Dehydration: Symptoms, Causes, Prevention

Dehydration: Symptoms, Causes, Prevention

I hope you will never experience something like this: dehydration. Although it may seem very unlikely to happen, it can happen to anyone really…

What is Dehydration?

It is a state of our body when there is a loss of water due to several factors. For example, sweating due to a long workout or hot environments, some type of disease or pathology (diarrhea, vomits…).


We run the risk of becoming dehydrated if we do exercise in very hot environments

As the water content from the blood drops, the imbalance of minerals, salts and sugars can have harmful effects for our health.

Why does Dehydration happen?

The dehydration occurs when the body loses more water than what it takes. Moreover, it tends to go with alterations of the mineral salts or electrolyte balance (specially in the sodium and potassium concentrations).

Hydration and Water

Drink water, stay hydrated specially when if you do running in the summer, do box or even on a mountain trip…

How do we lose Water?

The level of dehydration depends on the water intake and metabolic losses. Moreover, the main ways of losing water are urination, defecation, transpiration and breathing.

Sweating and exercise

However, these values are subjective and they can vary between different people

How does the Dehydration affect the Sport Performance?

Our physical performance will drop with just a loss of a 2-4% of water. In endurance sports, athletes need to hydrate themselves throughout the workout, otherwise their life could be in danger. Let’s not forget that we can lose several liters of water in long distance races for example.

Crossfit Games

“Wod Murph” one of the most demanding trials of the CrossFit Games, where there is a high risk of dehydration

Around a 65% of the human body is water. In fact, it is very important in several tasks like lubricating the joints and eyes, the digestion and excretion of metabolic waste and toxins

Dehydration reduces the quality of your workouts


Water is indispensable when it comes to regulating the body temperature and the recovery process. When we do intense exercises in a hot environment, most people will lose a lot of water.

Exercise Outdoors

Sweating is a physiological response to control the body temperature by secreting water. Nevertheless, this water loss is not always compensated for the intake of liquid and temperature regulation.

Physiological consequences in the organism

  • Increasing the heartbeat.
  • Reducing the blood flow, consequently compromising the oxygen and energy supply for the muscles.
  • Increasing the body temperature.
  • Hindering the performance.

Muscle cramps

In practice, it deeply hinder the performance, making us feel tired more quickly

If you do exercise under these circumstances, your body temperature will increase quickly and you will suffer injuries and cramps

Practical tips to avoid becoming Dehydrated during the workout

  • Drink 500ml of water 1 hour before training.
  • Taking carbohydrates is fundamental to recharge the energy and delay the fatigue.
  • Drink 100-150ml of water every 15-20 minutes of training.
  • Weigh yourself before and after training. This will help you know how much water/liquid you should drink after training. We suggest drinking 1 liter of water/liquid per lost kg.
Hydration in Endurance Runners: What to Drink Before, During and After Running

Dangers of Dehydration

Some of the dangers of dehydration is that our blood thickens. Consequently, our heart will have to pump more blood in order to keep the blood circulating, apart from increasing the body temperature. This can result in exhaustion, heat stroke and death in the worst cases.


However, it can be really harmful for any athlete even at a low degree. Sweating constantly during a long workout can result in losing 1.8l per hour

Symptoms of Dehydration

Info about Dehydration

How to prevent Dehydration?

A proper hydration is extremely important for the physical performance. Do not rely on thirst to control it, the simplest way to do so is the urination frequency.

In general, if you are properly hydrated, you will urinate every two hours approximately. If it takes longer than that, it is possibly due to a lack of water or liquids

Drink water

Drink before, during and after an intense workout or in hot and humid climates

Drink Without Being Thirsty

If we are going to do physical exercise, we should drink before the workout, even without being thirsty

The amount of liquid will depend on the body weight, physical activity and temperature, among other factors.

Moreover, we need to stay hydrated even if we are not going to do physical exercise. This is specially important if the climate conditions are adverse for our activity (trip on the mountain…)


Athletes need to pay special attention to their daily hydration in order to reach a good performance during the workouts and competition as well.

Liquid Intake and Exercise

Before Training

You should drink between 5-7ml of liquid per kg of body weight at least 4h before training. Moreover, you should drink between 3-5ml/kg of body weight 2h before.

During the workout

To avoid becoming dehydrated, it is advisable to drink small sips of liquid in the rest between the series, for example. Above all, this is specially important if you do exercise in hot places.

After training

In this case, we will drink around 600-700ml of liquid per 450g of lost weight. Thus, we have to foresee that we will have to urinate during the rehydration process. To enhance said rehydration, we suggest taking foods rich in mineral salts or adding electrolytes to our drink directly.

Supplements to Avoid Dehydration

Depending on the objectives, intensity and condition of the athlete, we can intra-workout include sport supplements in our diet.

There are recovery supplements specially designed to be used after a hard workout or competition. Therefore, it will supply all the indispensable substances to stimulate the recovery and tissue regeneration


  • Manual NSCA. Sawka, M.N., L.M. Burke, E.R. Eichner, R.J. Maughan, S.J. Montain y N.S. Stachenfeld. 2007. Exercise and fluid replacement position stand. Medicine and Science in Sports and Exercise 39 (2): 377-389

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About Javier Colomer
Javier Colomer
"Knowledge Makes Stronger", Javier Colomer's motto, sets out his clearest statement of intentions expressing his knowledge and fitness experience.
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