Back in 2023 I wrote two blogs on the 120 grams per hour question. The conclusion both times was the same. The evidence did not support it, the extra carbohydrate was not sparing glycogen, and for most triathletes it was not worth the gut risk.

That position has not changed. What has changed is the question.

Because the athletes at the front keep doing it. Aggressive fuelling has become standard across marathon, professional cycling and long course triathlon, and it has been associated with a run of record breaking performances. Worth being precise about that word. Associated. The trend is supported largely by anecdotal reports rather than by evidence, and nobody has shown these intakes caused those results. But it leaves two possibilities. Either those athletes are winning despite their nutrition strategy, or something is happening that our current models do not capture.

That is what we set out to explore in a new Current Opinion paper in Sports Medicine, written with Paul Booth, T...

Having recently returned from the Ironman World Championships in Kona, “Carbo Loading” in the race week was something mentioned is just about every conversation. Like it was a fact. However, carbohydrate loading prior to an endurance event is indeed ubiquitous – but why? And how should we do it? Let’s discuss.

Energy stores

This will be a refresher for regular readers of my blog, or of our monthly summary of the latest endurance science research, TSS – but understanding the whys and hows of pre-exercise carbohydrate loading requires some knowledge of the energy stores we have in the body, and how we use them during exercise.

During endurance exercise, particularly relatively even-paced events like marathons or Ironman triathlons, almost all of the energy production we need to power muscle contractions come from aerobic metabolism, or the breakdown of fuels in oxygen-dependent pathways. That’s why we have lungs, our heart, blood, and blood vessels, to deliver oxygen to our tissues fo...