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9. září 2010 v 13:33

Swimming Technique: Swim Like a Fish

Quelle / Source: New Scientist, 1. August 1998, No2145

© übersetzung Felix K. Gmünder

Forget raw power

If you want to swim really fast, stop thrashing about, relax and feel the water. Olympic coach Gennadi Touretski tells Daniel Drollette how to torpedo the opposition.

There's humiliation and then there's real humiliation

While swimming in the local outdoor pool in Canberra, a guy swept past me like a torpedo to my tugboat. I felt bad. I actually rocked in the water as he swam by. But the feeling didn't last long once I realised that the torpedo was Alexander Popov, two-time Olympic gold medal winner and holder of the world record for the 100 metres freestyle. In the next lane gleamed the menacing shaven head of Popov's training partner, Michael Klim, who has swum the fastest time ever in the 100 metres butterfly. I had unwittingly crawled into part of the pool where these elite athletes occasionally train for a change of scene from the indoor pool at the nearby Australian Institute of Sport.

Popov seemed to slide effortlessly through the water, elbow bent overhead in classic freestyle position, long arms slicing forward with elegant ease. In contrast, Klim crashed ahead with his arms locked straight as they emerged from the water in his trademark "windmill" version of the freestyle. Each man's style is unique, but both are world-beaters. And both are the products of the unorthodox ideas of the same coach, Gennadi Touretski.

Touretski, a colourful and sometimes controversial character, studies the motion of fish and writes physics equations on the whiteboard of his poolside office to explain the principles of hydrodynamics. His brand of science-based training has done much to promote the idea that it is not raw power that makes champion swimmers, but efficiency. Klim and Popov are taught to behave like fish, to "feel" the water and glide through it.

Now a naturalised Australian, Touretski is a product of the old Soviet system, in which as many as eight scientists would monitor the performance of the national team. He is a former swimming champion with a degree in engineering and training in biomechanics, biochemistry, fluid mechanics and sports physiology. He is known for using unusual props to get his ideas across: he once brought inflated condoms to the pool to show his fellow coaches the importance of maintaining a rigid torso while kicking forward. When deflated, the condoms flopped in the water; inflated, they skimmed across the surface with just a light push.

Touretski's swimmers swear by him. It was Touretski's idea, for example, for Klim to switch to the windmill style. "I've made straight personal bests ever since he made me make this change," Klim told me later. Popov is just as enthusiastic: "He's the reason I left Russia." Popov and Klim have the status of pop stars in Australia, while magazines and newspapers hail Touretski as the man who transformed top-echelon swimming in Australia. But amid all the hoopla, the question remains: how do Touretski and his swimmers do it?

The answers, says Touretski as he paces the poolside, lie partly in genetics and partly in technique. Elite swimmers tend to be born with certain advantages, such as superefficient metabolisms. Some long-distance swimmers, for example, have cardiovascular systems capable of delivering twice as much oxygen to starved muscle cells as the average fit young person, giving them an advantage before even entering the pool.

  Olympic swimmers also tend to be tall and long-limbed. When seen on land, both of Touretski's swimmers are as long and lanky as basketball players. Klim is 1.91 a metres tall (6 feet 3 inches), while Popov, at 1.97 metres (6 feet 6 inches), can touch the bottom of the deep end of the Canberra pool and still keep his head above water. The pair are designed for swimming. Or, as Touretski told them: "You have something given to you by God. You must develop it." Fair enough. But how?

There are two ways to swim faster, says Touretski: increase the force that swimmers use to propel themselves through the water or decrease water resistance. Both approaches come down to technique, but he thinks the second is by far the best.

To propel yourself through the water faster you might, for example, increase your stroke rate. But there's a problem here, Touretski says. You'd soon run out of steam. He cites a passage from his favourite book, Fish Swimming by zoologist John Videler of the University of Groningen in the Netherlands, which states that energy consumption in water increases as the cube of the stroking rate. In other words, doubling the speed at which you move your arms through the water takes eight times as much energy.

What's more, increasing stroke rate inevitably means taking shorter strokes, which is at odds with how most animals behave. When they want to move faster, they increase the distance covered with each movement. Touretski points to video clips for support: horses, Touretski points out, speed up by increasing the distance they cover with every stride, not by increasing the number of strides per second. Kangaroos do the same hopping on their two feet. Touretski believes swimmers should do what animals do, stretching as far forward as possible to get the longest pull with each stroke. Popov's first gold medal in the 1992 Olympics in Barcelona provided evidence to support this approach. When he beat the American swimmer Matt Biondi, Popov covered 50 metres with just 33 strokes to Biondi's 36.

So if increasing stroke rate isn't the answer, what about pulling harder and bulldozing through the water? Until the 1980s, swimmers and their coaches focused on power. They took inspiration from mechanical models such as propellers and paddle wheels. The typical swimmer had shoulders like a Bulgarian weightlifter, and the emphasis was on lots of long-distance training sessions, according to renowned coach Cecil Colwin, author of Swimming into the 21st Century. The science of biomechanics "has been incorrectly focused on emulating the actions of mechanical propellers instead of . . . mechanisms more akin to natural flight and fish propulsion", he wrote.

Touretski agrees with Colwin, for reasons based on physics. Fluid dynamics tells us that drag depends upon form and friction. Dolphins swim as fast as they do, for example, because they have a streamlined shape and because their skin is designed to reduce friction by stopping the formation of energysapping eddies around their bodies.

Making waves

Humans have neither of these advantages. But the real killer for competitive swimmers is a third type of resistance that arises at the interface between air and water- wave drag. Moving along the surface of the water inevitably creates waves. Physically speaking, swimmers force a mass of water in front of them to rise up against gravity. This not only robs swimmers of energy, but it has a disproportionately greater effect the faster they go.

The problem is that wave drag increases as the cube of any increase in swimming speed. And it gets worse if a swimmer makes jerky or uneven movements, either bouncing in the water or moving from to side, because this wastes still more energy making waves. Because of this, Touretski believes that trying to increase speed by propelling yourself harder through the water is pointless beyond a certain point. "More propulsive force will only produce higher waves, not higher velocities," he says.

If you can't beat water into submission, Touretski argues that it's better to learn how to avoid its obstructive influence. For a start, reducing friction with the water is important. This is one reason why Klim shaves his head. Form-or shape-is also a factor. For swimmers this means streamlining themselves with tricks such as pushing the head and chest down into the water, and rolling from side to side with each stroke, to present a narrower profile. To avoid wave drag, Touretski urges swimmers to eliminate jerkiness in their stroke. (One of the other curious consequences of wave drag is that it penalises short swimmers more than it does their taller rivals.)

To achieve a reduced resistance technique, Touretski's swimmers are trained to improve their balance, locomotion and "feel" of the water. The emphasis during training is on quality of performance rather than mileage. His idea is that with constant repetition, precisely practised movements become second nature-like reflexes.

To work properly this training method demands meticulous attention to detail. "If you can't do it exactly right, don't do it at all," Touretski says. He'd rather have his swimmers do a few movements properly than do a lot of movements incorrectly. Touretski and his swimmers talk in terms of "muscle memory".

So much time is spent on proper technique that by Olympic standards, Klim, Popov and the rest of Touretski's squad have relatively leisurely workouts- though they still swim about 70 kilometres a week. To outsiders, his methods appear odd. American coach, Bill Irwin, once told a reporter: "Popov does long sets with meticulously precise strokes and a consistently beautiful flow. In three weeks, I never saw him do a single lap that looked hard."

Slowly does it

Part of what we saw is Touretski's "superslow swimming" method. Touretski demonstrates by walking across his office in exaggerated slow motion. By moving extremely slowly, he has to concentrate on the exact placement of each muscle. Balance becomes imperative. "People are more wobbly when moving very slowly and they have to constantly shift weight to get their balance right," he says. The same applies in the pool, and when swimmers can travel smoothly at a very slow speed, they can move more smoothly at high speed.

Superslow swimming also forces swimmers to concentrate on extending their arms as far as possible, to get maximum range on each stroke. And it improves a swimmer's ability to relax at higher speed. When you absolutely know that your hands and feet will be in the right place at the right time, there are fewer frantic actions and less wasted energy during a race. Relaxation is often overlooked, but the great American swimmer Johnny Weissmuller once said that "the greatest secret of freestyle swimming is relaxation at top speed". (Weissmuller is best remembered today for his Hollywood portrayals of Tarzan, but until Popov came along, he was the only swimmer to win gold medals for the 100 metres freestyle in two consecutive Olympics.) Touretski elaborates: "Not all muscles are switched on at the same time. There's a wave of muscles contracting or relaxing simultaneously." Learning to relax the muscles that are not in use saves energy and staves off fatigue.

Training at slow speed also helps the swimmer hone the all-important intuitive "feel" of the water to anticipate, control and manipulate its flow. Swimmers get quite mystical when describing this ability, like artists describing "a good eye" for painting. To a swimmer, "feel" lets you know when you've properly caught the water with your palm and pulled your body forward with minimal resistance.

If superslow swimming does not help to develop this sense, Touretski tries the opposite approach, using his towing machine. This pulls swimmers through the water at high speed, so they get a heightened sensation of what happens when they position their arms and legs properly. It's like holding your arm out of the window of a moving car-when your palm is held vertically you feel the wind resistance pushing it back. Rotate it 90 degrees and your hand knifes through the air.

Touretski's methods are intended to optimise what he calls the "three Rs": stroke range, relaxation and rhythm. Rhythm is important for reducing jerkiness in the water. When a freestyle swimmer's hand digs into the water his or her body speeds up, but when it is withdrawn the body slows down. Like a one-cylinder engine, this results in uneven propulsion. The larger the changes, the more energy is wasted.

To move at a constant speed, one arm should always dig into the water as the other comes out, so that the motion is more like that generated by a two-cylinder engine, in which one piston drives the engine while the other recovers. To get their arms moving in synchrony, Touretski has his swimmers practise a "kayak manoeuvre" in which they stand on the poolside with a double-bladed kayak paddle and take an imaginary trip. Popov demonstrates how, as he paddles, one arm is always doing the opposite of the other. Once again, Touretski's swimmers drill in this manner until the technique becomes second nature.

These unusual drills and training methods seem to pay off. Touretski's swimmers don't waste much energy in creating waves. Besides the evidence of all his success, a study by Sergei Kolmogorov, head scientist of the Russian team, has shown that Popov's smooth technique allows him to consume 30 per cent less energy than other swimmers moving at the same speed.

Touretski hopes to improve his swimmers' technique still further. "I think Michael [Klim] will look better over time. He's still learning, still growing. I'm fighting for beautiful technique," he says. "Beauty and perfection are quite close."

Daniel Drollette is a freelance science writer in Australia on a Fulbright fellowship.

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