– Because three liters of drinking water in the hospital
In rare cases, excessive drinking can lead to dangerous overhydration. What is it and how to determine the correct fluid level.
Drink, drink, drink! Read and listen to this advice (not only) for heat sufferers around the world. Especially ambitious athletes sometimes take it to heart.
How Much Drinking Is Too Much?
A healthy adult would need to drink about ten to fifteen liters of water a day for water poisoning to occur. For seniors, less may be enough, as the example of an 85-year-old with treated high blood pressure and mild kidney and heart weakness showed: he drank a total of three liters of water during an easy one-day hike. In the evening he first got tired, and then within five minutes he was so mentally confused that he had to be taken to the hospital by air ambulance. Usually the kidneys prevent water poisoning by producing more urine. When there is water shortage and thirst, they reduce urine output, and when there is excess water (healthy) the kidneys increase it to a maximum of about 800 to 1000 milliliters of urine per hour.
How much water does a person need per day?
“It varies a lot from person to person. Physical activity plays a role here, as do age, weight, outdoor temperature and humidity, ”says Anna Erat, chief physician at the Hirslanden research center in Zurich. “The rule of thumb is a minimum requirement of 0.03 liters – or 30 milliliters – of water per kilogram of body weight per day.” A small part of it is consumed with food. “When we feel thirsty, we already have a deficit,” says Erat. However, not only water is needed, but salts and minerals as well, especially if you lose a lot of sweat in the heat or during hard workouts.
What happens to the body when you drink too much water?
Water poisoning leads to life-threatening brain edema, pulmonary edema with respiratory problems is also possible. In brain swelling, brain cells swell because they absorb more water from the tissue than is beneficial to them. This leads initially to discomfort and headaches, later to disorientation and, at worst, death.
The reason for this is that the sodium level in the blood is too low, known in technical parlance as “hyponatremia.” The sodium “binds” the water. However, it is diluted in the blood by excessive fluid intake. Result: blood binds less water and water migrates to tissues and cells.
What promotes water poisoning?
infections are one of the factors as they can affect kidney function. “Even taking diuretics and drinking more water at the same time can lead to water poisoning,” says Christian Aebersold, specialist in internal medicine and sports medicine for Bieler Seeland. Such drugs are often used to treat high blood pressure. The above-mentioned senior woman took such a drug.
Mental illness related to excessive drinking of water is another cause of water poisoning. Improperly performed medical advice, as shown by a 59-year-old woman, can also lead to this catastrophe. She had suffered from bladder infections for decades and was usually able to prevent the pain by following doctors’ advice to “drink a lot.” But one day she went overboard with “drinking a lot”. Result: She could no longer speak properly, staggered into the toilet and had to vomit several times. “I didn’t understand what happened,” she described her … state of danger later. “I saw my hand shake violently and wondered why I couldn’t help it. It was then that I realized my whole body was shaking. At that moment, I got scared. She could only dimly remember what had happened to her. She survived through prompt treatment, but it took her two weeks to fully recover.
Why is water poisoning a common occurrence in marathons?
Runners overestimate their need for water. Since losing around 2% during a race or training, there can be a decline in performance, since losing 4% is almost certain. Athletes want to avoid this by drinking a lot – but sometimes they achieve the opposite. Because some people lower their performance due to huge amounts of fluid and weigh more at the finish than at the start. At the Ironman race in New Zealand, the number of runners treated for hyponatremia fell from 3.8 percent to 0.6 percent after runners received more “conservative” drinking recommendations.
Which athletes are most affected?
Typical people who suffer from water poisoning are athletes who have been taking NSAID-type painkillers like ibuprofen, says one technical article. These drugs can affect kidney function. Heat and prolonged exertion also contribute to water poisoning.
What should athletes pay attention to?
“As a rule of thumb, you need 500 to 600 milliliters of extra fluid per hour of exercise,” says Christian Aebersold, whose practice also serves as a “Sports Medical Base” for Swiss Olympic. There, the doctor looks after and trains amateurs and elite athletes. “Performance-oriented athletes are capable of anything,” says Aebersold. From “completely dehydrated” to “drinking to the point where it is impossible”, he has been through a lot. He remembers a former Swiss athlete who, on the advice of an Olympic doctor, drank up to eight liters of liquid to drink enough.
What do rescuers need to know?
Overhydration can cause symptoms very similar to heatstroke, altitude sickness in the mountains, or lack of water (dehydration). South African sports doctors reported that an experienced ultramarathon runner was fatally misled by such a mistake. The 34-year-old felt nauseous during Ironman, but blamed him for dehydration and began to drink as much as possible. After the race, he weighed 5.5 kg more than usual and had to be hospitalized for hyponatremia.
What is the right amount to drink in the heat?
Christian Aebersold advises athletes to establish their fluid requirements before and immediately after training. As it varies from person to person, it also depends on environmental conditions such as heat, cold or altitude. Well-trained people tend to sweat faster and more than the potatoes on the couch, who rarely exercise.
“If you are half a pound lighter after training, this is roughly the maximum amount of water you should replace. If you are not thirsty, you can drink less, ”says Aebersold. In his experience, good sports watches also determine fluid requirements quite accurately. It is a very good help in calculating the requirements Drinking amount calculator by Swiss Sports Nutrition.
What else should athletes pay attention to?
Mere fluid replacement is not enough after intense exercise. Sweaty salt – easily recognizable along the brim of the salt on dark T-shirts – should also be replaced, whether with food, electrolyte solutions, or diluted fruit juice to which a pinch of table salt is added. “We used to add half a teaspoon of salt per liter to our drink,” recalls Aebersold.
What is salt for?
“So-called electrolytes such as sodium, calcium, potassium, chloride, phosphate and magnesium regulate nerve and muscle function and control the water-base balance,” explains Anna Erat, specialist in internal medicine and sports medicine. Electrolytes are excreted through the kidneys, our digestive system, or through the skin through sweating. “If you don’t have enough electrolytes during exercise – especially in the heat – this can lead to muscle cramps, weakness, confusion and even heart rhythm disturbances, as well as headaches and nausea.”
Older people often experience little thirst because of their age. How do you know if you’ve had enough?
“When you are dehydrated, your urine becomes more concentrated and dark yellow, your eyes droop, your skin and tongue become dry, and if you pinch the skin on the back of your hand into folds, they” stand “longer and don’t straighten out right away, says Erat. A pot of tea that is infused in the morning and that should be drunk empty throughout the day will often help reduce age-related thirst.
Are there any medications that (old) people should stop or take when the weather is very hot?
“Certain antihypertensive drugs with the active ingredient hydrochlorothiazide or taking psychotropic drugs result in increased salt loss. Then the proper supply of salt and minerals is particularly important – advises the head doctor. It is also useful to check your blood pressure. In the case of strong, prolonged heat, it may make sense to reduce the dose of the antihypertensive drug. Her advice: “If your upper systolic value falls repeatedly or consistently below 110 mmHg, see your doctor.”
Martin Frei is a science editor, family doctor and educated in public health. It mainly reports on medical and health topics and animals. In his column and in two books, he describes some very remarkable medical stories since 2009. More information
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