HYROX has dominated the functional fitness racing scene for years. Now there's a new format growing fast: ATHX. It borrows from the same world — functional movements, a running component, head-to-head competition — but it's a different beast entirely, and training for one won't fully prepare you for the other.
This article breaks down exactly what ATHX demands: the format, the specific movements, the energy systems involved, and how to build a training approach that actually prepares you for race day. If you've been considering signing up, or you've already registered and want to know what you're in for — this is the guide.
"ATHX rewards a different athlete than HYROX does. The overlap exists, but the gaps in preparation are where most people lose time."
WHAT IS ATHX?
ATHX (Athletic X) is a functional fitness competition format built around short, high-intensity efforts with minimal rest between movements. Where HYROX is a longer aerobic test — essentially a fitness race over 8km with functional stations — ATHX sits closer to a CrossFit-style competition in its intensity and time domain, but with a fixed, standardised format that competitors can train specifically for.
The key difference in character: HYROX rewards pacing and aerobic engine. ATHX rewards power output, barbell proficiency, and the ability to push into high-intensity zones repeatedly. Both reward fitness — but the profiles are meaningfully different.
- 8km total running, split into 1km segments
- 8 fixed functional stations
- Aerobic-dominant energy system
- Pacing strategy is critical
- No barbell work
- Time domain: 60–120+ minutes
- Shorter running intervals between workouts
- Multiple workout blocks with varied movements
- Mixed energy systems — aerobic and anaerobic
- Higher peak intensity demands
- Barbell and gymnastics elements
- Time domain: typically 45–90 minutes
THE FORMAT
ATHX competitions are structured around a series of workout blocks, each with a defined movement list and time or rep target. Between blocks there is a running or machine-based transition — similar in concept to HYROX, but shorter and more intense. Athletes complete all blocks in sequence, with total time determining the final result.
Each workout block typically contains 3–5 movements performed for a fixed number of rounds or reps. The challenge is that you arrive at each block already carrying fatigue from the previous run and block — which changes the difficulty of even simple-looking movements significantly.
THE KEY MOVEMENTS — FULL BREAKDOWN
ATHX draws from a wider movement library than HYROX. Here's a breakdown of the categories you need to be prepared for, and what each one demands from your body under competition fatigue.
Power cleans, hang cleans, thrusters, deadlifts, overhead press. These appear either as straight sets or as part of a complex (multiple movements in sequence without putting the bar down).
Technique under fatigue. A power clean you can do cleanly when fresh looks completely different at rep 8 of a set, after a 400m run. Bar path, hip contact, and catch position all suffer.
Training priority: Build technique at moderate load first. Then practise barbell movements specifically after cardiovascular work — even a 500m row or 400m run before your barbell sets will expose the technique gaps that matter on race day.
Pull-ups, toes-to-bar, box jumps, burpees, push-ups, ring rows. Depending on the event format: muscle-ups or handstand push-ups at higher levels.
Grip and shoulder endurance. Pull-ups that feel easy as sets of 5 become a slow grind when you're doing 4 rounds after two other workout blocks. Kipping efficiency drops with fatigue.
Training priority: Build pulling volume. Sets of 3–5 strict pull-ups are worth far more than kipping 10 reps with poor mechanics. If toes-to-bar are in the format, train them specifically — the hip flexor and lat demand is different from other core work.
Running, rowing, SkiErg, assault bike. These appear as transitions between workout blocks and sometimes as scored elements within blocks. Distances are shorter than HYROX — 200–400m runs are common.
Pacing judgment. The shorter distances tempt athletes to sprint — which spikes HR into a zone that compromises the barbell work that immediately follows. Smart athletes run controlled.
Training priority: Practice running at "conversation pace" even when it feels too slow. In ATHX, the transitions are a recovery opportunity as much as a scored movement — arriving at the next block with HR under control is almost always faster overall.
Sandbag carries, kettlebell farmers carries, yoke carries, atlas stone loading. ATHX often includes at least one loaded carry or odd-object movement per event — they appear less in CrossFit but are core to ATHX's identity.
Grip fatigue compounds with everything else. By the time you reach a farmers carry in block 3, your hands are already compromised from pull-ups and barbell work. Training carries in isolation doesn't replicate this.
Training priority: Add carries at the end of sessions, not the beginning. This is the only way to build the grip and stability endurance that actually shows up on race day.
THE ENERGY SYSTEMS AT PLAY
This is where ATHX differs most significantly from HYROX — and where most HYROX athletes who cross over are surprised. HYROX is primarily an aerobic event. You want to stay in zone 2–3 for most of the race and avoid going anaerobic. ATHX regularly sends you into zone 4–5, then asks you to recover and perform again.
ATHX workouts typically alternate between high-intensity anaerobic bursts (barbell complexes, gymnastics sets, loaded carries) and aerobic transitions. Your body needs to be efficient at both producing power and recovering from it quickly.
The physiological quality that separates good ATHX athletes from great ones is aerobic recovery speed — how quickly your heart rate drops between high-intensity efforts. The better your aerobic base, the faster you recover, and the harder you can push on the next block.
HOW TO TRAIN FOR ATHX
A well-structured ATHX programme has three distinct components running simultaneously, not in phases. Most athletes make the mistake of doing only the competitive movements and neglecting the aerobic base — then wonder why they fall apart in the later blocks.
The simulation day (Thursday) is the most important session of the week. It's where you build the specific capacity that race day will demand — executing movements under accumulated fatigue, managing transitions, and practising pacing decisions.
ATHX vs HYROX: WHICH SHOULD YOU DO?
Both events are excellent. The right choice depends on your background and what excites you.
Choose HYROX if you come from a running or endurance background, prefer a longer aerobic effort, and want a more accessible entry point — HYROX doesn't require barbell technique, which makes it easier to prepare for from scratch.
Choose ATHX if you have a strength or CrossFit background, enjoy higher-intensity efforts, and want a competition format that rewards power output and barbell proficiency as much as aerobic fitness. The learning curve for technique is steeper, but the variety is greater.
Do both if you want to build the most complete fitness profile. The crossover between HYROX aerobic base and ATHX power output is real — athletes who compete in both tend to develop faster than those who specalise in one format only.
Training for ATHX in Amsterdam West?
I work with athletes preparing for ATHX and HYROX at Het Gymlokaal West and Bodytime in Amsterdam West, and with online clients worldwide. If you want a programme built around your specific event and timeline, let's talk.
Book a Free Call →THE SHORT VERSION
ATHX is a functional fitness competition format that mixes barbell movements, gymnastics, loaded carries, and running transitions into a multi-block race. It demands more from your anaerobic system than HYROX, requires barbell technique under fatigue, and rewards athletes with a strong aerobic recovery base.
Train the movements specifically. Build your aerobic base — it underpins everything, even in a high-intensity format. Practise simulation days where you execute multiple movements under accumulated fatigue. And don't neglect the transitions — arriving at each block with your heart rate under control is one of the most underrated competitive advantages in the sport.