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We go walking for fun. Obviously physical fitness will affect how well we walk, but after that the single most important factor is probably water. Without enough water, we are in strife. If you have ever run out of water while walking on a hot day you wil
We go walking for fun. Obviously physical fitness will affect how well we walk, but after that the single most important factor is probably water. Without enough water, we are in strife. If you have ever run out of water while walking on a hot day you will know just how crucial water is; if you haven't (yet), that's an (undesirable) experience in store for you.
While you have enough water you just sweat. But once you start to run low there three stages you go through. (Terminology varies: this is what we use.)
Heat Stress means you are getting a bit hot and bothered. You may be running a bit short on water and your performance will start to go down a bit. Organisations like the Volunteer Bush Fire Brigades recognise this as a problem and encourage all volunteers to carry water, and also provide basic training on how to recognise the symptoms in yourself or others. Heat Stress is not good for you, but many walkers will admit that they have often suffered from it a bit on a hot day. Some may even go so far as to claim you can get used to it. Strictly speaking this isn't correct, but experienced walkers can get used to recogising and handling the symptoms. Once you realise you are a bit 'hot and bothered', you back off a little and make sure you stay within your limits. If posible, you also start drinking.
Heat Stroke is far more serious. While you have enough water in your body you will probably just suffer Heat Stress, but you can run low, and that's when Heat Stroke starts. You know when you make the transition quite easily: you stop sweating, and your skin gets very hot. CAUTION: this is serious! A common symptom also met is that the sufferer feels he or she cannot get enough air, and starts breathing very fast, even panting. The sufferer usually feels dizzy as well. What has happened here is that the feedback loops within the body have temporarily broken down. Your breathing is normally regulated automatically to give you enough oxygen and to help cool your core by evaporation. When you run low on water the evaporation stops working properly, so the breathing ramps up to try to get more of it. It becomes a run-away process. This leads to hyperventilation and contributes to the dizziness.
The recommended medical treatment for Heat Stroke varies, but lying down in the shade helps reduce the demands being made on the body. Some 'experts' strongly recommend an ice bath and a quick trip to Casualty. Wouldn't we all love the ice! More realistically, this happens when you are in the middle of the bush and short of water, and other treatments are needed. If the patient is hyperventilating, talk to him and persuade him to start holding his breath. He may argue that he feels he is suffocating: persist gently. Get him to control his breathing down to a very slow rate. This will stop the hyperventilation, and also lower the basic metabolic rate. Wait until the patient really has slowed down and relaxed: this may take quite some time, half an hour or more. A small snooze may help. Real success comes when the patient starts sweating slightly, but this may not always happen. Then you have to decide what to do next. You could try walking on slowly, watching the patient carefully. You could send some people off to find water. Or you could wait until the evening before moving on. I guess you could also use your EPIRB or mobile phone to yell for help, but that decision is up to you.
If you don't heed the warning signs and try to keep going, the next stage is collapse. The author thankfully has little experience here, and is not going to waffle. However, it is worth knowing what can happen if you push too far. A marathon runner killed himself not so many years ago in a race by 'pushing himself through the pain barrier'. Basically, his internal organs all failed. Part of the problem here is that you can lose common sense before you realise what is happening. While this does not happen too often here in australia, the Park Rangers at the Grand Canyon in America have to rescue people regularly. These are usually young males who think they are too tough to take notice of the warnings about dehydration.
At the same time, you can drink too much water. A very recent and very dangerous idealogy has been created that you should 'drink as much as you can'. Quite a few runners have died this way. T A recent (2004) race across Sydney saw two people collapse from hyponatraemia.
One of the more interesting topics which surfaces on aus.bushwalking occasionally is salt. There are those who swear by salt tablets, and there are those who swear against them. There are those who swear by 'sports drinks' for the salt and other 'electrolytes' in them, and there are those who sneer at them. There are those who believe in the recent fad for drinking huge volumes of water, and there are those who never do it and think it is dangerous (which it is). So herewith a collection of contributions on this general subject. Much of it is in the form of quotations from postings to aus.bushwalking, although some discrete editing has been done. Anything in  has been inserted by the maintainer as an alert that the quotation may not be correct. I have included a range of items as it is clear that opinions vary widely, and what might work for one person might not work for another. Please note that the maintainer certainly does not endorse everything quoted, only his opinions (as usual)!
From David Clayton in response to a question about cramp from Anthony Dunk:
(Only part of David's response is quoted; other parts have been omitted for various reasons.)
In my years of coaching martial arts I recommend against drinking straight sports drinks - a watered down mix I find is absorbed much more rapidly into the body. I like to use powdered staminade and mix it to my own concentration (around 2 teaspoons per litre) - it tastes like @#$% but I've never had any problems - it also takes away the bland taste of water or chemical tastes from adelaide water (or chlorine tablets when out walking). Here's some stats for you.
- Water makes up around 60% of the total body weight, and major reductions impares normal body performance
- Sweat contains the following electroyltes - Sodium, Chloride, Calcium, Potassium and Magnesium - technically these are all salts
- Many ... sports drinks contain the above electrolyte to a similar concentration as normal sweat - however the sodium concentration is often HIGHER than the sodium concentration in blood. Sodium (in salt as we know it) absorbs water, and is discharged through the body. Therfore excessive levels of sodium found in sports drinks actually blocks the absorbtion of water in the body.
- These electrolytes are best managed by eating a healthy balanced diet,
- The Australian Sports Commission and Australian Institute of Sport advise that it is not possible to drink too much water [WRONG] as the body will dispose of what is not necessary. HOWEVER, if a person slips into shock from dehydration water CAN be fatal [true] (follow normal shock proceedures - sipping, moisten lips etc)
- I recommend that my student begin hydration well before training - 2-3 hours. For high performance coaching I recommend begining hydration before going to bed the night before, drinking plenty of water before sleep and then a further 2 litres on waking. Sure this causes heavy peeing but the body is fully hydrated then for a full days training. I follow similar guidelines before extended walking.
This provoked a bit of discussion, and Doric Swain contributed the following.
As an undergraduate in a P.E. degree (in the 80's), I was taught that the blaming of cramps on salt loss was a myth. Since then, I've worked in the School Of Exercise & Sports Science at Sydney Uni (as a biomechanist, not as an Exercise Physiologist), and sat in on quite a few presentations on exercise in the heat (it was a prime research area of the Head of School and many post-grads). Some opinions that I formed over that time include:
- The causes of cramps are multi-factorial:- cramps occur in conjunction with heat, cold, dehydration, low blood sodium and/or potassium (& probably other eloctrolytes), fatigue, low blood sugar, high intensity (anaerobic) weight training, low intensity (aerobic) training, etc. Sometimes cramps occur for no apparent reason (like the cramps I get in the arch of my foot in the middle of the night).
- There is great individual variation in cramping - both between individuals experiencing the same conditions, and over time by an individual experiencing the same conditions.
- There is no 1 solution to cramping, and many professional athletes continue to suffer cramping despite the assistance of Sports Doctors, Exercise Physiologists, Dieticians and Trainers. Remember Pat Rafter had a history of cramping in long matches for many years (which I seem to remember was ""fixed"" with a few changes to his diet.)
- The application of salt (in tablets or drinks) may help some individuals who have a low dietary salt intake, sometimes. However, if the cause of the cramp is not due to low electrolyte levels, electrolytes would probably not assist.
I have to say that the above is put together from my rather ramshackle memories of various seminars, conversations and readings over more than a decade, in a research area I'm not an expert in. So take it ... (here it comes) ... (sorry to do this) ... with a grain of salt.
'Hyponatraemia': a potentially fatal medical condition brought about by drinking too much water.
How much water you should drink in a day? The short answer may be a lot less than many of the self-styled 'experts' have claimed. A recent editorial by Dr Noakes, Editor of the BMJ and world authority on sports medicine and fluid consumption, in the British Medical Journal1 suggests the the current dictum that you should 'drink the maximal amount that can be tolerated' is horribly wrong and leads to hyponatraemia2. To quote:
'To date at least seven fatalities and more than 250 cases of this condition have been described in the medical literature.' The editorial goes on to suggest that 'In particular, exercisers must be warned that the overconsumption of fluid (either water or sports drinks) before, during, or after exercise is unnecessary and can have a potentially fatal outcome. Perhaps the best advice is that drinking according to the personal dictates of thirst seems to be safe and effective.' Apparently marathon runners have been trying to drink over 1 litre per hour, possibly over 1.5 litres, and up to 15 litres in a day in one case, as a result of the drinking craze.
This editorial stirred things up a bit in the medical area, and triggered some 'discussion'. In response to some opposition, he went on to write in the correspondance pages of that journal3:
Consider first the definitive series of studies undertaken in the Nevada desert during World War II (35). There, in one study (36), groups of army conscripts exercised during the day in desert heat for as long as they could, usually up to 8 hours, without any fluid ingestion whatsoever. During this time they would cover up to 34 km. At the point of fatigue, caused by ""dehydration exhaustion,"" subjects exhibited the following symptoms and signs: They ""grew peevish and intractable; others walked in silence and were unresponsive."" All developed marked physical fatigue and ultimately became ""incapable of even mild physical effort."" Yet ""there were no obvious after-effects of dehydration. . . . We do know that man can suffer a water deficit so incapacitating that he can neither walk nor stand; yet he recovers his walking ability within a few minutes of water ingestion, and his feelings of well-being within half an hour or less after he begins drinking. With a meal or two intervening, his recovery is practically complete in 6 to 12 hours.""
If these army subjects, who developed levels of dehydration twice as great as those usually measured in modern endurance athletes, were able to recover within minutes of drinking fluids orally, where did the idea arise that much lesser degrees of dehydration are (1) life-threatening and (2) must be treated immediately with intravenous fluids? (8)
The second body of evidence--also conveniently ignored--is that up to 1969, endurance athletes were encouraged not to drink during exercise (2,12). Yet there are almost no documented case reports of complications experienced by these athletes. Thus, the impressively titled review article ""Heat Stroke and Hypothermia in Marathon Runners"" (37) mentions only one case of heatstroke in a competitive marathon runner, that of Jim Peters in the 1954 Empire Games Marathon in Vancouver. The reasons other than dehydration that explained Peters' only collapse in a remarkable competitive career have been described (38). Generations of competitive distance runners were, like Peters, able to set world records at a wide range of running distances without ever consuming anything (let alone maximal quantities) and without apparently suffering life-threatening complications (as is now frequently reported in those who drink too much). [The references may be found in the cited article3.]
This has two implications for bushwalkers. The first is that the current craze for a 'hydration bladder' with a hose over your shoulder and nipple to suck on is just that: a bit of a craze, principally designed to transfer dollars from your pocket to that of the manufacturers. You simply do not need to drink that much that often. The second is that most of the 'sports drinks' may be useless at best and possibly dangerous at the worst. Discussion in the medical journal following the editorial included the following quote3, but more may be read in the original article:
'Current sports drinks have low sodium concentration relative to sweat losses at maximum sweat gland function. Thus, it may be safer to increase the salt content of sports drinks to protect athletes performing under high heat rather than discouraging adequate replacement of losses. An added benefit would be that less serious athletes performing under lower ambient heat would not over-consume beverages with a higher electrolyte content. Normally hydrated individuals would find the brackish taste of more salty drinks less palatable. Such an idea obviously works against the thrust of the beverage industry that seek to cajole us all to drink as much as possible of any fluid they produce' [His words, my emphasis].
Subsequent discussion on aus.bushwalking was interesting and other references were given, including another one from Dr Noakes
Another reader, Andrew Taylor of UNSW, supplied a reference to a fascinating review by H Valtin in the American Journal of Physiology - Regulatory, Integrative and Comparative Physiology, 2002. The Review is entitled ""Drink at least eight glasses of water a day."" Really? Is there scientific evidence for ""8 × 8""? and goes on to document the author's search for any medical evidence to support the title. (""8 × 8"" refers to drinking eight 8oz glasses of water per day.) Not only did he find no supporting evidence, but he found many documented examples of the hazards of hyponatraemia. It's quite a lengthy and thorough paper, as you might expect from an Invited Review.
In addition, the author found two other common claims to be rubbish. The first rejected claim is that you are dehydrated when you start to feel thirsty; the second is the claim that the water content of tea, coffee and soft drinks can't be counted. In fact, the phrase 'severe water intoxication' is used in this Invited Review in all seriousness. Read the paper for yourself.
It's always interesting to read some of the old classics to see what previous generations thought and did. Lawrence of Arabia spent a lot of time with the desert arabs during one war. He rode with them on raids - he thought he was leading them, but maybe they were just enjoying themselves? Anyhow, these guys were travelling huge distances by camel, unsupported. Lawrence tried hard to match them in toughness: this included matching them in drinking, but not in the sense you might expect! The problem (for Lawrence) was that the arabs would drink a huge amount of (possibly suspect) water at one well, then ride for two days in the desert heat without another drink - until they reached another well. They drank like camels, and only when their camels could also drink. That was their norm! I don't think they suffered from hyponataemia, but neither did they all die from heat stress. Many older walkers may remember being taught in the 50s and 60s to just drink at breakfast and dinner times: similar idea.
1: British Medical Journal, vol 327, 19-July-2003, p113
'Overconsumption of fluids by athletes: Advice to overdrink may cause fatal hyponatraemic encephalopathy'
Dr Timothy Noakes, Discovery Health chair of exercise and sports science, MRC/UCT Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town and the Sports Science Institute of South Africa
2. Hyponatraemia: in simple terms a reduction in the sodium concentration in the body to a potentially dangerous low level. Obviously, drinking 15 litres as one person did could cause this problem.
3. BMJ, 19-Aug-2003, Rapid Response section, from William B. Greenough III, M.D., Professor of Medicine, Johns Hopkins University School of Medicine, USA
3. 'Hyponatremia in Distance Athletes, Pulling the IV on the 'Dehydration Myth', Timothy D. Noakes, MB ChB, MD, The Physician and Sportsmedicine, vol 28/9, Sep 2000
4. '""Drink at least eight glasses of water a day."" Really? Is there scientific evidence for ""8 × 8""?', Heinz Valtin, Am J Physiol Regul Integr Comp Physiol 283(5):R993-R1004. This article contains 100 references to the popular press and scientific literature. As you might guess, he finds no supporting evidence.
The author is not a doctor, and readers are cautioned to seek proper medical advice before believing anything written here.
No responsibility can be or is taken for what the reader does.
Inexperienced walkers should always stay on the cautious side of things!