Going for gold at 26 degrees Celsius
It's Olympic season but how are athletes from cooler countries going to cope with those Brazilian temperatures? It may be winter south of the equator, but temperatures are still predicted to reach 26 Celsius in the afternoons. How will this affect the, and what does the body do to keep cool? Dan Gordon is an exercise physiologist; he's also an athlete himself and has represented Great Britain in three different sports in the past and, as he explained to Chris Smith, he even holds a World Record...
Dan - The World Record is in track cycling; I still hold the outdoor World Record for a kilometer time trial.
Chris - So you must know all about handling the heat. So why is thermal situations a challenge for people out there in situations like this?
Dan - Yeah, it's an important question. The biggest challenge to the body's functioning is heat. If you think about muscle changing length and therefore generating force, 75% of the energy that's produced is lost in the form of heat. So we're producing vast amounts of heat and then we put someone into a hot environment, it really puts the body into a state of enormous compromise when you're trying to compete. And you're trying to generate very fast and rapid muscle contractions...
Chris - So it's not just dealing with having very good musculature and being highly trained, it's also being able to cope with the thermal stress of how to dump enough heat back into the environment to keep your body running efficiently in these situations?
Dan - Exactly, and that's the key to success. If you imagine you go to an olympic games and most of the athletes are of a fairly similar standard, if you take the top ten in the world they're a fairly similar standard. So one of the big factors that really determines the winner from the loser is the person who can cope with the heat and dissipate the heat the most effectively.
Chris - But can you train that, Dan?
Dan - You can. I mean you can train it in a number of ways. One of the ways is you can use what's called acclamation. So acclamation is where we put athletes or individuals into heat chambers and in the heat chamber you can expose them to the temperature you're going to get in the local environment, and the body will physically adapt. Or you can acclimatise somebody where you actually go to the hot environment and you're there for a number of days prior to whatever the competition's going to be.
Chris - And what sorts of changes or adaptations does the body make to your physiology in order to enable you to become more efficient at losing or controlling thermal stress?
Dan - OK, now this is the really cool bit!
Chris - Or not!
Dan - Yes, absolutely! If you go into a hot environment the first thing that actually happens is that you get an increase in the skin colour - the skin goes quite red, and the reason for that is the circulation is being redirected to the skin. The blood has a fantastic capability of dissipating heat from the body, so it's taking it from the core and dissipating it away from the body, so we get a redistribution of blood flow.
Chris - In most holidaymakers case that's just because of the local vino but we'll assume these athletes are not indulging...
Dan - In my case, it's just a natural sunburn.
Chris - So you bring the blood close to the surface of the skin and because the blood is hot, you've got a hot thing close to the skin so it's going to radiate some heat?
Dan - It's going to radiate the heat away from the body. But, that's quite an inefficient process because you're now redistributing the blood away and there's only a finite amount of blood and, of course, the blood carries the oxygen, and we have this compromise. So what we know...
Chris - It's not going to the muscles?
Dan - It's not going to muscles and it's being redistributed away from other organs. So what happens is, over time, as you start to expose something to the environment, and I think this is the bit that throws people, is you start to sweat more. We often think sweating is a bad response but, actually, it's a fantastic response because sweating is a far more efficient process in terms of that redistribution of blood flow, so the redistribution of blood flow is downregulated.
Chris - So you can train yourself to sweat more?
Dan - You can train yourself to sweat more...
Chris - How?
Dan - Well, you do it be exposing people to those hot conditions.
Chris - Do you get more sweat glands?
Dan - You don't get more sweat glands, it's just that what naturally happens is the body learns, through that exposure, to not get the redistribution of blood flow and then, therefore, promote the sweat response.
Chris - Ahh. So you're substituting sweating for rushing blood to the skin surface?
Dan - Correct.
Chris - So how much can someone sweat?
Dan - Well, I mean it really does depend. But you can see athletes loosing, I mean we're talking litres. But you also get individuals who don't sweat a lot. I mean there are a lot of athletes in Athens who we called 'dry sweaters.' They really didn't look like they were losing much but then you have a lot of athletes who sweat vast amounts, so it's very individual even in people who are acclimatised to the conditions.
Chris - And how long would it take - say you took me as a relatively untrained (at least in warm temperatures) individual and took me to Rio, what would you need to do to me to get me as acclimatised to cope with those temperatures and boost my sweat rate?
Dan - OK, so the key is making the most of the time. So in a normal situation, it takes about ten days to acclimatise to anything about 26 to 35/36 degrees C - about 10 days. We can speed that process up by doing acclimation prior to the event so, if we were doing acclamation every day for an hour to two hours a day, we could probably reduce the acclimatisation period down to about eight days.
Chris - OK. Now is there evidence that people who grow up in these countries - so if I am from Ethiopia I'm very good at marathon running not just because I've got good ways of extracting oxygen from my muscles, but because I've evolved to have very good, very strict temperature control - is that the case as well?
Dan - That is the case as well. So you know, unfortunately, the UK athletes had their time with London. We did well in London, it was a natural environment. We're now at a natural disadvantage and it's no doubt that the Kenyans, the Moroccans, the Ethiopians are at the advantage because they're got, as you say, great ability in terms of exercising and competing, but they've got that natural ability to dissipate heat and are really good sweaters.
Chris - Well they say a team always plays best at home don't they? It's certainly true in that case.
Dan - Very much.
Chris - I've always joked that the olympics is more a trial of genes and genetics than it is really about anything else. Would you agree with that? I mean it is basically your genetics against someone else's.
Dan - It is in the isn't it. It's no doubt that's what it comes down to and if you look at the bell curve, and we're right at the far extreme of the bell curve, and then at the far extreme of the bell curve, you're at the extreme of that extreme. And it really is about these extraordinary genetic specimens and, you know, it's a massive, massive component in terms of everything that's going on.