Sir Ranulph Fiennes endures ‘heat test’ to prepare for the Marathon des Sables

Ranulph Fiennes Heat Chamber

Sir Ranulph Fiennes will compete in the Marathon des Sables between 5 and 11 April, running 156 miles in the Sahara Desert to raise money for Marie Curie. As you might expect, it’s going to be very, very hot, over 50°C. That means it’s not just the long distances he’s got to be prepared for, but also the fierce heat. In preparation for this extreme heat, Sir Ranulph visited the heat chamber at Kingston University, where the effects of increases in temperature are examined. To mimic the desert climate, the chamber was heated to 40°C and the humidity was gradually increased from 20% to 30%. Sir Ranulph was in the chamber for an hour, running the whole time on a treadmill while his trainer, Rory Coleman, tested his running strategy and whether he was drinking enough. See how he got on in the film below.

So how did he do?

The tests focused on two things: Sir Ranulph’s core body temperature and his fluid loss and consumption. In normal situations, our bodies have a constant core body temperature of 37°C, but this can go up or down under extreme conditions. If it goes too high or too low, our bodies can get into serious trouble. When it comes to heat we need to keep below 40°C, or we’ll start to suffer heat stress or heat stroke. These are serious conditions that stop our bodies and brains working properly.  If our body temperature rises above 43°C, the consequences can be fatal. Sir Ranulph Fiennes in the heat chamber Sir Ranulph has recently turned 71 so he’s more susceptible to high temperatures because his body isn’t as efficient at getting rid of extra heat. He's also suffered two heart attacks, undergone a double heart bypass, a cancer operation and is in a constant battle with diabetes. Even so, Sir Ranulph’s temperature through the test was very good, peaking at 38°C at the end of the hour. His heart rate also stayed low and stable, showing the benefit of all his training. When it came to fluid loss and consumption, Sir Ranulph will have to be careful. Sweating is the body’s best way of keeping cool, so drinking enough water is essential. He sweated out more fluid than he drank, which, over longer periods, could leave him very dehydrated.

There’s still work to be done

Now that Sir Ranulph and his trainer know his water breaks are a little short, they can work this into training. More water breaks and consuming more fluid should help stop him getting too hot from a lack of water. However, Sir Ranulph will need to work hard and be careful. It’s recommended that athletes do five or six sessions in the heat chamber. With so many other commitments, Sir Ranulph has only been able to squeeze in one. And, as he points out in the film, running in the desert is very different to running in a lab. But if anyone can do it, Sir Ran can. Read the full report on Sir Ranulph Fiennes heat test results You can support Sir Ranulph Fiennes in his latest challenge by donating on his JustGiving page.