IRONMAN® World Championships

Carb-Loading: Neil is a seasoned Kona-racer, having competed on the Big Island four times before 2024. He made a few changes to his fuel strategy for this attempt, introducing a much more aggressive carb-load for the two days prior. He consumed ~610-660g of carbs per day (~8-9g per kg of bodyweight), and still felt full of energy without feeling bloated or sluggish. He did this by having plenty of sweets, PF 30 Chews, oat bars, bananas, oats, bread, rice and pasta, as well as some PF Carb Only Drink Mix. This will have bolstered his muscle and liver glycogen stores, increasing his available energy on race day. Check out our blog on the ‘art’ of carb loading for some example menus to help you hit these numbers.

Race Fueling: The majority of Neil’s carb intake was decoupled from his fluid, as he attempted to keep bottles for hydrating, and a larger-than-normal bottle with ~400g of carb from PF 300 Flow Gel for energy. This meant he could pull either lever independently, and avoid overeating because he was thirsty, or over-drinking when he was hungry. Thankfully, this worked well and his gut training to tolerate >120g of carb per hour paid off with interest, as he rode his best bike split on the island, and felt the strongest he ever had when starting the marathon. He had some Gels packed in his running belt but strangely three were missing, so his carb intake on the run was much lower than his ~75g/h target.

As you can see, Neil is a salty sweater, and has found great benefit from taking higher amounts of sodium to aid his performance during these long, hot endurance events. He struck a perfect balance of fluid vs sodium on the bike compared to his sweat losses. This demonstrated his calculated approach to achieving a relative sodium concentration close to 1,494mg/L. Neil used bottles of PH 1500 (Drink Mix) and picked up plain water to drink and tip over himself to limit the rise in his core temperature, and aid his thermal comfort. Neil was also wearing a Core Temperature Sensor to track his estimated core body temperature. He prepared for the race with some strict at-home heat acclimation protocol using the Core device. So, come race day, he was familiar with how his body responded to hot and humid conditions, and could use it to guide both his effort level and cooling strategy. You can see from his case study graphic that his average core temperature during the run was very high (~39.99℃ / 103.9℉), with a peak around halfway of 40.3℃ (104.5℉). Interestingly, this was also the point where Neil’s pace began to drop, and he started to feel an energy lull. After backing off the pace, focusing on putting plenty of ice in his tri suit and picking up an insulated flask of nearly-frozen PH 1500 (Drink Mix) from the personal needs aid station at this point, Neil managed to reduce his core temperature back below 40℃ (104℉). For context, most individuals who experience a core temperature >40℃ are extremely likely to develop severe heatstroke. Neil’s 15+ years of endurance training has essentially acted as ‘micro heat stress’, which has increased his tolerance to high temperatures, as well as his preparatory heat acclimation.