Long Mynd Valleys

[trilathon]

I guess I am lucky in that I sweat very little and have for example run a couple of marathons during which my intake of food/fluid was zero and yet my times were if anything better than those where I had indulged. 1 kg is about 1.5% of the average runners weight = 1.5% reduction in VO2max = 1.5% increase in time; a handicap I can do without. Are others really sure they need it, or are they sticking with the now discredited advice that you need to drink BEFORE you are thirsty.

that not correct at all....VO2 Max has a relationship with bodyweight and the surface area of an person but as anything you carry does not have a oxygen requirement, nor increase your surface area, in a direct sense, it will not act as the equivalent increase in mass.

Furthermre, your capacity to perform any work is massively compromised by a drop in blood plasma caused by dehydration which is going to afffect oxygen transport and many other metabolic activities so your actual vO2 max isn't going to be available for you to use, basically you will slow down far more than you realise though the percieved effort level will probably increase.

Again, whether you accpt this or not doesn't stop it being true

[trilathon]

That's all well and good, and supported by science and all that. But... how many of the top 50 carried any water? I guess they finish faster, so they can get away with it.

true enough, finishing in a hour and a half is a bit different than two or three hours...but they're still human...you want find many people who know anything about sport science advocating racing over the hour mark without addressing the nutritional needs of the body

does natural talent come pre-packaged with a contemporary knowledge of sport science or do people just copy what they see unless awareness is increased ?

[mischeavous elf]

I can see that you might want water to wash down food, but 200-300mls is only going to make a miniscule difference to your state of hydration.

thats what I'm saying, its a nerves issue for me (have drink if need it, self sufficient, and sipping just before start, rehyrate as much after and hopefully wee wees follow
lol

[Mike T]

that not correct at all....VO2 Max has a relationship with bodyweight and the surface area of an person but as anything you carry does not have a oxygen requirement, nor increase your surface area, in a direct sense, it will not act as the equivalent increase in mass.

Furthermre, your capacity to perform any work is massively compromised by a drop in blood plasma caused by dehydration which is going to afffect oxygen transport and many other metabolic activities so your actual vO2 max isn't going to be available for you to use, basically you will slow down far more than you realise though the percieved effort level will probably increase.

Again, whether you accpt this or not doesn't stop it being true

Disagree - any scientists out there care to contribute? - I have probably said enough on this for the moment.

[Mike T]

Mike T, are you saying the carrying of 1kg reduces V02 by 1.5%?

Yes - it is that simple - whether it is 1 kg of body fat or a litre of water - assuming 1 kg is 1.5% of your body weight. VO2 max is mls of O2 per minute per kg of body weight - if you weigh more your VO2 max goes down in proportion - carrying weight has the same effect on performance whether it is part of your body or not.

[Mike T]

More on this here: http://coachjoeenglish.wordpress.com...o2-max-part-i/

[Mike T]

VO2 max is maximal O2 consumption and is usually expressed relative to body weight - so it is essentially power to weight ratio. Of course if you carry a weight your maximum O2 uptake will not change, but your power to weight ratio will - and it is this that determines your performance. If a 50 kg runner carries 50 kg - to keep the sums simple - their power to weight ratio halves and their performance suffers accordingly - this applies to both an external weight or fat. For an external weight a good description of what is going on is EFFECTIVE VO2 max.The relationship between performance and changes in VO2 max is not linear with big changes, but not far from it: Noakes states marathon times of 2.43 fo a VO2 max of 60 and 4.43 for a VO2 max of 30. If you strap 1 kg of water to your back your EFFECTIVE VO2 max does go down by about 1.5% - and your performance suffers accordingly - and if you lose 10kg of fat - not muscle - your VO2 max will improve dramatically - but not many runners have 10 kg in weight to lose.

[Glenners]

not many runners have 10 kg in weight to lose.

Speak for yourslef!lol!

Interesting thoughts, assuming, as it seems some people are, the extra 1kg of water carried results in a loss of 1.5% in performance over a race that might take 2 hrs that equates to approx. 1min 48 secs (I think).

This doesn't however consider, the psychological effects of feeling comfortable, hydrated etc or from carrying electrolytes and so forth, not dehydrating and such, which would surely counteract some of the offset 1 min 48?

Also your equation doesn't account for the water drunk on the route, it is unlikely you'd carry the full 1 kg around for the entire 2 hrs thereofre surely the effects would be less?

Finally would the extra 1 kg at the start of the race affect anaerobic threshold and/or lactate tolerance as well as your VO2 max, I don't think one is necesarrily derived from the other but may be just as important in a race like this?

Answers on a postcard please?

[jtinnion]

I think we're getting mired in facts and stats again.

I've lost 9.5 kgs in the last year, through regular training and just following a slightly more sensible diet (smaller portion sizes when I'm not really hungry from running). The combination of weight loss and better conditioning has led me to much better performances. I was over seven minutes faster at Clee Hill on Saturday than I was last year.

I carried 500mls of fluid and a couple of gels (prob another 100g?) on Sunday. I tried hard to drink two or three sips every ten minutes or so after the first half hour (although I'm fairly careful to drink when I'm breathing least hard otherwise I tend to get trapped wind which does adversely affect my performance), and I had a gel on the climb out of Minton Batch (to give me some energy for Packetstone and Callow) and another at the bottom of the Callow Climb (for some go on the final ascent).

All I can say it that this approach seemed to work for me - I wasn't desperately thirsty when I finished (i.e. I was still reasonably hydrated) and I had good energy levels on Callow and Yearlet (I was passing a lot of people towards the end of the race). I know if I hadn't drunk or eaten anything the outcome would not have been as good!

Cheers all
Jim

[Dr Bob]

Hi Jim - did you get up to Bowland yesterday? HS offered me a lift to Stretton but unfortunately I had another seizure on Monday so wasn't running. Roll on the hospital appointment next Tuesday...

One thing I'd say is that thirst is not a great indicator of hydration. I did several experiments at university as part of a sports physiology course and urine colour is the strongest easily monitored indicator of hydration. How many times have we done a long training run or race in the summer and drunk 500-1000 ml afterwards and which has quenched thirst but still have orange urine an hour or two later. Lovely...