IRONMAN World Championships
Samantha'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.
Samantha’s slower pace during the final third of the marathon could be attributed to her carb intake dropping from ~94g/h on the bike to ~50g/h on the run. Given she rated her gastrointestinal comfort as 10 out of 10, Samantha may want to consider trialling increasing her carb intake during training sessions to take advantage of her “iron stomach”. Practically speaking, she could consider using the Flow Gel on the bike to take in bigger doses of gel and push over the 100g/h mark, and increase the frequency of her carb intake on the run.
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.
Whilst Samantha’s losses are on the moderate side, getting her hydration strategy right is still crucial when it’s hot and/or humid as her higher sweat rate in these conditions can result in significant net losses over the duration of a race.Learn more
Sam’s previous IRONMAN race at Coeur d’Alene resulted in her requiring a saline solution in the medical tent. As a result, she was keen to refine her hydration strategy and began measuring her sweat rate during hot and humid indoor sessions to prepare for similar conditions in Hawaii, and she took a Sweat Test, which showed she loses 901mg of sodium per litre (32oz) of sweat. Sam’s goal was to drink ~1L/h with ~1,000mg sodium per litre (32oz) in Kona and she hit this relative concentration pretty much spot on throughout the bike. She did endure a tricky spot at mile ~14 on the run when she experienced numbness and tingling in her extremities, but she increased her sodium intake by taking on more Electrolyte Capsules midway through the run, which helped the feeling subside.
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.
Sam was hesitant to take in too much caffeine, but she nailed her overall intake, tipping just over the typical recommendations, which was likely suitable for this full distance race. She spaced out her intake regularly throughout the race, and didn’t experience any negative side effects of taking too much, so likely struck the balance perfectly well.
How Samantha hit her numbers
Here's everything that Samantha ate and drank on the day...
Samantha's weapons of choice
Samantha's full stats
There is some confidence in the quantities and brands of products consumed but the data may lack specifics (e.g. volumes specific flavours). A high number of estimations have been made and the room for error is moderate-high. There may also be the possibility that some intake has been grossly over- or under-estimated.