IRONMAN® World Championship

Sam impressively averaged ~29g of carbohydrate per hour more than during her 6th place age-group finish at the World Championship in Hawaii in 2023, helping to fuel her to an overall age-group win in 2025. She used a similar combination of products on the bike to previous races, including PF Carb & Electrolyte Drink Mix, PH 1000 (Drink Mix), PF 90 Gels, PF 30 Caffeine Gels but this time incorporated some PF Carb Only Drink Mix into each of her six litre bike bottles to up her carb intake. Then on the run, she had two flasks containing overconcentrated PH 1500 (Drink Mix), again, to deliver more liquid carbs alongside two PF 90 Gels. Although this was a mixture and volume she had tested in training, Sam drank more fluid than she had before, and consequently her bike carb intake crept up as a result to over 120g/h. She went on to experience and push through some bloating and GI distress across the marathon. Although this was subjectively because of her hydration, given the extreme conditions in Hawaii, she may have benefited from decoupling her fuel from her hydration, by relying on her fluids for electrolytes and using gels and more solid fuel sources for carbohydrates. This would adjust her ‘hydration lever’ independently and drink more as required in the hot conditions, without overloading the gut ahead of the run.

After her podium-topping performance, Sam unfortunately ended up in the medical tent, which showed she finished the race ~1lb / 0.45kg heavier than when she started, which puts her at an increased risk of hyponatremia. In agreement with this data, Sam mentioned she drank a lot more fluid on the bike than in her training rides, usually taking on up to a litre per hour compared to over 1.2L/h here (which was even closer to 1.5L in the first hour on the bike). It was likely she was replacing more than the volume she was losing at times across the 5-hour bike leg, and likely led to her bloating, cramping and stomach discomfort from the start of the run. Collecting more condition-specific sweat rate data would’ve helped give Sam guidelines on how much she should be drinking to avoid over-doing it. Despite this, a flexible approach on the run and replacing her sodium losses consistently at ~1000mg/L allowed her to manage her symptoms, keep moving and maintain her lead to the finish.

Taking on three PF 30 Caffeine Gels across the race, one before the swim, one halfway on the bike and one just out of T2, put Sam right in the recommended range to enhance endurance performance. As well as being a dose that she has practised many times in training, keeping below 6mg/kg reduced the risk of negative side effects from the stimulant, including potentially impaired thermoregulation in such hot races.