IRONMAN® Leeds 2025

Jenny’s average carb intake at IRONMAN® Leeds was nearly identical to her intake at IRONMAN 70.3® Mallorca in May 2025, even though the race was double the distance and time. To hit ~63g/h, she banked energy on the bike (consuming ~10g more per hour) before the marathon. This kept her clear of the dreaded bonk and feeling fatigued throughout the race. While the strategy worked in terms of keeping her energy up, it still sat below the current recommendations for full-distance fueling, which encourages most athletes to push toward 75-90g/h. A higher intake would potentially increase her carbohydrate oxidation and a bigger buffer against late-race decline in performance from glycogen depletion and low blood glucose. Since Mallorca, Jenny has been refining her strategy by decoupling her carbs from her fluid in an attempt to avoid stomach issues. Her execution of this proved that she could sustain a low-moderate intake with no GI distress across the full distance. The next adjustment ahead of the IRONMAN® World Champs in Kona will be to train her gut further to nudge her intake up, especially on the run where she was more conservative with fueling. Ideally, this tweak will enable her to feel and perform even better on the Big Island.

The conditions in Leeds were warmer than expected for a British summer's day. She successfully increased her sodium intake to be closer to her sweat sodium losses, but fell just short of her target of ~1000mg/L. In future, carrying some Electrolyte Capsules in her trisuit pocket would help her hit this easier, especially when reaching for plain water at the aid stations on course to satisfy her thirst signals. Still, her hydration strategy was a huge improvement, as she felt well hydrated from start to finish. Peeing a couple of times throughout was, for her, a novel but welcome marker that meant she had moved from being somewhat dehydrated in her races, to be more in balance and avoid post-race dehydration symptoms that had undermined her earlier this season. Ahead of Kona, alongside some crucial heat training and sweat rate testing, it will be important for Jenny to practice drinking more in training, because she will no doubt need a higher fluid intake to support her performance in the high temperature and humidity of Kona.

Caffeine was more of a focus for Jenny in this race than it has been before. Her intake was slightly above upper end of the effective range, enough to enhance focus and perceived energy levels over almost fourteen hours of racing. She structured this intake to help sharpen concentration when fatigue and discomfort began to accumulate. She avoided the downsides of excessive use, experiencing no jitters, stomach upset, or post-race crash, suggesting that she found a dosing pattern that both suits her physiology and complements her fueling and hydration.