The Importance of Hydration in Sport

31 August 2018

The Importance of Hydration in Sport

The Importance of Hydration in Sport

Much care is given to food care in sport but, almost always, hydration is neglected. Then, let us give hydration the attention it deserves!

In the human body, water constitutes about 50% to 70% of the body composition, and in the muscular tissue this value corresponds to 75% of the weight. Intervenes in all chemical reactions of the body, in the transport of oxygen and nutrients and regulates body temperature. Its importance is even more evident when we practice physical activity, since the state of hydration profoundly affects physical and mental performance. More specifically, hypohydration can reduce exercise performance, especially aerobic exercise, and increase physiological effort and perception of exercise in hot environments.

Fluid and sodium intake recommendations are based on the athlete's individual characteristics, training intensity and duration, atmospheric conditions - such as temperature, humidity, and wind speed - and other factors that condition the availability of fluid intake.

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The American College of Sports Medicine recommends ingestion of ≈5-7 mL / kg at least 4 hours prior to exercise. If the individual does not produce urine or it is dark or heavily concentrated, an additional 3 - 5 mL / kg should be ingested approximately 2 hours before the event.

A good way to assess the state of dehydration is through the color of your urine and how often you urinate. If you pee every 2-4 hours and the color is pale it means you are well hydrated. The darker the color of urine, the more likely it is to be dehydrated. The following figure shows the urine staining scale:

In addition to fluids, 20-50 mEQ / L of sodium should be consumed. The concentration of electrolytes in sweat can also vary widely among individuals, and those who have higher rates of sweating and higher concentration of sweat in sodium may lose substantial amounts of salt (sodium chloride) in the workout. This is easily detectable by the appearance of whitish spots on the athletes' equipment or by the athlete himself - burning eyes caused by sweat and salty taste on the lips.

During workout, the goal will be to prevent excessive dehydration (<2% of body weight), and the hydration regimen will depend on the rate of sweating, exercise duration and hydration opportunities. The consumption of sodium along with water has been particularly recommended when the duration of the exercise is superior to 2h or when there are significant losses of this mineral (3-4g).

After workout, the goal is to balance the water balance again (difference between lost water and ingested water). Water losses due to sweat, exhaled air and urine remaining after training should be considered.

Weighing before and after exercise is a technique that can be used to monitor dehydration. The weight after exercise should be corrected with the volume of fluid that has been ingested, with the losses through the urine and its measurement must be done with the least possible clothing. It is recommended to drink a volume of fluids 1.5 times higher than the weight lost during training. For example, an athlete who has lost 1kg will have to ingest 1.5L immediately after training.

Sports drinks

Soon after exercise the athlete can also drink isotonic drinks with glucose and / or fructose and the main minerals lost by sweating (sodium, chlorine, potassium, calcium and magnesium).

A sports drink is basically a mixture of water, carbohydrates and electrolytes (mostly sodium). In high intensity events lasting 1 hour or more, or less intense but lasting more than 1h30m, the ingestion of a sports drink has very significant benefits. If you have not had enough carbohydrate before exercise, drinking these drinks can be very helpful. They can also be very useful in recovery after exercise and in the replenishment of energy stocks, in addition to the state of hydration.

The criterion that follows when choosing a sports drink is the carbohydrate content. The optimal content ranges from 6 to 8% (ie 6 to 8g of carbohydrates per 100ml).

By Joana Correia, Nutricionist