Bislett 24 Hour Challenge
Allan's headline numbers
Carbohydrate is the main fuel you burn when racing. Failing to fuel properly is a leading cause of underperformance in longer races.
Allan had planned to fuel the event mostly on real food, as is typically advised for ultra events which involve a low relative intensity. But, this changed within the first half of the race, around the 10 hour mark, when he struggled to stomach any solids so he switched to using more gels. This early GI discomfort was likely due to the higher than planned intensity of his running in order to keep pace with the leading runners early on. Over the 24 hours, Allan hit an impressive carb intake, especially considering it mainly came from one energy source (PF 30 Gels). His carb intake was slightly lower during the first 12 hours (~55g/h) when he was experiencing stomach discomfort and then picked up in the second half to average ~93g/h; including an extraordinary ~108g/h between hours 17 and 20. Despite his carb intake being lower than the recommended amount, Allan still managed to have a solid intake to get him through the race and stop any GI issues.
Taking on board an appropriate amount of fluid and sodium is essential to maintaining blood volume and supporting the cardiovascular effort needed to perform on race day.
Whilst the absolute amount of sodium and fluid consumed per hour is important, it’s critical to consider these in relation to each other. This is known as 'relative sodium concentration' and it’s expressed in milligrams per litre (mg/L). How much sodium you’re taking in per litre of fluid is more important than the absolute amount taken in per hour.
Sweat sodium concentration (mg/L) is largely genetically determined and remains relatively stable. Knowing how salty your sweat is enables you to replace a good proportion of your sweat losses, which can range from 200-2,000mg/L.
Given Allan’s losses are Very High (1,412mg/L), nailing his hydration strategy remains important, even when it’s Mild.Learn more
Being crewed by the PF&H Sports Science team, Allan was able to efficiently control his hydration strategy on the go. He brought three litre (32oz) bottles to the track, one containing PH 1500, one with Carb & Electrolyte Drink Mix and one with plain water. At Allan’s request, these were decanted into soft flasks, passed to him and remade throughout, which allowed him to replace a large proportion of his sodium losses by consuming a concentration close to his sweat. Allan’s moderate fluid intake appears sufficicent to replenish what he loses in mild conditions; however being indoors with limited air flow, significantly intensified that heat for all the runners. To cool down, Allan tipped a large proportion of water over his head and back each lap. This helped control his body temperature but didn't hydrate him, which was evident by the fact he only peed once during the 24 hours. This indicates he may have under hydrated, particularly in the early stages where his lowest intake was closer to ~320ml in an hour. During the final hour of the race, Allan experienced some mild-to-severe cramps. Cramps can occur due to a range of factors and it seems likely that conditioning will be a likely cause in this instance. Up to this point he had not run further than ~100km so to achieve ~264.88km was a monumental effort, but the extensive muscle fatigue and damage did take its toll.
Beyond the Three Levers of Performance (carb, sodium and fluid), caffeine is one of only a few substances that is proven to improve performance for most endurance athletes as it can help stave off mental and physical fatigue.
Allan didn't pre-caffeinate before this race due to the long duration and wanting to save the effects for further down the line. During the race, Allan got caffeine in his system from the large volume of cola he was drinking, especially in the second half of the event. This meant he had a total dose within the recommended range. However, due to the extreme length of this race, a slightly higher caffeine dose with a more stratified timing schedule may have been beneficial to help overcome the body's natural circadian rhythm and provide a greater perceived energy boost during the early hours of the race.
How Allan hit his numbers
Here's everything that Allan ate and drank on the day...
Allan's weapons of choice
Allan's full stats
There is a high level of confidence in the accuracy in the data. The numbers presented are believed to be a very close reflection of reality. There may still be one or two estimations made in the data (an inescapable part of field data) but there is reason to believe that these are accurate and that possible error has been kept to a minimum. It is data that has been collected and recalled as accurately as is possible given the uncontrolled settings/circumstances.