To drink or not to drink

Mike T wrote an article on the 'Long Mynd Valley' thread, suggesting that below 20degrees one need not drink at all during a marathon. This is it:

"Running a marathon, at 100 calories a mile, takes approximately 2600 calories. About 25% of this results in work/movement but 75% just results in heat which has to be dissipated to the environment or we would quickly become hyperthermic and die. 75% of 2600 is 1850 calories of heat to lose, and as long as the ambient temperature is less than 20C it is estimated that sweating only has to dissipate half of this ( or less as it gets colder ) as the rest is lost through radiation and convection. 1ml of sweat loses about 0.6 of a calorie so 925 calories needs about 1.5 litres of sweat. But glycogen breakdown liberates water at 2.7mls/gm - if half of the energy of the marathon is derived from glycogen at 4 calories/gm (and the rest from fat ) then about 800 mls of water is liberated and about another 400mls is generated as a by product of energy use ( carbohydrate plus O2 being converted to CO2,H2O and energy ). So the body has come up with 1.2litres of the 1.5 needed. But during exercise our temperature rises, so we don't need to lose all the heat we generate. A typical temperature rise would be from 36C to 39C, and as each degree of temperature increase is about 60 calories, or 100mls of sweat, we can subtract 300 from 1,500 leaving 1,200 - so there is no need to drink at all!"

So to those who understand the science in this article how many will now stop drinking during their marathons?

As a mouth breather, I reckon I lose some moisture that way even if I'm not sweating at all - like a dog!

Mike T I thought I'd bring your excellent post onto a thread of its own and query some of your theory. My concern is with the glycogen part of your calculation. You state glycogen yields 2.7mls of water per gram of glycogen. You also state that glycogen yields 4kcal per gram. My question is: was the glycogen in both parts of the calculation hydrated or dehydrated?

The other concern is with the amount of glycogen available during the marathon. Since the liver stores about 150gms(600kcal in dry form) of glycogen and little glycogen is used in the muscles during steady state exercise, where will the 1300kcal of glycogen come from?

I did about 30 marathons fairly seriously down to 2:30. Most of the water I picked up went over my head or on to my legs, less than a pint made it to my stomach. Only on very hot days would I deliberately drink more.

I don't have any idea whether I "need" to drink on longer runs (haven't done a marathon yet so can't comment there) but I do know I feel better and am able to refuel on the way round more comfortably if I do have some water. That said I did 19 miles this morning and took a 275ml bottle with me and only drank about a quarter to a third of it. I think sometimes it's more to do with comfort then actual need, but either way I won't be stopping to take any water on long runs as a result of some calculations.

Although I suspect this thread is more an attempt to wind up another forum member than a serious question

When doing my long training runs on roads, I never took any water or food. I deliberately trained 'dry and empty'.

I've found with long fell running, though, that I do need to take food on board and for that I also need water. I'm not sure whether that's a function of fell running or my age and lack of training.

Using glycogen both liberates water stored with it AND generates water when it is metabolised to CO2, H2O, and energy. Steady state exercise at very low levels like walking uses mainly fatty acids, but marathon like events completely deplete the slow twitch fibres and even some of the fast twitch ones of their glycogen stores (Noakes, Lore of Running, 3rd edition, pge 67) - so there is plenty of glycogen used to liberate/generate water. Even at only 30% VO2max, the main energy source is glycogen until after the 3 hour mark, when fat takes over (pge 76).
I am no great runner, and need all the help I can get in races - if those around me are willing to handicap themselves by carrying/consuming unnecessary water I suppose I should let them get on with it - but part of the joy of running is seeing others improve/succeed with fairly simple advice - such as an appropriate and scientific water strategy. I am not suggesting that everyone runs marathons without drinking, but as long as it is not hot it certainly works for me.

Horses for courses, I sweat like a pig when fell running, whether it's hot, cold, mild, wet. If I don't drink water it all goes to pot very quickly.

Some people sweat an amazing amount - at our local track are several who have water dripping off their noses after a few gentle warm up laps - and if you run behind them you get almost rained on. Each runner has to sensibly work out their water strategy, taking into account sweat rate/temperature/duration/access to water on the route and so on. Weigh yourself before and after a long run and work out your sweat rate, knowing that weight loss and dehydration are not the same thing. The only time I suffered from not drinking was on a 20 mile run on a hot day - high 20s - this was a deliberate experiment - I lost 7 lbs - just over 5% of my body weight - and was getting dizzy and slow towards the finish.

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Originally Posted by Alexandra

As a mouth breather, I reckon I lose some moisture that way even if I'm not sweating at all - like a dog!

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We all lose moisture this way, and roughly the same amount - exhaled air is close to 100% humidified whether we mouth or nose breathe - just like sweat it contributes to heat loss.

This is a totally unscientific observation, but I did a run yesterday: http://www.sportstracklive.com/track...ath/Run/129894 according to the weather stats on it, it was 8 degrees and 93% humidity, it was raining at the beginning but had stopped by halfway. I was sweating like a pig, as I always do! I drank about half a litre of water. I probably drank more than I needed to ( I also ate a cerial bar at the half way mark) as I want to get into a rythem of eating and drinking as I up my mileage, but I am sure I would not have been very comfortable if I had not drunk anything.
When I was riding long distances Polaris Challenge etc I found to stay comfortable I had to drink about a litre an hour to stay comfortable. I am guessing I will need about the same when running.
James

Last marathon I did 9 years ago I overdid it - had to stop 5 times for a pee en route!

Why stop?

I used to be convinced it wasn't a good idea to drink while running, in fact I was sure it would just make me feel ill and I never felt thirsty anyway. However, when I was up to running 20+ miles (and in the tropics) and I realised just how many pints of water I was drinking after arriving home I decided I'd have to try it. I feel so much better now towards the end of those long runs. I still don't drink a huge amount (at most 1 litre in four hours in temp. over 25C and high humidity, much less in cooler weather), but a couple of mouthfuls per hour does help. Admittedly in cool weather, not drinking wouldn't bring me to a halt, but if running for more than an hour I do prefer to have some water with me.

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Originally Posted by jhb0510

This is a totally unscientific observation, but I did a run yesterday: http://www.sportstracklive.com/track...ath/Run/129894 according to the weather stats on it, it was 8 degrees and 93% humidity, it was raining at the beginning but had stopped by halfway. I was sweating like a pig, as I always do! I drank about half a litre of water. I probably drank more than I needed to ( I also ate a cerial bar at the half way mark) as I want to get into a rythem of eating and drinking as I up my mileage, but I am sure I would not have been very comfortable if I had not drunk anything.
When I was riding long distances Polaris Challenge etc I found to stay comfortable I had to drink about a litre an hour to stay comfortable. I am guessing I will need about the same when running.
James

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Half a litre is trivial compared to your total body water of about 42 litres - but if you sweat a lot it makes sense to get used to drinking on the move for when you really need it on longer runs.

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Originally Posted by Welsh Harrier

Last marathon I did 9 years ago I overdid it - had to stop 5 times for a pee en route!

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First marathon I did as soon as we had started all these chaps went to the side of the road in a long line to have a pee - talk about over hydrated.

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Originally Posted by Mike T

First marathon I did as soon as we had started all these chaps went to the side of the road in a long line to have a pee - talk about over hydrated.

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more likely nerves than over hydration. im not a big drinker when i run tends to make me feel sick as it sloshes around but i do like to swill the mouth out to stop the dry throat.

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Originally Posted by Mike T

First marathon I did as soon as we had started all these chaps went to the side of the road in a long line to have a pee - talk about over hydrated.

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If I'm racing, I like to get to the line well hydrated and take a pee just before the start. That way I know I'm not going to need much fluid on the way round, and I won't need to stop during the race either.

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Originally Posted by Rob Furness

If I'm racing, I like to get to the line well hydrated and take a pee just before the start. That way I know I'm not going to need much fluid on the way round, and I won't need to stop during the race either.

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If you really do need to pee during a race - excluding what might be called a nervous dribble and also really long events - then you have drunk too much.

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Originally Posted by Mike T

First marathon I did as soon as we had started all these chaps went to the side of the road in a long line to have a pee - talk about over hydrated.

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Reminds me of this:

http://www.youtube.com/watch?v=16iNk1hLJt4


1min 15secs & 2mins 20secs into the clip !!

At a recent fell race on a long steep ascent I was coming up behind - no sniggering at the back - a female runner who seemed to be doing a curious sort of stretch with one hand in her crotch - it was not until I passed her and she apologized that I realized she had been having a well disguised pee.

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Originally Posted by Mike T

At a recent fell race on a long steep ascent I was coming up behind - no sniggering at the back - a female runner who seemed to be doing a curious sort of stretch with one hand in her crotch - it was not until I passed her and she apologized that I realized she had been having a well disguised pee.

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And your point is what?

You thought you had to share the fact that caught a woman having a pee?? Should we all giggle childishly???

That the woman was at fault - had drunk to much - and that was why she was having a pee at all??

Us woman that reguarly venture outdoors need to pee sometimes and don't have the luxury of a toilet nor the ease that men have in having a crafty wee. Most of us try and overcome our embarrassment of having to pull down half our clothing by reminding ourseves that all the others outdoors appreciate the fact that it is a human need, that it is not esasy for women to be discreet in having a pee, and nothing to be embarrassed about.

Yet here you are broadcasting the fact that you stumbled on a lady having a pee. Well done you. You must feel very proud of yourself for telling that story!!!:thunbdown:

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Originally Posted by Brotherton Lad

Why stop?

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I let it go, profusely, without breaking stride between CPs 1 and 2 at the Wadsworth Trog.

I'd made a spritely start and was jiggered if I was going to let a dozen people go past.

Must have got carried away with pre-race hydration.

I always stop, a nice chance for a breather, maybe grab a bite to eat or drink. Never really run that seriously to be arsed about my position! :)

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Originally Posted by ukhursty

I always stop, a nice chance for a breather, maybe grab a bite to eat or drink. Never really run that seriously to be arsed about my position! :)

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well maybe, but for the time this took, I'd've ended up at the back :o

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Originally Posted by ZootHornRollo

well maybe, but for the time this took, I'd've ended up at the back :o

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You were only a bit behind me!

Deffo drink a fair bit on runs now, usually Powerade if I'm feeling flush or its 2 for 1 :)

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Originally Posted by Flopsy

And your point is what?

You thought you had to share the fact that caught a woman having a pee?? Should we all giggle childishly???

That the woman was at fault - had drunk to much - and that was why she was having a pee at all??

Us woman that reguarly venture outdoors need to pee sometimes and don't have the luxury of a toilet nor the ease that men have in having a crafty wee. Most of us try and overcome our embarrassment of having to pull down half our clothing by reminding ourseves that all the others outdoors appreciate the fact that it is a human need, that it is not esasy for women to be discreet in having a pee, and nothing to be embarrassed about.

Yet here you are broadcasting the fact that you stumbled on a lady having a pee. Well done you. You must feel very proud of yourself for telling that story!!!:thunbdown:

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Sorry Flopsy and anyone else I have offended - but I did almost walk into the poor woman - she was not at all hidden/off the route - as I said if she had not apologised I would not have realized what she was doing. The point I have failed to make is that not only was she over hydrated she was also stationary when she should have been moving.

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Originally Posted by Mike T

If you really do need to pee during a race - excluding what might be called a nervous dribble and also really long events - then you have drunk too much.

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Oh dear, Mike, you don't know much about women. "Runner's World" forums are full of posts from women upset because as soon as they start running they want to, and indeed often DO pee. Women who have ever given birth are particularly prone to these difficulties, as are post menopausal women (older men have a problem starting to pee while older women have a problem keeping from doing so). Older women in the general population will risk their health by drinking too little because they are embarrassed to have to keep seeking out loos, and I imagine older men, with a pattern of little and often peeing due to very common prostate problems do the same.

When I was reconnoitring LDWA events, one of the things I was looking out for was pubic loos and convenient bushes/walls etc where I could have a reasonably discreet pee. The Myrtle Meander was the star event for this, with about 5 public loos en route (I imagine most of them have been closed now). In the past I have been so desperate for want of a public convenience, I have peed poorly concealed behind the yews in a churchyard - aware that if seen I would not only feel embarrassed but possibly have caused terrible offence. I have walked along a main road, bursting, looking longingly at the front gardens and wondering if anyone would notice ... It is likely that the woman you saw had previously gone through agonies of mind - would that rock be big enough? Could she veer off the track to that far off clump of trees? and then it just had to happen RIGHT NOW.

Surely everyone remembers Paula Ratcliffe's famous pee during the London Marathon. If anyone ever prepared meticulously for an event it would be Ms Ratcliffe. Do you really think she drank too much beforehand?

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Originally Posted by Mike T

The point I have failed to make is that not only was she over hydrated she was also stationary when she should have been moving.

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Mike, you are just digging yourself deeper and deeper. As far as I know, any woman peeing while running or even walking is likely to have to do the rest of the route with her shoes full of p***

Men do have an advantage in this regard. It's not a drama in the countryside, but city marathons can be more challenging. My finest hour was in Berlin in 1984, but it was drizzling, so no harm done.

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Originally Posted by Alexandra

....Paula Ratcliffe.....

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Radcliffe? ;)

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Originally Posted by Rob Furness

Radcliffe? ;)

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Is your pseudonym Spelling Bee?

PS As I posted this, there flashed up: "This site does not supply identity information". Big brother or what?

I think Paula did a No:2 not a pee, this site does not supply identity of poo or wee information though:rolleyes:

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Originally Posted by Alexandra

Mike, you are just digging yourself deeper and deeper. As far as I know, any woman peeing while running or even walking is likely to have to do the rest of the route with her shoes full of p***

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I was not suggesting for one second that she pee on the move, but that if she did not need to pee she could have kept moving and not been passed by multiple people - yet another reason not to over hydrate.

In my long experience, I'd agree it's better to stop for that. Anyway, back to drinking....

"If anyone ever prepared meticulously for an event it would be Ms Ratcliffe. Do you really think she drank too much beforehand?" (sic)

I have great respect for Paula, some of her achievements have had me close to tears - but she and her advisers do not get everything right - look at her injury record. Did she do a "1" or a "2"? - more to the point, how many times do we see the leaders in a marathon stop for a pee - virtually never. True, some may have chosen to do it on the move, in which case the men are as likely to get in their shoes as the women. I have done 21 events that took me over 3 hours, 11 of them over 4, and have not needed to pee during any of them. In training, I have tried to practise peeing on the move, but my brain will not let me, and I then have had to stop to finish the act. I maintain that if you need to pee during a race, whether you stop or not, then you are over hydrated, and this is to your detriment - long races, what I call nervous dribbles, and those with weak bladders of either gender excluded.

I came across the following on Anton Krupicka's blog, recounting his run in the Rocky Raccoon 100 mile race:

Lap 1: Within a couple hundred yards of the off Zach Gingerich disappeared into the dark and a substantial chase pack formed that included all of the other pre-race likely suspects: myself, Scott, Hal, Karl, Ian Sharman, Mike Wolfe, Mike Arnstein, and a few others. As we’re all pretty much friends, most of this lap consisted of playful banter and no real racing, of course. I remember having to stop to pee a couple of times and upon completing the task always being amused that most of the folks around me had taken the chance to do the same thing.

K went on to run 100 miles at sub-8mph pace. OK this was a long distance event, but he and his competitors needed to pee right after the start. If they were over-hydrated it didn't hold them back much. K was 3rd. The winner finished in 12:44:35.

Paula's stop was definitely a no 2 and sometimes you just have to do what you have to do!

I had a similar experience just after turning at the summit in the Oissy Oiks race a few years back - luckily the bracken was high and a good job I didn't need the map anymore:o

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Originally Posted by Alexandra

I came across the following on Anton Krupicka's blog, recounting his run in the Rocky Raccoon 100 mile race:

Lap 1: Within a couple hundred yards of the off Zach Gingerich disappeared into the dark and a substantial chase pack formed that included all of the other pre-race likely suspects: myself, Scott, Hal, Karl, Ian Sharman, Mike Wolfe, Mike Arnstein, and a few others. As we’re all pretty much friends, most of this lap consisted of playful banter and no real racing, of course. I remember having to stop to pee a couple of times and upon completing the task always being amused that most of the folks around me had taken the chance to do the same thing.

K went on to run 100 miles at sub-8mph pace. OK this was a long distance event, but he and his competitors needed to pee right after the start. If they were over-hydrated it didn't hold them back much. K was 3rd. The winner finished in 12:44:35.

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100 mile races are totally different - clearly if you do not eat/drink you will grind to a halt - and drinking helps to wash down the food. There is an argument in such events for being a bit over hydrated at the start so that you do not need to take so much in on the move. There is also the possibility in such long events of actually developing kidney damage - and one of the simplest ways of being fairly confident they are OK is peeing reasonable amounts of reasonable coloured urine. I would expect - indeed want - these runners to be peeing during the first of their five 20 mile laps. Cool climate marathons/Longmynd - like fell races are in a completely different category.

If I could run a marathon as fast as Paula then I don't think I'd need to stop for a pee either!! ;)

But I'm not even going to get into this debate as I know what works for me, as I suspect do many others here.