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The Pitfalls of Zone 2 Training in Hyrox Competitions

Hyrox is a high-intensity event, and the demands are much more specific than just aerobic conditioning. Let’s break this down.

1. Mismatch with Race Demands

Hyrox events are built around short bursts of effort, alternating between high-intensity cardio and strength-based tasks. These events are more about how your body handles lactate accumulation, fatigue, and recovery during intense intervals. Zone 2, which is primarily focused on increasing mitochondrial density and improving fat oxidation, is generally performed at a lower intensity (around 60-70% of VO2max). While it’s great for endurance over long periods, it doesn’t replicate the intensity demands of a Hyrox race.

In short, Low-intensity training won’t prepare you for the lactate tolerance or the specific intensity of the event. You’re missing out on developing that high-end aerobic capacity crucial for quick recovery between efforts.

2. Lactate Threshold Development

For Hyrox, your lactate threshold is a huge factor. The ability to push hard without crossing that threshold—essentially staying just below it so you can perform at a higher intensity for longer—is key. Zone 2 is typically too low to help with that threshold.

Instead, high-intensity intervals (around Zone 4-5) are better suited for improving this ability. These intervals replicate the kind of energy systems you’re using during a Hyrox race, forcing your body to clear lactate efficiently and condition you to perform at those higher intensities.

3. Specificity of Training

The principle of specificity tells us that the training should mimic the energy systems used in the event. Since Hyrox involves sprints, intense lifting, and other high-effort tasks, your energy systems need to be conditioned for that. Zone 2 doesn’t engage the same anaerobic pathways that will be stressed in a race. By focusing on higher intensities, you’ll better align your training with the specific demands of the event.

4. Adaptation to Fatigue

In a Hyrox event, athletes often experience deep fatigue in the legs and upper body, especially from the transitions between running and functional exercises. Training at higher intensities—whether through intervals or strength-endurance training—helps the body learn how to deal with this fatigue and recover quickly, as opposed to low-intensity aerobic training, which is more about improving overall endurance and not how quickly you can bounce back from each effort.

5. Misallocation of Training Time

Zone 2 training certainly has its place, especially in the off-season or for general endurance improvements. However, for athletes specifically preparing for Hyrox, investing too much time in low-intensity work might be time poorly spent. It can crowd out the higher-intensity efforts that are more aligned with the actual race demands. You need to get your athletes to push hard and recover quickly to truly simulate race conditions.

So, What Should Be the Focus?

  • High-intensity intervals (HIIT) are crucial for improving power output and lactic acid clearance, which are directly applicable to Hyrox.
  • Strength-endurance work like kettlebell swings, sled pushes/pulls, and burpees should be incorporated to simulate race tasks and challenge both the aerobic and anaerobic systems.
  • Tempo runs, or threshold training (slightly below your max effort) can help develop that ability to sustain high intensity for more extended periods without blowing up.

By focusing on specific, high-intensity efforts while maintaining a slight base of lower-intensity aerobic training for recovery and long-term endurance, you’ll have a much more effective program for Hyrox.

The comparison to how endurance sports like cycling and marathon running have influenced some coaching philosophies around Hyrox and the crossover between endurance-based sports and high-intensity competitions like Hyrox can sometimes be awkward because the physiological demands are very different, and the adaptation process varies significantly. Let’s unpack that a bit more.

1. Endurance Sports Are Primarily Aerobic; Hyrox Is Primarily Anaerobic

Endurance sports like cycling, marathon running, or even long-distance swimming primarily focus on aerobic energy systems. These athletes spend a lot of time in lower-intensity zones (Zone 2, sometimes even Zone 1) to build mitochondrial density, capillary networks, and overall aerobic capacity. This kind of training promotes fat oxidation and the body’s ability to use oxygen for long-term sustained efforts.

However, Hyrox is a high-intensity, interval-based competition. It’s an anaerobic event in which athletes alternate between explosive running and functional exercises like sled pushes, burpees, and rowing. These activities use different energy systems—mainly anaerobic glycolysis (fast energy systems that don’t rely on oxygen) and phosphagen systems (very short bursts of effort, think 0-10 seconds max output).

Aerobic conditioning developed through long-distance running or cycling doesn’t optimally transfer to Hyrox’s anaerobic needs. An athlete with a great VO2 max for long, steady-state endurance might struggle with the high-intensity work and quick recovery needed during the event because they haven’t trained the anaerobic energy systems to the same degree.

2. The Endurance Paradigm vs. High-Intensity Work

Coaches coming from endurance sports are often steeped in the belief that building a strong aerobic base will carry over to other sports, including those with high-intensity elements. This makes sense for sports that demand endurance, like a marathon or an Ironman, where the intensity is sustainable over long periods, and the heart rate is relatively low to moderate for most of the event.

But Hyrox and similar high-intensity competitions work in a completely different energy zone. A solid aerobic base will help with recovery between efforts and could help an athlete maintain some level of intensity throughout the race. Still, it isn’t going to be the key determinant of success. What really matters is how well an athlete can tolerate high-intensity output over the course of 1-1.5 hours—pushing hard during the run, dealing with short anaerobic bursts of strength work, then recovering quickly to hit the next effort hard.

The core principle here is the law of specificity: To get better at high-intensity races, athletes need to practice high-intensity efforts. Aerobic conditioning is still useful for improving general stamina, but it’s more of a “supporting” adaptation than the driving force.

3. The Risk of “Aerobic Overtraining”

Another pitfall of applying endurance-based training principles to Hyrox is the risk of aerobic overtraining, or spending too much time in Zone 2. Hyrox athletes might focus too much on aerobic capacity, assuming that developing the cardiovascular system at lower intensities will prepare them for race day. But the problem is that, in doing so, they neglect the lactate threshold and high-intensity tolerance.

If an athlete spends too much time in Zone 2 (long steady-state efforts), they might increase their ability to run a 10K or cycle for hours, but they’ll struggle when it comes time to handle the spikes in heart rate and power that happen in a Hyrox competition. And, because the body is being trained to rely more on fat as fuel during low-intensity efforts, the athlete might not be developing the kind of glycogen-efficient pathways needed for quick, powerful bursts of energy.

4. Anaerobic Capacity and Recovery

One thing that is often overlooked when transitioning from endurance sports to high-intensity competitions is recovery speed. In an endurance race, athletes can go slower to recover and still keep moving forward. But in Hyrox, it’s all about quick bursts of effort with minimal rest in between—meaning you need to be able to recover quickly between your runs and strength exercises.

High-intensity interval training (HIIT) or strength-endurance training does this best. By practicing these anaerobic efforts, the athlete’s ability to recover quickly between sprints or functional exercises improves. The aerobic base from cycling or marathon running doesn’t fully replicate this, because these energy systems are more about stamina over time, not recovery between explosive efforts.

5. Strength Training and Functional Fitness

Many endurance athletes have a limited background in strength training and functional fitness, which are integral parts of Hyrox. In an event like Hyrox, it’s not just the ability to run that counts but also the ability to perform powerful movements, lift weights, and transition between these movements. When endurance-based coaches focus too much on aerobic conditioning, they often neglect the need to build strength-endurance, which is vital for a sport like Hyrox.

The physical demands of Hyrox (sled pushes, burpees, wall balls, rowing) require a combination of strength, power, and muscular endurance. Zone 2 training does little for this, while targeted strength training and metabolic conditioning are far more specific.

The Shift in Mindset

Coaches coming from the endurance world often try to transpose what works in ultra-endurance sports to high-intensity, multi-modal events like Hyrox, but the physiological demands are different. Hyrox is about handling high-intensity efforts across multiple domains, recovering quickly, and executing a race that requires power, strength, and stamina all at once.

In short: Training too much like an endurance athlete—with long, slow, steady-state runs, long cycling rides, and excessive Zone 2 work—might leave a Hyrox athlete ill-prepared for the event’s intensity. The key is to focus on high-intensity interval training, strength endurance work, and techniques that improve recovery during short bursts of maximal effort.