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Most people know that when they exercise, they need to drink more. However, it is very easy to get confused around what to drink. How much do we need to drink and when, during or after physical activity?

This article will aim at guiding you towards a better understanding of the principles of hydration and the risks associated with dehydration.

During physical activity, the metabolic rate of the human body increases, which utilises energy from our reserves to use as fuel. The more energy we spend, the higher our body temperature will rise. In order to control this, the body uses a clever cooling mechanism: perspiration. Water is excreted via our skin and then evaporates.

If we do not replace this loss of water by drinking more, our body will overheat and become dehydrated. This imbalance will lead to a rapid decline in performance and a higher risk of injury. It is important to hydrate properly in a warm country like Singapore, as our body needs to cool itself down even more.

Generally speaking, for any exercise lasting less than 60 minutes, water alone will be sufficient and energy drinks will not be necessary. However, if you exercise for more than 60 minutes, you can consume water + salt tablets or water + energy drinks, depending on your preference and duration/intensity of effort.

Companies source their water through different means (natural source from the mountains, desalinated water from the sea, treated water from reservoirs…) and therefore do not have the same mineral content. Make sure to read labels and look for ions content: sodium, calcium, magnesium and potassium. If the water you drink does not contain any minerals, you should add some electrolytes tablets/powder to it.

In addition to drinking water, some people like to consume energy drinks. Most of these contain high quantities of sugar. Ensure you compare brands to identify one that does not contain too much sugar.

It is crucial to start a training session or a competition with good hydration levels. As a general rule, the human body is capable of absorbing approximately 500ml of water per hour, which means that if you try to drink 1 litre in 60 minutes, you are more likely to feel bloated and need to use the toilet. On the other hand, if you drink only 20ml, you are likely to quickly feel the effects of dehydration. It is suggested to drink up to 500ml in the hour before the race. This might seem too much for some athletes, so make sure to try a few options during training and apply what fits best for competitive events.

There are several signs of dehydration that you need to be aware of in order to avoid any problems: feeling thirsty, sudden loss of energy, cramps and uncontrolled fast breathing. These are the first signs of your body telling you to drink and slow down. Keeping up at the same speed can lead to severe cramps, muscle injury and a lack of concentration and falls. The more severe warning signs are: headache, nausea, vertigo and vomiting. As soon as you feel the onset of any of these, stop any physical activity. Try to walk or rest and hydrate slowly with an energy drink and mineral water. You can also wet your head to help your body cool down.

After a training session or a competition you will need to rehydrate: water and electrolytes. A good tip to know how much to drink in the hours following training is to weigh yourself just before going for a run and immediately after. The difference in weight is approximately the amount of water that you need to re-absorb to regain normal hydration levels.

Pierre Meslet
Registered Osteopath
The Osteopathic Centre Pte Ltd