Yes, HYROX training builds some muscle and a fair amount of strength, especially if you're new to lifting, but on its own it isn't an efficient way to get bigger. The stations load your legs, glutes, back and grip, while the running and high reps push your body toward endurance. This guide explains what concurrent-training research says about the "interference effect," what HYROX training builds and what it doesn't, and how to add muscle-building work without hurting your race.
This is general information, not medical advice. If you have a heart, joint or metabolic condition, are pregnant, or are coming back from injury, talk to your doctor or a physiotherapist before you start heavy or high-intensity training.
Does HYROX training build muscle?
It does for most beginners, and it maintains muscle well for experienced lifters, but it rarely adds much size once you're past your first year of training. That's the short answer. The longer one depends on what you mean by "HYROX training."
A HYROX race is eight 1 km runs with eight stations in between. In the one lab study of the race (Brandt and colleagues, 2025, 11 recreational athletes), runners spent about 51 minutes running and about 33 minutes on the stations in an 86-minute simulated race. So roughly 60% of the race is running, and the stations themselves are mostly long, sub-maximal efforts.
Nobody has yet studied how much muscle people gain from HYROX training. Everything below comes from research on combining endurance and strength training in general, which is called concurrent training. HYROX training is a very clear example of it.
What we can say from that research:
- Beginners gain muscle from almost any challenging training. A review by Konopka and Harber (2014) even showed that aerobic training alone can add some muscle size, mainly in people who were previously untrained or older.
- Experienced lifters need progressive, heavier loading to keep growing. The American College of Sports Medicine's position stand on resistance training says intermediate and advanced lifters need loads up to their 1 to 12 rep max, increased over time. A 100-rep wall-ball set doesn't do that.
- Strength training and endurance training can coexist. That's the good news, covered in the next section.
What is the interference effect?
The interference effect is the idea that doing endurance training alongside strength training blunts your strength and muscle gains. It's real, but it's smaller and narrower than gym folklore suggests.
The idea started with a 1980 study by Robert Hickson. People who lifted five days a week and also did endurance training six days a week gained strength at first, then plateaued and slipped back in the later weeks, while the lifting-only group kept improving. That was a very high training load, and it set up 40 years of "cardio kills gains."
Here's what the bigger reviews have found since:
| Review | What it found |
|---|---|
| Wilson, 2012 (21 studies) | Concurrent training built muscle, but less than lifting alone. Running caused more interference than cycling, and longer, more frequent cardio sessions caused more. |
| Sabag, 2018 (HIIT + lifting) | Interval training didn't reduce muscle growth or upper-body strength. Lower-body strength gains were slightly smaller. |
| Petré, 2021 (27 studies) | Lower-body max strength was blunted in trained lifters, mostly when cardio and lifting were in the same session. No effect in untrained people. |
| Schumann, 2022 (43 studies) | No difference in muscle growth or max strength vs lifting alone. Explosive power was slightly reduced, more so in same-session training. |
The most recent and largest review, Schumann's, is the most reassuring: across 43 studies, adding aerobic training to a strength program didn't reduce muscle growth or maximal strength. The one consistent cost was explosive power, such as jump height and speed-strength.
Two caveats keep this honest. First, most studies use moderate amounts of cardio, not the high running volume of a HYROX athlete preparing for a race. Second, physiologists Coffey and Hawley (2017) point out that long-term studies still show endurance work can blunt muscle and strength gains under some conditions, even though nobody has pinned down exactly why. Reviewers such as Murach and Bagley (2016) argue the effect on muscle size is weaker than many assume.
The practical takeaway: the interference effect matters most when you're already well trained, when you do a lot of running, and when you stack running and heavy legs in the same session. You can manage all three.
What does HYROX training build, and what doesn't it?
HYROX training builds muscular endurance, work capacity, grip and leg strength-endurance very well. It doesn't build much maximal strength or size once you're past the beginner stage, and it does little for your chest, shoulders and arms.
Here's how the main stations load you in the Open division (the rulebook sets the weights; men's Open loads are listed first):
| Station | Main muscles | Load (Open men / women) |
|---|---|---|
| Sled push | Quads, glutes, calves | 152 kg / 102 kg incl. sled |
| Sled pull | Back, biceps, grip, legs | 103 kg / 78 kg incl. sled |
| Farmers carry | Grip, traps, core | 2 x 24 kg / 2 x 16 kg |
| Sandbag lunges | Quads, glutes | 20 kg / 10 kg |
| Wall balls | Quads, glutes, shoulders | 6 kg / 4 kg |
The SkiErg, row and burpee broad jumps add pulling, hinging and bodyweight pressing, but at an intensity that's mostly about conditioning.
What it builds well:
- Leg strength-endurance. Heavy sled pushes and 100 m of lunges are hard leg work, and beginners often see visible changes in their quads and glutes.
- Grip and upper back. Farmers carries and sled pulls are among the best grip trainers in any sport.
- Work capacity. Being able to keep producing force while your heart rate is high is exactly what the race rewards.
What it builds poorly:
- Upper-body size. Apart from wall balls and burpees, there's very little pushing, and nothing heavy for the chest, shoulders or arms.
- Maximal strength. Heavier loads are better for one-rep-max strength, according to a 2017 meta-analysis (Schoenfeld, Grgic and colleagues). HYROX stations are sub-maximal.
- Explosive power. Long sessions and high running volume are where concurrent training tends to cost you some pop.
Muscle mass isn't what decides HYROX results anyway. In the Brandt study, VO2max, endurance training volume and lower body fat predicted faster finishes, while muscle mass and lifting volume showed no clear link. It's only one small study, but it fits what coaches see: you need enough strength to move the sleds comfortably, then fitness takes over.
Can you build muscle with high reps and light weights?
Yes, as long as the sets are genuinely hard. The 2017 Schoenfeld meta-analysis compared light loads (60% of your one-rep max or less) with heavy loads, with all sets taken to failure. Muscle growth was similar across load ranges. Heavy loads were better for building maximal strength.
The catch is effort and volume. A set of 25 wall balls during a conditioning circuit usually stops because you're out of breath, not because your legs have reached failure. That's great for your race but a weaker signal for muscle growth. So high reps can build muscle, but conditioning circuits are not the same thing as high-rep strength sets.
How do you add muscle-building work to HYROX training?
Add two or three focused strength sessions a week, keep them separate from your hardest runs, and make them progressively heavier. This is the plan most coaches use, and it lines up with the research above.
The rules
- Volume: aim for about 10 or more hard sets per muscle group per week. A 2017 dose-response meta-analysis (Schoenfeld, Ogborn and Krieger) found that more weekly sets produced more growth, with a trend favoring 10 or more sets per muscle.
- Load: mostly 6 to 12 reps, finishing each set one to three reps short of failure. The ACSM recommends adding 2% to 10% to the load once you can beat your target reps by one or two.
- Exercises: squats or leg press, a deadlift or hip-hinge variation, split squats, rows and pull-ups, a bench or overhead press, plus some direct arm and shoulder work if size matters to you.
- Separation: do heavy leg work and hard runs on different days, or at least about three hours apart. In Petré's review, trained lifters lost lower-body strength gains only when both were in the same session. If you must combine them, lift first.
- Running volume: add mileage gradually. Longer and more frequent endurance sessions were linked with more interference in Wilson's review.
A sample week
| Day | Session | Notes |
|---|---|---|
| Monday | Lower-body strength | Squats, hinges, split squats, 3–4 sets each |
| Tuesday | Intervals (run or erg) | Keep legs fresh for quality |
| Wednesday | Upper-body strength + easy run | Run in the morning, lift in the evening |
| Thursday | HYROX-style circuit | Stations and running together |
| Friday | Rest or mobility | |
| Saturday | Long easy run | Conversational pace |
| Sunday | Full-body strength (optional) | Lighter, higher reps |
As your race gets closer, flip the priority. Cut strength volume by about a third to a half in the last few weeks, keep the weights fairly heavy so you hold on to strength, and spend more time on race-specific work. Our intermediate training plan and advanced plan show how strength fits around a full HYROX block.
How much protein do you need to build muscle while training for HYROX?
Most people do well on about 1.6 g of protein per kg of body weight per day, spread across three or four meals. A 2018 meta-analysis of 49 trials (Morton, British Journal of Sports Medicine) found that gains in lean mass from strength training stopped improving beyond about 1.6 g/kg/day on average. The International Society of Sports Nutrition gives a broader range of 1.4 to 2.0 g/kg for active people.
For a 75 kg athlete, that's about 120 g a day, or roughly 30 g at each of four meals. You also need enough total food. HYROX training burns a lot of energy, and you can't build much muscle while eating well below what you burn. Our weight-loss guide covers fueling and calorie needs in more detail.
Will HYROX make you bulky, or make you lose muscle?
Neither is likely. Bulking up takes deliberate, heavy, high-volume lifting and a calorie surplus, which isn't what HYROX training looks like. Most people end up leaner and more athletic-looking.
Losing muscle is possible, but usually only if you drop strength training entirely, run very high mileage and under-eat for a long time. Keep two strength sessions a week and eat enough protein, and you'll hold on to what you have.
Why does building muscle matter beyond racing?
Muscle and strength are worth having for health, not just for sled pushes, though this evidence comes from strength training in general, not HYROX. The World Health Organization recommends muscle-strengthening activity on at least two days a week for all adults. A 2022 meta-analysis of cohort studies (Momma, British Journal of Sports Medicine) linked muscle-strengthening activities to a 10% to 17% lower risk of death from any cause, heart disease, cancer and diabetes, with the biggest benefit at about 30 to 60 minutes a week. Those are associations, not proof of cause, but they're a good reason to keep lifting.
That's especially relevant as you age. See HYROX over 40 and 50 for how to adapt strength work, and the benefits of HYROX for how muscle fits with the other health effects of training. The running side of HYROX matters for health too: see HYROX and your heart.
FAQ
Does HYROX build muscle?
Yes, some, especially if you're new to strength training. The sleds, lunges, carries and wall balls load your legs, back and grip. Once you're more experienced, you'll need dedicated heavier lifting to keep adding size, because HYROX stations are mostly long, sub-maximal efforts.
Does running for HYROX kill your gains?
Not much, if you manage it. The largest recent meta-analysis (Schumann, 2022) found that adding aerobic training to strength training didn't reduce muscle growth or maximal strength, though explosive power was slightly lower. Interference is more likely if you're highly trained, run a lot and do heavy legs and hard runs in the same session.
What is the interference effect?
It's the reduction in strength, power or muscle gains that can happen when you combine endurance and strength training. It was first described in a 1980 study with a very high training load. Modern reviews suggest the main cost is to explosive power and, in trained lifters, lower-body strength when both are done in one session.
Can you build muscle doing only HYROX classes?
Beginners can, at least for the first several months. After that, classes mainly maintain muscle and improve conditioning, because the loads don't increase steadily and sets usually end from breathlessness rather than muscle fatigue. Add two progressive strength sessions a week if muscle is a goal.
How many strength sessions a week should I do for HYROX?
Two or three for most people. Aim for about 10 hard sets per muscle group per week, mostly in the 6 to 12 rep range, and keep heavy leg days away from your hardest runs. Reduce the volume, but not the weight, in the last few weeks before a race.
How much protein do I need to build muscle while training for HYROX?
About 1.6 g per kg of body weight per day suits most people, spread across three or four meals. Research found no further average gains in lean mass above that, though up to about 2.0 g/kg is reasonable. You also need enough total calories.
Will HYROX make me bulky?
Very unlikely. Getting bulky takes heavy, high-volume lifting and a calorie surplus. HYROX training tends to make people leaner and more athletic, with stronger legs, back and grip.
Does more muscle make you faster at HYROX?
Only up to a point. You need enough strength to move the sleds well, but in the one lab study of HYROX, VO2max, endurance training and lower body fat predicted finish time, while muscle mass didn't. For most people, fitness is the bigger limiter.
Next steps
See how strength fits into a full program in how to train for HYROX, sharpen your sled technique with our sled push and pull tips, read the wider health picture in the benefits of HYROX, then pick a goal race from the race calendar.