It’s always good to remember that drinking water during physical activity (and also at other times of the day, of course) is essential. During exercise, excessive sweating leads to dehydration, with loss of body fluid and reduced blood volume. In addition to thirst and a drop in performance during exercise, the condition can have much more serious consequences, ranging from dizziness and headache to loss of consciousness. That’s why it’s so important to pay attention to correct hydration. After all, water is also considered a nutrient for our body. But did you know that just as too little water is bad, too much water is bad too?
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Hydration is key, but too much can also cause problems — Photo: iStock Getty Images
Let’s first understand what are some of the fundamental functions of water:
- Humidify the mucous membranes (mouth, eyes and nose), being the body’s first protective barrier against microorganisms;
- Compose the blood and act in the transport of oxygen and nutrients into the cells;
- Prevent constipation;
- Acting in the production of sweat, which regulates body temperature;
- Lubricate the joints;
- Serve as a solvent for other nutrients;
- Participate in the formation of urine, responsible for the excretion of metabolites.
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A study carried out at UFMG indicates that water is so important that it makes up about 50% to 60% of body weight, in addition to 75% of the brain, 86% of the lungs, 86% of the liver, 81% of the blood, 75% of the from the heart, 83% from the kidneys and 75% from the muscles – these percentages change slightly depending on gender. However, humans are not able to store water completely, so we always have to balance the loss with water intake. The recommendation is to drink at least two liters of water a day, however, this amount varies according to physical activity and body temperature. Drinking too little water causes dehydration. But what happens when we drink too much water?
So-called hyponatremia occurs when the level of sodium in the blood is too low, causing the body to retain water and further dilute the amount of sodium that is left. This imbalance in the body’s electrolytes, particularly sodium, can have several causes. Drinking lots of water can be one of them. Among its symptoms are:
- Mental confusion
In addition, we also eliminate mineral salts by perspiring, which can worsen the case if the water intake is not well calculated. In physical activity, we perspire more, we sweat. Water intake is essential, but if it is excessive, it can exacerbate this electrolyte imbalance.
– When replacing water excessively, the concentration of sodium in the body drops even more – explains Luanna Caramalac, nutritionist with a postgraduate degree in integrative functional clinical nutrition.
It is worth remembering that hyponatremia, which may even require the patient to be hospitalized, is an uncommon condition in people who exercise regularly and moderately. But the situation can occur in long-term, endurance sports such as marathons, triathlons and ultra-distance races or in places with high temperatures.
When you consume more than three and a half liters of water during exercise, you lose a lot of water and sodium in sweat. If the athlete replaces only water in large amounts, the sodium will dissolve and can compromise the body at the level of brain problems, impairing performance in the modality that he practices and other activities of daily life. Therefore, it is important to consult a nutritionist, who can advise on the consumption of isotonic drinks, which replace mineral salts, during long-term exercises.
– Hyponatremia became a bigger problem even than dehydration, due to the increased incidence in amateur and unguided athletes who practice long-term sports. The ideal is that the water intake is 1ml for each calorie lost, and the nutritionist will analyze each case individually – indicates Luanna.
How do I know how much water I should drink a day?
To dose the amount of water that should be ingested during exercise according to your weight, a calculation must be made:
Your current weight X 35 ml (which converted to liters is 0.035)
Suppose a person who weighs 60 kg:
This person should drink 2 liters and 100 ml of water a day, alternating between four bottles of 500 ml each or even seven glasses of 300 ml each. This recommendation is for days with and without training. Some studies speak of 40 ml per kilo of weight. In this case, a 60 kg person should drink 2.4 liters of water per day (60 x 0.04). That is, you will be fine if you drink between 2 and 2.5 liters of water daily.
Hydration before, during and after training
- THEbefore starting trainingit is interesting that this person already keeps the body hydrated, thus improving oxygenation, energy, disposition and performance: the ideal amount is 500ml of water two hours before training and 200ml when there are 30 minutes left to start.
- during exercises, water intake is also worth it, as it keeps electrolytes replenished; after all, they are fundamental for the functioning of the muscles, the nervous system and the internal balance of the body. The ideal amount is around 150 to 300 ml of water over every hour of activity..
- At the end of training, replenishing fluids is also necessary. The amount varies according to body weight, as we saw in the previous topic. But mineral salt replacement may be necessary, so water can be replaced by sports drinks during and after physical activity, according to individualized nutritional guidance.
For sedentary people who are starting to train, these guidelines are also valid. Even if the training intensity is not very high.
That’s because during the practice of physical activities, blood flow is concentrated in the active muscles and what we call vasodilation occurs, when blood vessels dilate to increase the transport of nutrients and oxygen to the muscles. Therefore, sedentary people should also be careful with excess water intake.
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Luanna Caramalac Munaro is a nutritionist from Uniderp (MS) with a postgraduate degree in integrative functional clinical nutrition from the VP (Functional Nutrition Center).