The isotonic beverage, as its name indicates, is designed to help rehydrate and replenish the body’s electrolytes during or after physical activity. During sports practice, we lose water and minerals through sweat, which must be replenished in order to maintain performance and hydration and prevent, for example, muscle cramps, among other issues.
Isotonic beverages are formulated using a combination of:
- water
- carbohydrates
- mineral salts (such as sodium, potassium and magnesium)
The main characteristic of isotonic beverages is that they have a solute concentration similar to that of bodily fluids. As a result of this quality, isotonic beverages are absorbed very quickly by the body, promoting the replenishment of lost fluids and electrolytes.
The differences between isotonic, hypotonic and hypertonic beverages:
Isotonic, hypotonic and hypertonic beverages are mainly distinguished by their solute concentration in relation to blood plasma and their impact on hydration.
Isotonic Beverages:
- They have a solute concentration similar to that of blood plasma. They contain a balanced amount of sugars and mineral salts that facilitate rapid absorption and rehydration.
- They are the most consumed type of beverage within this classification.
Hypotonic Beverages:
- Their main characteristic is that they have a lower solute concentration than blood plasma.
- They contain fewer sugars and mineral salts than isotonic beverages. They are absorbed very quickly by the body.
- They are consumed less frequently than isotonic beverages.
Hypertonic Beverages:
- They have a higher solute concentration than blood plasma.
- Their main characteristic is that they include a higher amount of sugars and mineral salts than isotonic beverages.
- They are absorbed more slowly by the body and may cause a feeling of fullness or stomach discomfort if consumed during exercise.
How is an isotonic beverage absorbed by the body?
After drinking an isotonic beverage, it is broken down in the digestive tract into water, carbohydrates and electrolytes. In the small intestine, the isotonic composition facilitates rapid absorption into the bloodstream. The nutrients are transported through the blood to the cells to provide energy and replenish fluids and electrolytes.
What are the benefits of rapidly replenishing fluids and electrolytes?
- It may improve performance in endurance training and competitions, especially when the duration is >90 minutes, and during intermittent efforts.
- It helps maintain and promote hydration and also replenish electrolytes during exercise.
- It may increase the carbohydrate oxidation rate during exertion.
- It may delay the onset of fatigue during exercise.
- It may promote recovery after a training session.