Rottnest Channel Swim
Paul'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.
Paul planned to focus on fueling with more carb per hour than he ever had previously, which ended up being ~43g per hour. While from a scientific point of view you would have to double this carb intake to reach the top end of general recommendations for optimal performance at an event of this length and intensity, this was still a significant increase for Paul and provided him with more available energy than he’s had for his previous 11 outings at this race. To increase his carb intake further, Paul could undertake a period of gut training to push his carb intake further. During the race Paul also had to contend with the impracticality of having to tread water and not touch his accompanying paddler’s boat while fueling, which naturally makes getting anything on board very tricky. For this reason he opted for a strategy of stopping every 30 minutes, alternating between gels and drink mix.
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 Paul’s losses are on the moderate side, getting his hydration strategy right is still crucial when it’s hot and/or humid as his higher sweat rate in these conditions can result in significant net losses over the duration of a race.Learn more
We know from experience that getting fluids on board during long swims can be difficult due to the practicalities of stopping to drink, so it's important to make sure you start optimally hydrated. Paul sensibly made sure this was the case by preloading with a PH 1500 tablet in 500ml of water before the race started. Paul drank a total of ~1.75L of fluid while swimming, which averaged out to ~356ml per hour. The one thing Paul would have changed about this race was drinking a little bit more. However, he was held back by some bladder discomfort, and being unable to pee in his very tight swim skin suit. Weighing himself before and after the race meant we were able to calculate a sweat rate of ~720ml per hour. For context this means if he hadn’t drunk anything, he would have lost ~3.5kg (7.7lbs) in sweat, which is equivalent to ~4.5% of his body weight. This is important to know, as the scientific literature generally suggests that physical performance may start to decline in individuals after around 2-4% dehydration, and so could have caused some issues. Although, having done this type of event successfully for a long time, it’s likely that Paul’s tolerance to moderate dehydration is more robust than others.
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.
In future events of this length, Paul may look to reap the benefits associated with caffeine. Weighing in at ~77kg (170lbs) he would need to take 230-460mg to optimise his intake. An easy tweak to his race strategy if he were to do this is to swap out one of the PF 90 Gels for three PF 30 Caffeine Gels, although he’d have to consider the practicality of the smaller packages when in the water.
How Paul hit his numbers
Here's everything that Paul ate and drank on the day...
Paul's weapons of choice
Paul'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.