IRONMAN World Championships
Jocelyn'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.
Six months on from IRONMAN Texas, Jocelyn implemented an improved fueling strategy by taking in greater amounts of carbohydrate on the bike leg (~99g/h in Hawaii compared to ~74g/h in Texas). After experiencing some gut issues at the 100km (63 mile) PTO races prior to Kona, Jocelyn opted to add a bottle purely for hydration, rather than relying solely on carbohydrate drink mixes during the first-half of the race, which worked particularly well in the heat. Jocelyn dropped her carb intake down on the run (~73g/h) to follow the trend of triathletes frontloading their fuel intake on the bike (seen in 83% of our full distance case studies), although this drop-off may have been a little too steep given she felt hungry towards the end of the marathon.
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 Jocelyn’s losses are on the low 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
We know from Jocelyn’s Sweat Test that she isn’t a particularly “salty sweater”, but she loses a high volume of sweat and sweat rate testing has shown she can lose more than two litres (64oz) per hour in hot conditions. In the renowned heat and humidity of Kona, her fluid intake pushed over ~1.3L per hour on the bike. This is the highest we’ve seen from a female over a full distance race. She then dropped closer to ~750ml/h on the run as a large amount of the fluid she picked up at this point was used for cooling. Alongside this, Jocelyn took on a relative sodium concentration much greater than her sweat sodium concentration in an attempt to replace her net sodium losses, which is a common strategy in long-course triathlon where fluid access on the run can be challenging. However, Jocelyn did experience some swelling in her extremities on the run, which may have been caused by an imbalance of fluid and electrolytes in the body. She will continue to refine her sodium and fluid strategy through some more trial and error and collecting further sweat rate data, in the hope to avoid any swelling in future races.
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.
By taking three PF 30 Caffeine Gels and one on-course caffeine gel, Jocelyn pushed over the top end of the recommended caffeine guidelines and effectively doubled the amount of caffeine that we’ve seen her take in previous races. This higher dosage was good for the longer, high intense World Champs race to maximise her perceived energy levels throughout.
How Jocelyn hit her numbers
Here's everything that Jocelyn ate and drank on the day...
Jocelyn's weapons of choice
Jocelyn'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.