In recent years, the fitness community has found itself split into two camps: committed CrossFit loyalists and newly converted Hyrox fans (with the ultrarunners observing from afar, shaking their heads at the chaos).
Between CrossFit and Hyrox, both modalities require a high level of athleticism. However, exercise scientist Gomarr D’Hulst explains in a recent WOD Science YouTube video that the underlying demands on your body couldn’t be more different.
‘Hyrox is fitness racing,’ says D’Hulst. ‘CrossFit is the sport of fitness. Both use functional movements performed at high intensity, combining aspects of strength and endurance. This naturally makes them quite similar. However, different types of athletes tend to excel in the top competitions of each sport.’
Event Preparation
While CrossFit is famous for keeping you guessing, Hyrox is built on consistency and preparation, explains the exercise scientist. ‘In Hyrox, we know exactly the workout that will be put forward to us, so the high predictability is a major difference – because CrossFit is known for the ‘known and unknowable’. Most people, athletes, sometimes don’t know the workouts when they are warming up, for example in the Games or semi-finals.’
Put simply, this difference dramatically shifts how each athlete prepares. Hyrox competitors can tailor their training down to the station, whereas CrossFitters must train broadly for the unexpected.
Energy Systems
‘CrossFit is more sitting on the left side of the [lactate] curve with their workouts – from three seconds, which is obviously very lactic creatine phosphate system (for example, a muscle-up or a 1 rep max deadlift), but also 10-minute workouts where you’re really sitting into this glycolysis metabolic pathway,’ explains D’Hulst. ‘Hyrox is much more conditioning, to the right side of this graph,’ he adds, ‘More of a mix between fat oxidation as well as glucose oxidation.’
Essentially, CrossFit is powered by short, high-output bursts of anaerobic effort. Hyrox is about aerobic sustainability over a full race.
After testing elite CrossFit athletes, D’Hulst discovered a surprising pattern. ‘What was interesting to me is that their aerobic base – their basic conditioning – is actually not that high.’
‘If the athlete had a bigger base, the lactate curve would be shifted more to the right. Lactate is produced by anaerobic systems. When the athlete has to tap into their anaerobic system from the early intervals, obviously lactate production would go up.’ He continued, ‘That’s what we see in a lot of CrossFit athletes – even the best in the world.’
To contrast, a strong Hyrox athlete would ideally produce less lactate and rely longer on aerobic energy systems before hitting fatigue.
Tall vs Shorter AthletesCrossFit
‘We profiled 60 very well-trained and even elite world-class CrossFit athletes.’ D’Hulst continues, ‘And they were not very tall: 176 cm. What was more interesting is that there was a strong correlation between the length of the arm or the length of the thigh and their Open rank. For example, 28% of the variance in Open rank – so how well they did – was determined by their core length as well as their arm length.’
Related StoryHyrox
‘You see that the top 10 male athletes in the Pro division are substantially taller (5.5 cm taller on average than the CrossFit athletes). That makes sense: sled pushes, wall balls, lunges, rowing, running,’ He continues, ‘Literally all movements that are better biomechanically for taller athletes.’
Programme Structure
D’Hulst explains that with Hyrox, you can structure your training much more easily. ‘You can do interval sets, use the movements that we know are going to pop up in the workout, and combine this in intervals or EMOMs or AMRAPs of longer duration.’
‘With CrossFit, it’s more difficult,’ he says. ‘You don’t know what’s going to happen, so you have to train everything. It’s going to be more random. There’s going to be more interference between strength and endurance.’
Hyrox athletes benefit from Zone 2 training which are long, low-intensity aerobic sessions. ‘For example, 75% of your functional threshold power for 45 minutes.’ says D’Hulst. ‘Most CrossFit athletes train in Zone 4 and 5 instead of Zone 2, except if you are really, really bad in conditioning.’
Nutrition
Another key variable between the two disciplines, is how we fuel. ‘In Hyrox, we are talking about 60 to 90 minutes, so you are really tapping into your glycogen reserves,’ says D’Hulst. ‘Glycogen is stored glucose in your liver and your muscles. You need to have those as fuel. If you are low in glycogen at the end of a Hyrox, you will have to throttle down and decrease your power output.
‘It is recommended to actually have some carbohydrates in Hyrox during the competition. You can go up to 60 to 90 grams of a combination of glucose and fructose, depending on how well your gut is trained.’
He explains that for CrossFit it is a slightly different matter, which comes down to logistics and workout length. ‘Obviously you cannot eat during a 10-minute workout. The nutrition will be much more structured around and before your training.’
The Bottom Line
Whether you’re drawn to the unpredictable intensity of CrossFit or the structured endurance required of Hyrox, understanding the physiological demands behind each sport is key. The two disciplines tap into different energy systems and require tailored approaches to training, fuelling, and recovery. Both demand grit, but they test it in distinctly different ways.
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Kate is a fitness writer for Men’s Health UK where she contributes regular workouts, training tips and nutrition guides. She has a post graduate diploma in Sports Performance Nutrition and before joining Men’s Health she was a nutritionist, fitness writer and personal trainer with over 5k hours coaching on the gym floor. Kate has a keen interest in volunteering for animal shelters and when she isn’t lifting weights in her garden, she can be found walking her rescue dog.