Together we ran an Exogenous Carbohydrate Oxidation Test — a method that measures how much of the carbohydrate you consume is actually used by your body as fuel during exercise.

• Each athlete consumed a known amount of carbohydrate (from Puresport Gels) during controlled running sessions.
• The gels were labelled with Carbon-13 isotopes — a harmless natural marker that allows scientists to track how much of the ingested carbohydrate is oxidised (burned for energy) versus how much stays in the gut or is lost.
• Breath samples were analysed throughout the session to quantify oxidation rates precisely.

• The group’s average carbohydrate oxidation rate was 49 g per hour.
• Individual results ranged from 36 g/h (lowest) to 59 g/h (highest).
• When adjusted for real-world conditions — athletes rarely absorb 100 % of what they take in — using an accepted ~80 % efficiency factor, the optimal fuelling rate equals ≈ 60 g of carbohydrate per hour.

That’s almost a perfect match to our simple guidance: 30 g every 30 minutes.

Even under ideal conditions, not every gram of carbohydrate eaten becomes energy:

• Some remains unabsorbed in the gut.
• Some is fermented by gut bacteria.
• Gastric emptying and transporters in the intestine (SGLT1 for glucose, GLUT5 for fructose) have a finite capacity.

Research using isotope tracers consistently shows oxidation efficiencies of ~75–85 %, so 80 % is a realistic, science-backed adjustment for real-world fuelling.

• Most runners perform best when fuelling around 60 g carbs per hour.
• Each Puresport Gel = 30 g, so taking one every 30 minutes hits that target perfectly.
• This rate maintains blood-glucose stability, delays glycogen depletion (“the wall”), and supports faster recovery for the next session.

We tested it.

We measured it.

And the data proved it: our gels deliver exactly what runners need, when they need it