Patagonman

Laura’s carb intake was lower than we have seen from her in recent full distance races where she has impressively reached over 90g/h. This time out, Laura wasn’t able to hit her usual target of fueling every 15-20 minutes due to difficulties with the valves of her soft flasks, which affected how much gel she was able to consume. She also had an issue with her bike computer which meant she couldn’t see the time or usual fueling interval alerts. Furthermore, the extreme nature of this race which involves challenging terrain alongside cold and windy conditions, impacted when she could access her fuel and drink from bottles. These setbacks resulted in her lower than ideal carb intake and no doubt contributed to the dip in energy that she experienced midway through the run.

The cold conditions in Patagonia were a stark contrast to those that Laura usually trains and races in, and polar opposite to Laura’s last race at the IM World Championships in Kona. She carried out some sweat rate data collection in cooler conditions to help plan her fluid intake, considering she is an athlete who previously has drunk over 1L per hour throughout full distance races. Therefore, Laura’s fluid intake was considerably lower (~300ml per hour less) compared to the heat and humidity of Hawaii to more closely match her reduced sweat losses. Laura needed to pee frequently throughout the race, which is a feeling she does not normally experience. Although exercise often reduces the urge to pee, over a race of this duration it is not unexpected to pee once or twice, but frequent peeing can be a sign of overhydration. In this situation however, a phenomenon known as cold water diuresis was likely at play. When the body is exposed to cold water, physiological responses including vasoconstriction in the extremities ultimately lead to diuresis (peeing). Laura reduced her fluid intake to account for the cooler conditions, but alongside this, her sodium intake was also minimal, with the majority of her fluid on the bike being plain water or diluted PH 1500. Given sodium’s positive influence on water retention, Laura could increase the relative sodium concentration in her drinks, as she only took in half of her sweat sodium concentration.

Laura has a high tolerance for caffeine and we’ve seen her take more than twice the recommended dosage previously, without experiencing any negative side-effects. Although the scientific literature doesn’t show any additional benefit of taking more than 6mg/kg, Laura has become accustomed to taking these high quantities during races to help increase her perception of energy.