Sports drinks are usually categorised according to their osmolarity, i.e. the speed at which they are absorbed by the body.

Osmolarity is the concentration of particles in a litre of liquid. The absorption of liquids in the human body is related to the osmotic pressure of blood plasma: when the osmolar pressure of the consumed liquid equals the relevant indicator of blood plasma, the body doesn’t have to do extra work to transport electrolytes and sugars through the cell membrane (which is why absorption is faster).

Based on this, sports drinks are divided into three types:

• Isotonic – most sports drinks are isotonic. Their osmolarity is ca 300 mosm/l (like blood’s), which is why they are quickly absorbed into the blood. People who do recreational sports can drink both isotonic and hypotonic sports drinks during and after a workout.

• Hypotonic – sports drinks whose osmolarity is below 300 mosm/l are called hypotonic. Drinks of this type are suitable for recovering the liquid reserves lost due to sweating without gaining any extra energy. Hypotonic drinks should be consumed fifteen minutes before and during a workout to allow them to start working properly.

• Hypertonic – the absorption of hypertonic drinks into the blood is the slowest. Arctic Sport Grapefruit is a good example of a hypertonic drink, as its osmolarity is ~500 mosm/l. This means that it’s not quickly absorbed by the human body, which makes it suitable for recovering the glycogen reserves of the muscles after a long workout.

When should sports drinks be used?

The rule of thumb in sports is: the higher the intensity, the bigger the loss of energy and carbohydrates. The quantity and concentration of the sports drink should therefore be selected according to the intensity of the workout. Having a sports drink is a must during and after a workout if it lasts longer than 45 minutes. Having a sports drink before a workout is enough in the case of a shorter session.

Moderate aerobic exercise

Moderate exercise makes the body lose liquid but consumption of more carbohydrates for physical recovery is not necessary. An ordinary isotonic sports drink, where the level of carbohydrates is 5-8%, is enough for recovery after such a workout.

High-intensity training

A high-intensity workout makes the body lose carbohydrates and energy. In these situations, energy capsules or gels should also be consumed in addition to sports drinks. The protein level of the body must also be restored, which can be done with a protein drink.

Sources: Tallinn University, Fundamentals of Recreational Sports; Salutaris Health Store; Fitness.ee.