For a recent episode of the Rox Lyfe podcast, we sat down with Thierry Willigenburg, Elite 15 doubles athlete and sports scientist, to talk about the evolution of HYROX performance, doubles racing, and the science behind training smarter.
Alongside former Pro world record holder Hidde Weersma, Thierry has become one of the fastest doubles athletes in the sport, recently clocking the fastest run splits in the Elite 15 doubles field in Warsaw. But this conversation goes beyond race results. We dive into the training philosophy, pacing decisions, muscular endurance work, and performance data that underpin elite HYROX racing today…
From Middle Distance Running to HYROX
Thierry’s sporting background started in athletics, with a focus on middle-distance running, cross country, and steeplechase before eventually transitioning into triathlon. That endurance base still shapes how he approaches HYROX today.
Interestingly, he believes middle-distance athletes may actually transfer better into HYROX than traditional marathon runners because they often combine stronger aerobic ability with more muscularity and resilience.
“The middle distance specialists, occasionally you see a bit more muscle, a bit more buff, a bit bulkier athletes… I think that transfers maybe even better than the longer distances.”
That background is also reflected in how he and Hidde race doubles.
“We attack the runs and we survive the stations.”
But Thierry admits the level in Elite 15 doubles has shifted dramatically over the last year.
Improving Wall Balls
After Hamburg in Oct 2025 (where they finished 4th), Thierry and Hidde knew wall balls were costing them valuable time against the top doubles teams.
Rather than simply adding endless wall ball volume, Thierry explained that they focused on several more specific areas:
- Stricter judging on squat depth
- Improving cycle rate
- Fatigue-specific muscular endurance work
- Better pacing into the wall balls themselves
Hidde even experimented with using a metronome to improve his rhythm and turnover.
Thierry also described one of the methods that helped his own wall balls most:
“What really helped me with my wall balls is drop sets.”
These sessions involved combinations of:
- Push presses
- Thrusters
- Heavy wall balls
- Standard race-weight wall balls
The goal was not maximal strength, but creating the same muscular fatigue patterns experienced late in a HYROX race.
Why HYROX Is More About Muscular Endurance Than Max Strength
Thierry made an important point about strength training for HYROX that aligns with what many elite coaches and athletes are now saying.
“You don’t need to be that strong for HYROX.”
Instead, he believes the key is sustaining submaximal output repeatedly under fatigue.
“If you’re a bit less strong, but you can perform at eighty percent of that one rep max for a sustained period of time, then I think that’s a lot better than being that extremely strong explosive guy.”
That philosophy shapes how his training changes throughout the season. In winter, he uses more traditional strength work. Closer to racing, nearly everything becomes HYROX-specific and fatigue-based.
Using Muscle Oxygen Data in HYROX
Beyond racing, Thierry is also one of the founders of Train.Red, a company developing wearable muscle oxygen sensors for athletes and coaches.
The technology measures local muscle oxygenation directly within working muscles during exercise.
Unlike heart rate, which reflects whole-body effort, Thierry explained that muscle oxygen data reveals local fatigue patterns during specific stations.
For example:
- Sled push creates massive local muscular fatigue despite heart rate sometimes dropping
- Farmers carry often shows relatively stable oxygen demand
- Rowing heavily taxes the upper legs if technique is efficient
- Wall balls and lunges produce steep oxygen desaturation
This allows athletes to analyse pacing and recovery decisions more precisely.
One example Thierry shared involved reviewing their Hamburg race data and realising they may have paced Run 7 too conservatively before lunges and wall balls.
Why Recovery and Lifestyle Matter More Than Ever
Thierry also highlighted something becoming increasingly obvious within Elite 15 racing: many top athletes are now essentially full-time professionals.
Discussing Hidde Weersma’s progression, he pointed not just to training volume, but to recovery quality and daily decision-making.
“Every single decision that he makes is in line with performance.”
That included:
- Nutrition choices
- Sleep
- Injury risk management
- Recovery prioritisation
- Training consistency
According to Thierry, those small daily decisions compound over time.
To check out the full interview, watch below or listen on the Rox Lyfe podcast…
