Dehydration......I did Warn You

[NATURAL ANKLING]

Hi,
Last week did a almost non stop ride over 5hrs and took only 2.2 litres of fluid with me, at home I was over 2 kilos lighter.
Tuesday I took 3.2 litres of fluid on a 3 hr 20 min ride still over a kilo lighter at home
I am not on any type of med which could dehydrate me, I was before a few years ago, well that is what I thought, commonly losing over 2 kgs even when drinking over about 2 hrs 40 min. I do take salts in the fluid of one sort or another.
OK so maybe I sweat a lot.

I have read that if you drop more than 2 % body weight then your performance is affected.
But I was reading the other day that athletes do train to perform with up to 5 % or more (endurance) loss in body weight through dehydration.
Obviously if you lose a lot of fluid you will also need salt otherwise fluid will not be absorbed.

Best advice I can find is to drink when thirsty, this appears to be a thin line to time it correctly, apparently only 800 mls can be absorbed an hour, so over drinking can then also cause dehydration.

Normally over say 12 - 50 hrs (11 in 12 hrs & say30 in 50 on bike) I can come home only 1 kg lighter so I must be doing something correctly, resting and eating whilst drinking balances it up.

[Tangled Metal]

I heard thirst is a very poor indicator for rehydration. It only kicks in after you're significantly dehydrated, can't remember if that's at 2% or greater.

The advice I've read is to drink a little and often. Drink before your thirst response kicks in.

The worst I've been is 9 and 7 litres of fluids over a 12 hour period. I suspect I was washing out a little because only about 3 or 4 litres included hydration mixture. The rest was filled up at streams and the water fountain at the carpark or cafe at the end.

Nuun tabs are worth carrying. IIRC lemon flavour is good. Being a walker worst case scenario I'm filling up at a stream in the hills. I once got told that if you use a tablet to kill the nasties (chlorine IIRC) nuun lemon works well at masking the sterilizer tablet after it has done their work.

[Mick F]

I take water with me on rides, especially during the warmer weather, but rarely drink enroute. I take it with me "just in case".

Out on Monday, I rode 27miles with 3,000ft of ascent in the mid 20s deg C, and never drank a drop.
I had a cup of tea when I got home, and threw the water in the bottle down the drain.

[mjr]

The advice I've read is to drink a little and often. Drink before your thirst response kicks in.

I have a large bottle with a sippy straw in a cage on my handlebars in this weather.

I usually don't drink much, but last Saturday's intake was epic: almost 2 large bottles (800ml each IIRC), 1 regular 750ml bottle, 2 pint and 3 half-pint glasses of water to do just under 40 miles across the fens.

It's that time of year where it's good to identify likely water sources around a route before setting off. http://www.searchosm.com → position the map → search (magnifying glass) for travel and tourism: water. Let us know if you know any which aren't mapped yet.

[softlips]

It's very important to stay hydrated. Dehydration will affect your performance and can cause arrhythmias.

[NATURAL ANKLING]

Hi,

Today 2 hrs 25 min, drank 1.75 litres still lost 0.7 kg.
The links I could not find earlier-

http://www.humankinetics.com/excerpts/e ... erformance

"A study investigated the capacity of eight subjects to perform treadmill walking (at 25% .VO2max with a target time of 140 minutes) in very hot, dry conditions (49° C [120° F], 20% relative humidity) when they were euhydrated and when they were dehydrated by a 3%, 5%, or 7% loss of body mass (Sawka, Young, Francescone, et al. 1985). All eight subjects were able to complete 140 minutes walking when euhydrated and 3% dehydrated. Seven subjects completed the walk when 5% dehydrated, but when dehydrated by 7%, six subjects stopped walking after an average of only 64 minutes. Thus, even for relatively low-intensity exercise, dehydration clearly increases the incidence of exhaustion from heat strain. Sawka et al. (1992) had subjects walk to exhaustion at 47% .VO2max in the same environmental conditions as their previous study. Subjects were euhydrated and dehydrated to a loss of 8% of each individual’s total-body water. Dehydration reduced exercise endurance time from 121 minutes to 55 minutes. Dehydration also appeared to reduce the core temperature a person could tolerate, as core temperature at exhaustion was about 0.4° C (0.7° F) lower in the dehydrated state.

The main reasons dehydration has an adverse effect on exercise performance can be summarized as follows:
• Reduction in blood volume
• Decreased skin blood flow
• Decreased sweat rate
• Decreased heat dissipation
• Increased core temperature
• Increased rate of muscle glycogen use"

Then-
http://running.competitor.com/2014/05/n ... ance_76027

"Signs And Symptoms

Although the signs and symptoms of hyponatremia have been described as similar to those of dehydration. Noakes points out that the only true symptom of dehydration is thirst. Symptoms associated with hyponatremia include:

— Disorientation
— Confusion
— Headache
— Muscle weakness
— Nausea and vomiting

If left untreated or misdiagnosed as dehydration, hyponatremia can progress to seizure, brain swelling, pulmonary edema (fluid buildup in the air sacs of the lungs), comatose, cardiorespiratory arrest, or death.

Is Dehydration Really Detrimental To Performance?

The current recommendation for hydration is four to eight ounces of fluid every 15 to 20 minutes of running. However, these recommendations were based on early studies conducted in the 1960’s, which suggested that dehydration determines the body temperature response to exercise and thus, the development of heat-related illnesses."

--------------------*************************-------------------

However-

"However, more recent studies have now shown that dehydration, or rather a reduction in body weight due to exercise, is a normal part of exercise.

A recent meta-analysis of laboratory-based studies examining the impact of dehydration on performance resulted in the following conclusions:

— It was found that a reduction of body weight of 2.2 percent was not associated with a decrease in performance.
— It isn’t dehydration itself that is responsible for any decrease in performance, but rather not drinking in response to thirst.
— Drinking enough to satisfy thirst resulted in a 90 percent performance advantage compared to drinking below thirst and a 63 percent performance advantage over drinking above the thirst response.

The only symptom of dehydration is thirst and often, this thirst becomes so overwhelming that the athlete is compelled to drink when fluid is available.

Furthermore, studies have disproved the claim that a reduction in body weight of less than 2 percent results in impaired performance. For example, a recent study confirmed that Haile Gebrselassie lost 10 percent of his body mass due to dehydration during his world record marathon run in Berlin.

The results of this latest research show, for the first time, that drinking according to thirst is the superior hydration protocol to maximize performance."

[ianrobo]

Best advice I can find is to drink when thirsty

If that is the best you found I dread to think what the worse was !

IMHO the best advice is to drink little and often and especially when NOT thirsty. I sweat a lot and a few times when I first started longer rides I was in trouble. However for me (and all this is very individual) then I take two bottles (900ML) 3 high 5 tabs for electrolytes and that last me 4 hours in normal UK conditions.

[Bonefishblues]

When fishing (Tropics) I absolutely load with water in the very early morning and then still expect to drink 4-5 pints over the course of the day, finishing at about 3-3.30pm.

I think my level of consumption is unusual, but if I don't it's headache time by lunchtime, plus gritty eyes as my tears dry up and contact lenses start to (literally) grate. I just seem very sensitive to being anything other than fully-hydrated.

[ianrobo]

Also there is a lot of concern about over drinking and some of us (as I did) think drinking too much is a problem. However because of sweating etc (even if naturally you do not) makes this concern OTT.

[NATURAL ANKLING]

Best advice I can find is to drink when thirsty

If that is the best you found I dread to think what the worse was !

IMHO the best advice is to drink little and often and especially when NOT thirsty. I sweat a lot and a few times when I first started longer rides I was in trouble. However for me (and all this is very individual) then I take two bottles (900ML) 3 high 5 tabs for electrolytes and that last me 4 hours in normal UK conditions.

Hi,
I think I worded that wrong at the time, I was anticipating that I included a link, which is now in my last post above.

It seems controversial if you look at the two links.
On long rides I am normally ok, its the shorter training rides I seem to suffer, I am going to try harder to drink more, but without any salts / food it can be counter productive due to hypernatreamia (too much water).

https://authoritynutrition.com/water-intoxication/

"Bottom Line: The kidneys are capable of excreting up to 7 gallons (28 liters) of fluid per day. However, they cannot excrete more than 1 liter per hour. Therefore, drinking more than this is not a good idea."

"Bottom Line: Water intoxication is most common among soldiers, endurance sports athletes and schizophrenia patients. Several hyponatremia cases and deaths have been reported in these populations."

[ianrobo]

but surely sweating i not a function of the kidney's ?

[Cyril Haearn]

I think it is difficult to drink much too much in most circumstances, if one drinks a bit too much one just has to pee more often

After several occasions where I had apparently drunk too little (cycling in hot weather, or train trips) and been very ill the next day (headache, vomiting, unable to keep food down), I often have another cup of tea when I get home late. Might need to get up for a pee in the night, that is not so bad. I surmise that the metabolism and digestion slow down overnight if one has not drunk enough

[david7591]

I imagine everyone is different in their hydration requirements, and each of us needs to figure out what works for us, as individuals, rather than rely on formulas.

On Wed, this week I cycled 51 miles, with 6,200 feet of climbing. Ok it was in South Lakeland, where it was warm ( low twenties centigrade) rather than the excessive heat further south. I took two 750ml bottles with High 5 energy powder mixed with water, which I find better than pure water whilst cycling. I drank around a bottle and a half during the ride, more than usual due to the relative warmth and humidity. At the end of the ride I'd lost 1 kilo in weight (normal weight 67K so approx 1.5% of body weight). I did not feel any loss of performance during my ride, other than beginning to feel slightly tired towards the end, but that I believe was a normal consequence of the effort of my ride, rather than dehydration. Nor did I feel unduly thirsty after finishing. To be honest, I would have been ok (just) with one 750ml bottle. (I do think there is a tendency to drink what is avaliable rather than what is needed). I believe my temporary weight loss was a normal reaction to moderatly strenuous exercise, and not dehydration. If I hadn't have drunk at all, I would probably have suffered from dehydration to some extent.

Someone else though might need more, or less, fluid intake than me in similar circumstances. In the OP, you mention losing 2K during a ride. Did you feel dehydrated or ill? If not nothing to worry about.

Like other commentators I have read that if you feel thirsty, you are already in the early stages of dehydration, and therefore should start taking small sips early in you ride, before thirst sets in.

And of course, most importantly of all, make sure you are fully hydrated and 'fuelled' prior to your ride, and top up with food and water as soon as possible after finishing.

[nez]

I imagine everyone is different in their hydration requirements, and each of us needs to figure out what works for us, as individuals, rather than rely on formulas.

On Wed, this week I cycled 51 miles, with 6,200 feet of climbing. Ok it was in South Lakeland, where it was warm ( low twenties centigrade) rather than the excessive heat further south. I took two 750ml bottles with High 5 energy powder mixed with water, which I find better than pure water whilst cycling. I drank around a bottle and a half during the ride, more than usual due to the relative warmth and humidity. At the end of the ride I'd lost 1 kilo in weight (normal weight 67K so approx 1.5% of body weight). I did not feel any loss of performance during my ride, other than beginning to feel slightly tired towards the end, but that I believe was a normal consequence of the effort of my ride, rather than dehydration. Nor did I feel unduly thirsty after finishing. To be honest, I would have been ok (just) with one 750ml bottle. (I do think there is a tendency to drink what is avaliable rather than what is needed). I believe my temporary weight loss was a normal reaction to moderatly strenuous exercise, and not dehydration. If I hadn't have drunk at all, I would probably have suffered from dehydration to some extent.

Someone else though might need more, or less, fluid intake than me in similar circumstances. In the OP, you mention losing 2K during a ride. Did you feel dehydrated or ill? If not nothing to worry about.

Like other commentators I have read that if you feel thirsty, you are already in the early stages of dehydration, and therefore should start taking small sips early in you ride, before thirst sets in.

And of course, most importantly of all, make sure you are fully hydrated and 'fuelled' prior to your ride, and top up with food and water as soon as possible after finishing.

I sail as well as cycle and know you can get dehydrated by the wind at sea when you're not taking much exercise. It makes me wonder if the wind passing over every cyclist isnt dehydrating them to a level above the norm.


I'm a trendy consumer. Just look at my wobbly bog brush using hovercraft full of eels

[Tangled Metal]

https://authoritynutrition.com/water-intoxication/

"Bottom Line: The kidneys are capable of excreting up to 7 gallons (28 liters) of fluid per day. However, they cannot excrete more than 1 liter per hour. Therefore, drinking more than this is not a good idea."

"Bottom Line: Water intoxication is most common among soldiers, endurance sports athletes and schizophrenia patients. Several hyponatremia cases and deaths have been reported in these populations."

28 litres per day but only 1 litre an hour? Hmmm! My maths tells me that means there's 28 hours in a day according to the authors of the quote above. Have I really lived my life 4 hours out of synch with everyone else?

Bottom line IMHO and IME too much plain water is bad, it doesn't quench thirst and it leaves you feeling worse than just pure dehydration.

The other bottom line I have experienced is that there's a delay in absorption of water and fluids. That means thirst kicks in and you get a delay to quenching it. That is why in top up with fluids before thirst kicks in. Add to the fact my digestion of foods and absorption of nutrients appears to slow with exercise. It's one thing to carry out tests in laboratory conditions but another in real life conditions. Whilst I'm sure it's right I just don't agree its completely right.

Washing out is ott or unlikely? Well I certainly have felt the beginnings of it and I'm no endurance athlete (well challenge walks apart). I did hear of an endurance athlete completing a distance trail race. He rehydrated post race and on his train home. He never made it but collapsed on the train. On reaching hospital he was dead. It was washing out in the extreme and IIRC heart issues did it. Whatever the truth is I've had days drinking huge volumes of water without quenching my thirst. I just kept feeling thirsty. It ended after I'd eaten a rather salty meal (a steak pie cooked in a large bowl with pastry lid, plenty of gravy, chips, peas and even a salad with dressing. Mmmm! Plus beer! Well steak pie needs beer IMHO!

Little and often is my hydration strategy. Find yours!