hydration during ironman

just read an article on nutrition for ironman......and for the bike the said 


B) Drink 1–1.5 litres of fluid per hour. This is two small bottles (600ml) to two large bottles (700ml) per hour, depending on climate and your perspiration rate. (Simple calculation: Weigh yourself pre- and post- ride during training. Every kilogramme lost is one small water bottle of fluid deficit, and this will negatively impact your marathon.)


even on a hot day like outlaw.there is no way i would drink over a litre an hour...in fact i only had the one drinks bottle and just change it at feed stations......so 3 litres for the whole bike plus maybe 750 ml of gels......

are they right or am I not taking in enough


  • I think we balanced the fluid intake numbers on the Monday at the pub.

  • I dont think 3L was enough last year on such a hot day. Plus, you were closer to only 2L if you did only drink 3 bottle (3 x 700 = 2100mL).

    Simple question - did you pee during the bike (if yes, how many times?), or very shortly after starting the run (if yes, how big a pee)?

  • ... and if the answer was none then it wasnt enough   image

  • surely that *is* a watering can ?

  • I had a speedfil for Outlaw 12 and I think having the straw in my face meant I drank more often a day didn't have to break out of aero position to drink. I kept refilling it so think I got through about 5l. 

    Peed lots in the swim and a few times on the bike. image

  • kittenkat wrote (see)

    Are your potted plants still alive? image

    They are a bit orange round the edges

  • The last thing I wanted to do was to start the run phase with any signs of dehydration. That didn't happen. I ingested water during the swim, can't pee whilst floating, let alone actively swimming. Desperately needed the bogs on getting out the water.

    On the bike, I needed a leak 5 times. Perhaps I over hydrated? But I had nothing like the quantity referenced.

    No need to stop on the run phase.

  • At Outlaw last year I used a speedfill bottle and filled it with two bottles between feed stations in total I drank 9 x 750mls and only peed once on the bike and once on the run and didn't have any issues  with hydration and felt good at the finish image

  • I hadf a full bottle to start with and with 4 stations that would make 2.8 litres but to be honest the water at the last station was so warm i hardly drunk it......

    on my tribars aI had a double bottle.one full of isogels so probably had about 600 ml of that and a small one of coke.....maybe 250 ml at most...

    I am usually fully hydrated after a swim as I drink so much of the water....

    I didn't stop at outlaw but was absolutely bursting for a pee by the time i got to T2 and managed to just hold out for the portaloos just outside T1


    so i expect i was close to the mark considering the weather.....but i don't think I can carry any more liquid

  • I think people over-estimate the volume they actually drink during the swim. I doubt its much more than a couple of 100mL. Plus, most people conveniently assume they dont sweat during the swim, which is also probably not true for the majority.

    Seren, can you put another cage on the frame? I dont remember how many feed stations there were at Outlaw, but did you empty your aero bottle fully between each one? If so, you'll have to be a bit more inventive with how to take on additional fluid when it's hot - for example, grab a bottle and stick it in your back pocket or in the back of your shorts while you take another one, fill your bottle, then drink a significant volume from the stored one before discarding it.

    Having said that, Outlaw was probably a freaky heatwave. But in answer to your original question, I think a litre an hour is about right (and they do say conditions dependant) and I dont think you have been drinking enough. The better hydrated you are, the better you can cope when its hot.

  • I can only put one bottle on my frame...which is the one I exchanged each feed station.......

    I filled up my aerobottles at the start .mainly with isogels and didn't top up those at all...

    trouble with grabing one in the pocket is then you are stuck with it as you can't disgard it between feed stations.seen DNF's for that


    something to think about ......I think i must drink loads in the swim as I usually pee 6 or 7 times in an ironman race.I must learn to shut my mouth........or learn to swim properely

  • I'm a bit confused - does your aero bottle have two compartments? One you had gels in, what was in the other? Coke? Why cant you top up the aero bottle?

    In my example, you drink from and discard the bottle you shove in your pocket while going through the aid station, once you've changed the bottle on your frame. You can probably get 500mLs down you before the final bottle drop.

  • I use the litre compartment for the gels and the small one of just over 300 for emergency coke....

    might go for the drink at the feed stations and discard......

    my first ironman this year has drinks available every 11 miles so isn't a problem....

  • If it were me, I would put the gels in the small one and have energy drink in the large compartment. Dont they offer Coke at aid stations anyway? If its the caffeine that you might need in an emergency, I'd have a caffeine gel taped to the bike/in your bento box. Otherwise, save the coke for the run. Its kind of wasting the space to have the gels in a litre. Are you diluting your gels? Could you switch to isogels, so thats not necessary?

    Probably academic though, as every 11 miles is plenty frequent enough, as you say.

  • I think teh coke is a security blnaket......

    all 14 of my energy gels in the bottle are caffinated isogels.  hence needing most of the litre container.....


  • Seren you do say that you suffer in the heat whereas perhaps the hydration may solve your heat issue ....

  • PadamsPadams ✭✭✭

    1-1.5 litres per hour seems a huge amount to me. I doubt I've ever got through more than 3 litres in the 5 hours or so. I'm sure there's science behind it, but is that to maintain a constant hydration? Supposedly you can function just as well a bit less hydrated - top marathoners finish the race much lighter than when they started and I know one sub-2:20 British didn't drink or eat anything in his PB race.

    Clearly proper dehydration is bad though....

  • seren nos wrote (see)

    all 14 of my energy gels in the bottle are caffinated isogels.  hence needing most of the litre container.....

    So do you empty the gels into the bottle then? or have them in their packets in the bottle?



  • 9sqrun wrote (see)
    seren nos wrote (see)

    all 14 of my energy gels in the bottle are caffinated isogels.  hence needing most of the litre container.....

    So do you empty the gels into the bottle then? or have them in their packets in the bottle?



    Don't know about seren but empty them into the bottle - why wouldn't you?! So much easier.

  • Much less messy to put the gels into a bottle and prediluted. No messy wrappers.
  • i have struggled so often opening gels....( don't ask to see the photo from last years white horse sportiveimage)....and so much time wasted in trying to get them out and open them that i would rarely take one........all in a bottle........(mine are isogels so ready to drink straight away.....

    i found this worked so much better for my ironmen last year....

  • image you're not still trying to convince people that was gel all over you after the White Horse challenge last year, are you image

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