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Dan Collins' scorecard

London Marathon

Sunday 3rd October, 2021

Within recommended ranges

Just outside recommended ranges

Significantly outside recommended ranges

  • 37g

    Carb per hour
  • 332mg

    Sodium per hour
  • 396ml

    Fluid per hour
  • 837mg/L

    Relative sodium concentration
  • 0.86mg/kg

    Caffeine per bodyweight
  • How Dan hit those numbers

    2 x Slices of toast with peanut butter and jam
    1 x Coffee
    500ml x Energy drink mix with caffeine (44g carb, 28mg caffeine)
    3 x PH Electrolyte Capsule
    1.05L x Plain water
    2 x Energy gel (23g carb)
    2 x Energy gel with caffeine (23g carb, 30mg caffeine)
    100ml x Energy drink (32.5g carb)

    How Dan's hydration and fueling went...

      • Dan is an amateur long distance runner and PH customer who had a great run in the London Marathon crossing the finish line in just under 2 hours 40 minutes. He was ‘over the moon’ with his time and rated his race satisfaction at 9/10
      • The one point deduction came from his belief that he ‘definitely could have managed the race better, be that hydration or more even pacing’
      • But, it was Dan’s first proper marathon (he completed the virtual London marathon the year previously) and he went on to conclude that ‘you have to run a tactically bad race before you run a good one!’


      • Dan consumed an average of ~396ml/hr (~14oz/hr) of fluid across the marathon which he mostly achieved by collecting plain water at aid stations. Given the milder environmental conditions, on the face of it this is an acceptable level of fluid intake, especially when you consider the pace (03:47 min/km) that Dan was moving at
      • This degree of fluid replacement is certainly on the lower end of our recommendations especially as Dan reported that he sweated quite a lot in the first part of the race. Dan said that he felt he drank enough water but definitely not enough fluids containing electrolytes
      • He mentioned experiencing a craving for a sweet, salty sports drink towards the end of the race which is a good indication that he was toeing the line on his fluid, sodium and carbohydrate intake, and possibly under-doing things. This is in line with Dan not peeing during the race - which isn’t necessarily unacceptable for a race of this duration - but reporting that his urine being ‘very, very dark afterwards’
      • Lastly, Dan did experience some feelings of cramp starting around mile 22. From there on he experienced ‘lots of twinges’ which he was concerned would turn into full-blown muscle cramping so ‘slowed a fair bit to manage them’. Dan took three PH electrolyte capsules to stave off some of this; whilst the final electrolyte capsule eased it somewhat, it was not enough to allow him to run freely


    Quick Carb Calculator Recommendation


    carb 30 mins before


    carb per hour during
      • Dan ate a good breakfast, high in it’s proportion of carbohydrate, but possibly could have eaten a bit more. Dan commented, ‘the gels felt a bit like they were landing on an empty stomach at times’, in which case that final 30g dose may have been beneficial
      • Dan snuck into the recommended carb range by consuming ~37g/h across the race. He chose to use energy gels to fuel his performance, spacing these evenly out across the marathon, and using a caffeinated one in the second half to provide a boost to his energy levels
      • He had assumed that more energy drinks would be available along the way which would have subsided his carbohydrate intake but that in reality these were few and far between. In an ideal world, we would be recommending Dan to be hitting a carb intake in the upper end of this range, closer to 60g/h, especially given the intensity he was racing at
      • Despite this, Dan felt good during the run from an energy perspective, rating his energy levels a 9/10
      • Unfortunately, the run wasn’t without some GI discomfort. Dan reported feeling ‘pretty fine most of the way’ but started to experience some issues around the halfway point. This began with a stitch after ingesting a gel but fortunately this was eased by consuming some water
      • Later, around mile 22/23, his gel made him feel sick and three out of the last five miles he described himself as feeling ‘stressed, sick and tight’ but ‘still pretty strong’. Overall, the GI comfort was poor enough that Dan rated it just a 4/10
      • It’s unclear quite what caused Dan’s gut issues during the race and often these things are multifactorial. Whilst fundamentally it may have been the consumption of gels causing some discomfort, these issues can be made worse by poor management of fluids, anxiety or stress and the physical jarring of a long, fast run to the GI system
      • The good news is these issues can be avoided, or reduced in severity, by extensive and systematic gut training in the race lead-up, which might be something Dan considers for future events


      • Dan was happy overall with his performance and felt as though it went well. He recognised that areas to improve were eating a greater breakfast and following more of a strategic hydration plan
      • Dan experienced some cramping towards the end of the race which impeded his performance somewhat but he did manage to overcome the cramps enough towards the end to pick up the pace in the last 200m and finish strongly which he was pleased with
      • Overall, it seems Dan was treading a fine line with his sodium, fluid and carbohydrate intake and could have benefited from dialling each of these three things up. But, that said, he still pulled out a great time for his first ever proper marathon and we look forward to what he can achieve as he further refines his fuelling and hydration strategy

    Key info

    Dan Collins



    Overall Time

    Event information

    London Marathon
    London, England
    3rd October, 2021
    Total Distance
    42.2km / 26.2mi

    Race conditions

    Weather Conditions
    No Rain
    Min Temp
    12°C / 54°F
    Max Temp
    16°C / 61°F
    Avg Temp
    15°C / 59°F

    Athlete feedback

    Race Satisfaction
    Hydration rating
    Energy levels
    Toilet stops
    GI comfort
    I’d say about three miles of the last five were pretty hellish. Felt stressed, sick and tight, yet still felt pretty strong
    Twinges but not full-on cramps

    Dan's Thoughts

     I’m over the moon with my time, but I definitely could have managed the race better - be that hydration or more even pacing

    Dan's full stats

     Carbohydrate (g)Sodium (mg)Fluid (ml)Caffeine (mg)Relative sodium concentration (mg/L)
    Total intake998791,05060837
    Per hour3733239623

    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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