IRONMAN World Championships

Laura primarily used gels for her fueling over the course of the race. On the bike she had 14 PF 30 Gels, two PF 30 Caffeine Gels and one PF 30 Chew, which provided over 500 grams of carbohydrate, averaging ~108g of carb per hour. She maintained a strong level of fueling on the run course, alternating between PF 30 Gels and PF 30 Caffeine Gels, as well as getting additional carb from aid station energy drinks. This delivered an average intake of ~107g/h while running and ~99g/h on average for the whole race (34% higher than her intake at Roth). This is a great demonstration of an athlete being able to exceed the 90g/h that was traditionally thought to be a ‘ceiling’. There’s a host of emerging evidence to challenge this theory, and Laura’s intake is just one of many examples.

Laura had prepared bottles of PH 1500 (Tablets) on the bike, and she also picked up water from aid stations, taking sips and dumping some on her head to keep cool as the temperatures soared. As you can see in this video on Laura’s Instagram page, the intake of fluid from aid stations is hard to approximate when running at such high speeds. From our calculations, she had around 4.1L (139oz) total fluid on the run in Hawaii, which represents a ~48% increase on what she drank during the run at Challenge Roth. This can largely be attributed to the more extreme temperatures in Kona causing Laura to have a higher sweat rate, which in turn meant that she increased her intake to account for higher fluid losses. Laura knows that she isn’t a very salty sweater, so despite achieving an average relative sodium concentration of ~396mg/L (mg/32oz) for the race (which would be potentially problematic for many of athletes in the heat of Kona) she was happy to report absolutely no cramping and an 8 (out of 10) rating for her hydration on the day.

With a total of ~738mg across the race, Laura likely reaped the physical and mental benefits associated with caffeine. This intake is more than double the general recommendation for caffeine intake during endurance activity of 3-6 milligrams per kilogram of bodyweight, putting her at ~12.1mg/kg. It’s similar to what we saw when analysing her intake from Challenge Roth (11.31mg/kg), and s someone with a clearly high tolerance for caffeine, it isn’t necessarily something she needs to change. To note, there is no need to exceed this though, as no additional benefit has been found.