Hydration during Sports: Basics of Drinking Regimen

Body fluids are a fundamental source and transport medium of energy in the organism. Establishing a drinking regimen for sports is a more complicated matter. When choosing the right drink, consider the duration and type of exertion and the climatic conditions in which you prepare for physical activity. What is good to know about the drinking regimen?

"A person can survive without food for 3 months, but without water, they die within 3 days"

The drinking regimen is a fundamental part of nutrition in everyday life as well as during sports performance, whether at a competitive or recreational level. More or less, any living organism depends on water.

Water maintains the stability of the internal environment and ensures the transport of substances in the organism. It delivers nutrients to the cells and removes metabolic waste. It regulates body temperature and is indispensable for digestion and absorption of nutrients. A lack of water is a crisis situation for any organism.

During a regular daily regimen, drink at least 2.5 to 3 liters of fluids per day. The key is regularity. Don’t wait until you feel thirsty, and always have a bottle of water with you. Thirst signals that the organism is dehydrated and the body is calling for help. In summer and during prolonged exposure to the sun, increase fluid intake to up to 5 liters. It is essential to provide not only water but also minerals, which we lose through sweating. Therefore, part of the daily fluid intake (1–1.5 liters/day) should also consist of mineral waters rich in essential ions.

For athletes, dehydration leads to a critical state. Their organism overheats, and performance deteriorates. The body lacks the medium that would supply nutrients to the cells and remove waste products. Due to a lack of fluids, recovery cannot occur perfectly. When exercising, pay double attention to your drinking regimen!

And what about caffeine? If you need strong coffee to function, increase your daily fluid intake. Caffeine dehydrates the body, so it is necessary to drink at least 3 times more water with coffee.

Drinking Regimen during Sports

Establishing a drinking regimen for sports is a more complicated matter. When choosing the right drink, consider the duration and type of exertion and the climatic conditions in which you prepare for physical activity.

There is a significant difference between a spring hour-long bike ride with children and an all-day cycling tour at a brisk pace through the hills of the Austrian Alps. In the first case, where it is a low-intensity performance, plain or mineral water will suffice. We recommend shaking out the bubbles! Carbon dioxide worsens water absorption and causes unpleasant digestive problems during movement. Ion or energy drinks are not necessary here. The body can rely on its own mineral reserves.

When it comes to higher intensity exertion, as in the second case, pay more attention to sports drinks. During physical exertion, the body loses not only fluids but also essential minerals through sweating. Pure water will only dilute the minerals that remain in the body, and the resulting concentration of ions will be even lower than before drinking. This will further dehydrate the body, and your performance will drop rapidly. Prevent this situation and use special sports drinks during exercise that contain the necessary amounts of minerals.

Why are the minerals mentioned above so important? They regulate the volume and osmolality of body fluids.

Osmolality – the amount of substances dissolved in fluids

Osmolality indicates the size of the osmotic pressure of substances dissolved in 1 kg of fluid. The quantity is expressed in milliOsmomoles/kg. The amount of water and minerals supplied to the organism must be in balance, which is determined by the osmolality mentioned above. A healthy individual should consume 2–3 kg of water daily (including water contained in food) and in it, 100–200 mOsmol of sodium ions and 60–80 mOsmol of potassium ions. The normal value of blood osmolality is 285–290 ± mOsmol/kg.

According to the osmolality of body fluids, sports drinks are divided into three categories:

• Isotonic drink – osmolality equal to 290 ± 15 mOsmol/kg
• Hypotonic drink – osmolality equal to or less than 250 mOsmol/kg
• Hypertonic drink – osmolality equal to or greater than 340 mOsmol/kg

Osmolality of Sports Drinks

ISOtonic Drinks

Isotonic drinks have an osmotic pressure equal to that of body fluids. Human sweat has a lower osmolality than body fluids, and during exertion and increased consumption of isotonic drinks, it can lead to a higher intake of electrolytes than their output and thus also their need. In such cases, you unnecessarily burden the organism. Isotonic drinks can be well used during high-intensity performances and after physical activity in the recovery phase as the first supply of fluids, energy, and minerals.

HYPOtonic Drinks

Hypotonic drinks have an osmolality lower than that of body fluids. They are therefore very suitable for use during physical exertion. What resulting concentration of the drink should you choose? Consider the basic factors:

• Duration of exertion – the longer the exertion, the greater the need for energy and electrolyte intake and thus the higher the concentration
• Temperature and humidity of the environment – the higher the temperature and greater humidity of the air, the greater the water output for cooling the organism (sweating) and thus the lower the concentration.

Most manufacturers provide options for what concentrations to choose in specific situations.

HYPERtonic Drinks

Hypertonic drinks have an osmolality greater than that of body fluids. Their use during physical exertion is mostly inappropriate. Unconsidered use leads to disruption of internal balance and decreased performance. The use of these drinks is appropriate during phases of significant depletion of electrolyte reserves, but never during physical exertion. Most of these drinks can be diluted to obtain a drink with lower osmolality that can also be used during exertion.

What else to choose from?

On the market, you can also opt for drinks rich in energy. Their main purpose is to balance blood sugar levels, which are consumed during exertion, and to provide depleted energy. However, we must adhere to several principles for the drink to fulfill its purpose.

The concentration of sugars should not exceed 10%, and the hourly dose of sugars should not exceed 60–70 grams. In addition to simple sugars, energy drinks are enriched with energizing substances such as caffeine, guarana, or taurine. You can use these drinks in both everyday life and during sports. They will help you combat unpleasant fatigue while driving and give you a boost before physical exertion.

What to drink during sports activities for better performance? Read Part 2 Hydration During Sports.

Author: MUDr. Karel Martinek
The spiritual father of online cycling training in the Czech Republic. A long-time doctor of Czech professional cyclists, both track, road, cyclocross, and in recent years also MTB professionals.