Over the years coaching athletes for HYROX (and similar events), one of the most common problems I’ve seen is that someone is technically good at all the pieces (they can crush a sled push, they have no problem with wall balls, their rowing technique is solid) but come race day or even just a simulation session, they fade. They start strong, but 15 or 20 minutes in, the wheels start to come off. They lose steam, and finishing strong feels almost impossible. They don’t seem to have the aerobic system for HYROX.
This article is for that athlete.
If I were working with someone like that (as I have, many times), my immediate focus wouldn’t be on grinding through more HYROX-style workouts or simulating the race every weekend (this is a super common trap). Instead, I’d zoom out and look at what’s really limiting their performance, and more often than not, it’s an underdeveloped aerobic system. They have the strength. They have the skill. But their engine just isn’t built to sustain the effort for the full event.
So in this article, I’m going to walk you through exactly how I’d approach that situation. It’s not a specific person’s story, but rather a composite case study based on real clients I’ve coached. We’ll look at why just doing HYROX classes isn’t enough, why aerobic development is critical for hybrid athletes, and most importantly, how to build an aerobic system that actually supports performance when it counts.
Let’s dig in.
Improving The Aerobic System for HYROX Case Study Overview: The “Strong But Fading” Athlete
If you’re not familiar with HYROX, it’s one of the most exciting and challenging events in the fitness world right now. It combines running with functional strength movements (think sled pushes, burpee broad jumps, rowing, lunges, etc.) spread across eight stations, with 1km runs between each one.
On paper, it sounds simple enough. But anyone who’s done one, or even just trained for one, knows just how demanding it is. It’s not just about being strong, and it’s not just about being a good runner. It’s about sustaining effort across a long, grinding, hybrid event.
Let me paint the picture of a typical HYROX athlete I’ve worked with, who needs to improve their aerobic system for HYROX performance.
They come in with a solid fitness background. Maybe they’ve done CrossFit, maybe they’ve come from a strength or “functional training” background, or maybe they’ve just been training hard in the gym for years. Either way, when you look at them on paper, they seem ready for HYROX. They’re strong. They can move well. They don’t shy away from hard work.
They’re pretty damn dialled in. They can push a sled no problem. Wall balls are not an issue. Their rowing technique is decent, they can hold pace on a SkiErg, and they can grind out burpees with good form. In a class setting or short workout, they often perform quite well. They’re the kind of athlete that looks “fit” and seems like they should crush a HYROX.
But here’s what actually happens.
They start the race strong, flying through the first run, smashing the SkiErg, feeling great. But somewhere around the second or third station, things start to unravel. Their pace drops. Heart rate stays high and never comes back down. The legs feel heavier, breathing becomes laboured, and by the time they hit the sled pull or burpees, they’re deep in survival mode. That strong, confident athlete from the first 10 minutes is now just trying to survive to the end.
If this sounds familiar, you’re not alone. It’s incredibly common.
Now, the most typical response I see from people in this situation is: “I just need to do more HYROX simulations. If I can just get used to the grind, I’ll build the fitness for it.”
On the surface, that makes sense. But here’s the thing, this approach rarely actually works long-term. Doing more race-paced training when you’re already lacking the aerobic foundation to do it effectively just isn’t going to improve your aerobic system how you want it to. You’re just reinforcing fatigue, not fixing the reason you’re getting fatigued in the first place.
When I coach someone like this, the problem almost always comes back to one thing, their aerobic system isn’t built to support the demands of the event. They’ve got the horsepower, but not the engine endurance. Unless we address that directly, they’ll keep hitting the same wall, no matter how many HYROX sims they do.
Why Just Doing HYROX Classes Isn’t Enough
Don’t get me wrong, HYROX classes absolutely have their place. They’re a fantastic way to build familiarity with the movements, get comfortable with transitions, and dial in race-day flow (and practice your HYROX performance nutrition tactics). On top of that, the community vibe and competitive energy can really help push you to new levels mentally. I often encourage athletes to keep at least one HYROX-style class in their weekly routine for those reasons alone.
But here’s the catch.
If all you’re doing is HYROX classes, your progress is going to plateau. Especially if you’re someone who’s already technically proficient but fading mid-event. That’s because these classes tend to sit in a very specific training zone: high-intensity, high heart rate, near-threshold work (Zone 3 or Zone 4).
That might feel like the right way to get fitter, after all, you’re breathing hard, sweating buckets, and crawling off the floor at the end, but it’s not necessarily helping you fix the real problem.
What I’ve seen time and time again is a situation where HYROX classes tend to reinforce what you’re already good at. Strong athletes dominate the strength stations. Naturally fast runners push the runs. But that class format rarely gives you the space to address your underlying aerobic limitations, which is the very thing that’s causing you to crash and burn mid-race.
It’s like trying to build a bigger, flashier house on top of a weak foundation. Sure, it might stand for a while. But as soon as the pressure’s on (like during a competition) you find the cracks. The structure starts to fail. And no amount of cosmetic upgrades (i.e., doing more threshold workouts) will fix it.
To really improve, and to go from “fading halfway through” to “finishing strong and steady”, you need to step back and build that foundation properly. That means training the aerobic system directly, methodically, and with intention. Unfortunately, that’s where most HYROX-focused programming falls short. There isn’t enough hype around building the aerobic system for HYROX.
Don’t get me wrong, in a few years, this will certainly be old news as people realise just how important building a strong aerobic base is for HYROX. But for now, it is a major competitive edge for you if you can build that base now while everyone else is just winging it.
The Critical Role Of The Aerobic System For HYROX
One of the biggest misconceptions I come across when coaching HYROX athletes is the idea that the event is all about power, speed, and intensity. While yes, those things definitely matter, the real engine behind high-level HYROX performance is your aerobic system.
HYROX is a 60-90 minute event for most competitors. That puts it squarely in the endurance zone, meaning your body is relying heavily, predominantly even, on aerobic energy systems to get you through. Sure, you have bursts of anaerobic demand (like during the sled push or burpees), but those are short spikes in an otherwise long, steady effort.
What that means is that the more developed your aerobic system is, the longer you can perform at a consistent level without hitting a wall.
It is pretty similar to other repeated sprint events, such as football (soccer). It seems to be more anaerobic in nature when you zoom in on any single minute of the game, as there are people sprinting about. But when you zoom out, most of the game is spent at a slow jog, and even when there is lots of sprinting, each subsequent sprint is much slower than the initial ones because they are just being fuelled more and more by the aerobic system than the anaerobic system.
It is also important to keep in mind that the aerobic system is what recovers the anaerobic system. So if you want to be able to perform those high-intensity efforts repeatedly, you are going to need to have a super-efficient aerobic system that can restore the anaerobic system.
When I’ve worked with athletes who start strong and fade early, it almost always comes down to their aerobic base being underdeveloped. Their body can’t efficiently produce energy over time, so once those early energy reserves are used up, there’s no backup system to keep them going. They hit the dreaded “red zone” and never recover.
Here’s what a strong aerobic system actually does for you in HYROX:
1. Fatigue Resistance
Your aerobic system allows you to burn fuel more efficiently and clear waste products like hydrogen. That means you can keep moving without the heavy-legged, burning, gasping-for-air feeling that comes when you’re too anaerobic for too long.
2. Recovery Between Stations
Between each big station, you’ve got a 1km run. If your aerobic system is well developed, you can actually use that run to recover. You can lower your heart rate, catch your breath, and prepare for the next effort. Without that ability, each station feels harder than the last, and the fatigue snowballs.
3. Mental Clarity Under Duress
This one’s massively underrated, but a strong aerobic base helps regulate your nervous system and breathing, keeping you calmer and clearer-headed in the middle of the chaos. When your body isn’t constantly screaming for oxygen, you can actually make smarter decisions, like pacing properly, managing transitions, or pushing at the right moments.
4. Sustained Pacing Strategy
HYROX is a game of consistency. The athletes who perform best aren’t the ones who go out hot, they’re the ones who can hold steady output from start to finish. That’s only possible if your aerobic system can support that level of work for the entire duration.
So if you’re fading halfway through, struggling to recover between stations, or finding it hard to hold pace, don’t just assume you need to get tougher or push harder. You might just need a better engine.
Building that engine is just about building the aerobic system. Of course, we want to build the aerobic system for HYROX specifically, and not just become an endurance runner.
Identifying Weaknesses: Performance Diagnostics
When I’m working with a client who’s strong but fades mid-HYROX, the first step is always to identify why. We can’t just throw more training at the problem and hope it sticks, we need to pinpoint the limiter.
In these cases, I take a diagnostic approach. Before we even start changing the program, I want to understand exactly where the system is breaking down. Here’s what I look at:
1. Recovery Rate Between Intervals
How quickly does the athlete bounce back after a hard effort? If we do a few rounds of sled push and run intervals, are they recovering within 1-2 minutes, or are they still gasping five minutes later?
A slow recovery is a strong indicator that their aerobic system isn’t efficiently clearing byproducts like hydrogen or replenishing oxygen stores, both of which are key for maintaining effort across the 60-90 minutes of a HYROX race.
2. Heart Rate Response and Recovery
I’ll often track heart rate during workouts, not to obsess over the numbers, but to look at trends.
Does their heart rate spike early and stay elevated for the entire session? Do they recover back to baseline quickly between stations, or does it stay stuck in the high zone?
An inability to bring the heart rate down is usually a sign that their parasympathetic recovery response is underdeveloped, which again points to an aerobic system that needs more work.
3. Time to Fatigue During Steady-State Efforts
If I have them run or row at a moderate, sustainable pace, how long can they hold it before form breaks down or their effort level spikes?
This tells me a lot about their endurance threshold (where they can function without slipping into anaerobic territory). If they fatigue quickly at what should be an easy pace, it’s a sign they’re over-reliant on high-intensity systems and lack aerobic capacity.
4. Breathing Patterns and Perceived Effort in Long Efforts
I pay close attention to how they breathe during longer efforts.
Are they breathing through their chest or belly? Is it controlled and rhythmic, or are they already huffing and puffing 10 minutes in? Do they feel like they’re dying even at moderate intensities?
Perceived exertion tells me just as much as the raw data. If an athlete is struggling mentally or physically at intensities that should feel manageable, it’s usually a sign that their aerobic system can’t handle the volume/intensity.
5. Running Efficiency (If Running Is a Limiter)
Running makes up half of HYROX, so if someone’s leaking energy here, it adds up fast.
I’ll watch their form, cadence, breathing, and posture during runs. Do they look relaxed or tight and heavy-footed? Are they overstriding? Are they slowing dramatically over time?
If running is inefficient or exhausting, we’ve got to fix that, not just for aerobic benefits, but because poor form here makes every station that follows even harder.
The bottom line is that before we start building, we need to understand exactly what needs reinforcing. Once we’ve got a clear picture of where the weaknesses are, we can create a plan that actually moves the needle. Instead of just repeating the same grind and expecting different results.
Aerobic Development Strategy
As I said before, we aren’t just trying to become an endurance runner here. We have to actually build the aerobic system for HYROX. That means our training needs to be specific.
Building a Base: Why and How
When I start working with an athlete who’s hitting a wall halfway through a HYROX event, this is often where we begin: aerobic base building.
Now, I get it, “aerobic base building” doesn’t sound nearly as exciting as high-intensity sled pushes or burpee broad jumps. But if you’re serious about improving your HYROX performance, this is the foundation everything else sits on. You can have all the strength in the world, but without an aerobic base, you won’t be able to express it over the full duration of a race like HYROX.
What Is Base Building, Really?
In endurance training, “base building” refers to a block of time, usually several weeks to a few months, where the primary goal is to develop your aerobic energy system through lower-intensity, longer-duration efforts.
That means more time spent in Zone 2, less time redlining, and a focus on consistency over intensity. It’s about creating the physiological changes your body needs to become more efficient, durable, and fatigue-resistant.
Why It Works: The Key Physiological Adaptations
Here’s what’s happening inside your body when you commit to base building:
- Mitochondrial Density Increases: These are the “power plants” of your cells and the more you have, the more efficiently you can produce energy aerobically. That means less reliance on sugar-burning, lactate-producing anaerobic energy.
- Capillary Growth: More capillaries means better blood flow to working muscles. That improves oxygen delivery, waste removal, and overall muscular endurance.
- Improved Fat Oxidation: A strong aerobic base trains your body to use fat as a fuel source more efficiently. That spares glycogen for high-intensity bursts and helps you avoid bonking mid-race.
- Lower Resting and Working Heart Rate: As your aerobic system improves, your heart becomes more efficient, beating slower and stronger, both at rest and during exercise. That leads to lower perceived exertion at a given pace and faster recovery between efforts.
These are the behind-the-scenes upgrades that make you feel like a totally different athlete when you race. You don’t just survive the back half of the event, instead, you actually stay composed, in control, and strong throughout.
How Long Does It Take?
Unfortunately, this is a long game, and that’s why so many people avoid it. The timeline depends on your training history, current fitness level, and how well your past programming has supported aerobic development.
For most athletes I coach, I’ll spend 8-16 weeks in a dedicated base-building phase. That might seem like a lot, but the goal here isn’t to just survive one race, it’s to level up your entire system so you can perform better across every HYROX, and so that you can improve your overall health.
And once the base is there, you can build more speed, strength, and intensity on top of it far more effectively, all without falling apart halfway through the race.
So, how do we build this aerobic base?
Zone 2 Training: The Core of Aerobic Development
If base building is the strategy, then Zone 2 training is the tool. It’s the unsung hero of endurance development. It’s the kind of work that doesn’t feel flashy but delivers massive returns when it’s done consistently over time.
When I’m helping an athlete rebuild or strengthen their aerobic base, Zone 2 is almost always where we spend the bulk of our time.
What Is Zone 2 Training?
Zone 2 refers to a specific range of intensity where your body is working aerobically, meaning it’s primarily using fat for fuel and relying on oxygen to produce energy. It’s moderate, sustainable, and should feel very manageable, maybe even “too easy” if you’re used to constantly pushing hard.
There are a few simple ways to find your Zone 2:
- The Talk Test: You should be able to hold a full conversation without gasping. You should be able to talk, but the other person would know that you were exercising. If you can’t speak in complete sentences, you’re going too hard.
- Heart Rate Zones: For many athletes, Zone 2 falls roughly between 60-70% of max heart rate, though using a percentage of your lactate threshold or functional threshold heart rate (if tested) gives more precision.
- Perceived Effort: On a scale of 1-10, Zone 2 is usually a 4 or 5. You’re working, but it feels controlled and comfortable.
It may not feel intense, but that’s the point. It’s building the deep, low-gear endurance your body needs to perform for an hour-plus without falling apart. Try to keep in mind that this is building, not testing.
You can use our heart rate zones calculator to workout your exact zone 2 heart rate.
Why Running Is Ideal for HYROX Athletes
While you can do Zone 2 on a bike, rower, or other machines, I almost always encourage HYROX athletes to prioritise running for this work. Here’s why:
- Improves Running Economy and Skill Under Fatigue: Since running makes up half the HYROX event, every opportunity to reinforce technique and efficiency helps. The more relaxed and rhythmical your running becomes, the less energy it costs on race day.
- Reinforces HYROX-Specific Biomechanics: Running at low intensity lets you groove better mechanics (foot strike, posture, cadence, etc) without the stress of going fast. Over time, that transfers directly into smoother, more efficient race-day runs.
- Mental Familiarity: The more time you spend running, the more mentally comfortable you become with it. So you’re less likely to dread or “check out” during the running segments of a race.
Sample Protocol: Getting Started with Zone 2 Running
Here’s how I typically structure Zone 2 running for a HYROX athlete in the base-building phase:
- Frequency: 3 to 5 runs per week. More frequent, shorter runs tend to be more sustainable and recovery-friendly than fewer long ones, but if you really want to build the aerobic adaptations, your runs are going to have to eventually get to a stage where they are quite long.
- Duration: 30-90 minutes per session. Start on the shorter end if you’re new to aerobic training, and build up gradually. Once you are adapted, 45-60 minutes is a good duration for most people who have other things going on in their lives. But if you can go up to 90-minute sessions, your aerobic fitness will be in a very good place.
- Nasal Breathing Drills: Try breathing only through your nose for the majority of the run. This naturally limits your effort level and encourages better diaphragmatic breathing. It will be difficult at first, but unless you have a structural issue, you will get used to it.
- Heart Rate Cap: Use a heart rate monitor to stay honest. If you tend to go too hard, set an upper HR limit (say, 140 bpm depending on your exact zones) and walk if needed. Yes, walking is better than going over. You want to learn what it feels like to run at the right pace for your aerobic system.
The Key Is Patience
Zone 2 running doesn’t give you the immediate dopamine hit of a hard class or brutal metcon, but over time, it transforms your engine. It builds the “low gear” that lets you recover faster, run smoother, and hold pace longer in HYROX.
Once your Zone 2 base is strong, that’s when we layer in intensity. But without this aerobic foundation first, you’re just stacking firepower on a weak chassis.
Daily Steps and Zone 1 Movement
When we talk about improving aerobic capacity, most people think about structured workouts like runs, intervals, or long sessions. But one of the most overlooked (and low-stress) tools in the aerobic development toolbox is simple daily movement, specifically, Zone 1 activity like walking.
This is where NEAT (non-exercise activity thermogenesis) comes into play. It refers to all the movement you do outside of formal workouts: walking, cleaning, fidgeting, taking the stairs, etc. And while it might not feel like “training,” it actually has a massive impact on your overall aerobic system.
Why NEAT Supports Aerobic Development
When I work with a client who’s trying to build a bigger engine, I don’t just look at how hard they’re training, I look at how much they’re moving across the entire day. The more low-intensity movement you can build in, the more aerobic volume you’re accumulating without much extra fatigue or recovery cost.
Zone 1 movement (like walking) helps by:
- Improving circulation and capillary density
- Encouraging better metabolic flexibility (your body gets more efficient at using fat for fuel)
- Supporting recovery between hard sessions
- Reducing stiffness and promoting mobility
- Keeping your energy expenditure high without burning you out
It’s essentially free aerobic training, which is especially helpful when we’re trying to build volume without risking overtraining.
Steps: A Simple, Powerful Metric
One of the easiest ways to track Zone 1 movement is with a step goal. I’ll often set clients a target of 7,000 to 15,000 steps per day, depending on their lifestyle and current baseline. It doesn’t have to be all at once, and it’s more about cumulative movement across the day.
If you’re serious about improving your performance, don’t overlook the basics. Get your steps in, move often, and make walking a non-negotiable part of your daily rhythm. It’s simple, sustainable, and quiet powerful at improving your aerobic system for HYROX.
Progressive Overload in Aerobic Training
Just like with strength training, aerobic development follows the principle of progressive overload, but the way we apply it is a bit different.
Instead of piling on more weight or doing more reps, we’re increasing volume, frequency, or time spent at specific intensities (gradually) to help the body adapt without tipping into fatigue, injury, or burnout.
Gradual Progress Is the Name of the Game
When I’m building an aerobic program for a client, especially one coming from a strength or high-intensity background, the biggest challenge is usually pacing. They’re used to pushing hard and chasing the “feel” of a tough workout, but aerobic development doesn’t work that way.
We focus on slow, deliberate increases in:
- Weekly mileage or time
- Frequency of Zone 2 sessions (e.g., moving from 3 to 4, then 5 sessions/week)
- Duration per session (e.g., from 30 to 40 to 60 minutes)
- Step count and general movement
If you go too fast, too soon, the risk of shin splints, plantar fasciitis, chronic fatigue, or just plain burnout rises fast. But if you build patiently, week over week, the gains compound.
Consistency > Intensity
Here’s something I drill into every one I coach: intensity is easy, consistency is hard.
You can’t brute-force aerobic capacity. You have to show up, stay in the right zones, and let the volume stack up over a long time. One hard session doesn’t build your aerobic engine. But six weeks of consistent Zone 2 running will do a lot for improving the aerobic system for HYROX.
It’s not glamorous, and it won’t leave you gasping on the floor, but it works.
Use the Right Tools to Track Progress
To make sure you’re progressing, and not accidentally overdoing it, I recommend using a few simple tools:
- Heart Rate Monitor: This is especially useful for keeping yourself honest during Zone 2 runs. It’s easy to accidentally drift into Zone 3 without realising it.
- RPE (Rate of Perceived Exertion) Scale: Train your internal gauge. A true Zone 2 effort should feel like a 4–5 out of 10, or something where you could maintain it for hours, not minutes.
- Training Logs: Keep a written or digital record of each session, stuff like duration, how it felt, HR averages, what terrain you ran on, etc. This helps identify trends, catch signs of overreaching early, and celebrate progress over time.
The goal here isn’t to train as hard as possible, it’s to train as smart as possible, for as long as possible. A well-built aerobic base isn’t something you can crash-build in 2 weeks. But if you layer it in with the right structure and progression, it becomes the engine that powers everything else.
In the next section, we’ll talk about how to start layering in higher-intensity aerobic work once that base is in place, and how to tie it back to HYROX-specific performance.
Specificity and Aerobic Capacity Work
Once an athlete has put in the time to build a solid aerobic base (through Zone 2 work, daily movement, and progressing volume) the next step is to start sharpening the system. This is where we move from just building endurance to building the kind of sustainable intensity that directly translates to better HYROX performance.
Think of this as going from “having an engine” to “being able to drive it hard for 60+ minutes without blowing up.”
Introducing Higher-End Aerobic Work
Now that the aerobic foundation is in place, we can safely start incorporating higher-intensity aerobic sessions, designed to raise your ceiling without pulling you into full anaerobic suffering.
Some of the key tools I use here include:
- Tempo Runs: Sustained, controlled efforts just below threshold. These teach you to hold pace under moderate fatigue which is perfect for HYROX runs between stations.
- Progression Runs: Start easy, finish hard. Do the first 45-50 minutes at your usual Zone 2 pace and then have the last 10-15 minutes at a hard and fast pace. This helps build pacing control and aerobic strength while reinforcing the ability to finish a race fast and strong.
- Aerobic Intervals: For example, 4 x 5 minutes at tempo pace, with 1-2 minutes rest. This trains your ability to hold strong efforts while staying aerobic. The key to this though, is that you should finish the session feeling like you could do one more round.
Functional Aerobic Threshold Work
This is one of my favourite tools for hybrid athletes. It’s essentially low-rest circuit work at low-to-moderate RPE, like a HYROX workout, but deliberately controlled.
Think:
- 20-minute EMOMs
- Long AMRAPs with simple, cyclical movements (e.g., ski/row/run, light carries, bodyweight work)
- Heart rate capped at ~80–85% max
These sessions simulate the flow and movement patterns of a HYROX event without tipping into threshold too early. It teaches athletes to move efficiently, recover actively, and manage intensity, skills that directly carry over to race day.
Bringing It Back to HYROX: Specificity with Control
As we start blending intensity into the program, this is where we begin to reintroduce HYROX-style workouts, but with a twist:
- Controlled HYROX Circuits with a Heart Rate Cap: Instead of going full send, we cap the intensity, say, 150-160 bpm, and focus on smooth transitions, steady pacing, and movement quality. This teaches you to approach the event aerobically, not just as a max-effort grind.
- Long Duration Efforts with Strict Pacing: 45-60 minute sessions that mimic the race structure (e.g., run + station), but with clear pacing instructions. The goal is not to crush it, but to execute it cleanly and leave gas in the tank.
Control and Quality > Speed and Suffering
At this stage, a lot of athletes are tempted to go back to all-out, race-pace efforts. But what separates great performers is that they can do race-like training without racing it every time. They’re able to stay calm, composed, and aerobic even as the intensity ramps up.
This is where you build confidence and control, and the ability to show up on race day and know exactly how to manage your energy, stay steady, and finish strong.
The best athletes aren’t the ones who train the hardest. They’re the ones who train the smartest, with intention and precision.
Complementary Strategies
While aerobic development is the focus of this case study, performance in HYROX is never built in isolation. To truly get the most out of your training and race-day performance, there are a few complementary strategies I always layer into a well-rounded plan.
Strength Maintenance
One of the biggest mistakes athletes make when shifting focus to aerobic training is abandoning strength work entirely, or going the other direction and trying to do it all.
For most HYROX athletes, the sweet spot is 2-3 strength focused sessions per week, focused on compound lifts (think squats, deadlifts, lunges, pressing, pulling etc.). These sessions should be:
- Heavy enough to maintain strength,
- Low enough in volume to avoid interfering with aerobic recovery,
- Focused on movement quality and precision.
The goal isn’t to PR your deadlift mid-training block, it’s to stay strong, resilient, and injury-proof as you are improving the aerobic system for HYROX.
Nutrition: Fuel Your Engine
Aerobic training is incredibly reliant on consistent fuelling, so your nutrition will need to be dialled in. If you’re under-eating or constantly training fasted, you’re limiting the adaptations you’re trying to build.
- Pre-session: Have a small carb-rich snack 30–60 minutes before Zone 2 runs or aerobic intervals.
- During long sessions: For efforts over 90 minutes, start practising fueling mid-session (hydration, electrolytes, and easy-to-digest carbs).
- Post-session: Replenish with carbs and protein within an hour, especially after longer or more intense sessions.
HYROX nutrition can seem complicated, but you don’t need to be perfect. However, you do need to give your body the resources to adapt.
Recovery: Where the Adaptation Happens
All the aerobic training in the world won’t matter if you’re not recovering from it. That means:
- Sleep: 7–9 hours per night, non-negotiable.
- Deload Weeks: The frequency of these will be dictated by your training program and experience, but you should have periods of reduce volume or intensity to allow supercompensation and avoid burnout.
- HRV or Resting HR Tracking: Use wearable data or a simple morning heart rate log to track trends. If HR is high or HRV tanks for multiple days, it might be time to pull back. Stress management and stress monitoring can really give you the edge.
Recovery isn’t slacking, it’s how you actually progress from all the work.
Breathwork
Breathwork is certainly not essential, but it can be highly effective, especially for athletes who get breathless too soon or panic when the intensity climbs.
Simple drills like box breathing or nasal-only warm-ups can help:
- Improve diaphragmatic control
- Lower resting heart rate
- Build calm under fatigue
- Enhance endurance by improving oxygen utilisation
These are small additions with big returns, especially in events where staying composed under fatigue is half the battle. I do also like to use breathwork to help my athletes deal with stress.
Putting It All Together: Periodisation Example
Let’s take all of this and turn it into a structured, real-world approach. Here’s how I’d periodise a 12–16 week training plan for a HYROX athlete looking to build aerobic capacity and peak for a race.
Phase 1: Aerobic Base Building (Weeks 1–6+)
- Focus: Develop Zone 2 running capacity, increase daily movement, maintain strength.
- Training Includes:
- 3–5 Zone 2 runs/week
- 8–12k steps/day
- 2–3 full-body strength sessions
- Optional HYROX focused aerobic circuits (low RPE and just focused on keeping skills in a good place)
Phase 2: Aerobic Capacity + Specificity (Weeks 6–12)
- Focus: Begin introducing intensity, simulate race format at a controlled effort.
- Training Includes:
- 2-3 Zone 2 sessions/week (maintain base)
- 1-2 aerobic intervals or tempo runs
- 1 HYROX-style circuit (HR cap, control pacing)
- Continued strength work (reduced slightly)
- Active recovery and walking on off days
Phase 3: Peak and Taper (Final 2–3 Weeks)
- Focus: Sharpen race-specific skills, dial in pacing, reduce volume to absorb training
- Training Includes:
- 1-2 high-quality HYROX-specific sessions (simulate intensity + transitions)
- Shorter aerobic maintenance work
- Deload strength volume, maintain intensity
- Prioritise sleep, nutrition, and stress management
Improving The Aerobic System For HYROX Conclusion
HYROX might look like a test of grit and toughness, and sure, there’s no denying it requires serious mental and physical resilience, but if there’s one thing I hope you take away from this, it’s this:
HYROX success isn’t just about how hard you can push, it’s about how well you’ve prepared your body to handle the push.
The athletes who consistently perform well aren’t necessarily the ones who suffer the most in training or crush every class. They’re the ones who’ve taken the time to build a well-developed aerobic system, layer by layer. That’s what allows them to:
- Recover between stations
- Maintain pace across the entire race
- Finish strong rather than just survive
If your current approach is grinding through HYROX sims and high-intensity classes, but you’re still fading halfway through, the answer isn’t more suffering. The answer is building the engine that can actually support your strength, your skill, and your mindset.
By taking a smart, structured approach (starting with base building, layering in aerobic capacity, and aligning it all with the demands of the event) you can dramatically improve performance without sacrificing power or explosiveness.
Toughness matters, but only when it’s backed up by physiology and a real aerobic engine.
Client case studies, such as this case study on improving the aerobic system for HYROX, are a phenomenal way to learn how to coach someone. While we teach people how to coach exercise, there is just so much to learn and you often need examples to illustrate the concepts.
Unfortunately, you can’t really find these online, and it leads coaches to make the same mistakes over and over, and it makes it difficult for coaches to know what to do. They end up feeling lost and unsure.
Case studies also help the average person who may find that they have roughly the same characteristics and problems covered in the case study, and thus they get a peak into how coaching may help them solve their problems.
As we are very interested in both helping the average person with their health and fitness (this is why we put out so much free content) and we want to improve the health and fitness industry by creating phenomenal coaches, providing free access to these case studies makes sense.
If you need help with your own exercise, you can always reach out to us and get online coaching, or alternatively, you can interact with our free content, especially our free exercise content.
If you want more free information on exercise, you can follow us on Instagram, YouTube or listen to the podcast, where we discuss all the little intricacies of exercise and nutrition. You can always stay up to date with our latest content by subscribing to our newsletter.
Finally, if you want to learn how to coach nutrition, then consider our Nutrition Coach Certification course, and if you want to learn to get better at exercise program design, then consider our course on exercise program design. We do have other courses available too. If you don’t understand something, or you just need clarification, you can always reach out to us on Instagram or via email.
