Home » How Much Exercise is Too Much?: Tim Noakes at TEDxCapeTown (Full Transcript)

How Much Exercise is Too Much?: Tim Noakes at TEDxCapeTown (Full Transcript)

Tim Noakes


So you see, what I don’t understand is why I have to go through all this pain. But when I do see something I don’t agree with, I become addicted to try to answer what is the truth.

Today I’m going to talk about some of the ideas that I’ve focused on. They come in many different topics and you can see they cover medical problems in marathon runners. Rugby injuries. Are all rugby players overplayed? Something about nutrition. Should we be eating carbohydrates or should we be eating fats? And particularly what regulates our exercise performance? And then, is it possible to swim at the North Pole at -18°C in a speedo?

So I’m going to talk about those questions and I’m going to begin by the very first question that ever came to me as a scientist was: Are marathon runners immune to heart disease? And this was a theory developed by a Californian pathologist and he said on the basis on any contrary evidence, it looked like if you ran a marathon you’d never have a heart attack.

So I mean I knew that it was absolutely bogus but to prove it was all the more difficult. At the time in the 1970s this was the bible of running. It was written by James Fixx and he described at length the whole hypothesis. Tragically seven years after this picture was taken, James Fixx died of a heart attack while running.

But by then we had in fact already shown that it was possible for people to have heart disease. So we looked for when we saw reports of people dying in marathon races we would go and collect their hearts and we would examine them and eventually we found the evidence and so we published a paper in the New England Journal of Medicine showing that there were runners who had disease and the disease here is — this is coronary artery disease in which there’s obstruction of the coronary arteries causing heart attacks and we were able to show that this man had had a heart attack whilst he was running a marathon. So that was published and so that disproved that’s obviously very easy to do, it’s easy to find a few cases that disprove a theory.

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The next one that I really got involved with is in the 1980s was: Should we be drinking more or less during exercise? And at the time in the 1960s it was held that actually if you drank during exercise that wasn’t a very good idea. Abebe Bikila who was the first African runner to win two Olympic gold medals in the 1960 and 1964 Olympic marathons he ran both races without drinking anything. That was what runners did in those days.

And then all of a sudden in the 1960s and 1970s things changed and we were told that if you didn’t drink enough, you were going to die during exercise. I became interested in why that would be the case. And the epiphanous moment occurred on 1 June 1981 when an athlete started the Comrades Marathon in Bourbon and she reached 70 km and her husband withdrew her from the race because she didn’t recognize him and he felt that wasn’t a good idea. And he then took her for medical care and in short order within two hours she was unconscious having epileptic seizures, and she had to be taken back to hospital in Bourbon.

And when she was admitted to hospital she became the first case of this condition which — a long name we don’t need to understand what it is at the moment. But here’s her chest x-ray and this shows that she’s got fluid in her lungs and it took five days later before the fluid had gone out of her lungs but this is what happened. What really happened was that her blood sodium concentration which should normally be at 140 and is tightly regulated, it’s one of the most regulated features of the body had dropped to 114 that’s heroically wrong, something had gone tragically wrong.

And she asked me what had happened. And I said, “We have absolutely no idea.” And it was the first case in the world so we had no idea. Over the next four or five years we picked up couple of more cases and worked out that they probably had overdrunk and in other words they’d drunk too much during exercise. And then at the 1988 Comrades Marathon we could prove it by hospitalizing eight people who were really sick with this condition and follow them during their recovery and we were able to show that they all passed an excess of fluid during recovery and so this athlete here passed six liters of fluid extra during recovery and that she had dropped her blood sodium concentration to a very low level and you can see there was a nice relationship.

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So the more you overdrink the lower your sodium and the sicker you were and we published that in 1991 and thought that’s the end of the problem. We cured the problem, we know what causes it, it’s overdrinking and we thought the problem would go away. But unfortunately at the same time we were doing that, industry would come along and said, “No actually, the more you drink, the better.” So there’s an advert saying that not only must you drink but you must drink heroically during exercise. This is 12 liters per hour or your performance will suffer.

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