IRONMAN World Championships
Livia'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.
Livia worked closely with the Sports Science team at PF&H and her coach to optimise her fueling approach, striking an ideal balance between PF 30 Gels and bottles of Carb & Electrolyte Drink Mix to maintain a steady carb supply and avoid ‘taste fatigue’. Her fuel intake was lower than we’d usually expect from athletes of her standard, but this reflects her bodyweight of 47kg (103lbs), and was still a vast improvement from her previous IRONMAN. This meant her fuel intake still amounted to ~1.7g per kg (2.2g per lb) on the bike and run, which is in line with what we typically see from other athletes at this level. Livia’s lighter breakfast was a strategy to avoid any forced toilet stops like in her previous full distance race. This may explain the brief energy dip in the swim, so trialling some larger carb-rich breakfasts may help prevent this in future races.
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 Livia’s losses are High (1,290mg/L), nailing her hydration strategy becomes especially crucial when it’s hot and/or humid.Learn more
Having had a Sweat Test earlier in 2023, Livia actively managed her intake using bottles of Carb & Electrolyte Drink Mix and PH 1500 (Drink Mix) to keep her sodium consumption controlled along with plenty of plain water from aid stations to help her balance the relative concentration to closely match her losses. Her excellent subjective hydration rating indicates she nailed this. Livia also doused herself in water, consumed a measured amount of fluid and electrolytes and executed a controlled pacing strategy to help regulate her core temperature. This all helped her deliver one of the fastest amateur marathon times during the IM World Champs 2023.
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.
Livia’s smaller body mass meant that her four Caffeine Gels put her ~33% above the general recommended intake for endurance performance enhancement. That being said, she didn’t experience any negative side effects, and is a frequent caffeine user, so likely has a higher tolerance than others. It’s worth noting that Livia won’t have received any additional performance benefits from exceeding the recommendations.
How Livia hit her numbers
Here's everything that Livia ate and drank on the day...
Livia's weapons of choice
Livia's full stats
There is an adequate level of accuracy in the data collected and the numbers reported. The athlete manages to recall what they ate and drank including most specifics (brands flavours quantities plausible estimations of volumes). However there are estimations made within the data which affect the overall confidence level in the data reported.