2 work off your feet on some days. Cycling and the StairMaster produce the same cardiovascular stimulus as easy running without the impact load. Running accumulates eccentric stress through the quads, calves and Achilles even at easy pace. Spread that load across too many easy runs and you’re managing tissue fatigue on top of your actual training.
The bike gives you the aerobic work without that cost. Your running capacity builds, your legs stay fresher for the sessions that matter, and your injury risk drops.
How to know if you’re actually in Zone 2
The talk test is straightforward. If you can’t hold a relaxed conversation, you’re not in Zone 2. If your heart rate is above 70% of your maximum, you’re probably not in Zone 2. Both checks point to the same thing: slow down.
Going slower than feels right is the adjustment most athletes need to make. The adaptation still happens at that pace. It just requires patience that most training plans don’t account for.
See how your running splits trend across events in ROXFIT. roxfit.app
