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Respect your fluid and mineral balance during sport

- getting too little fluids may be fatal

Respect your fluid and mineral balance during sportFluid depletion (or volume depletion) lowers your performance and may be life-threatening in worst case. However, it can be every bit as dangerous to drink too much water. In fact, there have been several deaths as a result of this among athletes. Another thing is that one should not just focus on water. When engaging in strenuous sport, there is a very delicate balance between fluids and minerals. Many sports beverages contain too much sugar and caffeine that often do more harm than good, so the question is how much liquid you need when engaging in the different types of sport. Read more about the subject in the following.

When you exercise, train, or compete it is essential to look after your fluid balance. How much you sweat is determined by factors such as body weight, the duration and intensity of your activity, your condition, the climate, and what type of clothes you wear. Your lungs also give off more fluid because of increased respiration. With sports disciplines like trekking, mountain climbing, and skiing, it is also essential to look at how much fluid you lose, even though you don’t perspire as much. When engaging in physical activities of longer duration, make sure to drink once in a while. Also, make sure to compensate for your loss of carbohydrate and minerals. Be sure not to drink too much, on the other hand.

Water accounts for 70 percent of the human body and its functions include:

  • transporting nutrients to the cells
  • getting rid (by way of the kidneys) of salts and waste products from the metabolism
  • contributing to the regulation of body temperature via perspiration
  • helping to maintain firm skin

Fluid requirement and fluid intake during sport

It is particularly important to maintain your fluid balance when you exercise, regardless if it is training or competition. The balance between sodium and potassium is very important for the electrolyte balance of your cells, which controls your cells and their ability to receive nerve impulses, absorb nutrients, get rid of waste products, and maintain the fluid balance. Here are some facts and some advice:

  • The body’s fluid requirement equals its fluid loss through urine, sweat, feces, and expiration
  • Under normal conditions, your daily need for fluid amounts to approximately 30 ml for each kilo of body weight. A person who weighs 70 kilos needs about 2.1 liters of fluid.
  • The need for liquid increases the more you lose
  • In a tempered climate, the fluid loss amounts to about 1-1.5 liters per hour if you engage in intensive physical activities. You lose more fluid in very hot weather
  • Activities that last for less than 30 minutes normally don’t require a greater intake of fluid
  • If an activity lasts over 60 minutes, you must drink fluids at regular intervals
  • In the case of prolonged activities, excessive sweating, or conditions where your sodium levels are too low, it is a good idea to consume salt-containing fluids or proper sports beverages that are designed to adjust the body’s salt and electrolyte balance
  • Prolonged physical activities may also cause calorie depletion
  • It is a good idea to consume carbohydrate together with your liquids
  • The optimal sports beverages contain 4-6 percent carbohydrate
  • Carefully read the label on your sports beverage or make your own mixture
  • Always drink liquids after you have finished your training session
  • As a rule of the thumb, do not drink more liquid than you lose by sweating

At the end of this article, you can find advice on proper fluid intake in connection with marathon runs

Did you know that your brain is particularly sensitive to disturbances of your fluid and electrolyte balance

Fluid depletion and imbalances in the electrolyte balance

If you have fluid depletion, your blood becomes thicker, which impairs the transportation of oxygen and nutrients to the cells and the removal of waste products – including lactic acid.
If the fluid depletion represents two percent of your body weight (approximately 1.4 liters of fluid for a person who weighs 70 kilos), your muscles will not function optimally. If your fluid depletion reaches four percent, it can reduce your performance by 50 percent.
Fluid loss can also result in poor concentration, fatigue, headache, nausea, and overheating. If your fluid loss amounts to 10-15 percent of your body weight, the condition may become life-threatening.
If endurance athletes (marathoners, triathletes, and long-distance bicyclists) only drink water and continue to sweat for several hours, it will upset their electrolyte balance, and the sodium concentration in their blood may decrease to the point where they develop hyponatremia. This may lead to headaches, nausea, cramps and, in worst case, blood clots, and pulmonary edema.

Look at the color of your urine

  • if your urine is very dark and yellow, you may be lacking fluid
  • if your urine is light and slightly yellow, you have a good fluid balance
  • if your urine is transparent, you may have fluid retention

Mortality and malpractice in cases with excessive fluid intake

Most athletes know that it is important to drink liquids. However, all things can be toxic if you ingest them in sufficiently large quantities, even water. Overconsumption of water may result in a fatal disruption of the body’s electrolyte balance because it dilutes the blood’s normal concentration of sodium.
There have been several deaths as a result of excessive water consumption in connection with different sports disciplines. One example is a 47 year-old woman who trekked 10 kilometers in the Grand Canyon National Park of the United States. Before she embarked on her journey, she managed to drink four liters of water, and she only ate very little. The woman collapsed just one hour after taking her first steps. In spite of doctors trying to save her life, she died of cerebral edema caused by overhydration (water intoxication).
In cases like this, it is extremely essential not to drink more water because the problem is overhydration, not dehydration. Unfortunately, many doctors have difficulty with identifying overhydration and giving the correct treatment.
The risk of overhydration is not made any less by the fact that water bottles have gained such popularity in every imaginable way. In any case, it is useful to know how to identify the early symptoms of overhydration, which include feeling unwell, nausea, vomiting, and headache. Because the symptoms of overhydration are similar to those of dehydration, it is important to look at your fluid intake.

Your weight may reveal both fluid loss and fluid retention

It is commonly known that fluid loss is detectable by weighing yourself before and after any sports activity. Weight loss, which is mainly caused by loss of water, indicates how much you need to drink. If, on the other hand, you have gained weight, it may be a sign of fluid retention and overhydration, especially if your urine is colorless and transparent.

Good sports beverages

Sports beverages should compensate for the actual loss of fluid and nutrients. With normal exercise, drinking plain water is fine, and a normal diet (possibly helped by supplements) can provide the necessary vitamins and minerals. If you engage in prolonged, intense activities, your beverages should ideally contain carbohydrate, as well. Aim for a four to six percent concentration (40 to 60 grams of carbohydrate for every liter).
You may also want to include sodium and perhaps potassium plus other minerals. Sodium, because it retains water, may help prevent unnecessary urination that is inconvenient and may hobble your athletic performance.
Try this: Add a teaspoon of sea salt and 1-2 tablespoons of cane sugar to a liter of boiled water. Sea salt and cane sugar contain more minerals than refined salt and white sugar.
Another idea is to mix mineral water with some tasty fruit juice in a 1:1 ratio.
Mineral water with fruit provides vitamins and minerals, and the carbohydrate concentration is just about 4-6 percent (as recommended).
There are also commercially available isotonic sports beverages with a concentration of water, carbohydrate, salts, and minerals that is very similar to the body’s own fluid.

Avoid the bad sports and energy beverages

Studies have shown that the majority of sports and energy beverages do more harm than good because they contain far too much sugar. Their impact on the body’s blood sugar levels is much greater if they also contain caffeine.
Soft drinks, coca cola, fruit juice, and juice contain that much carbohydrate (10-12 percent) that gastric emptying and intestinal absorption are reduced. Instead of supplying the body with fluid and minerals, the sweet beverage just lies in the stomach and may cause indisposition and dehydration.
Many athletes tend to consume too much sugar from various beverages like soft drinks, energy drinks, energy bars, and candy. Sugar drains the body’s stores of B-vitamins and vitamin C plus calcium, magnesium, potassium, chromium, and zinc, nutrients, which athletes need, in the first place. The sugar-rich beverages should therefore be limited and replaced with useful sports beverages, so make sure to study the labels carefully.


Too much sugar from soft beverages, sports beverages, and other sources increases your risk of weight gain. In addition, it lowers the content of minerals in the bones, increasing the risk of osteoporosis later in life.

Avoid too much caffeine

Caffeine is found in coffee, black and green tea, Coca Cola, cocoa, guarana, and mate. Many sports and energy beverages such as Red Bull also contain caffeine. It turns out that caffeine not only increases your sedentary fat burning but even steps up the burning of fat during muscle work. Caffeine also influences your brain impulses and stimulates the release of dopamine, so that you become more enduring.
Although caffeine is no longer on the doping list, consuming larger quantities of the substance is bad for your digestion and nervous system. Caffeine even increases urination, which is rather inconvenient when exercising. Moreover, caffeine may cause heart palpitations, insomnia, and addiction.
Most people from the age of 18 years of age are bound to feel side effects of ingesting more than 400 mg of caffeine daily. This is the same as 3-4 cups of coffee or five small (25 cl) cans of energy beverage. The daily intake of coffee should normally not exceed 2-4 cups. However, coffee also contains antioxidants, and a moderate coffee consumption actually has certain health benefits.

Suggestions for fluid intake in connection with a marathon run

  • Drink a normal amount of liquids until a few days before the run
  • Drink two extra glasses of water in the evening before the run
  • Drink around 1-1.5 liter of liquid in the morning before you run, and drink a little more if the run is in the afternoon
  • Stop drinking liquids an hour to an hour-and-a-half before you run
  • Drink 0.2 - 0.3 liters of water just before you start running
  • Drink 2-3 dl of a good energy drink for every 20-30 minutes of running (typically at every pit stop)
  • Always drink tempered liquid


Elsevier. Doctors warn hikers, other endurance athletes, and medical personnel about the risk of water intoxication. ScienceDaily 2015

Pernille Lund: Rigtig kost til motionister og elitesportsfolk.


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