< Back to case studies

Rebecca Clarke's scorecard

IRONMAN New Zealand

Saturday 4th March, 2023

Within recommended ranges

Just outside recommended ranges

Significantly outside recommended ranges

  • 81g

    Carb per hour
  • 430mg

    Sodium per hour
  • 833ml

    Fluid per hour
  • 517mg/L

    Relative sodium concentration
  • 597mg

    Total caffeine
  • How Rebecca hit those numbers

    750ml x PH 1500 (3/4 x tablet)
    2 x Gluten Free English Muffins
    1 x Serving of Peanut Butter
    1 x Banana
    1 x PF 30 Gel
    *** Try to avoid drinking too much at this point in the race!
    750ml x (1/2) PH 1500 (Tablets)
    500ml x PF Carb & Electrolyte Drink Mix
    5 x PF 30 Gel
    2 x PF 30 Caffeine Gel
    1.9L x Plain water
    1.5 x Energy chew packet with caffeine (48g carb, 100mg caffeine)
    1.75 x Energy bar (24g carb)
    2.25L x Energy drink (22g carb)
    500ml x (1/2) PH 1500 (Tablets)
    3 x PF 30 Gel
    2 x PF 30 Caffeine Gel
    1.3L x Plain water
    160ml x Energy drink (22g carb)
    320ml x Cola

    How Rebecca's hydration and fueling went...

      • Having claimed 2nd place at IRONMAN New Zealand in 2021, Rebecca returned to the course in 2023 with aims of replicating her podium performance
      • After dropping a part-finished bottle of PF60 Drink Mix on the bike, Rebecca did well to adapt her strategy on the fly by utilising aid stations to hit strong carbohydrate numbers and ensure she had energy left in the tank for the run leg
      • Despite this, she felt a slight energy lull heading onto the run course, but dug deep to secure a 3rd place finish, averaging 4:40 mins/km (7:30 mins/mile) for a 3:16 marathon


      • After speaking with the PF&H Sports Science team, Rebecca knew that a strong electrolyte drink before her race would help her to start optimally hydrated. To do this, she chose to drink ¾ of a PH 1500 tablet in 750ml (24oz) of water, rather than the 500ml (16oz) that we would usually recommend. This will have had the effect of reducing the relative concentration slightly and potentially limited the positive impact it would have on her blood plasma volume
      • While on the bike, she dropped a half-finished 1L (32oz) bottle of PF 60 Drink Mix, meaning she lost a source of fluid, carbs and electrolytes all at once
      • Rebecca tried to combat this from a fluid and electrolyte point of view by picking up plain water and isotonic sports drink from the aid stations, as well as finishing her remaining bottle of PH 1500
      • Then, she took a soft flask containing ½ a PH 1500 tablet out of transition with her, which she further diluted using water, sports drink and cola from aid stations along the run course
      • Rebecca reported feeling thirsty while running, which may in part have been due to her fluid intake dropping from ~1.1L/h (35oz) on the bike to ~690ml/h (22oz). At the same time, temperatures peaked on course at around 23ºC (73ºF) meaning she was losing more fluid too, due to a higher sweat rate
      • Overall, Rebecca consumed ~833ml (28oz) of fluid per hour, with a relative sodium concentration of ~517mg/L (mg/32oz)
      • While this electrolyte intake may have been insufficient some ‘saltier’ athletes, Rebecca knows that she’s a ‘low salt’ sweater, who loses just 563mg of sodium per litre (32oz) of sweat, meaning she likely replaced a good proportion of what she lost in her sweat


    Quick Carb Calculator Recommendation


    carb 30 mins before


    carb per hour during
      • After analysing her intake during her win at the Tauranga Half around 6 weeks prior to this race, Rebecca was aware that she would need to increase her carb intake for maximal energy availability on the day
      • To help boost her stored energy, Rebecca ‘carb loaded’ in the days before the event, culminating in a race-day breakfast of English muffins with peanut butter and a banana
      • Rebecca also topped up her blood glucose levels with a final PF 30 Gel within the last 30 minutes before swim start, to help conserve some of her stored energy for utilisation later in the race
      • Confidently leading the race out of T1, Rebecca involuntarily donated ~500ml (16oz) of PF 60 Drink Mix to the bike course due to a bump in the road and had to adapt her fuel plan while riding, deciding to use the on course isotonic sports drink to replace these lost carbohydrates
      • Along with her ‘fuel bottle’ which contained several PF 30 Gels and two PF 30 Caffeine Gels, this meant she still hit an impressive intake of ~104 grams of carb per hour while cycling - 59% higher than her intake during the bike at ‘Tauranga Half’ (61g/h)
      • Onto the run course, Rebecca initially felt a lull in energy, which may have been caused by slightly mistimed caffeine / carb consumption, combined with the sudden change in muscle activation going from bike to run which can often cause a dip in blood glucose
      • She bounced back from this to finish 3rd with a blistering 3:16 marathon time, taking five PF 30 Gels as well as some cola along the way
      • Rebecca is going to trial adjusting the timing of one of her PF 30 Caffeine Gels toward the end of the bike leg in her upcoming ’brick’ sessions to see if this helps her avoid experiencing an energy dip at the start of the run in future races
      • Overall, Rebecca had a solid average hourly carb intake of ~81g. Especially considering her average intake of 60g per hour at the Tauranga Half just a few weeks prior
      • Impressively, despite this increased intake, Rebecca experienced no gastrointestinal discomfort while on the bike, and only minor distress while drinking and racing at her limit on the run course - something that’s very common amongst elite triathletes and runners
      • Rebecca also nailed her use of caffeine during this race, with an intake of ~594mg putting her just above the general recommendations of 3-6mg per kilo of bodyweight for performance enhancement. This ensured she maximised the chance of experiencing all of the benefits associated with caffeine


      • Rebecca did well to overcome adversity and still crush her carb, fluid and electrolyte intake targets throughout the race
      • Going forwards Rebecca is going to experiment with the timing of her carb and caffeine intake to optimise her perceived energy levels, especially when transitioning from bike to run
      • Overall, this was an excellent early season race for Rebecca which should give her confidence for upcoming events. Additionally, finishing 3rd here means she secured her ticket to Kona for the World Championships later in 2023

    Key info

    Rebecca Clarke

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


    Overall Time
    Swim Time
    Bike Time
    Run Time

    Event information

    Full distance
    IRONMAN New Zealand
    Taupo, New Zealand
    4th March, 2023
    Swim Distance
    3.9km / 2.4mi
    Bike Distance
    180.2km / 112.0mi
    Run Distance
    42.2km / 26.2mi
    Total Distance
    226.3km / 140.6mi

    Race conditions

    Weather Conditions
    Hot and Humid
    No Rain
    Min Temp
    16°C / 61°F
    Max Temp
    23°C / 73°F
    Avg Temp
    20°C / 68°F

    Athlete feedback

    Race Satisfaction
    Hydration rating
    I felt quite thirsty on the run
    Energy levels
    I felt pretty good throughout the bike, but felt I was lacking some energy at the start of the run
    Toilet stops
    This suprised me considering that I managed to go in Kona where it was far hotter!
    GI comfort
    I had a few periods of discomfort, all while on the run and relying more on aid stations
    Twinges but not full-on cramps

    Rebecca's Thoughts

     I'm happy to have been on the podium and bagged my slot for Kona, but being so close to the win makes small mistakes seem so much more impactful.

    Rebecca's full stats

     Carbohydrate (g)Sodium (mg)Fluid (ml)Caffeine (mg)Relative sodium concentration (mg/L)
    Total intake7403,9457,635597517
    Per hour8143083365
    Bike and Run
    Total intake7103,9457,635597517
    Per hour8648092973
    Total intake5163,4325,375366639
    Per hour1046931,08674
    Total intake1955132,260231227
    Per hour6015769271

    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.

    Rebecca's recent case studies

    see all

    Related case studies

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