RACE-DAY NUTRITION

A meticulous fuelling programme will pay dividends on the race course…

First up, race-day breakfast. It’s standard fare but, as Jonny Brownlee mentioned earlier, you can’t go wrong with porridge. Toast and jam is also another easy, proven option. When it comes to duringrace nutrition, if you’re a lively sprint-distance athlete, then theoretically you won’t need a calorie as performance isn’t limited by the availability of muscle glycogen stores. That was traditional thinking – turned on its head thanks to Dr James Carter.

His first study showed that glucose infusion led to no improvement in a 1hr cycling effort. The next showed that carbohydrate ingestion led to improvement in a 1hr cycling effort. He hypothesised that sensors in the mouth detected the presence of carbs, stimulating the central nervous system to improve pacing.

According to research professor Asker Jeukendrup, there’s now strong evidence that in race situations of 45-75mins, mouth rinsing or intake of a small amount of carbohydrate enhances performance by 2-3%.

Those of you racing for 75mins or longer require a different approach, comprising bars, gels, blocks, rice cakes… whatever suits your palette. Up to 2:30hrs, you’re looking at 60g of carbs per hour from glucose or maltodextrin. Longer than that and it’s time to train your gut.

“The theory is that if you want to perform optimally in an endurance sport lasting more than 2:30hrs, you need to ingest 90g of carbohydrate per hour,” explains nutritionist Peter Hespel. For years, sports scientists were convinced that 6070g of carbs per hour was the most you could ingest, the reason being that transporters in the intestine become saturated at that point and couldn’t carry any more glucose into the bloodstream. But then Jeukendrup had the idea of adding fructose to the glucose solution because fructose uses a different intestinal transporter. Jeukendrup’s results meant nutritionists could deliver up to 90g of carbohydrate an hour without causing gastro issues like sickness and diarrhoea.

Increasing from 60g to 90g and you’ll ingest an extra 120 calories over the glucose-only option – 360 calories per hours against just 240 calories. Add that up over a 12hr Ironman and, theoretically, that’s an extra 1,440 calories!

Manufacturers like Etixx and Powerbar now incorporate this ratio of glucose to fructose in many of their products. The problem is, many recreational triathletes can’t stomach this 90g figure but, like skeletal muscle, you can train your stomach to assimilate more carbs.

Whatever your hourly calorie count, how this breaks down into energy bars, gels and/or drinks is very much individual. Two gels offer 60g of carbs an hour, as does one SiS mini bar and one gel. Or a 500ml water bottle filled with 7% carb solution equates to 35g of carbs. So one bottle and a gel again roughly ticks off that 60g figure. It’ll take some nutritional mathematics but your stomach and performance will appreciate it.

“If you want to perform optimally for more than 2:30hrs, you need to ingest 90g of carbs per hour”