Western States® 100-Mile Endurance Run

Ahead of Race Day: Having not raced the Western States® Endurance Run (WSER) or any 100-miler before, Peter built his fueling strategy based on his first-place finish at Transvulcania in 2025 and second-place finish at CCC in 2024. Estimating his race splits, Peter planned to carry enough carbs between crewed aid stations in the form of PF Carb Only Drink Mix in his flasks alongside PF 30 Gels and PF 30 Chews to hit ~90g/h. Anticipating the usual WSER heat, Peter also made the smart decision to reduce the carb concentration of his drinks from Michigan Bluff, one of the hottest points of the race just past halfway (mile 55.7). Going from 30g to 15g of carb per 500ml in his soft flasks gave Peter a more ‘decoupled’ approach, allowing him to drink more fluid without overloading his gut.

Race Fueling: Over the 16 hour race, Peter consumed ~1,1kg of carbohydrate (the equivalent of over 36 PF 30 Gels)! This averaged ~70g/h overall, a little lower than he intended but still a steady stream that never dropped below 60g in an hour and supported his top 10 finish for his first attempt at this distance.

Peter reported a side stitch at Robinson Flat (mile 30) which limited his intake early in the race of PF 30 Gels and PF 30 Chews, averaging ~64g/h from the start to mile 30, then ~73g/h from miles 30-38 and just ~61g/h until mile 55. After a reset and blister tape-up at two crucial aid stations (Michigan Bluff and Foresthill), he increased his intake back to over 80g/h for the next 5 hours which correlated with his highest subjective energy levels. In the final third of the race, Peter again felt some stomach discomfort, describing a ‘full stomach’ and backed off from the plan to moderate this. He wasn’t surprised by the symptoms, acknowledging he had never run for this duration and therefore not taken on this volume of fuel (especially in these high temperatures which reduces blood flow to the gut and increases the risk of GI discomfort, as blood flow is redistributed to the skin for cooling). His energy started to dip alongside this reduced intake, but his early and consistent fueling had set him up to finish strong regardless.

Ahead of a race like WSER, there is a huge amount of planning, especially on the hydration front. Having not raced here before, Peter did an excellent job with the help of some of his PF&H crew team to prep everything he needed, ensuring both crews had lots of spares and back-up options of foods and drinks he may want. A big consideration for 100-milers is how to carry your hydration, and Peter smartly used a variety of methods, starting with a hydration pack early on when crew stops were less frequent, switching to a belt mid-race, and finishing with handheld flasks. This flexible strategy allowed Peter to carry additional fuel as well as flasks pre-filled with spare carb and electrolytes to make filling up at non-crewed aid stations a breeze, whilst also saving some weight by not carrying additional full flasks.

Though not a heavy or particularly salty sweater, the very hot Californian conditions meant Peter needed to be more proactive than normal to stay on top of his fluid and sodium needs. He consistently carried two 500ml soft flasks containing PH 1000 (Tablets), filling at least one at each water stop and replacing both with fresh, cold flasks at the eight crewed checkpoints. Other than around mile 30, Peter never felt behind on his hydration, and as shown in the pictures above, he adjusted his fluid intake to meet the increased demands during the hottest, most intense parts of the day. The effectiveness of this strategy was evident with a pre and post-race body weight measurement showing a -2.67% change, a well-managed level of dehydration for a 16-hour race.

The current caffeine recommendations for endurance exercise were not designed with a 100-mile, 16-hour effort in mind, a duration that extends far beyond the ~4-5 hour half-life of the stimulant. Therefore, it was appropriate and practical for Peter to exceed the upper limit of the general guidelines by taking around 1.5 times the ‘normal’ higher dose (6mg/kg). To reach this quantity (9.6mg/kg), Peter drip-fed caffeine by spacing PF 30 Caffeine Gels and flasks of cola between every crewed aid station. This will have maintained his circulating caffeine levels throughout the day, without taking too large a dose at any point, avoiding significantly elevated levels. Doing so will have maximised and sustained caffeine’s ergogenic effects of enhanced alertness and reduced perceived fatigue levels, both crucial in counteracting the natural decline in both physical and cognitive performance across Peter’s longest race to date.