Hydration MTB – how much should you/do you drink?

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  • Hydration MTB – how much should you/do you drink?
  • steve_b77
    Member

    I’m the only one of very few “racing” types that take a hydration pack (USWE in my case) but note it’s more common in the US Marathon scene to do so. I often wonder how the pros / others get through 3hrs with a single bottle in their frame.

    I don’t think they do, a lot of marathon style bikes take two 750ml bottles now-a-days, unfortunately mine doesn’t so if I intend to not stop I have to use the small camelbak.

    If you can’t get a 2nd bottle in the frame and don’t run a dropper you can run a 2nd bottle on a post mounted cage.

    I think it’s more common in the US and Oz as it’s a damn site warmer than it is over here. The MTB Marathon series rounds here have well spaced feed stations, that suit a 1 bottle approach – although I’ll pack my pack at the weekend for Llandovery as I don’t know the set-up yet and 100km is a rather long day out 😉

    kittyr
    Member

    Once read advice to skiers to take a litre an hour, of course that will be altitude related (dry air), you wouldn’t think they’d be sweating much.

    I do some big backcountry ski touring – there is no way people take a liter an hour. Would be far too heavy to carry!

    You can be out for 8 hours, most of that climbing uphill… 2 liters is enough with a big drink in the morning and on return. You do sweat quite a lot hauling yourself uphill even in the snow 🙂

    We as humans are not balanced on a knife edge of hydration and dehydration. We can be ok whilst being a bit thirsty.

    I probably drank too little on Saturday- 4h ride in the sunshine and only did a 750ml bottle as didn’t really feel like drinking more. Did have a second with me. Nailed a couple of pints of water when I got home, but then went to the pub and def felt dehydrated after a few pints of cider!

    Rockhopper
    Member

    Member
    Thirst is a pretty good indicator. If you feel like you need a drink, drink; don’t try and reduce your intake just to comply with some sort of recommended average.

    I actually though thirst was a poor indicator – by the time you feel thirsty your already dehydrated.

    For example https://www.bcm.edu/news/sports-medicine/thirsty-you-are-already-dehydrated

    Premier Icon Yak
    Subscriber

    steve_b77/ kryton – there are some 2 bottle work-arounds available for single bottle full suss frames. The Lyne Holy Rail set up is particularly neat:

    https://www.lynecomponents.com/blog

    Thirst is an excellent measure of water needs; we’ve had millions of years of evolution to get it right and stay in good physical condition for running away from predators or chasing food to bring back for the family. The dehydrated Bushman can still chase the antelope until it drops, then gets to take a meal home afterwards, while probably still dehydrated.

    As a medic in ultra-distance sports, I give out this simple advice every race: drink to thirst. That’s it. Any salt in your drink or in your food intake is irrelevant compared to the kilo-plus that’s already in your body. Over-hydration at events isn’t just harmful, it can kill and does so remarkably quickly; I’ve seen and treated numerous hyponatraemic athletes.
    Salt added to drinks is a false crutch; any fluid that you can stomach is still much more dilute than your blood, so you’re still diluting yourself further.

    mrlebowski
    Member

    Drink to thirst.

    bsims
    Member

    That’s interesting stuff. It would appear to be caused not only by excess water intake but also by excess loss of salts during extended activity. I don’t think what I was suggesting would cause this, but if I every do an ultra event I will be very careful.

    I realise that the amount of water needed will depend on fluid and salt losses, has any body any idea how much you would need to drink to cause hyponatremia?

    Yesterday at Cannock my urine in the pre ride slash was a faint yellow colour. I rode for 3 hours at a moderate pace and drank approx 2.3 litres of water, my post ride slash was dark straw coloured. To me this suggests I had not drunk enough.

    Edit: I have never heard about adding salt to drinks as suggested, prior to reading this thread I would have thought it to be a bad idea.

    kcr
    Member

    I actually though thirst was a poor indicator – by the time you feel thirsty your already dehydrated.

    I wouldn’t suggested waiting until you are absolutely parched to have a drink. Once someone has a good idea of their personal fluid requrements, I think it is easier and more effective to drink the required amount by swigging regularly, particularly when racing.
    I was thinking more about what the OP originally wrote. If he’s going through X litres of water to quench his thirst, that’s probably a good indication he does need X litres of water overall (rather than aiming to drink some specific amount dictated by a rule of thumb).

    I tend to drink 500-800ml of water before heading out. Not in one go, more during the time it takes to get ready.

    Will get through 300-500/hr in cool to cold conditions and easily double that in hot/humid. Will sometimes take a bottle of Torq and tuck into that when going harder.

    However, I sweat a lot and therefore drop a pint of water with a High 5 electrolyte tab straight after. In certain conditions I’ll down another pint with or without protein powder.

    IMO it’s not just what you drink when you’re out, it’s your pre- and post-rose I take too.

    Varies enormously depending upon ambient temp, temp of water (ice cold water seems to help it last for me on hot days) and how hard you are riding.

    Last year’s heatwave was an eye opener for me, I quickly found that chasing PBs up cat4 hills at ~30C was a bad idea, I could go through the best part of one of my then two 750ml bottles while climbing for ~8mins and then recovering while descending over the next ~10mins!

    This app might help you locate some places you can refill your bottle(s) while on a ride…

    Refill App

    jayx2a
    Member

    Lots of very interesting and differeing opinions!

    I always drink a lot but as mentioned – maybe its habit, but for the most part its because I feel a little dry mouthed – not thirsty as such.

    I need to try out maybe a 750 bottle rather than the 610 one. Not a huge difference I know. Maybe thinking of a clearer bottle too as I do like the ‘sleek’ look of a black bottle but maybe a clear bottle will make me manage my fluids better as you can see how much is there!

    Then again, I have been comfortable drinking as much as I do for a while, so maybe its just how I am!

    Premier Icon BadlyWiredDog
    Subscriber

    I found this article from Outside quite useful:

    https://www.outsideonline.com/2148776/new-rules-hydration

    ‘There’s an easy method to figure out exactly how much fluid you need: weigh yourself before you go out for an hour of exercise, and then weigh yourself again when you get home. That’s the weight of fluid you should be taking in per hour. As the saying goes: a pint’s a pound the world around. So plan to drink a pint, or two cups, of liquid for every pound you lose during exercise. For example, if you come back half a pound lighter, you should drink one cup of water per hour of exercise. Do this in a range of temps and intensities, says Sternlicht, and you’ll have guidelines to follow in every possible set of conditions. Just don’t take in substantially more water than you lose—that’s a recipe for hyponatremia.’

    tetrode
    Member

    I like to subscribe the drink to thirst philosophy but there have been times, especially once where I was doing a long distance hike in Nepal where I was walking all day, was drinking to thirst and feeling fine, then I go for a pee and it’s very, very dark yellow, showing classic signs of dehydration. I didn’t even notice at all. After that I had to make an effort to drink regularly, even if I didn’t feel particularly thirsty. It seems like it can creep up on you.

    Premier Icon philstone
    Subscriber

    if you come back half a pound lighter, you should drink one cup of water per hour of exercise

    Interestingly – I read somewhere – (may have been a RedBull athlete interview with Gee Atherton I think..) that 1 litre for 1kg was recommended..

    tjagain
    Member

    eight hour ride I will drink a litre or so. 3 hour ride I rarely bother at all tho I will have a 700ml bottle. Never been dehydrated to the point I can see a difference in my pee ( apart from at work!) even when riding when its hot

    Premier Icon andybrad
    Subscriber

    3 hour ride about 2.5l.

    id like to just take a bottle but i cant see how..

    tjagain
    Member

    Way too much andybrad – that way lies blood dilution and cerebral odema 8+ pts of water killed leah Betts

    Premier Icon kelron
    Subscriber

    I’ll get through about 2 to 2.5L in 3 hours, if I’m not pacing myself for a longer ride. Have tried weighing myself but even drinking that much I come back lighter. I get headaches and fatigue but reducing fluid intake doesn’t seem to help, I think it’s probably the helmet or posture.

    Premier Icon andybrad
    Subscriber

    really?

    i tent to ride at max effort all the time (im slow and fat and im trying to keep up with mates) so i find drinking helps keep cramping at bay

    tjagain
    Member

    Kelron – I bet you are diluting your blood, getting some cerebral oedema hence the headache and your body reacts by peeeing out water ( so you lose weight) to try to get blood back to its correct dilution

    Seriously guys – some of the amoun ts of water you drink is absurd and potentially dangerous. 8 pts ie 5l of water can kill

    Premier Icon kelron
    Subscriber

    Thing is its not forced, I’m not trying to take in some quota of water. I drink when I’m thirsty, and feel worse for it when I don’t.

    Just for you I’ll try taking a couple of bottles out instead of a hydration pack and see how I get on 🙂

    tjagain
    Member

    I drink when I’m thirsty, and feel worse for it when I don’t.

    Fair enough. Its the people who think ” I must drink a litre an hour” I am really aiming at.

    Even working outdoors all day in Aus with temps in the high 30s I did not drink the amounts of water that some folk on here seem to.

    jayx2a
    Member

    I obviously drink too much then. Have done for past 3 years on the MTB and I’m not dead yet!!

    I don’t get how some people drink so little! Maybe you have e-bikes or are just super fit.

    The average fat bastard like me needs fluid as we sweat like pigs.

    If I don’t drink around 3 litres a day, I get quite odd symptoms when running. My vision is blurred around the edges and the inside of my cheeks get a strange numbness. I’ve had it a fair few times now, and it’s definitely a lack of hydration that does it.

    Worst time is a friday morning, if I’ve been at a track session the night before sweating buckets, then go for an early morning pre-work recovery run, I’m pretty much guaranteed to get it, only way to avoid it is to get up even earlier and get a litre into me.

    So in that case, going ‘by thirst’ doesn’t really work for me, as I’m not thirsty before I head out.

    Don’t really get it when cycling, but I very rarely ever push the envelope when biking compared to running tempo stuff regularly.

    We’re all different though, some folk don’t seem to comprehend this, as per some of the ‘you’re drinking too much/too little’ comments above. Local guy died doing Ironman Germany a couple of years back, his names still all over the top of the local strava segments, too much water and hadn’t got his nutrition right sadly.

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