Marathon des Sables

It’s worth mentioning that for all of Pierre’s headline numbers, they are an average of his average intake from each stage during MdS.

The Marathon Des Sables (MdS) requires runners to be fully self-sufficient with their fuel supply, carrying at least 2,000 calories per day in their pack. All food is checked before the race and must be clearly labeled with nutritional values, even if repackaged to reduce weight. Although this presents a logistical challenge, it also provides the opportunity to fine-tune the fueling strategy and make sure there’s a solid plan in place! Pierre tried to balance his energy needs with minimizing pack weight, ensuring he had enough fuel without unnecessary bulk. To achieve this, he relied on dried and powdered fuel, which he mixed with provided water at mealtimes, keeping his pack as light as possible without skimping on calories.

Pierre consumed over 18 litres (609oz) of drink mixes, compared to just ~7.5L (254oz) in 2021, while carrying 15 fewer PF 30 Gels. The biggest difference came during the 90km stage four, where he averaged ~39g per hour, down from ~58g per hour 2 years prior. While additional carbs might have helped in another race, MdS’s self-sufficiency rule meant he opted to pack slightly less nutrition in order to save on weight. And in the end, Pierre finished two hours faster, proving his strategy worked and the benefit of a lighter pack weight slightly ‘outweighed’ the negative of less fuel.

Fluid: Each day at the MdS, Pierre carried 1.5L (48oz) of water from camp, with an additional 3L (96oz) available at each checkpoint. With temperatures at times exceeding 50ºC (>122ºF), fluid replacement was crucial. His sweat rate testing prior to the race showed he could lose ~1.5L (48oz) per hour in such conditions, so he took a proactive approach and, compared to his 2021 experience, he increased his fluid intake by 71% in 2023, helping him manage the extreme conditions more effectively.

Electrolytes: Alongside fluid replacement, electrolyte balance was critical, particularly sodium to support muscle function and fluid retention. Pierre used PH 1500 (Tablets), PF Carb & Electrolyte Drink Mix, and race-provided salt tablets, all of which helped him keep up with his sweat sodium losses. Under normal circumstances, an athlete with Pierre’s sodium loss would use PH 1000, but since weight and pack space were major considerations, he opted for the more concentrated PH 1500 to reduce bulk. This approach helped him stay proactive with his hydration needs, reporting only mild dehydration after the toughest stages.

Pierre made a decision to largely avoid caffeinated products during his runs after the first couple of days when he felt himself overheating, and attributed this to the acceleration of metabolism associated with caffeine. Whilst caffeine has proven performance benefits when a dose sits in the range of 3-6mg/kg, its use should ultimately come down to personal preference and tolerance.