Brian'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.
Brian’s positive subjective feedback from this unique event was encouraging, and suggests he was balancing his energy input well against his energy output. It may appear from his average carb intake that he wasn’t getting enough relative to the general scientific recommendations, but he did make sure to pre-fuel and refuel adequately with high-carb foods such as rice, croissants and bread between every swim. Before almost all his swims, Brian drank a bottle of carbohydrate drink mix to top off his blood glucose and prime his body for exercise. The longest swim Brian completed was on day three, where he swam for three and a half hours. During this he knew that pre-fueling with his usual carbohydrate drink mix alone wouldn’t suffice, so he stopped half-way through at the on-course aid-station (which was actually on a boat) to pick up 120g of much-needed carbohydrates to sustain him for the rest of the swim.
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.
Brian is right that during each of the swims, he’s unlikely to have become so dehydrated that his performance was impaired. Furthermore, considering the logistics of drinking whilst swimming, with only a static boat to collect fluids from, he would have had to stop, drink, then continue, rather than the traditional ‘feeding’ method where swimmers can continue moving whilst feeding. One thing Brian didn’t do, and so should consider before his next long distance swim, is preloading with a strong electrolyte to help him start optimally hydrated and primed for lots of sweating. This could be done once per evening if the race followed a similar format to the UltraSwim33.3, which has several swims on consecutive days, sometimes including multiple swims per day.
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.
Brian decided that he would use caffeine to boost his performance as and when he felt like it. Because no swim was longer than ~3.5 hours, and he had a coffee every morning, he often felt like taking additional caffeine mid-swim wasn’t necessary. He decided to take a PF 30 Caffeine Gel during each of the two longest swims. Considering the 45 minute delay between caffeine consumption and peaking in the bloodstream, Brian likely reaped the maximal benefits within the final few kilometres of each swim.
How Brian hit his numbers
Here's everything that Brian ate and drank on the day...
Brian's weapons of choice
Brian'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.