You can ride harder than you think when dehydrated

Interesting study but I do wonder about the effects of dehydration beyond the ride in question. I suspect that poor hydration may have an impact on recovery and for this reason it could be argued that it's beneficial to 'over-drink' on training rides etc. to assist recovery after the event.

Personally I tend to drink a bottle an hour. It changes a bit depending on the temperature but not a great deal and I find that I rarely lose any fluids beyond what I sweat and breath out.

Christ, I never know where the hell I am with this constant updating of sports science wisdom. Just do what seems right for you, I reckon!

This makes for interesting reading: http://sportsscientists.com/2007/11/sports-drinks-sweat-and-electrolytes/

I find that I need electrolytes and sugars on longer rides (4+hrs) otherwise I cramp/bonk.
I drink a lot in the day generally when I'm not riding too because it makes me feel better.
I guess we're all different.

I changed to the pee test last autumn and it works great ...

as for sports drinks and tells, I like gels, nice and refreshing on distance rides. However ditched the energy drinks and I find oats so simple bars are perfect really.

It's good to have an independent study. Not suprising that the results were not so in favor of rehydration as the studies performed by sports drink companies.

I use the urine colour test to tell if I am hydrated/dehydrated and I've noticed when dehydrated I have a higher heart rate. I've read medical studies that back this up. What I understood from them is that, essentially, when dehydrated you have a lower volume of blood plasma. The heart beats faster to keep your blood pressure at the correct level.

If my heart rate is higher the I hit the red line sooner.

I carry water not only to drink — often not to drink at all — but for many other uses. Hand washing after roadside fettles, for instance, or — hopefully not — wound rinsing! That's one reason why it's only water, not "sports drink".

Last summer I did London to Paris with average temps at 25C and I drunk loads but at night could not eat as mouth too dry to swallow. I presumed that was the sweating I did, however reading more when I got back home it was suggested I drunk too much !

I regularly knock out 150-odd/9hr mile hilly rides with a couple of bottles on the bike and still have some left when I get home. Unless it's swelteringly hot I just don't seem to need anywhere near as much liquid as is usually advised.

(In fact trying to drink the recommended amount just makes me sick!)

There is no doubt on a 2 hour leisure ride hardly any need for water. I do carry a small bottle of water just to refresh. However I do sweat a lot, miles more than the normal person and this has to be taken into account on these discussions.

I seem to recall reading somewhere about studies where test subjects were allowed to swill their mouth with water but not swallow it and that the drop in performance was negligible compared to those who could drink (I also remember reading something similar about sugary energy drinks). It'd probably go some way to explain it, that it's in your head that when you're thirsty you can't perform as well but physiologically it makes little difference.
I've stopped using energy drinks/gels when riding, other than the first ride without them I can't say I've noticed much difference.

Dr Rob Child of MTN Qhubeka said in a talk I attended, if you've hydrated properly before the event you can ride for 2 hours in most conditions without further liquid. You may feel thirsty, your throat may be dry, but in term of of performance you're body can keep delivering.

So when you see guys out for a 2 hour ride with 2 kilos pf water strapped to their £6k, 6kg bike, they're literally pi$$ing their money away

It's only a small study but would confirm what a lot of people already know. Interesting to note that much of the 'science' associated with sports nutrition and fluid intake was produced in association with.... sports nutrition and fluid companies...

And don't get me started on those poor unfortunates who simply cannot spend a day without sucking on a bottle of expensive water having absorbed the myths of dehydration in our temperate climate. My workplace looks like a bloody corner shop at times with all the bottles of crap.

http://www.theatlantic.com/health/archive/2012/07/the-controversial-scie...

It strikes me that it should be an easy one to work out for yourself.. Weigh yourself before you head out, weigh yourself when you get back. Unless you've used a toilet, there's only one way to account for the weight difference.

Every 100g is a 100ml of liquid you've lost. How much of that you need to top up whilst you're riding Vs after the ride is another matter.

Having done a couple of 4ish hour rides the last 2 weekends (not that hot admittedly) using the drink when thirsty principle I didn't quite get to the end of a 600ml bottle.

How on earth I could consume between 2.5 and 5 times that amount is slightly beyond me, unless we're talking Tour of Qatar conditions. And no, I wasn't going (that) slowly

Questions like 'where would you carry it? ' and 'how often would you have to stop to dispose of the inevitable consequences' spring to mind!