IRONMAN® Italy

This was Liv’s first IRONMAN®, after signing up earlier in 2024 alongside her dad, Tim. She consulted with the Sports Science Team to discuss how she was going to a) beat the 17 hour cut off, and b) enjoy the race. She kept her fuel plan very simple and used a reminder set on her watch to consume something every 30 minutes. She also avoided the dreaded ‘flavour fatigue’ by mixing the taste and texture of her fuel products by alternating between a bottle of PF 30 Gels and some PF 30 Chews. During the run, it became clear that Liv may have overdone the carbs compared to what she’d practised, as her stomach began to cramp and she had to stop eating. This occurs from malabsorption in untrained guts and can be caused by carbohydrates drawing water into the intestine or being fermented by gut bacteria after remaining in the stomach for too long. Similar to other working muscles, however, evidence suggests that the stomach can be trained to upregulate certain enzymes and proteins that enhance the speed and efficiency of carbohydrate absorption during exercise, improving GI comfort and energy availability as a result. Considering the long effort required for an IRONMAN®, Liv should practice with higher carb intakes (e.g. 75g/h) than she plans to race with during training sessions to improve her carb tolerance on race day. Dropping her carb intake down on race day should then feel more comfortable and sustain her performance better. To accomplish this, our blog on how to train the gut (and consume more carb) provides some protocol and progression examples.

Similar to her fueling, Liv could improve her fluid and electrolyte intake. During her first IRONMAN®, she listened to her body in the latter stages, and felt like she wasn’t sweating that much so reduced her fluid intake. This lesser fluid intake may have reduced the volume of the blood passing through non-vital organs (like the gut), and possibly contributed to her stomach discomfort by reducing the absorptive capacity of carbohydrates. Novice athletes are not expected to have well-adapted pace judgement when it comes to metering out effort in their first long distance race. It’s also, therefore, unfair to expect those same athletes to have finely-tuned innate biofeedback skills to help them to determine how much to drink in real time, and how much electrolyte they might need in that drink. Ahead of her next race of this duration, Liv should try and stick to her hydration plan more closely, replacing fluids and electrolytes similar to her known sweat sodium losses, and her known sweat rate whilst, of course, not ignoring her body’s messaging entirely.