Impact of hydration in endurance athletes

Hidratación y Rendimiento Deportivo

Rehydration strategies for any athlete during physical activity determine their level of performance.

  1. What is the concept of hydration?
  2. The importance of hydration for the body
  3. What are the types of rehydration drinks?
    1. Isotonic Drinks
    2. Hypotonic Drinks
  4. Hydration and sports performance
  5. How to apply the best hydration strategy to perform better?
  6. Bibliography

01 | What does the concept of hydration consist of?

Hydration is, without a doubt, one of the strategies that athletes have to take care of the most, since it will determine the desired performance and adaptations through sport. Taking into account that 60% of our body weight is water, this is clearly evident.

A good hydration strategy should start even before you feel thirsty, since it is estimated that approximately 30 minutes after starting our activity we can already be dehydrated by 3% and that compromises our performance .

Hydration in most cases is understood as the correct amount of water in our body and that is not the case, or not strictly. The important thing is the concentration that exists in a solution between the amount of liquid and the amount of solid in that amount of liquid. This is known as the osmolarity.

The concept of hydration is much more complex and basically has to do with two aspects:

  • The osmolarity of plasma and interstitial tissue (extracellular medium)
  • The osmolarity within the cells (intracellular medium)

This means that in sedentary people with a correct intake of water (2 liters / day), the body is already able to regulate the osmolarity between the inside and outside of the cell. But this is not the case when we do physical activity, since the loss of water and salts is magnified. We will see below how to restore this balance.

01.01 | The importance of hydration for the body

Hidratación y Rendimiento Deportivo

Approximately 60% of a person's body weight is made up of water. This is divided into 2 compartments, the extracellular medium, made up of plasma and interstitial tissue, and the intracellular medium.

  • The plasma
  • The interstitial tissue
  • The intracellular environment

All physiological processes that allow life are directly or indirectly conditioned by hydration levels.

01.02 | What are the types of rehydration drinks?

There are 3 types of rehydration drinks, distinguished by their liquid/solute concentrations or osmolarity:

  • Isotonic Drinks – concentration approximately equal to that of plasma
  • Hypotonic Drinks – concentration slightly lower than plasma
  • Hypertonic drinks – concentration higher than plasma

02 | Hydration as a basis for sports performance.

In any sports practice, the increase in body temperature induced by the muscles forces the body to thermoregulate through sweating.

In our sweat, water and salts that come from the aforementioned extracellular medium are being eliminated from the body.This compromises the balance of osmolarities very quickly and that is why from a very early moment, in our sports practice, we have to start rehydrating ourselves in order to maintain high levels of performance

These are performance drops per % dehydration in endurance sports:

3 to 5% dehydration - no symptoms or sensation of thirst - 10% decrease in performance,
5 to 7% - feelings of fatigue and gastrointestinal discomfort– nausea and diarrhea when ingesting gel or something similar,
8 to 9% - general system failure - renal hyperkalaemia K* - can lead to severe heart failure in physical activity.

Another fundamental aspect that has to do with the capacity of our intestine to absorb the salts contained in our rehydration drink is the different types of sugars and carbohydrates that they contain and the proportions between them . This is due to the fact that the different channels that the enterocytes of our intestine go through are very specific and certain molecules enter each one in specific quantities. On the other hand, in others, two molecules can enter at the same time. It is for this reason that in many cases rehydration drinks that are not designed according to our physiology generate gastrointestinal problems in athletes.

03 | How to apply the best hydration strategy?

Hidratación y Rendimiento Deportivo

The best way to optimize our performance in terms of maintaining good hydration during physical activity follows a few basic patterns that we note below:

  • Start rehydrating well before feeling thirsty, approximately 15 to 20 minutes after the start of our activity.
  • Make drinks that are palatable to us but that are neither too abundant nor too short, as this could induce antidiuretics and vasopressin, making us want to urinate or retain fluids.
  • Use ISOTONIC drink in those activities or sections of the same in which we do not plan to eat food such as gels or bars.
  • Use HYPOTONIC drink in those long outings in which we do have a nutrition strategy during the activity itself.
  • Use water naturally when we feel a lot of sweetness in the mouth or when the body asks for it.

Bearing in mind this knowledge, without too many complications, we are going to make sure that our body can perform at its maximum level.

It is not very difficult to do it right, but doing it wrong can be a big problem in terms of sport and performance.

04 | Bibliography


FALCÓ, Ricardo Segura. Sports drinks: isotonic, hypertonic and hypotonic. High Performance: Sports Science, Training and Fitness, 2004, no 15, p. 7.

MURRAY, R., et al. Comparison of Gastric Emptying Characteristics of Selected Sports Drinks-G-SE/Editorial Board/Dept. Contents. PubliCE, 2000.

HOPKINS, Will G.; WOOD, Matthew R. Optimal Composition of Sports Drinks for Endurance Sports-G-SE/Editorial Board/Dept. Contents. PubliCE, 2006.

URDAMPILLETA, A., et al. Hydration protocol before, during and after physical-sports activity. Motricity.European Journal of Human Movement, 2013, vol 31, p. 57-76.



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