155g of Carbs Per Hour in 32°C Heat

Hitting 155g of carbohydrates per hour on the bike is at the upper limit of what the human gut can absorb and oxidise. Doing it in 32°C heat, without gastrointestinal issues, is a different level of execution entirely.

Here is why that matters.

Carbohydrate absorption has a ceiling

Most research places the upper limit of exogenous carbohydrate oxidation at 120–140g per hour for athletes using glucose and fructose blends. Well-trained guts can push closer to 150g. Getting to 155g without GI distress in the heat — where blood is diverted away from the gut to the skin for cooling — signals serious gut adaptation built through consistent high-carb training.

Heat changes the calculation

At 32°C, the body is managing two competing demands: delivering oxygen to working muscles and shunting blood to the surface to regulate core temperature. This cardiovascular strain makes absorption harder and GI issues more likely. Fuelling at that level under those conditions is not something that happens without preparation.

The caffeine decision

Dropping caffeine in extreme heat was the right call. Caffeine is a mild vasoconstrictor and raises core temperature slightly. In normal conditions it is a useful performance tool. In 32°C heat, that trade-off tips the other way.

Sodium preloading

Arriving at the start line already topped up on sodium through Precision tablets and elevated fluid intake in the days prior means plasma volume is expanded before the race begins. In the heat, that is a genuine physiological advantage, not just a comfort measure.

Cooling on course

Using bottles for external cooling rather than drinking them keeps skin temperature down, reduces the cardiovascular cost of thermoregulation, and frees up cardiac output for the muscles. In extreme heat, that choice has a direct impact on sustainable power output.

Fuelling at this level does not happen by accident. It is built through training the gut, understanding the conditions, and making deliberate decisions before and during the race.

The products used are available at Endurance Kollective.