Why HYROX feels so hard
The first scientific study of HYROX measured 11 recreational racers, eight men and three women with a median of 18 months in the sport, through a full simulated race at Open standard. Their median finish was 86.5 minutes, and their heart rate barely came down in any of it. Every figure below is the group's median.
- 79.5 percent of the race above 90 percent of maximum heart rate, and almost all the rest between 70 and 90 percent.
- Average heart rate 170.9 bpm, and higher at the stations (173.7) than on the runs (168.9).
- Blood lactate peaked at 8.5 mmol/L after the stations and 7.7 after the runs, which the authors read as the body drawing on both aerobic and anaerobic energy to finish.
- Perceived effort reached 18 on a 6 to 20 scale at the stations and 16 on the runs. Heart rate, lactate and effort all peaked at the last station, the wall balls.
In a gym session you rest between sets. In HYROX the station is the next effort, and in that study it pushed heart rate higher than the running did. That is why the race feels harder than any single part of it looks on paper.
Read the numbers with their limits: 11 people, each racing alone in a gym with the runs on a treadmill, and a fit, experienced group in which all but one had very good to excellent aerobic fitness. These were not beginners, and the race still held them near their maximum.
Which parts hurt most
The sleds hurt by load, not by time
In the same study the sled push and sled pull were the shortest stations, with medians of 2.1 and 2.6 minutes. They are also the heaviest: the men's Open sled push is 152 kg and the women's 102 kg, sled included. The study's authors note that even these short stations ask for a large force held for two to three minutes, with anaerobic energy a key contributor. So two minutes on the sled push cost more than the clock shows, and six runs and six stations still follow it.
The burpee broad jumps, and the run after them
The 80 m of burpee broad jumps take the whole body to the floor and back, again and again. Run 5, the run straight after them, was the slowest in the study at a median of 7.4 minutes.
The wall balls, last
100 wall balls on legs that have already lunged 100 m. In the study, the wall balls brought the highest heart rate, lactate and effort of the whole race. See how the race is laid out for the full order.
Harder than a marathon, a half marathon or a triathlon?
No study has put the same racers through HYROX and another race, so there is no measured verdict. What separate studies show is a different kind of hard: shorter than a marathon, with heavier efforts inside it.
A marathon
A study of ten male recreational runners in the 2019 Paris Marathon found their heart rate settled at 88 to 91 percent of maximum after the first 5 km and stayed there. They finished in between 2 hours 50 and 5 hours 11. So across the two studies, both races held a heart rate around 90 percent: the marathon holds it far longer, over 42.2 km of running, while HYROX holds it for a shorter race with 8 km of running and adds heavy stations that drove heart rate and lactate above the level of its own runs.
If you have trained for a marathon, you have built the kind of fitness that went with faster times in the HYROX study, where quicker finishers had a higher VO2max and did more endurance training. What you have not done is run straight after pushing a sled.
A half marathon
The HYROX study noted that its racers ran slower than recreational half-marathon runners in other research. The authors suggest the stations explain it: running on legs full of lactate, or straight after heavy upper-body work, upsets technique and economy. So expect your HYROX runs to be slower than your half-marathon pace. Already a runner? See how running and HYROX share one training week.
A triathlon
We found no study that compares the two. This is our judgement at Smash Coach, not a measurement: a triathlon builds the endurance base HYROX stands on, and a run off the bike is the nearest feeling to a run off the sleds, but nothing in it prepares you for heavy carries, lunges and 100 wall balls at the end.
CrossFit, DEKA and Spartan races are compared on how HYROX differs from other races. Planning a marathon or triathlon in the same season? Read training for two races at once.
Can you do HYROX without training?
The rules let you. HYROX is open to anyone 16 or over with no qualification, and the 26/27 rulebooks set no overall time limit. Check your event's athlete guide before race day all the same.
That is not a promise you will always reach the finish. A racer who does not complete a station gets no result, and if blood, vomit or other bodily fluids pose a welfare risk, a Race Director can withdraw a racer on medical grounds, which is recorded as Did Not Finish.
The bigger question is what an hour or more at that effort asks of an untrained body. The trained, experienced racers in the study above spent most of the race above 90 percent of maximum heart rate. Arrive untrained and the same race lands on a heart, lungs, legs and grip that have had no preparation for it.
- Build up first. The WHO guidelines advise starting with small amounts of activity and increasing how often, how hard and how long gradually. Start with our guide to a first HYROX, or the run-walk start if you do not run yet.
- Fitness lowers the risk. The American College of Sports Medicine notes that exercise is safe for most people and that its cardiac risk falls as people become more active and fit.
- See a doctor before you start training if you have warning signs such as chest pain or fainting, or a heart, metabolic or kidney condition and you are not active now. Already active with one of those conditions? Check with a doctor before you train hard. If a warning sign appears during training, stop and get help.
Are you ready?
HYROX publishes its own fitness test, the PFT, with time bands that suggest a division. Use it once you are training regularly, not as a first workout: what the PFT can and cannot tell you.
Is HYROX good for you?
The training is. The WHO guidelines ask adults for 150 to 300 minutes of moderate activity a week, or 75 to 150 minutes of vigorous activity, or a mix, plus muscle-strengthening work for all the major muscle groups on two or more days. Training for HYROX covers both: running and ergs for the aerobic side, sleds, carries, lunges and wall balls for strength. The HYROX study's authors make the same point and call it an efficient way to meet the WHO guidelines.
The guidelines link that activity with lower all-cause and cardiovascular mortality, less high blood pressure, type 2 diabetes and some cancers, fewer symptoms of anxiety and depression, and better sleep and thinking. Whether the HYROX format itself works for health promotion, the same authors say, is still to be tested.
Training for it carries a cost too. In a 12-week study of 89 HYROX athletes, about 30 percent reported a health problem in any given week, nearly three in four injuries came from overuse, and the knee and lower leg carried the heaviest burden. It is one more reason to build up gradually.
The race is one hard day. The benefit comes from the weeks of steady training before it, and from arriving ready rather than hoping.
Making it less hard
- Race Doubles. You and a partner do every run side by side, then split each station however you choose. See how Doubles works.
- Race a Relay. A team of four, each doing two runs and two stations, and the team decides who does which. See how the Relay works.
- Choose Open. Open is the standard race; Pro is the same course with heavier weights. Compare the divisions.
- Pace it evenly. A review of pacing research suggests that in events longer than about two minutes, a more even pace may give faster times. Start the first run at a pace you could hold for all eight, and judge your result against your own last race in the same division, as the finish times page explains, not a friend's.
How Smash Coach starts you
When you add your race, you pick your division and format and say whether you are chasing a time or aiming to finish. None of it has to be perfect, and you can edit all of it later.
Your first week is a baseline week: each session is real training that also takes one easy measurement.
With Pro or during your trial, you can report an injury or fatigue at any time and your plan is rebuilt around it straight away. Your coach is a training tool, not a medical service.