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Pierre Meslet's scorecard

Marathon des Sables

Friday 21st April, 2023

Within recommended ranges

Just outside recommended ranges

Significantly outside recommended ranges

  • 66g

    Carb per hour
  • 1,961mg

    Sodium per hour
  • 1,468ml

    Fluid per hour
  • 1,336mg/L

    Relative sodium concentration
  • 600mg

    Total caffeine
  • How Pierre hit those numbers

    6 x Porridge Oat Packets
    1 x Banana
    4 x Dried Ultra Marathon food packs
    200g x Mixed Nuts
    90g x Beef Jerky
    1 x Vegetarian Tikka Rice
    2 x Protein Powder servings
    2 x Protein recovery powder servings
    3 x Carbohydrate recovery powder servings
    2 x Coconut energy bars
    2 x Tablespoons Olive Oil
    4.5L x PH 1500 (Drink Mix)
    7L x PH 1500 (Tablets)
    17.6L x PF Carb & Electrolyte Drink Mix
    1 x PF 30 Gel
    5 x PF 30 Caffeine Gel
    4L x Plain water
    500ml x Energy drink mix with caffeine (80g carb, 100mg caffeine)
    52 x MDS electrolyte capsule (195mg sodium)
    1 x Vanilla Flavoured Carb & Protein Drink Mix

    How Pierre's hydration and fueling went...

      • After finishing the 2021 Marathon des Sables in 9th place, Pierre returned to the Sahara Desert for the 37th edition of the race and finished in a hugely impressive 6th place by going more than two hours quicker than his previous appearance
      • Despite contending with sandstorms and the extreme temperatures which are synonymous with an event that’s known as ‘the hardest footrace on earth’, Pierre was extremely satisfied with his fuel & hydration strategy.…
      • The best part of this for Pierre was playing a key role in his team, representing France, and becoming the first non-Moroccan team to win the event in 28 years
      • The headline numbers on this page present calculations of Pierre’s best recollection of what he ate and drank whilst running, but we’ve also broken down how he went about recovering each day in the text below too


      • Each day at the MdS, Pierre and all other participants were given 1.5 litres of plain water to take out on course with them from camp, and an additional 3L at each checkpoint they passed through
      • While this seems like a lot of weight to be running with, temperatures on the ground were reported to have soared to more than 50ºC’s (>122ºF) at some points, making replacement of fluid lost as sweat a priority
      • Pierre knows from sweat rate testing that he loses ~1.5L (48oz) of fluid per hour in those conditions, so he took a proactive approach to replacing his sweat losses - he consumed ~1.47 litres of fluid per hour (48oz/h) during more than 23 hours of running, across six separate days
      • Based on his experience of the 2021 race, Pierre felt he could increase his fluid intake in 2023 and that this would be to his advantage - he drank 59% more fluid during the 2023 edition than he did two years previously
      • The other key factor Pierre had to contend with from a hydration point of view was electrolyte loss in his sweat over time, due to the importance of sodium in particular on factors like muscular contraction and fluid retention
      • Having had a Sweat Test in 2021, Pierre knows that he loses 921mg of sodium per litre. He was also aware from his previous MdS appearance that his body tolerates both PH 1500 (Tablets) and PF 60 Energy Drink Mix (1000mg sodium per litre) well, in addition to the salt tablets which are handed to the competitors by race organisers
      • We’d normally recommend someone with Pierre’s sweat sodium concentration (921mg/L) uses PH 1000 strength products, but having to carry all of his race nutrition for the week in his pack meant that the more highly concentrated PH 1500 tablets made sense from a weight and space-saving point of view
      • TOP TIP: When running with our electrolyte tubes, stuff something soft into the cavity so that the tablets can’t shift up and down causing them to break
      • Having significantly increased his hourly fluid consumption compared to 2021 it was crucial for Pierre to also increase his hourly electrolyte intake in order to maintain a relative sodium concentration which reflected his individual losses
      • Knowing that this was important, Pierre did increase his sodium intake from ~1229mg per hour in 2021, to ~1961mg per hour in 2023, and in doing so achieved a suitable concentration of ~1336mg in each litre (32oz) of fluid he drank.
      • Happily, other than feeling slightly dehydrated at the end of the Stage 4 (the longest day) and Stage 5 (marathon day), Pierre was incredibly pleased with his hydration strategy for this race


    Quick Carb Calculator Recommendation


    carb 30 mins before


    carb per hour during
      • The Marathon Des Sables rules stipulate that a runner must be self-sufficient when it comes to their fuel supply, including carrying a minimum of 2,000kcal per day in their pack. All food is checked prior to the race and even if decanted into clear bags to save weight, must be labelled with the nutritional values
      • Pierre aimed to find the perfect balance between taking too much fuel and unnecessarily carrying it around with him for a week, whilst also packing enough so that he would provide his working muscles with appropriate energy
      • Cleverly, in order to achieve this, most of Pierre’s fuel was either dried or in a powder form, meaning he could mix it with the provided water rations for mealtimes and keep his pack light simultaneously
      • He drank more than 18L (~609oz) of various drink mixes in 2023, compared to just ~7.5L (254oz) last time, whilst carrying 15 less gels
      • In total, Pierre consumed more than 1,500 grams of carbohydrate while on the move, with an average intake of ~64g per hour. Although this is slightly lower than his ~70g per hour average in 2021, the main difference was during the longest day, stage four
      • In 2023 he averaged ~39g/h during the 90km stage four, while in 2021 he took on board ~58g/h at the same point. In any other race, we would say that additional carbohydrate would have been beneficial for him in this situation. However, the nuance of the MdS and having to be self-reliant means packing slightly less nutrition and still ultimately finishing two hours quicker than his last attempt can’t be deemed as anything but successful
      • Pierre mainly relied on PF 60 Energy Drink Mix for fuel during his runs and he reported energy levels of 10 (out of 10) most days with absolutely no gastrointestinal discomfort all week
      • He 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
      • With all the food Pierre consumed in camp taken into consideration, we estimate that he averaged an intake of ~2,360kcal per day on his way to claiming the team win in this brutal ultramarathon. For context, this is still less than the daily recommended intake of 2500kcal for a sedentary male in the UK, let alone someone with the additional expenditure of running ~245km in the Sahara desert!


      • Pierre was incredibly satisfied with his performance in the 2023 MDS, giving subjective ratings of 10 (out of 10) for both his fueling and hydration strategy
      • He reflected that the only thing he could have changed slightly would be to pack more ‘recovery’ drink mix powder to have in the evenings to avoid being as hungry when heading to bed
      • It’s extremely impressive for someone to complete this race, let alone place in the top-10 and realise their ambition of claiming the team victory. Nailing his fuel and hydration throughout the week, Pierre was able to achieve all of the above and feel relatively good while doing so!

    Key info

    Pierre Meslet

    Sweat sodium concentration
    Sweat sodium classification
    * determined by a PH Advanced Sweat Test


    Overall Time

    Event information

    Marathon des Sables
    Sahara Desert, Morocco
    21st April, 2023
    Total Distance
    245.0km / 152.2mi
    Total Elevation
    2,101m / 6,893ft

    Race conditions

    Weather Conditions
    Very Hot
    No Rain
    Min Temp
    35°C / 95°F
    Max Temp
    45°C / 113°F
    Avg Temp
    40°C / 104°F

    Athlete feedback

    Race Satisfaction
    Hydration rating
    Energy levels
    GI comfort
    No cramping

    Pierre's full stats

     Carbohydrate (g)Sodium (mg)Fluid (ml)Caffeine (mg)Relative sodium concentration (mg/L)
    Total intake1,53545,70234,2006001,336
    Per hour661,9611,46826

    Data Confidence







    There is an adequate level of accuracy in the data collected and the numbers reported. The athlete manages to recall what they ate and drank including most specifics (brands flavours quantities plausible estimations of volumes). However there are estimations made within the data which affect the overall confidence level in the data reported.

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