Author Topic: Rehydration in Hot Weather on Audaxes.  (Read 3135 times)

Re: Rehydration in Hot Weather on Audaxes.
« Reply #25 on: June 03, 2019, 08:49:19 pm »

I really think much of the battle is dealing with excess heat before it creates issues with the body attempting to compensate with sweating. A wet flannel can cool you quickly and cheaply.

Wouldn't it be great if all shops sold small bags of ice designed to perfectly fit inside a cycling cap?

You're tight of course, I'm am loath to pour water over myself, seeing it as a waste.  Will think more on this option and try this if I find myself overheating on another ride. Plus stop and rest in shade a while.

hellymedic

  • Just do it!
Re: Rehydration in Hot Weather on Audaxes.
« Reply #26 on: June 03, 2019, 08:49:30 pm »
I can't say I really liked these technical wicking tops when it was really hot, TBH. They left my skin wet and sticky, which wasn't the case with old-fashioned cotton.

I am a Luddite (but was never DNF due to overheating).

Re: Rehydration in Hot Weather on Audaxes.
« Reply #27 on: June 03, 2019, 08:53:26 pm »
I can't sayI really liked these technical wicking tops when it was really hot, TBH. They left my skin wet and sticky, which wasn't the case with old-fashioned cotton.

I am a Luddite (but was never DNF due to overheating).

Well the above is what I get from the polyester cycling tops but not from merino / smart wool.

On the other hand I deal well with cold and can often be riding in shorts and with bare arms when others are fully togged up.

Re: Rehydration in Hot Weather on Audaxes.
« Reply #28 on: June 03, 2019, 10:06:32 pm »
This is not a simple topic - made less simple by sport drink marketing propaganda.  care is required - dehydration doesn’t necessarily have anything to do with being too hot, and sweating might raise your electrolyte levels not lower them.

Useful series of articles here:

https://sportsscientists.com/2007/10/fluid-intake-dehydration-and-exercise-part-i-history-of-fluid-intake-and-a-conflict-of-interest/


simonp

  • Omnomnomnipotent.
Re: Rehydration in Hot Weather on Audaxes.
« Reply #29 on: June 03, 2019, 10:22:24 pm »
TrainerRoad podcast discussed sodium loading in episode 201 which I happened to listen to tonight. I’d take such ideas with a pinch of salt.

IGMC.

They’ve covered heat acclimatisation in the past. I think this is certainly something you can work on on the turbo.

hellymedic

  • Just do it!
Re: Rehydration in Hot Weather on Audaxes.
« Reply #30 on: June 03, 2019, 10:32:37 pm »
This is not a simple topic - made less simple by sport drink marketing propaganda.  care is required - dehydration doesn’t necessarily have anything to do with being too hot, and sweating might raise your electrolyte levels not lower them.
Useful series of articles here:
https://sportsscientists.com/2007/10/fluid-intake-dehydration-and-exercise-part-i-history-of-fluid-intake-and-a-conflict-of-interest/

My point is that trouble with hydration occurs after a rider has become too hot and is unable to balance water and minerals. An overheated rider may not absorb food and fluid well if blood is shunted to the skin and away from the gut.

All the smart drinks in the world won't cure someone who is puking until they cool down and stop vomiting. At this point, it may be too late to save a ride.

My general strategy for Audax success is to address minor issues BEFORE they escalate into major problems.

That is what has worked for me.

Re: Rehydration in Hot Weather on Audaxes.
« Reply #31 on: June 03, 2019, 10:41:28 pm »
What even IS the evolutionary driver behind the whole - "Hey, we need to assimilate water and salt for the next few hours because it's freakin' hot, so let's commence a PUKE-A-THON!". Homo Sapiens - making zero sense, since 200k BC.

Re: Rehydration in Hot Weather on Audaxes.
« Reply #32 on: June 03, 2019, 10:56:18 pm »
I had a check of the weather data along the route and it looks to have peaked at 23 degrees, which matches my recollection of it being hot but not roasting. It sounds to me like something more complicated happened to you than simple dehydration in hot weather. I wouldn't like to speculate on what though.

hellymedic

  • Just do it!
Re: Rehydration in Hot Weather on Audaxes.
« Reply #33 on: June 03, 2019, 10:57:50 pm »
Anyone with a hap'orth of sense would stop cycling, strip off, sponge down and rest before confounding the issue with a SCIENCE overload.

Primitive man would not drink if nauseous...

Re: Rehydration in Hot Weather on Audaxes.
« Reply #34 on: June 03, 2019, 11:29:15 pm »
This is not a simple topic - made less simple by sport drink marketing propaganda.  care is required - dehydration doesn’t necessarily have anything to do with being too hot, and sweating might raise your electrolyte levels not lower them.

Useful series of articles here:

https://sportsscientists.com/2007/10/fluid-intake-dehydration-and-exercise-part-i-history-of-fluid-intake-and-a-conflict-of-interest/
Thank you very much for providing that link - well worth reading imo. Drink to thirst.
Deep in the 4th article is this (slightly edited):
"My sweat tastes salty

"Yes, it certainly does, and that is because it does contain some sodium. However it contains profoundly less [per volume] than the fluids in your body, and is still mostly water—body fluids have a sodium concentration of 140mM while sweat has a value of 20-60mM. Therefore when you remove a liter of sweat from your blood, it has much more of an effect on the volume compared to [an effect on] the solutes (sodium), and what happens is that the osmolality rises in response to sweat losses. This is absolutely crucial to realise – you cannot lose sodium, even if you are a “salty sweater”. If the sodium content of the blood is dropping, it’s because you’re drinking too much water [in extremis leading to hyponatremia - more dangerous than dehydration per se], not because you’re sweating sodium! In fact, a very interesting study was published in 1992 by Robert Cade (Gatorade). During a marathon 3 groups of runners were given Gatorade, or 1/2 Gatorade (half water, half Gatorade), or water. The really interesting finding was that the water group maintained their sodium concentration (a surrogate for the total osmolality) just fine, while the Gatorade group actually increased its concentration. This explains why people drink more of a sports drink compared to water—the sports drinks keep your osmolality higher and therefore makes you thirstier. So instead of lowering osmolality, which is what your body wants you to do, the sports drinks raise it. Seems kind of counter-intuitive, doesn’t it?"

Re: Rehydration in Hot Weather on Audaxes.
« Reply #35 on: June 03, 2019, 11:39:22 pm »
I find blackcurrant Dioralyte works quite well in warm conditions - unlike some sports drinks it is easy to drink without feeling sick.

If you want to increase the amount you drink you could try a CamelBak style pack. They make drinking easy compared to bottles and hold up to 3 litres which would keep you well hydrated if you fill up at each control. Not sure whether it would be comfortable to wear one on a 600 though.


Re: Rehydration in Hot Weather on Audaxes.
« Reply #36 on: June 03, 2019, 11:51:29 pm »


Sun gloop will impair your sweating.



Don't forgo sunscreen though as the cumulative effect of all that UV and IR will increase your body temperature.
If you have sensitive skin or it's being exposed to sun for the first time, then use SPF 30 or even 50.

I wear a large handkerchief round my neck during hot weather. It protects the back of the neck, absorbs sweat and when soaked with cold water, it helps to keep me cool.
It can also be used as a facecloth.

+1 for the Dioralyte or similar, but really you have to force or train yourself to drink more often.

Re: Rehydration in Hot Weather on Audaxes.
« Reply #37 on: June 03, 2019, 11:57:01 pm »
The problem is not helped by the reliability of modern cars, and the closure of filling stations.

Quote
in 2000 there were around 14,500 filling stations in the UK, which has shrunk to around 8,400, with 300-400 closing every year, up until five years ago.

Every filling station had an outdoor tap, where you could fill bottles, and if it was really hot, dowse your hat and shirt, and fill your shoes with water. These days radiators don't need topping up, and the garage store wants to sell you bottled water. There are always churchyard taps, but you have to know where they'll be.

I remember cramping big-time on the 24 in 1999, in 30+ degrees, stopping at a garage cum shop, and buying 500gm of salt. I don't think the garage is there now. Lots closed down because they couldn't meet changed storage regulations.

Kim

  • Timelord
Re: Rehydration in Hot Weather on Audaxes.
« Reply #38 on: June 03, 2019, 11:57:13 pm »
ETA, don't forget solar radiation, wear light colours not dark.

Noting that the colours your eyes are sensitive to may not accurately reflect the albedo of the jersey.  I'd hope that most manufacturers of proper cycling kit would get this right in their choice of dyes.
To ride the Windcheetah, first, you must embrace the cantilever...

Re: Rehydration in Hot Weather on Audaxes.
« Reply #39 on: June 04, 2019, 12:06:02 am »
In my experience heat exhaustion can be caused by too much direct sun to the head and neck areas. That can make me nauseous and exhausted without even doing any activity or getting dehydrated. I always wear a helmet when cycling regardless of how hot it is, but switch to my best white one with plenty of vents when it's going to be hot. I find this insulates my head from the sun and as long as I'm moving air flows through the vents keeping my head cool.

On my hottest three rides last year, Mille Pennine, Mersey 24 and Dolomites Super Randonnee 600, I wore white leg and arm warmers/coolers throughout the events and found they worked well, reflecting some heat and giving a cooling effect as sweat transpired through them. I also wore shorts with coolmax inserts and thin short sleeved jerseys with no base layer and long zips during the heat of the day. The arm and leg warmers/coolers also saved me from having to bother with sun cream.

I'm not keen on drinking plain water especially when it starts getting warm so I use white or silver coloured bottles to delay the warming process and I put a high5 zero tablet in each 750ml bottle as this makes it tastier as well as replenishing any electrolytes I might be loosing. I usually have a couple of scoops of energy powder in each bottle too. I rode a DIY 200km on Saturday and wore my thin long-sleeved old AUK top, dhb shorts and white helmet. My legs got slightly sun burnt, but I was otherwise ok. I drank the two bottles of energy/electrolyte drink I'd made up at home and felt fine during the ride, but I was sweating a lot after I'd finished so drank a protein shake and two pints of water shortly after finishing. If it had been the first 200km of a 600km I would probably have drank an extra litre during the ride, but as a stand alone 200km I got away with drinking less and did the whole ride non-stop.


quixoticgeek

  • Mostly Harmless
Re: Rehydration in Hot Weather on Audaxes.
« Reply #40 on: June 04, 2019, 12:59:43 am »
I find blackcurrant Dioralyte works quite well in warm conditions - unlike some sports drinks it is easy to drink without feeling sick.

If you want to increase the amount you drink you could try a CamelBak style pack. They make drinking easy compared to bottles and hold up to 3 litres which would keep you well hydrated if you fill up at each control. Not sure whether it would be comfortable to wear one on a 600 though.

I'm gonna actually suggest that a camelback style bladder system, has a weakness. You can't easily tell how much you have drunk. You may think you've taken a sip every few minutes, so that must be loads, but then find you've still got 2 litres in the bladder. This is more or an issue when it's in a frame bag, or when there is other stuff in the backpack when back mounted.

Personally I like a 1L bottle. I  carry 1 or 2 of them, depending on temperature.

Last summer I did.3 200k DIYs in 6 days, in ~34°C temps. There was minimal breeze, next to no shade, and little cloud cover. I wore a white helmet, a short sleeve merino jersey, shorts, short socks, and what felt like half a litre of factor 50... On each ride Iost count of how much liquid I took in at 6L. Mostly water, with some coke and Fanta at cafes. On the hottest day of the 3, despite the constant input of liquid, I went 8+ hours between toilet visits. I planned my rides based on available water sources (did I mention the drinking water POI overlay of Osmand?), Literally riding from drinking tap to drinking tap. Usually 40-50km between each. Consuming at least 1l during that distance.

My clothes had a coating of salt crystals by the end of each day. There were times when having filled my bottle I had a brief moment of trying to decide, do I drink it, or pour it over my head. On one occasion where I did do spray it over my head to cool down, it just washed all the salt into my eyes, which stung... On only one of the rides did I wake up the next day dehydrated. Which was soon fixed. I didn't take any fancy hydration salts, but did have a packet of ready salted crisps each day, as well as a portion of salted fries.

I'm of the view that the trick is to drink lots, starting before you start riding, to keep a good idea of how much you've drunk, and if in doubt, drink.

J
--
Beer, bikes, and backpacking
http://b.42q.eu/

bludger

  • Randonneur and bargain hunter
Re: Rehydration in Hot Weather on Audaxes.
« Reply #41 on: June 04, 2019, 01:26:57 am »
I have long wrestled with the colour question - for instance we take it as a given that light colours reflect the light away, but in the middle east and Africa it seems dark colours are very popular, such as among the Tuareg.

I have a probably more than  questionable theory that light colours will reflect energy back inside to the body as much as they 'bounce them away' from the surface, and that dark fabrics better radiate the heat away from the body.

In any case it seems to me that the research finds the whole thing makes little odds on that question https://science.howstuffworks.com/science-vs-myth/everyday-myths/light-colored-clothes-in-hot-weather.htm

Certainly the rocks will melt under the sun before I wear white shorts.
Bikepacking bargain basement: reviews of high value kit great for the tourer, bikepacker and randonneur on a budget

https://yacf.co.uk/forum/index.php?topic=109048.msg2312359#msg2312359

Re: Rehydration in Hot Weather on Audaxes.
« Reply #42 on: June 04, 2019, 07:13:32 am »


Sun gloop will impair your sweating.



Don't forgo sunscreen though as the cumulative effect of all that UV and IR will increase your body temperature.
If you have sensitive skin or it's being exposed to sun for the first time, then use SPF 30 or even 50.

I wear a large handkerchief round my neck during hot weather. It protects the back of the neck, absorbs sweat and when soaked with cold water, it helps to keep me cool.
It can also be used as a facecloth.

+1 for the Dioralyte or similar, but really you have to force or train yourself to drink more often.

I've used the wet handkerchief round the neck to great effect. Simple to carry and evaporative cooling to some major blood vessels. I wasn't hot enough to need it on Saturday. I drank a lot, especially at the controls before eating. Other than that I was wearing a lightweight merino vest and thin summerweight club cycling top.
Reine de la Fauche


mattc

  • n.b. have grown beard since photo taken
    • Didcot Audaxes
Re: Rehydration in Hot Weather on Audaxes.
« Reply #43 on: June 04, 2019, 07:15:33 am »


Certainly the rocks will melt under the sun before I wear white shorts.

 ;D
Has never ridden RAAM
---------
No.11  Because of the great host of those who dislike the least appearance of "swank " when they travel the roads and lanes. - From Kuklos' 39 Articles

mattc

  • n.b. have grown beard since photo taken
    • Didcot Audaxes
Re: Rehydration in Hot Weather on Audaxes.
« Reply #44 on: June 04, 2019, 07:19:11 am »
They’ve covered heat acclimatisation in the past. I think this is certainly something you can work on on the turbo.
turbo???

What's wrong with a nice Arran jumper?

(one can solve problems without a turbo ... )
Has never ridden RAAM
---------
No.11  Because of the great host of those who dislike the least appearance of "swank " when they travel the roads and lanes. - From Kuklos' 39 Articles

Re: Rehydration in Hot Weather on Audaxes.
« Reply #45 on: June 04, 2019, 07:58:46 am »
I've used the wet handkerchief round the neck to great effect.

I wear a gel one and found it helps. Soaked in cold water, the cooling effect lasts hours. As someone who suffers in the heat my other tactic is simply not to ride. Not an ideal solution by any means, and obviously not one that is conducive to qualifying for (nor indeed riding) PBP but it does nonetheless remain an option.

Some people have winter off seasons, I have a summer one!

andyp

  • Andrew Preston
Re: Rehydration in Hot Weather on Audaxes.
« Reply #46 on: June 04, 2019, 08:47:02 am »
hi,
I met a GP from Melbourne at the start of PAP: he had been found fitting at the side of the road at the end of day 1 of a hot US 1200 a few years ago: he almost died, and has no recollection at all of the journey to the US, or the ride! He'd been drinking water all day. He now adds pure salt to his water bottles by the teaspoon - he assured me it's all you need, and that you do need it. he wrote a well researched / definitive article in the Australian audax newsletter on the subject which would be worth searching for I think.

+ 1 to looking out for streams, water fountains, water troughs to wash your face / dunk your head / cap / feet in on hot days: it drops your core temp, and is a complete reviver.

Re: Rehydration in Hot Weather on Audaxes.
« Reply #47 on: June 04, 2019, 08:54:12 am »

I really think much of the battle is dealing with excess heat before it creates issues with the body attempting to compensate with sweating. A wet flannel can cool you quickly and cheaply.

Wouldn't it be great if all shops sold small bags of ice designed to perfectly fit inside a cycling cap?

You're tight of course, I'm am loath to pour water over myself, seeing it as a waste.  Will think more on this option and try this if I find myself overheating on another ride. Plus stop and rest in shade a while.
I wouldn't think of it as a waste. If you're only using enough to wet your garments it's just short circuiting the sweating process. It will only end up there anyway if you drink it, taking with it less easily replaceable salts.

If you are feeling hot/sick then cooling is the main requirement. I would think electrolytes in water are what's missing if you are cramping up despite drinking enough liquid.
   Eddington  81 miles  112 kms

Ben T

  • I do find that slightly bizarre, I must admit.
Re: Rehydration in Hot Weather on Audaxes.
« Reply #48 on: June 04, 2019, 08:58:13 am »
There's a lot talked about in this thread of salt being a good thing and I'm sure to some extent it is, but personally I avoid eating anything too much of anything very salty e.g. bacon, on an audax as it makes me too thirsty.
I find from subsequent thirst levels McDonald's is more salty than it tastes.
It is what it is. It's not what it's not, so it must be what it is.

Re: Rehydration in Hot Weather on Audaxes.
« Reply #49 on: June 04, 2019, 11:18:35 am »
One tip that I haven't seen mentioned yet: dampen your entire jersey (either under the bathroom tap in a pub or in a plastic bag with a squirt of water by the roadside) for that lovely "oooh cold cold cold" feeling as you put it back on. I find that once it's damp it's easy to top up the dampness via a squirt over the shoulder or down the back of the neck, whereas doing that with a dry jersey leads to wasteful runoff.

Applying water directly to your skin (rather than via your digestive system and sweat glands) isn't wasteful unless you spill lots IMO, and it preserves electrolytes and cake digestion capacity.