Many of us take supplements to enhance our performance, but something as simple as a glass of water could be just the boost we need.

When you train or compete, you increase your fluid loss mainly through perspiration. Some people can tolerate body water losses amounting to up to two percent of body mass without significant risk to physical wellbeing or endurance exercise performance when the environment is cold (5°C-10°C) or temperate (20°C-22°C); but when exercising in a hot environment (30°C or more), dehydration at even two percent of body mass impairs exercise performance and increases the possibility of suffering a heat injury.


Dehydration occurs when a person loses two percent of their bodyweight through water; at four percent, it is considered severe dehydration, and can cause big performance limitations. When you reach 10 percent, the situation is critical and can be fatal.

Daily Hydration

We don’t need to do physical activity to start losing water. In fact, we use and lose around 2.5l of water per day just living and breathing. Drink before you feel thirsty, because thirst is the first sign of dehydration.


Drinking excessive amounts of fluid is not helpful, and in rare cases can be dangerous. Hyperhydration can be as dangerous as dehydration and can cause a lot of damage, including brain seizures and even death. Hyperhydration provides no advantages over normal hydration regarding thermoregulation and exercise performance in the heat.

American College of Sports Medicine’s Stand On Hydration

  1. During competition prep, athletes should aim for a balanced diet including appropriate fluids in the 24-hour period prior to an event, particularly for meals directly before training or exercise.
  2. To allow for proper hydration and excretion of excess water, athletes should drink about 500ml of water two hours
    before training.
  3. Athletes should drink water at regular intervals throughout training in order to replace fluid
    at the same rate that it is being lost from the body through sweat.
  4. To promote its appeal, water should be served cooler than the ambient temperature and can be flavoured. Attention should be paid to the drinking container so that it is easy to drink from without disrupting the training drill.
  5. For exercise events that are longer than one hour, carbohydrates and/or electrolytes can be added.
  6. For intense exercise lasting longer than one hour, additional carbohydrates such as glucose or sucrose, or starch such as maltodextrin are also recommended at a rate of 30-60g per hour to maintain oxidation of carbohydrates
    and delay fatigue.
  7. For exercise events that are longer than one hour, sodium is also recommended to increase palatability and fluid retention. In most cases, sodium levels in athletes can be regulated during meal times, but some people suffer from a condition called hyponatraemia caused by low sodium in the body, which can lead to swelling in the body’s cells.


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