In this blog, we analyze Hyrox test event data and provide you with five tips to improve your Hyrox performance. Hyrox is all about endurance, strength, and mental resilience. It is a new form of fitness competition where participants alternate between running one kilometer eight times and completing eight functional exercises at full throttle.

The better you understand how your body generates energy for exertion, the more effectively you can train. In this blog, I analyze lactate data, heart rate data, and subjective experiences during a Hyrox test event. The “victims” were Remon and Jeroen, whom I coached for Hyrox Amsterdam. I compare this data to the results of a previous exercise test. I couldn’t believe my eyes when I saw the heart rates and lactate levels during the Hyrox test event.

The blog concludes with five tips to improve your Hyrox performance. Whether you’re training for your first Hyrox race or you’re already familiar with it, the combination of exercise tests, training, data, and coaching will help you train smarter and more efficiently.

1. Why Hyrox testevent data are essential for your Hyrox performance

The focus of this blog is on exercise physiology. The foundation for a good Hyrox performance is your ability to generate as much energy as you can over an extended period. Let’s take a look at the different ways your body can produce energy.

2. The three energy systems you use during your Hyrox

Your body has three energy systems to produce energy.

a. Anaerbic alactic system (creatine phosphate system)

This system provides energy for very short, explosive efforts of 10-20 seconds, such as sprints or heavy strength exercises. Creatine phosphate (CP), stored in limited amounts in your muscles, is used to rapidly produce ATP (adenosine triphosphate), which is the direct energy source for your muscles. The advantage of this system is that it does not require oxygen or carbohydrates and does not produce byproducts like lactate. The downside is that this system becomes exhausted after a maximum of 20 seconds.

b. Anaerobic lactic system (glycolysis)

The anaerobic lactic system quickly generates a lot of energy by breaking down carbohydrates. This process releases ATP, and as a byproduct, lactate. This lactate enters your mitochondria through your blood and intracellular exchange, where it serves as fuel alongside fats and oxygen. However, if you fully utilize this system, it is not sustainable. You can only maintain anaerobic efforts for one to max two minutes. When your aerobic system can no longer process the lactate produced by your anaerobic system, you must slow down, no matter how mentally strong you are.

c. Aerobic system

The third way to generate energy is through your aerobic metabolism. This system produces energy using oxygen by converting fats and lactate into energy. Lactate is converted into pyruvate, which then enters the citric acid cycle. Fats are broken down into free fatty acids, which also enter the citric acid cycle. together with lactate, they are broken down into carbon dioxide and water.

So much for the biochemistry lesson.

Although your aerobic system delivers energy much more slowly than the two anaerobic systems, it is far more efficient and can provide energy for hours without you becoming “too tired.” A well-functioning aerobic system is crucial for sustaining performance and aiding recovery during rest periods. The better your aerobic system, the more effectively you can process the lactate produced by your anaerobic lactic system.

It’s important to note that your body always employs a combination of energy systems. Even at low intensities, your anaerobic and aerobic systems work simultaneously. As intensity increases, the balance will shift—from primarily aerobic to primarily anaerobic.

3. Lactate as key to measuring energy systems

Now that we know your body always utilizes a combination of anaerobic and aerobic energy, the question arises: can you measure the ratio between the two? Because if you know this, you can set up your training zones to train more effectively. You can determine in which zone your aerobic energy system is primarily engaged and where the transition lies between primarily aerobic energy delivery and anaerobic energy production—the so-called aerobic threshold. You can also determine your anaerobic threshold, which is the intensity at which you start to produce more lactate than you can process. This will also help you better manage your exertion during your Hyrox, so you don’t accumulate too much lactate and need to reduce intensity or take breaks to recover.

Indeed, you can measure the ratio between the energy production of your anaerobic and aerobic systems. By measuring the lactate concentration in your blood—I use the Lactate Plus—you can determine the ratio between your aerobic and anaerobic energy production at different intensity levels.

The lactate concentration in your blood represents the balance between lactate production (through anaerobic energy production) and lactate utilization (in aerobic energy metabolism). By measuring lactate, you gain insight into how your energy systems function at different levels of exertion.

By conducting lactate measurements during a fitness test, you can determine your individual training zones and gain insight into how to optimally train your aerobic and anaerobic systems. By training purposefully, you can improve your body’s efficiency, allowing you to perform at higher intensities for longer before fatigue sets in. The data from a fitness test also provide the context needed to interpret Hyrox test event data.

4. Exercise tests as the foundation for Hyrox training

Exercise tests formed the foundation for the conditioning part of Remon and Jeroen’s training plan. For the functional part of their plan, we used 1 repetition-max tests as input for the strength program. I won’t go into that further here. Below is the data of Remon’s test.

Interpreting lactate data is beyond the scope of this blog. The key observations from this test:

• You can see that in step 2 (10 km/h – 2.7 mmol), Remon scores a lower lactate value than in step 1 (9 km/h – 2.8 mmol). This is because the aerobic system takes time to activate. In step 2, his aerobic system was able to burn more lactate than in step 1, which is a positive sign.
• Ideally, I would like to see an endurance athlete start in the lowest zones with lactate values (well) below 2 mmol. The results suggests room for improvement in the aerobic foundation.
• The maximum lactate value is 10.4 mmol. Ideally, for a Hyrox event, I’d like to see this between 12-14 mmol. Higher maximum lactate values indicate a well-developed anaerobic lactic system, which is especially important for the more intense parts of a Hyrox event, such as the sled push, burpee broad jumps, and wall balls.

5. Hyrox test event data

I notice you are getting impatient: when will we get to the Hyrox test event data? Well, here it is;) We needed the above information to make sense of the numbers.

Two weeks before Hyrox Amsterdam, Remon and Jeroen participated in a Hyrox test event at De Sportloods. They completed the full Hyrox program, which consists of 8x1km runs and the eight exercises. In the graph below, you can see the different exercises on the x-axis. The white line represents heart rate. The yellow line depicts the Borg scale scores, which is a subjective measure of how hard each exercise is perceived. The Borg scale starts at 6 (no effort) and goes up to a maximum of 20 (all-out effort).

Analyse heart rate and Borg scale data

• Remon experienced the running segments as significantly easier (ranging from 9 for the opening kilometer to 12 for the other kilometers) compared to the functional exercises (minimum of 14 for the rower, maximum of 19 for the wall balls).
• The subjective perception of the exercises correlates with the heart rate. For the running segments, his heart rate ranged between 170 and 175. By the end of the first kilometer, his heart rate was 175. He intentionally ran that faster (5:15/km) because he wasn’t fatigued yet. The other kilometers were run at 6:00/km to recover from the previous exercise and prepare for the next one.
• During the exercises, his heart rate ranged from 176 (sandbag lunges and wall balls) to 190 (sled push). During the exercise test, where he had to push to his limit, Remon reached a maximum heart rate of 194. In Hyrox, you approach your maximum heart rate during the most intense exercises. His heart rate for the anaerobic threshold was 178. During the running, he consistently stayed below this (to recover), while during the exercises, he reached or exceeded it.

In the second graph, the exercises are also plotted on the x-axis. The white line shows the heart rate data at the end of each exercise. The yellow bars represent the lactate values during the test event.

Analysis of heart rate and lactate data

• The lowest lactate value was 5.9 mmol, recorded after the first run. For the remainder of the 1 hour and 36 minutes (Remon’s finishing time), his lactate values were 8.4 mmol or higher (!).
• That exclamation mark is an understatement. Let me explain. Data should always be viewed in context. If you compare the lactate values from the test event with those from the exercise test, you’ll see that a Hyrox event produces extremely high lactate levels. The maximum lactate score during the exercise test was 10.4 mmol. During the Hyrox event, they reached up to 17 mmol. (Side note: I would have liked to retest this for verification, as it was quite an outlier.) Even after exercises like burpees (13.4 mmol), the rowing ergometer (13.0 mmol), and the sandbag lunges (14.1 mmol), the lactate values were significantly higher than the maximum seen during the exercise test. This shows just how physically demanding the exercises in a Hyrox event are.
• The lactate value at the end of run 6 was 8.4 mmol, which confirms that running acts as a recovery phase. The lactate built up during the exercises needs to be processed during the running segments—otherwise, you won’t be able to sustain the effort.

6. Five tips for your Hyrox

Hyrox is a complex sport. You need to be both anaerobically and aerobically very fit. Here are five tips for your Hyrox training.

Tip 1: Improve your aerobic base.

The better your aerobic base, the faster you can run—and the better you can recover. In this blog, you’ll find tips to get the most out of your endurance training. Contrary to what many people think, you can continue improving aerobically well into your 40s. It’s mainly a matter of maintaining the right intensity and consistently “building out your engine.” A great side benefit: the fitter you are aerobically, the lower your risk of lifestyle diseases. That’s an extra bonus! 😉

Tip 2: Determine your training zones.

To train effectively, you need to know your zones. The zones shown by your sports watch are often inaccurate. An exercise test will help you determine your individual zones. This allows you to fine-tune your training intensity for maximum results. It also gives you a reference point to track your progress.

Tip 3: Train your lactate shuttle.

By now, you know that the lactate you accumulate during functional exercises needs to be processed while running. You can train this by doing ‘lactate shuttle‘ sessions. These are workouts where you alternate between Hyrox exercises and running circuits. When done at the right intensity (not too hard, not too easy), you train your body to process lactate more quickly.

Tip 4: Use Hyrox test event data as the basis for your race plan

By doing simulations during your preparation, you can create a realistic race plan. After the test event, I made a race plan for Remon and Jeroen, with optimal pacing and heart rate guidelines for each section. This helped Remon achieve his goal of finishing in under 1 hour and 30 minutes—despite a 5-minute penalty for missing a lap;)

Tip 5: Have fun and don’t take it too seriously

Hyrox is a new sport with great potential, offering challenges and appealing to different audiences. The comparability and data it generates can easily distract you from what’s most important: enjoying the sport and being grateful for the health that allows you to even participate in a Hyrox.

Three days before Hyrox Amsterdam, a friend asked if I wanted to do the double with him, as his double partner had hurt his back. So, I ended up doing my first Hyrox without specific preparation. I had a blast. And after the sandbag lunges, I was completely wiped out. More on that in the next Hyrox blog.

7. Hyrox Coaching Commercial

Would you like to be coached for your next Hyrox? Or are you curious about your training zones and want to do an exercise test? Book an appointment!