Exercise and Water: What You Need to Know

3 mins
January 6, 2017

Water and the human body in a bite

Water is an essential liquid for life; it is the most abundant component in the human body representing about 45 to 70% of the total body weight and is distributed in the tissues. In lean tissues (group of cells with very low fat such as muscle and heart) there’s a high amount of water (about 75%), whereas adipose tissues (group of cells that store fats) have just about 10%. As humans, we have 3 ways of obtaining water, liquid water from beverages, water from food and we produce water ourselves in metabolic reactions (metabolic oxidation).

Normally, intake of liquids and food provides the body with the raw materials necessary to maintain adequate volume of liquids (with proper balance of fluids in the body), concentration of various electrolytes and acid-base balance (the balance of acid and base in your body). On the other hand, we must take into account that we lose water through sweat, urine, faeces and perspiration of breathing. A very clear example of the dehydration is water lost through sweat when performing an exercise routine or a specific sport. This causes a great change in bodily fluids and the extents of loss during exercise varies from one person to the other. The negative effect of dehydration on sports performance and health that can be avoided by the consumption of fluids to compensate for sweating losses.

Best practices for replenishing water during exercise

The determination of fluid losses in the exercise is particularly important when the exercise is prolonged, for example, more than 3 hours, since the longer the exercise, the greater the risk of dehydration or hyponatremia (low concentration of sodium in the body which could be as deadly as high concentrations of sodium the body requires). In order to help check the amount of water you lose during a workout or a sporting activity, the recommendation is that you check your weight before and after exercise, to have a better estimation of the amount of fluid to be consumed to replenish the lost water. According to Robert A. Ronzio, for every half kilogram lost you should drink 500ml water. Another suggestion would be to take the amount of liquid in this order of intake: 2 hours before exercise take 2 glasses of liquid (400 to 600ml), 15 minutes before exercise 1 glass, 1 glass every 15 or 20 minutes during the exercise; that is to say at regular intervals drink liquids at a rate that allows to replace the water and the electrolytes lost by the perspiration and to maintain the levels of glucose in blood to maintain the energetic efficiency, and at the end of the exercise 2 or 3 minimum glasses in order to replace any deficits of liquids and electrolytes as much as possible.

Rehydration options

On the market there are different types of drinks, but not all are suitable to hydrate during exercise:

• Energy drinks provide energy, but they have a high amount of carbohydrates that can cause stomach pain and slow the absorption of fluids in the body when you are exercising.

• Smart drinks include vitamins, but they contain stimulants such as caffeine, taurine, or guarana that cause dehydration and by stimulating, they only deplete the body's energy reserves.

• Water is the universal moisturizer and can be used to rehydrate during exercise. However, it eliminates the feeling of thirst before it is fully hydrated and does not replace the lost minerals, as well as it stimulates more quickly the elimination of liquids through the urine.

• Sports drinks have been created to rehydrate quickly during exercise. However, not all sports drinks are the same; You should look for 5 characteristics that are key: they must have:

1. At most 14g of carbohydrates per 240 ml (or 5.83g of carbohydrates per 100ml),

2. Suitable mixture of carbohydrates (i.e. sucrose, glucose and fructose because these are easily absorbed),

3. No gas,

4. Adequate level of electrolytes (sodium and potassium) and

5. A good taste (you may not be able to detect this from the label on the drink).

Coconut water has proven to be a suitable rehydration beverage as it contains 95% water, has a low carbohydrate content, rich in minerals, vitamins and even proteins to help revitalize your body after a workout or sporting activity.

Remember that water is very essential in your overall well-being and that you need to replace the water you lose through exercise or sporting activity by drinking a lot of fluids (eg. pure water and coconut water).

How do you revitalize yourself after a workout or a sporting activity? Share your thoughts below.

Edú is a Mexican Full-time Research Professor at Universidad del Istmo. He holds a Bachelors degree in Nutrition (Univsersidad Veracruzana, Mexico) and Masters degree in Food and Nutrition Security from Universidad Veracruzana (Mexico) and McGill University (Canada).