Ian Sample

playing football at the intensity that these elites are going to be playing at.

But there's also a concern about what this might mean for the spectacle of the World Cup, for the performance of the players.

The body has to sort of dilate all the blood vessels near your skin and it pumps more blood through those areas.

So you have the blood near the skin and sweat on your skin.

As that evaporates, it takes heat away from the blood, okay?

Well, if you think about how the body cools down, obviously it cools down in a bunch of ways, but the main way is through sweating.

So that cooler blood then gets pumped back to the heart and circulates around the body.

The body has to sort of dilate all the blood vessels near your skin and it pumps more blood through those areas.

But

If you think about it at the same time, for these footballers, their muscles will be demanding an awful lot of blood as well.

So those are in competition.

So you have the blood near the skin and sweat on your skin.

And you can get to the point where this cooling just stops working.

As that evaporates, it takes heat away from the blood, okay?

It doesn't do enough.

So that cooler blood then gets pumped back to the heart and circulates around the body.

And that is when it hits performance and obviously carries these health risks as well.

And the worst case scenario is that you get heat stroke, and that can be fatal.

But

If you think about it at the same time, for these footballers, their muscles will be demanding an awful lot of blood as well.