How does playing football in hot temperatures affect the brains of players?

Here in the UK, players are accustomed to shivering after the half time break or layering up to keep warm during most of the football season. This is the case for football leagues in European countries, while for those in the southern hemisphere, it’s a different story...…

Major international competitions are usually held in the summer so that they do not disrupt the domestic and continental club competitions. As these tournaments are held in different locations around the world, players can sometimes find themselves having to play in high temperatures.

But playing in more than 40°C heat in the Qatar summer? Such high temperatures are probably not great for players to play their best football. That’s why this year, for the first time, the World Cup is not being held in June or July but during the football season in the winter. At this time of year, average temperatures in the middle eastern states are in the mid-20s.

But why is it difficult to play football in hot temperatures? And what effects do high temperatures have on the brain?

When our body heats up, either due to exercise or to hot air temperatures, we cool ourselves by radiating heat through the skin and sweating. However, when the air temperature is high and you’re exerting yourself, this may not be sufficient to reduce body temperature. With continued exposure to high temperatures, you become dehydrated and can no longer sweat. The body temperature then rises further, leading to a condition known as ‘heat stroke’.

Many of the symptoms of heat stroke reflect decreased brain function: confusion, headache, dizziness and, in severe cases, seizures and loss of consciousness. Since our brain cells (neurons) are mainly composed of water, even mild dehydration caused by heat during exercise can affect brain function, particularly memory.

So how might this affect playing football?

When body temperature rises researchers have identified a number of consequences for the brain. First, there is a decline in short-term memory, so remembering instructions given on the pitch might become more challenging. In addition, reaction times slow down, meaning that you might be slower to move into space or to respond to balls passed to you compared to when you’re playing under cooler conditions. Perhaps even more problematic are findings that the signalling of information from motor neurons to the muscles may be interrupted, which could result in difficulties in moving around the pitch or kicking the ball.

The reasons for these effects are not well understood, because it is challenging to study the effects of hyperthermia, or overheating. However, one of the consequences of the body heating up is that blood flow is directed towards the outer parts of the body, and away from the brain. During exercise under hot temperatures, the total blood flow to the brain is almost 20% lower compared with normal temperatures. In addition, the connections between different brain regions start to work differently when people are exposed to 50°C heat for one hour. This happens especially in the front part of the brain, a region that is important for decision making.

So, what can players do to avoid these effects?

During exercise it is clearly important to drink lots of fluids, something recognised by the ruling that allows for drinks breaks when the temperature is over 30°C. Scheduling matches at cooler times of the day such as morning or evening is also a good idea. Players can help slow the heating up of their body by having a cool bath with 15°C water before the match. We have also known for some time that acclimatisation to higher temperature by spending time in hot environments before the actual competition can help the body to deal with heat. Finally, more futuristically, there are thermometers that you can swallow that can monitor body temperature during the football match and warn players when their temperature gets too high.

Fortunately, the timing of the 2022 World Cup should mean that players can avoid these extreme reactions. But if global temperatures continue to rise, these measures may need to be adopted for future World Cups. Or perhaps there will be a limited number of locations where summer tournaments can be held.