Fuelling for HYROX: Insight, Innovation, Inspiration

At SiS, collaboration and conversation are at the heart of developing groundbreaking products and education. Interaction with athletes is a vital part of our process: Sharing ideas, discussing issues, and finding solutions. What starts in the lab finds meaningful expression in the gym. Ultimately, it’s in the competitive arena that we see results.

Our Head Nutritionist, Dr Marc Fell, recently hosted members of the HYROX community for just such a session. With four athletes from the SiS family competing at the world championships in Stockholm this weekend, and momentum building across the HYROX space, there’s great energy and a shared hunger to understand more and to bring original thinking to both training and events. 

Marc presented an insightful overview of where nutritional science currently engages with the hybrid discipline. With a true academic’s rigour, he acknowledged that what we don’t know is as important as what we do. Things are moving fast. It’s here that the Science in Sport team is pushing the boundaries of how we approach this multifaceted event. 

What is HYROX?

HYROX is a unique sport with a unique combination of physiological challenges: 

• Consistent cardiovascular endurance 
• Repeated, high-intensity, functional strength
• Sustained physical and mental performance under fatigue
• Thermoregulatory strain due to indoor venues or hot, humid climates

This means it demands uniquely tailored nutrition and hydration strategies. Energy management is decisive. As the innovators who transformed cycling and distance running turn their focus to HYROX, the potential for more headlines is genuinely inspiring. 

The development of fuelling in HYROX

Considering the increase in participation, HYROX-specific technical studies have been slow to follow. Most expert guidance has been unsatisfactorily translated from endurance- and strength-focused research. As Marc points out, the field is advancing urgently and – as bespoke, targeted fuelling plans emerge – the potential for performance gains is truly exciting. 

We know that: 

• HYROX demands explosive power, sustained intensity, and endurance – taxing our three principal energy systems simultaneously 
• Over an hour of relentless work relative to threshold (around 85% of VO₂max) comes with a high glycogen cost
• Strategic carbohydrate intakes and purposeful fuelling are redefining the limits of performance across many sports
• At the world-championship level, nutritional strategy can be the difference between holding pace or fading 

In the early days, competitors were grabbing what they could in the chaos of the Roxzone and just hanging on. More recently, smartly timed gels and drinks have had a telling influence on energy delivery, while caffeine strategy and recovery are both now paid more attention. Personalisation, gut training, and practice have been established as key factors. This trend will only continue. 

What we don’t yet know is just how low HYROX-tailored fuelling can push times. The field continues to evolve, and cutting-edge nutritional advances promise game-changing impact at all levels. 

“Our goal is greater understanding of exactly how nutrition optimises HYROX adaptation, performance, and recovery. We’re developing specific guidance to help educate and support athletes, both for training and events.” 
(Marc Fell, Head of Nutrition, SiS) 

Marc also shared insight into the importance of the cognitive dimension – focus, concentration, coordination, control, pacing, and perceived exertion. Penalties and no-rep calls on the more technical stations are every competitor’s nightmare. This is a further area where knowledge is progressing rapidly. 

Then there’s HYROX training, in all its variety and complexity. Sports science never sits still. The ongoing study of the physiological demands and fuel substrates of different hybrid sessions has the potential to raise the bar even further. 

Marc concluded by emphasising that we’re at an endlessly interesting moment, as discipline-specific research evolves into tangible advances in both product and technique. We can confidently expect HYROX records to keep getting broken – and then broken again. 

WHAT DID OUR ATHLETES FIND?

The round-table discussion that followed covered all the issues that concern the Hyroxer at the business end. As always, the practical elements – timing, ease of use on the move, gut comfort – were at the forefront. And, of course, the debate over flavours was a lively one. It’s here, where lab theory meets athlete experience, that we relentlessly move forward. 

Already, we’ve seen elite Hyroxers report significant gains attributed directly to their fuelling strategy: 

“Working with Marc Fell and the SiS team has completely changed how I approach both racing and training. Their evidence-based advice has translated directly into measurable performance improvements.”  
(Saskia Millard, HYROX Elite Athlete) 

The hybrid fitness community is buzzing with expectation and confidence that this is just the beginning of further breakthroughs. 

As the sport continues its phenomenal growth, and sports science dedicates to it the attention it deserves, these are exciting times. From elite athletes pushing record times ever lower to the growing army of enthusiasts starting their journey, the potential of HYROX-specific nutrition is inspiring. 

At Science in Sport, we remain focused on leading the way in research and innovation.