IAU 24h World Championships

To break the world record for ‘greatest distance run in 24 hours on a track (female)’, Sarah made a dramatic change to the strategy she adopted during her debut 24-hour race in April earlier this year. She almost halved her carb intake from ~90g/h to ~46g/h, which isn’t something we often see, but it worked perfectly for Sarah to prevent the severe GI issues she experienced with the higher carb numbers. This emphasises how high carb intakes are beneficial to performance if they can be tolerated, our planner would recommend 60g/h for an event of this duration which would be the happy medium between the two intakes Sarah’s tried to provide consistent energy without GI discomfort. She avoided flavour fatigue, a common issue during ultra-events, by consuming a mixture of PF 30 Gels, sweets and some real food, as well as liquid carbs; this variety of products sat well in her stomach. A closer look shows Sarah’s intake dropped by ~17g/h from ~55g/h to ~38g/h in the second 12-hours; while this is expected, she would most definitely benefit from aiming to stabilise her intake throughout the event to help sustain her energy levels to the very end.

To ensure she was drinking enough fluid for both the environmental conditions and the intensity of exercise across 24 hours, Sarah drank to thirst. While Sarah’s fluid intake remained relatively stable throughout the race (317ml/h in first 12 hours vs 270ml/h in second 12 hours), her choice of drink changed, with a greater focus on water and PH 1000 (Tablets) in the first half, and then shifting more towards cola in the second half. Sarah combatted flavour fatigue again by changing her choice of fluids and adding in some chocolate milk and ginger ale to maintain her fluid intake. The conditions (~9℃) in Albi meant Sarah’s sweat rate was likely quite low and so her fluid intake of ~294ml/h would have prevented performance deteriorating dehydration and ensured she felt well hydrated, without overloading her stomach. Sarah’s relative sodium concentration fell below her sweat sodium concentration as she consumed PH 1000 in smaller than ideal volumes throughout the event, the additional fluids she took onboard diluted the overall sodium concentration. The cool conditions and her low sweat rate meant her sodium and fluid losses didn’t seem to accumulate to a performance impacting level, but increasing her sodium intake towards 1000mg/L through PH 1500 or Electrolyte Capsules would help Sarah’s body retain more of the fluid she is taking on in the future.

In events of this duration there is benefit to saving caffeine until later into the race when mental and physical fatigue begins to really kick in. Sarah utilised this strategy in her 24 hour event by waiting until hour 8 to have her first PF 30 Caffeine Gel. Following this 100mg dose, Sarah ramped up her caffeine intake with two more caffeine gels and a total of 1.25L of cola, which provided small but frequent doses of the stimulant. While Sarah exceeded the 3-6mg/kg recommendation, this is expected in a 24-hour event and her caffeine strategy will have reduced her perception of fatigue, increased her mental alertness and helped her keep strong through the night.