As temperatures hit 43C at the Australian Open in Melbourne, officials decided it was just too hot to play tennis.

Play was suspended on all uncovered courts for more than four hours in the middle of the day because of extreme heat.

There is little doubt that people had been suffering in the sweltering conditions.

With readings in excess of 40C all week, ball boys were fainting, spectators wilting and players complaining of exhaustion and dehydration.

So what impact is the heat having on their bodies?

It is not surprising that by running around a tennis court for several hours in extremely dry conditions, players were generating a lot of heat.

According to Prof George Havenith, professor of environmental physiology and ergonomics from Loughborough University, players will be producing the heat equivalent of around 20 60W light bulbs.

When the effects of direct sunshine and radiation from the court surface are taken into consideration, as well as heat from the spectators watching and the lack of air flow around the court, this could increase the heat count by up to another 50%.

The key to coping with this level of heat production is losing it again through sweating.

"In Melbourne that's possible because it's dry, unlike a tropical country where the humidity is high. So it's easier to evaporate sweat.

To give themselves the best chance of coping with a match in the Melbourne midday sun, tennis players should be preparing their body beforehand.

Pre-cooling is now a common practice, which can mean a cold shower or ice bath before playing and the intake of lots of cold drinks in the run-up to a match to help maintain hydration levels.