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Hydration and Exercise

An individuals body water content can range between 40-70% of a their total body mass, depending on age, gender and body composition. With water being involved in practically all functions in the body it is vital that we do not overlook how important proper hydration is for our health.

How Hydration affects our health

  1. Concentration and energy levels - Being dehydrated can negatively affect your concentration and lead to higher levels of fatigue.

  2. Visual attention and mood - Can be improved with water consumption.

  3. Kidney stones - Better hydration has been linked to a lower chance of having kidney stones.

  4. Weight loss - Drinking water before a meal and with a meal increases satiety and feelings of hunger. Drinking 500ml of water at each meal (3 meals total) alongside a calorie deficit was shown to decrease weight more than a calorie deficit alone. This is thought to be due to a reduction in meal energy intake prior to water consumption.

  5. Temperature regulation - Having optimal hydration maintains plasma volume which optimizes the circulatory and sweating response which is vital when exercising to help regulate body temperature. Water loss during exercise depends on intensity of the exercise and the temperature of the environment you are working out in. Therefor when performing high intensity exercise or in hot environments it is even more important to stay hydrated.

  6. Impact on physical performance - A drop of 2% or more in body weight due to dehydration can lead to significant impairments in physical performance. This study also shows that dehydration may cause a reduction in muscle endurance, strength, and anaerobic power and capacity. So it is clear that dehydration can negatively affect exercise performance so knowing how to stay hydrated is vital for getting the most out of your training.

Daily water intake

A sedentary adult requires 2.5L of water a day. Add a hot environment and exercise and that requirement can jump to between 5-10L daily. This however does not mean you have to down a 10L bottle of water however as your daily liquid intake is also provided by the foods you eat and metabolic processes. 25% of a sedentary person's daily water requirement for example is provided by the process of metabolizing (breaking down) of food molecules for energy. The best place to get water from food is from fruits and vegetables. Most fruits and vegetables contain 90% water compared to less than 20% water in chocolate, oils, butters and cakes.

Water intake for performance

Most of us will take a bottle of water with us when training and drink a fair amount while exercising, but this may not be enough to stop you being dehydrated during your workout. Often when you are thirsty you are already dehydrated and because fluid absorption happens predominantly in the small intestine this will not be immediately solved by drinking a lot of water all at once. This may however result in uncomfortable sloshing in the stomach during your workout. Hydration from the water you drink will depend on the rate of gastric emptying, the intestinal absorption of the water and the speed at which the water is utilised. So it is recommended that you stay hydrated throughout the day and to delay dehydration before exercise you can drink 400-600ml, 10-20 minutes before starting.


What are they?

you have no doubt heard about electrolytes in your sports drinks but what are they? Sodium, potassium and chlorine are called electrolytes as they are dissolved in the body to make electrically charged particles called ions. One of their major functions is to modulate fluid exchange in the body, such as nutrients and waste product exchange. Electrolytes play a major role in the transmission of nerve impulses involved in stimulating muscle contraction and the proper functioning of glands.

Are sports drinks needed when exercising?

There is actually no need for sports drinks if you have a well-balanced diet. The body actually reduces the amount of sodium and water lost through the kidneys when you start vigorous exercise. Even when doing prolonged exercise in hot temperatures a pinch of salt ingested with water is actually all that is needed to replenish electrolytes lost in sweat.


Adequate Hydration can improve our health in many ways including, increasing muscular endurance, reducing body weight and improving our energy levels. Our daily water intake not only comes from the beverages we drink but also the food we eat and our metabolic processes. Fruits and veggies are especially great for hydration as they have a large water content. Regular water intake and a well-balanced diet will provide us the electrolytes and hydration we need for vigorous exercise without the need of sports drinks.

Extra Reference:

Weitz, C. A. (1987). Exercise Physiology. Energy, Nutrition and Human Performance.

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