Jack Davis
Cork Marathon
CorkTop 50, M30-34Jack's headline numbers
Jack's strategy
Fueling
T - 1-4hrs: Ate a carb rich meal (Low in fat & fibre)
T - 15mins: Took in a final dose of carb
"I felt good throughout and didn't have any moments of really low energy. I just fatigued as the race progressed."
Jack, our Head of Wholesale & Pro Sport, nailed his carb load leading into the Cork Marathon. He executed his first two-day carb loading protocol with 10g of carb per kg bodyweight each day in the 48 hour window before the race to optimise his muscle glycogen stores. A carb-rich breakfast, followed by a PF 30 Caffeine Gel within 30 minutes of the race meant Jack crossed the start line ready to push hard from the off. During the race, he carried two Flow Flask 120s, each containing ~90g carb from PF 300 Flow Gel as well as one PF 30 Caffeine Gel; this was a very efficient fuelling method, meaning he could carry just two small flasks but take on the equivalent dose of eight PF 30 Gels! This strategy provided him with ~96g/h, a ~36g carb per hour increase in his intake from London Marathon 2025. This higher intake, made possible through structured gut training, will have better supported Jack’s energy levels and facilitated his *ten minute* personal best.
Hydration
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.
Jack1248mg/L
Jack has been Sweat Tested to dial in his hydration plan
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 Jack's losses are High (1,248mg/L), nailing his hydration strategy remains important, even when it's Mild.
Learn moreT - 60mins: Drank ~500ml of strong electrolyte drink
"I followed my plan and didn't notice any issues with hydration. I tend to drink small amounts whilst running so this was a solid effort for me, although I would like to try to increase it given my high sweat rate."
Jack has a very high sweat rate (~3.5L/h at 38℃ in our heat chamber!) and is also a salty sweater, so his hydration strategy is crucial for success in endurance racing. He started the race well hydrated having preloaded both the night before and morning of the race with 500ml of PH 1500 (Tablet). In Cork’s mild conditions, Jack’s fluid intake of ~389ml/h was appropriate to avoid any symptoms of excessive dehydration. However, ahead of future races he should continue to do sweat rate testing in training to ensure he is replacing enough of his losses to avoid losing more than 2-4% of his body mass. Five Electrolyte Capsules meant the relative sodium concentration of Jack’s drinks averaged ~1136mg/L, close to his sweat sodium concentration of 1248mg/L.
Caffeine
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.
T - 0-4hrs: Had a final hit of caffeine
Jack had a coffee and a PF 30 Caffeine Gel before the race, then two more PF 30 Caffeine Gels during to hit the recommended dose of 3-6mg/kg bodyweight. This would have reduced his perception of fatigue especially through the latter phase of the race, when things get really tough.
How Jack hit his numbers
Here's everything that Jack ate and drank on the day...
Final thoughts
“I hit the taper, carb load, race and result exactly as planned and I’m very happy with the performance, especially achieving a 10-minute PB.”
“Jack nailed his fuel and hydration strategy in Cork which supported him in such an excellent performance. Continuing to measure his sweat rate to further dial in his fluid intake will be beneficial ahead of future marathons especially if they’re in warmer conditions.”
PF&HJack's full stats
Data Confidence
We rate each of our case studies from 1-5 based on the level of accuracy, and our confidence in the data.
There is good confidence in the accuracy of the data reported. An athlete feels that the numbers closely reflect what they consumed despite a couple of estimations which may carry some degree of error. The majority of what was consumed is recorded to a high level of specificity (most volumes are known through the use of bottles brands quantities flavours). The numbers are very plausible and align with previous data recordings (if an athlete has collected data previously).