Hydrating: Should You Do It Before, During, or After Physical Activity?

Proper hydration is essential for good sports performance and so you don’t feel discomfort while performing physical activity. However, some people do not know how much water to drink or when to drink it.

hydrating sports

Water and Physical Activity

Water is important for optimum physical performance for several reasons:

  • Water makes up a large portion of your blood, which carries nutrients and oxygen to all muscles involved in physical activity, including the heart muscle.
  • The electrolyte balance regulates nerve impulse transmission and muscle contraction; therefore, if there is dehydration or over hydration, this balance is altered and compromises performance.
  • Water is a component of synovial fluid, which is the fluid in the joints that serves to lubricate them. Water is essential for nourishing cartilage and reducing friction during movement.
  • Metabolic waste is produced during physical exercise and water can help disposed of it.
  • Water is responsible for thermoregulation, which is important because when physical activity is carried out, nutrients are burned for energy, producing a lot of heat. In order to regulate this heat, your body sweats as a means of removing the heat through perspiration in order to not increase your body temperature.
  • Dehydration is associated with decreased sports performance and increased risk of injury. During physical activity it can manifest itself with weakness, cramps, headaches, nausea, exhaustion, etc.

When Should You Drink Water?

Thirst is a sign of early dehydration, which is why it’s ideal to drink a moderate amount of water before you become thirsty.


During the 4 hours prior to the practice of sports, even more so for long-term and endurance activities, you should drink approximately 7 ml (.2 ounces) of water per kilogram (or per 2 lbs.) of body weight, which is equivalent to half a liter of water in an adult who weighs 70 kilograms (roughly 150 lbs.).

Just before training or competition, you should drink one or two glasses of water to start with an optimum level of hydration.


Some athletes may get an upset stomach if they drink too much water during exercise. They may even avoid consuming water while they engage in physical activity for this reason. However, it’s important to drink small amounts of water while training in order to adjust your body to hydrating during physical activity.

It’s recommended you drink between 100-200 milliliters (3 to 6 ounces) of water every 20-30 minutes, so that you recover the water that is lost and avoid heatstroke without suffering discomfort. However, even if you hydrate during physical exercise, it doesn’t compensate for the loss of fluid through sweat, which can be up to 3 liters (101 ounces) in a high performance athlete.


In order to know how much fluid you lost during exercise, you should weigh before training (or competition) and after finishing it. The difference in your body weight will reflect the water lost and will be your guide to knowing how much fluid you need to replace.

Even if you don’t feel very thirsty, you should replace all of the water you lost. The metabolic window should be used, which corresponds to 45-60 minutes after physical exercise, as the body more easily assimilates water and nutrients. You can even have a lemonade.

What About Isotonic Sports Drinks?

For a person who performs physical activity to take care of their health and well-being, but is not a professional athlete, water is sufficient for hydration. However, for those who perform strenuous exercise or are engaged in physical activity that is over 2 hours long, isotonic sports drinks can be excellent for recovery.

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