Isotonics are sports drinks that are an aqueous solution of body electrolytes: calcium, magnesium, sodium and potassium chlorides), often with the addition of carbohydrates. In addition to compensating for the loss of fluid lost by the body during physical activity (which regular water also copes with), isotonic drinks help compensate for the loss of minerals in the body that are lost during sweating. And glucose provides the body with fast fuel for work.

Drinking People

Isotonics are sports drinks that are an aqueous solution of body electrolytes: calcium, magnesium, sodium and potassium chlorides), often with the addition of carbohydrates.

If the fluid is lost, the athlete exhibits certain symptoms:

  • losing 1% of the total weight will make you thirsty
  • 2% – reduced endurance
    loss of 3% – reduced strength
  • 5% – reduced salivation, urination, increased heart rate, apathy, muscle weakness, nausea and sometimes dizziness.

Dehydration causes significant mineral loss and electrolyte imbalance. Such loss primarily affects the conduction of nerve impulses into the cell and its response, and aerobic power decreases. For this reason, glucose polymers and multivitamin complexes are used for isotonic drinks.

Components of isotonic


These are minerals dissolved in water, which form salty gel shells around and inside cells.

Such cells exchange electrical charges, react with other minerals and – most importantly – transmit nerve impulses, signaling muscle contraction and relaxation. In addition, the electrolytes regulate the fluid balance inside and outside the cells.

It is especially important to restore the electrolyte balance at workouts associated with increased endurance and those that last longer than 45 minutes. The density of the isotonic solution is approximately equal to the density of the blood plasma, so the necessary substances are quickly absorbed and effectively help maintain the water-salt balance.

drinking man


Most of the isotonic contains between 4 and 10% sugar. This concentration of glucose promotes increased absorption into the blood, which is very close to the absorption rate of water. The 8-10% solution is almost instantly absorbed, which significantly increases the body’s functional capabilities.

Sweet tonics used during training or competitions improve athletes’ performance, increase their endurance during long periods of exercise by supplying muscles with fast carbohydrates that come to help depleted glycogen reserves.

Minerals, salts, and antioxidants

The main task of antioxidants is to maintain oxygen balance in the blood. Antioxidants (most commonly carotenoids, flavonoids, and herbal extracts) reduce the effects of free radicals. These oxygen-containing molecular fragments actively grow under intense physical activity and initiate cell destruction and death.

Vitamins and minerals in isotonic perform hematopoietic (iron) and regulatory functions – synthesis of protein and connective tissue (zinc), stimulate the immune and nervous systems (magnesium, selenium), nourish muscle tissue, including heart muscle (potassium, magnesium).

When to drink

Isotonics take 1-1.5 hours before training. If no hard workout is expected, you can also drink degassed mineral water or freshly squeezed juices instead of tonics.

Drink also during a workout to compensate for the loss of macro and micronutrients, and/or immediately after a workout – to restore the acidic basic state and within 1-2 hours after completion of workout to fully restore the water balance and compensate for the loss of vitamins and salts.

Everything You Need To Know About Isotonics