Monday, 7 September 2009
Glasgow Running Seminar Part 2 .... water, water everywhere, but not a drop to drink!
Tim Noakes was a fascinating presenter with that off-the-wall style that is so effective, continually joking and making asides, usually to himself!
His presentation started with a long illustrated guide to human evolution. I'll cut this short as I can, but that will be difficult!
Humans evolved into hot, sweaty, furless mammals for a very good reason..... hunting. And in this evolution, the environment was more important than genes. Man developed, arguably, in the High Veldt of South Africa or in East Africa.(The arguably coming from where your scientist lives, in Noake's case, SA.) When the environment left him nothing to eat he was forced to chase down animals. He did this by running after them until he caught and killed them by strangulation or with a rock. Thus, man had to learn to run long distances and to overcome hyperthermia, or overheating. Animals may be able to run faster than man but, eventually, they must slow down and stop as their core temperature reaches 43 degrees centigrade at which point they suffer from paralysis by hyperthermia. By following the animals at a steadier pace over many miles and hours man was able to catch even the fastest animals.
He managed this by adapting from a four legged beast to a biped, thus reducing the surface exposed to the sun to the head area whereas the animals had to expose their entire length. Man developed a sweat system where he cooled his body by sweating and other anatomical changes such as smaller pelvis,large Gluteus Maximus, shorter arms,longer legs, counter-rotating trunk and the ability to keep the head fixed in relation to that rotation... ensured he could run.
Due to the requirement to keep moving during the chase, man also developed the ability to delay drinking. Unlike the animals who had to drink lots at set times to avoid the predators who could catch them when they drank, man was able to drink frequently in small amounts delaying full correction of fluid deficiencies generated by exercise until the evening meal.
I'll repeat that, because Noakes did. We drink our fill at meal times and less during exercise. We fully replenish any fluid imbalance only after eating!
How is that? Humans can adapt so that they are better able to exercise in the heat due to the ability to conserve sodium.And if they were to drink excessively during exercise then Hyponatraemia could set in.
So how much water do we need?
Professor Noakes showed a video of Haile Gebrselassie running a marathon. He sipped, and I mean sipped, about four times during the race and had his bottle in his hand for a total of 58 seconds! And that was mostly carrying it while he thought about drinking. In other words he sipped only enough to take away his thirst.
So why is there a belief that we need to maintain hydration. The answer is fairly simple......... sales of sports drinks!
When sports drinks companies wanted to increase sales, they engaged sports scientists and nutritionists to encourage people to stay hydrated during exercise, with dire warnings of serious collapse or death if they failed to stay fully hydrated. However, deaths in marathons and Ironman Triathlons started to occur. When one occurred during an African ultra doctors at the race inserted a catheter in the unconscious patient and, surprise,surprise, found the patient was over hydrated! At this point they started to raise the alarm about the condition, but deaths continued as the sports drink and running magazines continued to warn against the dangers of dehydration. Noakes spoke to one magazine publisher who refused to publish his warnings as it would alienate advertisers - the sports drink industry.
He told of one runner whose husband was watching her race and waited at the 35k mark to watch her go by. She collapsed in front of him and their two infant children and her husband realised she was suffering from overhydration. Paramdics attended and said she was dehydrated and against the wishes of her husband connected up yes,IV fluid. She died. A journalist wrote in the Chicago Tribune of these dangerous practices and, within an hour, received two phone calls from "sports scientists" ordering him to retract as he was going to cause many deaths. A bit of investigation found that they were in the pay of the sports drinks manufactureres. How else, asked Noakes, could Californian scientists learn in one hour what had been written in a Chicago paper?
He then moved onto fatigue or rather the concept of fatigue. Those of you who have read the book Brain Training For Runners will be familiar with the concept that the brain controls the runner's performance. Noakes took this concept and illustrated it with his Model for Fatigue.
The brainless runner can be best described as an athlete on a treadmill whose speed is set by his coach or a scientist. There is no input from the athlete. The coach can increase the speed and keep increasing it until the athlete collapses with fatigue.
The Runner With A Brain is a different animal! He can set the pace according to the signals he receives from his brain. These continuous signals cover both physiological and psychological input from all the systems in his body. He therefore can decide how to run according to the conditions. Heat was one of these conditions on which Noakes concentrated. He asked is weight a factor in the performance difference between E.African and white athletes.
He pointed out that the average weight of the African runners they surveyed is 53.9kg whilst that of the US runners was 63.7kg. Heat loss is greater according to the heavier weight of the athlete. Therefore, the white, heavier athlete is going to suffer more in the heat. And, as he knows this, his brain will ensure he sets off at a slower pace than the African in order to ensure he doesn't overheat. Beaten before he starts.
Further, an examination of split times of Gebresellaise's world records show that his fastest kilometer is always his last. How could that be when he is so tired? In contrast, the record breaking white runners splits were normally slower at the end, a steadier run in other words. Noakes said that the indicator of fatigue should be the inability to vary speed. In other words power input should vary all the time and the loss of that variation shows that fatigue has set in. He illustrated this by saying that tests of fresh runners show that their pace and stride length vary all through the run but when fatigue sets in, their pace and stride length become uniform. Hence the ability of the Africans to constantly vary the speed of their running during races, an ability that white athletes struggle to master.
Finally in this section before the break, he stated that instead of measuring VO2max in athletes to guage fitness they should be measuring muscle function as it is the brain's ability to recruit muscle fibres in exercise that governs how fit he is rather than heart and lung function.
Noakes summed up by saying that man evolved as an endurance runner(and nothing explains sprinting evolution!) He is built to resist the effects of water loss!
The body will also excrete excess sodium through sweat and urine, but is able to withstand low levels of sodium although it requires calcium to fire the muscles. Hormones control the conservation of water and salt in the body. (These hormones are rendered less effective by overhydration and non-steroidal anti-inflammatory drugs(NSAID).
His message: THE BODY CAN RESIST THE EFFECTS OF WATER LOSS
At this point we adjourned for refreshments.
In part 3 ...... my chat with Noakes and his explanation for my increased level of creatine kinase after the WHWR!
Also Noakes gets more time to lecture and an insight into Ethiopian training.