Your body has fuel.
It is not unlimited.
Running relies on a mixture of carbohydrate and fat, but the harder you run, the more important carbohydrate becomes. Muscle and liver glycogen provide a limited internal carbohydrate supply, while carbohydrate taken during exercise provides an external source that can help maintain carbohydrate availability as the session gets longer.3
That does not mean every run needs a gel. For shorter easy sessions, normal pre-run food and your existing glycogen stores are usually enough. Fuel becomes more relevant as the session moves beyond roughly an hour, especially when pace, intensity or total duration are high.
If the run is long enough that carbohydrate will matter, build a plan before you start. Do not make the first decision about fuel when you are already fading.
The clock changes
the strategy.
The Australian Institute of Sport's sports gel guidance scales carbohydrate intake to exercise duration. That makes the clock a better starting point than a blanket “take a gel every X kilometres” rule.1
Usually none.
Mid-run carbohydrate is generally unnecessary. Arrive normally fuelled and focus on the session.
Small can work.
For sustained high-intensity work, small carbohydrate amounts or carbohydrate mouth sensing may help, but most easy runs still do not need active fueling.
30–60 g / hour.
This is the standard evidence-based range for longer endurance work. Choose an amount you can tolerate and sustain.
Up to 90 g / hour.
Higher intakes usually require multiple transportable carbohydrates and should be practised repeatedly before race day.
Start before
you need rescuing.
Research comparing feeding patterns suggests that taking carbohydrate early and regularly during prolonged exercise is more useful than holding the same fuel back until late in the session. The goal is to maintain availability rather than chase a deficit once it has already arrived.2
For a run that clearly needs fuel, begin in the early part of the session and distribute your planned carbohydrate across the hour. The exact interval depends on the carbohydrate content and format of what you are using, your tolerance, and the opportunities you have to drink or eat.
Know the target.
Decide whether this is a no-fuel run, a 30–60 g/h run, or a longer event requiring a more advanced strategy.
Begin the plan.
Do not wait for hunger, dizziness or a pace collapse. Start early enough to spread intake rather than swallowing large amounts late.
Repeat small doses.
Use regular opportunities across the session. Consistency is usually easier on the gut than trying to catch up.
Recover normally.
Once the run finishes, return to normal recovery nutrition based on the demands of the next session rather than continuing a race-style fueling plan.
Think in grams
per hour.
During-run carbohydrate targets are commonly expressed as grams per hour, not as a fixed number of gels. That distinction matters because products vary widely in carbohydrate content, and different formats can be combined across a run.
For 1–2.5 hour endurance sessions, 30–60 g/h is the established range. For longer efforts beyond roughly 2.5–3 hours, guidance rises toward 90 g/h, with glucose-fructose combinations preferred at higher intakes because they use more than one intestinal transport pathway.3
A 90 g/h strategy that works for a trained marathoner or ultra runner is not automatically better for you. Use the lowest effective strategy for the session, then build only when duration, pace and tolerance justify it.
Fueling is a skill.
Practise it.
Your gut adapts to what you repeatedly ask it to do. Higher carbohydrate intakes are much more likely to work on race day if the same strategy has been rehearsed in training. Sports nutrition literature commonly refers to this as “gut training”: repeated exposure to the planned intake can improve tolerance and reduce gastrointestinal problems.4
Use long runs to test the same products, amounts, fluid pairing and carrying method you expect to use in an event. Change one variable at a time. If a plan repeatedly causes bloating, nausea or urgency, that is useful information — not something to ignore until race day.
Nothing new
on race day.
Race-day fueling should be the version you have already proved in training. Know roughly how many grams of carbohydrate your chosen products provide, where aid stations sit, how you will carry fuel, and what you will do if conditions or pace change.
Also remember that fueling and hydration are connected but not identical. A sports drink may contribute both fluid and carbohydrate, while a gel may need to be paired with fluid depending on the product. Count what you actually consume rather than assuming every item is “one serving of fuel.”
The mistakes are
usually simple.
Fueling every run.
Short easy runs often do not need mid-run carbohydrate. Match the strategy to the actual session.
Waiting until you are empty.
Long-run fueling works best as a plan, not an emergency response to late-session fatigue.
Ignoring the label.
Gels, drinks and chews contain different amounts of carbohydrate. Count grams, not packages.
Trying a high intake cold.
Moving straight to 60–90 g/h without practice can create unnecessary gut problems.
Copying elite protocols.
Your ideal intake depends on session demands, event duration, pace, tolerance and the rest of your nutrition plan.
