< Back to case studies

Louise Small's scorecard

Rotterdam Marathon

Sunday 16th April, 2023

Within recommended ranges

Just outside recommended ranges

Significantly outside recommended ranges

  • 65g

    Carb per hour
  • 397mg

    Sodium per hour
  • 596ml

    Fluid per hour
  • 667mg/L

    Relative sodium concentration
  • 39mg

    Total caffeine
  • How Louise hit those numbers

    0.5 x PF 30 Gel
    1 x Bagel with butter
    1 x Serving of Almond butter
    1 x Boiled egg
    1 x Cup of Tea
    800 x Scotch Pancake
    1 x Caffeine Chewing Gum
    1L x PF 60 Energy Drink Mix
    2 x PF 30 Energy Gel
    100ml x Plain water
    400ml x Coca Cola Original

    How Louise's hydration and fueling went...

      • Louise is a British Hoka sponsored athlete and running coach who has previously represented Great Britain across multiple disciplines on 13 occasions
      • She approached the 2023 Rotterdam marathon with the goal of running 2:33, and with the help of the PF&H sports science team, had really focused on training her gut to tolerate more carb with less discomfort in the build up to the event
      • On the day, she was extremely satisfied to run her way to a personal best, and tolerate a higher carbohydrate intake than ever before, giving her enhanced energy availability, while still being able to report her gastrointestinal comfort as a 9 (out of 10)


      • Louise approached her hydration for this race with her own tried and tested method of adding salt to squash and sipping on this the morning of the race. Louise did this as she has had stomach problems after using some effervescent electrolyte products previously
      • The issue that can occur when mixing your own electrolyte drinks, is that table salt (NaCl) is actually only ~39% sodium, which is the important factor when it comes to preloading
      • Going forward, we would recommend Louise trials something without unnecessary flavourings but with a precise, highly concentrated dose like the PH 1500 (Packets) to ensure she starts optimally hydrated without having to estimate the appropriate quantities of individual ingredients
      • Once the race started, Louise did really well to hydrate using PF 60 Drink Mix, flat Coca Cola and a little bit of water, giving her an average intake of ~596ml (20oz) of fluid per hour, with a relative sodium concentration of ~667mg/L (mg/32oz)
      • This fluid volume would have replaced a good proportion of what she was losing as sweat, to keep her from becoming so dehydrated that it would cause a performance decline (often thought to be around 2% body weight loss)
      • While Louise hasn’t yet had a Sweat Test, she may fall on the lower end of the ‘saltiness’ sliding scale given that she was able to report zero cramping using her strategy for this race. However, if she was closer to the average sweat sodium concentration we have found (~950mg/L), electrolyte related issues could potentially emerge without additional sodium in longer or hotter events


    Quick Carb Calculator Recommendation


    carb 30 mins before


    carb per hour during
      • Louise did well to increase her stored carbohydrate in the days before the race, while not overeating by increasing the proportion of carb rich foods and reducing things like fats and protein slightly
      • One thing which Louise could consider for future races is the timing of her last bit of carbohydrate. By having a final PF 30 Gel 10-15 minutes before the start she would boost her blood glucose levels and spare some stored carb for use later in the race
      • During the race, she mainly got fuel on board via PF 60 Drink Mix and an additional two PF 30 Gels, with flat cola contributing slightly too
      • This intake meant she averaged ~65g of carb per hour. While this is below the Fuel & Hydration Planner’s general 75-90g/h recommendation, it is far more that Louise has taken on board previously, and meant her perceived energy levels were a perfect 10 (out of 10)
      • Something which has really helped Louise over the last few months is specifically targeting one intense session and one long session per week to use as ‘gut training’. This will have improved her body’s ability to process glucose and fructose, and make it more comfortable to run hard with the additional carb in her stomach
      • Louise decided for this race to have a cup of tea and some caffeinated chewing gum before the start. Again, this is after some negative previous experiences with other caffeinated products
      • However, consuming caffeine during hard efforts is something she’s going to experiment with ahead of her next race in order to reap the performance benefits associated with it


      • Louise was incredibly satisfied in running a ‘dream race’ and finishing significantly under her target with a very impressive 2:31:53
      • Her gut training in the build up to this event helped her ability to fuel with more carbs than previously, which undoubtedly helped her experience perfect energy levels on the day
      • Going forwards, Louise is going to experiment with a more structured pre-loading protocol, top up her carbs just before race start and incorporate some mid race caffeine to see if this helps her beat the PB she set in Rotterdam

    Key info

    Louise Small



    Overall Time

    Event information

    Rotterdam Marathon
    Rotterdam, Netherlands
    16th April, 2023
    Total Distance
    42.2km / 26.2mi
    Total Elevation
    30m / 98ft

    Race conditions

    Weather Conditions
    No Rain
    Min Temp
    8°C / 46°F
    Max Temp
    10°C / 50°F
    Avg Temp
    9°C / 48°F

    Athlete feedback

    Race Satisfaction
    Hydration rating
    Energy levels
    Toilet stops
    I only started needing the toilet right at the end
    GI comfort
    I felt great!
    No cramping

    Louise's Thoughts

     DREAM RACE! I was aiming for 2:33 and felt fantastic the whole way through

    Louise's full stats

     Carbohydrate (g)Sodium (mg)Fluid (ml)Caffeine (mg)Relative sodium concentration (mg/L)
    Total intake1621,0001,50039667
    Per hour6539759615

    Data Confidence







    There is some confidence in the quantities and brands of products consumed but the data may lack specifics (e.g. volumes specific flavours). A high number of estimations have been made and the room for error is moderate-high. There may also be the possibility that some intake has been grossly over- or under-estimated.

    Louise's recent case studies

    see all

    Related case studies

    Nail your next event with a FREE Fuel & Hydration Plan
    Get started