• Matt completed this 400km Audax mainly to test a nutrition strategy he aims to use for his Fastest Known Time attempt across the North Coast 500 in Scotland later in 2023
• His target event is likely to be ~27 hours long, but this 13.5 hour tester gave him a good indication of how his body responds to an aggressive fueling strategy for long durations

Hydration

• Matt didn’t preload his sodium levels for this race, but hydrated well in the days prior, and had ~300ml (12oz) of plain water the morning of the ride. To ensure he’s starting optimally hydrated in future, increasing his blood plasma volume and maximising his cooling capacity, Matt may want to include some PH 1500 in his pre-race fluid intake
• During the ride, his fluid strategy was primarily determined by his ability to carry bottles on his bike, and the available stop-offs where he could refill them
• In total, Matt drank ~7L (246oz) of fluid, giving him an hourly average of ~523ml (16oz) for 13 and a half hours. This is a relatively large intake for Matt’s likely low sweat losses, especially as temperatures were mild (~12℃ / 54℉), which ties in with Matt’s fairly frequent pee stops, suggesting he may have been over drinking slightly
• Matt maintained a relative sodium concentration of ~648mg/L (mg/32oz), primarily through the 1,000mg per litre (mg/32oz) concentration found in the ~4.5L (158oz) of PF 60 Drink Mix. He diluted this somewhat by also drinking ~2.5L (88oz) of plain water
• Matt’s sweat sodium concentration is 1,064mg/L (mg/32oz), so in future he may want to replicate this concentration in his drinks, especially when completing races of this duration, where his net sodium losses could mount up
• If he does choose to drink some plain water during events, he should consider taking some Electrolyte Capsules (one for every ~250ml/8oz he drinks) to ensure he doesn’t deplete his electrolyte levels too much

Fueling

Conclusions

• This race, whilst not an “A race” for Matt, served as a useful learning experience, in the lead up to his NC 500 attempt
• To help dial in his strategy going forwards, Matt should consider preloading his sodium levels to ensure he’s starting optimally hydrated
• He may also want to increase his sodium concentration during races to more closely match his sweat sodium concentration and avoid depleting his electrolytes too much, potentially reducing the frequent desire to pee