ENDURANCE FUELLING IS CHANGING: HOW MUCH CARBOHYDRATE DO YOU REALLY NEED?
From 30 g to 120 g per hour — what does the latest research actually tell us?
If you've spent any time around endurance sport, you've probably heard the familiar advice:
"Have a gel every 30 minutes."
For years, that was a pretty common approach to endurance fuelling.
But sports nutrition is evolving.
We're now seeing elite endurance athletes routinely consuming 90, 100 and even 120 grams of carbohydrate per hour during prolonged training and racing.
So has the old 60–90 g/hour advice changed?
Yes — but there's more to the story.
The latest research is challenging the idea that 90 g/hour is the absolute ceiling for carbohydrate intake during endurance exercise. At the same time, 120 g/hour is not a recommendation that every athlete should immediately adopt.
The real evolution is understanding that carbohydrate intake can be trained, individualised and progressively increased.
FIRST, WHAT DOES THE AIS RECOMMEND?
The Australian Institute of Sport (AIS) remains one of our most useful evidence-based resources for sports nutrition.
Its current guidance gives the following carbohydrate targets during exercise:
Exercise duration Current AIS guidance
Under 45 minutes Generally not required
45–75 minutes, high intensity Small amounts may be useful
1–2.5 hours 30–60 g carbohydrate/hour
Exercise duration Current AIS guidance
2.5–3+ hours Up to 90 g carbohydrate/hour
For prolonged endurance exercise, the AIS also recommends practising your fuelling strategy in training and choosing an approach that suits your individual goals, hydration needs and gut comfort.
So where does the new 120 g/hour conversation come from?
90 G/HOUR ISN'T NECESSARILY THE END OF THE STORY
For a long time, the practical thinking around carbohydrate intake was that approximately 60 g/hour was the upper limit for glucose-based carbohydrate.
This is because glucose is absorbed through a transporter in the small intestine called SGLT1. Once this pathway becomes saturated, simply adding more glucose doesn't necessarily mean more carbohydrate will be absorbed and used.
It can also increase the likelihood of gastrointestinal problems.
But researchers discovered something important:
Different carbohydrates can use different transport pathways.
Fructose, for example, is transported through a different pathway.
This led to the development and use of multiple-transportable carbohydrate strategies — typically combinations of glucose-based carbohydrate and fructose — allowing athletes to potentially absorb and oxidise carbohydrate at higher rates.
The AIS now specifically recognises multiple-transportable carbohydrate products as useful when athletes are targeting higher carbohydrate intakes during prolonged exercise.
And this is where the research gets really interesting.
THE MOVE TOWARDS 120 G/HOUR
A recent study published in the Journal of Applied Physiology investigated carbohydrate intake of 60, 90 and 120 g/hour in eight elite male marathon runners.
These weren't recreational runners.
The athletes had an average marathon personal best of approximately 2 hours 23 minutes.
The researchers found that carbohydrate oxidation increased as intake increased, with the 120 g/hour condition producing greater exogenous carbohydrate oxidation than both 60 and 90 g/hour.
They also observed a lower oxygen cost of running at 120 g/hour.
However — and this is important — gastrointestinal symptoms were also a consideration at the higher intake.
So the takeaway isn't:
"Everyone should now consume 120 g/hour."
It's:
"The human capacity to use carbohydrate during prolonged exercise may be higher than previously thought — particularly in well-trained athletes using multiple-transportable carbohydrates and a trained gut."
That is a very different message.
WHAT ABOUT 120–200 G/HOUR?
This is where we need to separate what athletes are experimenting with from what the research has firmly established.
Elite endurance sport is increasingly seeing athletes consuming carbohydrate at rates above 90 g/hour, with some strategies reaching 120 g/hour and beyond.
But the evidence does not currently justify telling every endurance athlete that they should consume 120–200 g/hour.
Higher is not automatically better.
The emerging research is asking a much more interesting question:
What is the highest carbohydrate intake an individual athlete can effectively absorb, tolerate and use during their particular event?
And that answer will be different for different athletes.
YOUR BODY WEIGHT DOESN'T GIVE YOU THE WHOLE ANSWER
This is an important point.
It is tempting to create a simple formula:
Body weight × X grams = your hourly carbohydrate target.
But that's not how the current AIS recommendations are structured.
The AIS carbohydrate targets are primarily based on exercise duration and intensity, rather than simply body weight.
A 55 kg runner and an 80 kg runner completing the same marathon don't automatically need completely different hourly carbohydrate targets.
However, body size can still provide useful context when developing an individual fuelling strategy. So rather than giving you one "correct" number based on your weight, think in terms of ranges and progression.
A PRACTICAL CARBOHYDRATE SCALE
This isn't an AIS prescription. It's a practical framework for understanding how carbohydrate intake might progress as an athlete becomes more experienced with fuelling.
Training / racing level Carbohydrate target:
Starting out 30–45 g/hour
Regular endurance training 45–60 g/hour
Well-practised endurance athlete 60–90 g/hour
Highly trained athlete 90–120 g/hour*
Above 120 g/hour Emerging research — individual/experimental
*120 g/hour should be viewed as an advanced strategy, not a universal recommendation. It is most relevant to prolonged, demanding endurance exercise and should be introduced progressively.
The AIS currently supports 30–60 g/hour for 1–2.5 hours and up to 90 g/hour for ultra-endurance exercise lasting more than approximately 2.5–3 hours.
The newer research suggests that some highly trained athletes may be able to use more.
But getting there is a process.
YOU CAN TRAIN YOUR GUT
This might be one of the most important concepts in modern endurance fuelling.
Your legs aren't the only thing you train.
You train your gut too.
If you're used to consuming 30 g of carbohydrate per hour and suddenly attempt 120 g/hour on race day, there's a very good chance your stomach is going to let you know about it.
Instead, carbohydrate intake can be progressively increased during training.
For example:
Week 1–2: 40 g/hour
↓ Week 3–4: 50–60 g/hour
↓ Week 5–6: 70–80 g/hour
↓ Later training: 90 g/hour
↓ Advanced strategy: potentially 100–120 g/hour
The exact progression will depend on the athlete, the sport and the duration of training.
The important principle is:
Don't race with a fuelling strategy you haven't trained.
The AIS specifically recommends practising your fuelling plan during training and notes that the gut can be trained to improve carbohydrate tolerance.
WHY TAKE SMALL AMOUNTS MORE OFTEN?
Let's say your target is:
90 g carbohydrate/hour
You could consume:
45 g every 30 minutes
But you could also spread it out:
30 g every 20 minutes
or:
22–23 g every 15 minutes
Your total hourly intake is approximately the same.
For some athletes, smaller and more frequent amounts can simply be a more practical way to manage their fuelling.
And this is one of the reasons we love using a soft flask.
Instead of carrying six individual gels and trying to remember when to open each one, you can carry your prepared carbohydrate fuel in one reusable flask and take smaller amounts throughout your session.
WHAT DOES 120 G/HOUR ACTUALLY LOOK LIKE?
This is where the numbers start to sound pretty intimidating.
60 g/hour
15 g every 15 minutes 20 g every 20 minutes 30 g every 30 minutes
90 g/hour
22.5 g every 15 minutes 30 g every 20 minutes 45 g every 30 minutes
120 g/hour
30 g every 15 minutes 40 g every 20 minutes 60 g every 30 minutes
Suddenly, you can see why how you carry your fuel matters.
Trying to consume 120 g/hour exclusively through individual sachets can mean a lot of packaging, a lot of opening and a lot of decision-making.
A soft flask allows you to prepare your total fuel in advance and take smaller amounts as you go.
DOES EVERY ATHLETE NEED 120 G/HOUR?
Absolutely not.
This is probably the most important message in this entire article.
If you're running for 60 minutes, you don't suddenly need 120 g of carbohydrate per hour because elite marathoners are doing it.
If you're doing a 90-minute training session, 30–60 g/hour may be perfectly appropriate depending on the intensity and your individual goals.
If you're racing a marathon, Ironman, 70.3 or ultra, your carbohydrate requirements may be considerably higher.
And if you're a highly trained endurance athlete preparing for a long, demanding event, progressively training towards 90–120 g/hour may be a strategy worth considering.
The goal isn't to consume the biggest number.
The goal is to find the highest intake that works for you.
WHAT ABOUT HYROX?
HYROX is an interesting one because it sits somewhere between endurance and high-intensity functional fitness.
A HYROX race isn't a traditional endurance event, but it can still take well over an hour for many athletes and involves sustained running combined with repeated high-intensity functional stations.
Carbohydrate availability matters during this type of training and racing too.
For a shorter HYROX session, you may not require the same carbohydrate strategy as someone completing a four-hour Ironman bike leg.
But for longer HYROX training sessions, race simulations or athletes completing multiple sessions across a training week, carbohydrate fuelling can become an important part of the overall strategy.
Again:
The demands of the session determine the strategy.
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