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How does dehydration affect football performance?
During a game of football, your body temperature can increase to over 39 degrees. In an attempt to reduce internal heat, the body increases its rate of sweat production. Professional players can sweat as much as two litres during match play even when the temperature is only 10 degrees. For a 75 kg player, this sweat loss equates to 2% dehydration and if enough fluid isn’t consumed, your performance will suffer.  Dehydration of this magnitude reduces the ability to perform repeated sprints and can even impair the ability to perform technical skills such as dribbling. In a dehydrated state, your body temperature and heart rate increases, while you deplete your carbohydrate stores quicker and perceive the exercise to be more intense. This means you have to work so much harder just to perform at the same intensity.

What are electrolytes?
In addition to losing fluid, our sweat also contains important electrolytes such as sodium, chloride, potassium, calcium and magnesium.  Loss of sodium is bad for players as it helps them actually retain water. Football players can lose between 2-13 g of sodium during training or a game. The importance of high sodium (i.e. salt) losses are also shown by observations linking them to exercise-related muscle cramps. For this reason, it is important to find out if you are a salty sweater so you can learn how to stay hydrated.  Keep an eye out for white patches on your clothes after matches – if you find any, it could mean you’re sweating a significant amount of salt during the game.

How do I know if I am dehydrated?
The easiest way to avoid dehydration is to ensure you start the game well hydrated.  A simple way to check your level of hydration is to monitor the colour and volume of your urine. If it is pale and plentiful then you are probably well hydrated (aim for lemonade colour); if it is dark (think apple juice colour) and low in volume or you haven’t been to the toilet then chances are you are slightly dehydrated. Monitoring your morning weight can also indicate if you are dehydrated. If your morning weight changes by >1% from the morning before (e.g. a 75 kg player decreases to below 75.25 kg), then it is likely another sign you are dehydrated.  You should check the colour of your urine in the morning upon waking so that you have plenty of time before kick-off to get fluid onboard.

What and how much should I drink before the match?
To start the match hydrated, it is recommended you consume 5–10 ml per kg of body mass of an electrolyte solution (e.g. SiS GO Hydro) in the 3 to 4 hours before exercise.This time-scale should allow your urine output and volume to return to normal before the match. Consuming 500-750 ml of SiS GO Electrolyte with your pre-match meal will have the added benefits of providing electrolytes and carbohydrate so that you can help achieve your pre-match hydration and fuelling goals at the same time.

What and how much should I drink during the match?
Consuming SiS GO Hydro or SiS GO Electrolyte during the game will help to maintain hydration better than plain water. It is recommended you consume enough fluid during the game to prevent a body mass loss. Given the limited opportunities available to drink during the match, it is important to consume fluid in the final minutes before the match and half-time as well as taking opportunities to drink during natural breaks in play.

Aiming for 500 ml of fluid per hour of match play is a useful starting point and if you need more, your thirst will let you know.  By monitoring how much fluid you drink during the game and changes in your weight before and after the game, you can quickly assess if you are drinking enough to maintain appropriate hydration status.  Remember that your sweat rate will increase in higher temperatures and the harder the match is, so pay close attention to your drinking habits in these conditions.

Key advice

Dehydration of 2-3% can reduce football performance by decreasing our ability to perform high-intensity exercise and perform technical skills such as dribbling.

Checking your urine colour and volume along with your day-to-day changes in morning body mass is a simple way to monitor your hydration status.

To begin the match in a hydrated stated, aim to consume 5-10 ml/kg body mass of an electrolyte drink with your pre-match meal.

Aim to consume an electrolyte drink before, during and at half-time of the match at a rate that prevents body mass losses >2-3%. You should practice your hydration strategy in training so you get it right on match day.

Dr James Morton
Written By

Dr James Morton

World Class Knowledge Director