JONNY KELLY – The effect of dehydration on sports performance

WITH the recent hot weather it is a good time to discuss how dehydration affects sports performance.

The body is made up of 60 per cent water, and the muscles themselves are made up of 79 per cent water.

Dehydration is a medical term that describes fluid imbalance in the body due to excessive loss of water or insufficient fluid intake.

In this article, we will cover the benefits of keeping hydrated to stay on top of your game.

The benefits of drinking water for athletes

Maximise performance

Staying hydrated reduces muscle fatigue and improves concentration levels.

This is evident in endurance sports, and studies have shown that athletes can run further and longer, compared to those who are dehydrated.

Dehydration can also reduce your reaction times and reflexes.

Reduce headaches

If you suffer from headaches, then drinking 1.5 litres of water per day will reduce the severity of them.

Improved digestion

Digestion is required for the body to process and absorb water, minerals and vital nutrients such as protein and carbohydrates.

Increasing your fluid intake is the most effective way to treat constipation and other symptoms of indigestion.

Regulate body temperature

Drinking sufficient amounts of water helps your body regulate its core temperature.

This will reduce the loss of water and electrolytes through sweating.

Signs you are dehydrated

Prevention is better than the cure but there are signs and symptoms to be aware of that would indicate your body is in a state of dehydration and needs attention.

If you have any of the following symptoms, you could be dehydrated and your performance on the pitch will be affected:

●Headache

●Fatigue

●Dry mouth

●Dry skin

●Decreased urination

●Dark urine

●Dizziness

●Constipation

●Increased thirst

●Light-headedness

How to calculate how much fluid I need in a day:

As a general rule, to work out the amount of fluid intake required per day, multiply your body weight in kilograms by 0.033. (Body weight (kg) x 0.033 = amount of water in litres).

For example, if you weighed 80kg, you would need to drink 2.6 litres of fluid per day. (80kg x 0.033 = 2.6 litres)

Best drinks for hydration

A study from the American Journal of Clinical Nutrition analysed the hydration effects of different drinks.

They showed that full fat milk, skimmed milk, orange juice and an electrolyte sports drink were the most effective at staying hydrated.

Surprisingly, water was grouped to have the same effectiveness as cola, tea, coffee and beer.

Takeaway message

Dehydration refers to the excessive loss of water that does not get replaced.

This condition can negatively impact an athlete’s physical performance.

Milk, orange juice and electrolyte sports drinks are the most effective at staying hydrated.

Are you frustrated with injury?

Jonny Kelly is a chartered Sports Physiotherapist and owns Physio Performance in Belfast.

He has helped get world-class athletes back on the pitch and performing at their best.

Contact us for a complimentary Sports Injury Consultation at