CJ's headline numbers
CJ's strategy
Fueling
Carbohydrate is the main fuel you burn when racing. Failing to fuel properly is a leading cause of underperformance in longer races.
CJ was able to execute a solid fueling strategy with a high carbohydrate intake during the Boston Marathon, consuming ~108g of carbs per hour using PF 30 Gels placed at elite aid stations, which were supplemented with some carb intake from PH 1500 (Drink Mix). This intake is consistent with best practice recommendations for marathon racing at elite intensities. Despite a slight drop-off in gel intake compared to his original plan, he still maintained a strong fueling rate throughout the race. This would’ve been critical to supporting his energy levels, especially in a marathon where glycogen depletion without carb intake is certain. CJ rated his energy levels high, and while he cited leg fatigue rather than feeling low on fuel as his primary limiter, his ability to maintain a strong finish confirms the suitability of his fueling strategy.
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.
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 CJ’s losses are on the moderate side, getting his hydration strategy right is still important if he wants to perform at his best.
Learn moreCJ’s hydration plan was also well thought-out and executed. He consumed ~442ml/h of solely PH 1500 (Drink Mix), balancing fluid and sodium intake appropriately given his sweat sodium concentration, and the cool and dry race conditions. Sweat rate modelling suggested he finished with a ~2.3% body mass loss, which is within the tolerable dehydration range (<2-4%) for endurance performance in cool weather. Dousing himself with water proved effective, helping to reduce both sweat rate and thermal strain caused by his fast running pace. The absence of significant thirst, post-race fluid cravings, or severe cramping indicates his hydration approach was effective overall.
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.
CJ’s caffeine strategy involved a 200mg caffeine tablet ~90 minutes before the race and a PF 30 Caffeine Gel within 30 minutes of the start. This falls nicely into the recommended caffeine dose for endurance events (3-6 mg/kg bodyweight). This likely contributed to his feelings of alertness and maintained focus throughout the race. It’s clear CJ has found a caffeine routine that supports his performance, but he should consider delaying his large dose of caffeine (200mg caffeine) until ~60 minutes pre-race to better time the peak of caffeine in his system closer to the race start, rather than before.
How CJ hit his numbers
Here's everything that CJ ate and drank on the day...
CJ's weapons of choice
Final thoughts
CJ
PF&HCJ's full stats
Data Confidence?
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).