A Lesson Learned

Many people feel that the introduction of the high-tech, full-body suits did more harm than good to the sport of swimming. At the very least, they devalued the World Record and perhaps worse, they erased some records that might have stood a long while otherwise. If there is one thing we should all have learned from this experience, it is the relative importance of fluid mechanics in swimming.

Think about it. 180 or so World Records did not fall in 1 ½ years due to some miraculous breakthrough in training, nor in nutrition (even banned performance-enhancers would be hard pressed to match that). Nor is it conceivable that so many swimmers got faster in such a short period of time for any other reason but one. The new suits reduce drag….significantly.

There is no doubt about that. Research has shown that the suits reduce both friction and pressure drag, just by changing the material and compressing the body inside it. I don’t think anyone would have predicted the dramatic effect these suits would have on times when they first appeared. What we now have learned, if we didn’t appreciate it before, is that for the human body in water, little changes can make huge differences in drag….and speed. The lesson to be learned is to not focus on a better suit to make the human body more streamlined, but how to reduce drag on the human body without using the high-tech suits. In other words, we need to focus much more on improving stroke technique to reduce drag, not just on improving aerobic fitness and power.

Recently I had the opportunity at The Race Club to test a Velocity Meter, a very sophisticated device that measures the velocity of the human body in water and synchronizes the velocity to video imaging. There are a few ways to accomplish this, but none are easy. As a physics major in college who studied fluid mechanics, I am fascinated by this new technology. What I learned in just one day from using and studying this Velocity meter was substantial. Basically, it validates what I had suspected all along; that little changes in the water make huge differences. The sensitivity that very small changes in our stroke technique or body position have on drag and the resultant velocity changes in the water is extreme.

Let me give you an example. Most coaches have long known that proper head alignment and high elbows underwater help swimmers go faster. But how much and why? The answer is related to drag.

Using me as a subject, I swam a series of 15-meter freestyle sprints from a push off, with the Velocity meter and video cameras (4) recording about 1000 bites of information per second. Each time I swam, however, I tried to change only one variable but attempted to maintain a constant all-out effort with no breathing. For example, first I swam with my head held very high. Then I swam with dropped elbows. Then, I swam with a bent-arm recovery followed by a straight-arm recovery. Finally, I swam breathing every stroke. Here is what I learned.

The Velocity meter doesn’t just give you an average speed over the 15 meters. It gives you the instantaneous speed at any point in those fifteen meters, so you can match your exact point in the stroke with the speed you are generating. Most swimmers and coaches might be surprised to learn that if your average speed is 2 meters per second (50 meters in 25 seconds), that the speed varies from about 2.6 meters per second at the highest point to around 1.4 meters per second at the slowest, during one single arm stroke. Further, with the kick thrown in, the speed may go up and down four times in that same stroke cycle; ie less than a second. That means quite a difference in speed occurs within just a few tenths of a second over and over again through the race.

Another misunderstanding is that there is some delay between the effect of the forces of propulsion and/or drag and the resultant velocity of the swimmer. Not true. The velocity at any given moment in time is a direct result of the propulsive forces minus the resistive drag forces at that same exact moment. What you see is what you got.

Now for my results: I selected approximately 5 seconds of my swim in the middle of the fifteen meters (after the push off the wall had ended and before I neared the end of the swim) so it was basically pure swimming, unaffected by those two events. First, with my head up, my average speed over that time was 1.89 meters per second. That would translate into a 52.91 for 100 meters if I were able to sustain that speed (wishful thinking). Next, I dropped my elbows and averaged 1.875 meters per second, which translates into 53.33 for 100 meters. With head down, high elbow and bent-arm recovery, I averaged 1.92 meters per second, which is a 52.08 for 100 meters and finally, with straight-arm recovery I averaged 1.874 meters per second or 53.36 seconds for the 100 meters. And for good measure, I did one breathing every stroke cycle (one breath for 2 strokes) and averaged 1.884 m/ sec or 53.07 seconds for the 100 meters. In my opinion, a range of 1.3 seconds in the 100 between the fastest and slowest techniques is significant, particularly when races are won or lost by hundredths of seconds.

Now please don’t come to any wrong conclusions. I cannot say for certain, for example, that straight-arm recovery is not as good as bent-arm, just because I swam faster on one swim. Everybody might be different on that one. Also, the comparison would need to be repeated several times for any swimmer. But I would be willing to bet a lot of money that everyone with a high head and dropped elbows will be significantly slower than the same swimmer with the head down (in alignment) and elbows held high!

What is really exciting here is not only the big differences gained or lost among swims…..but the fact that it provides instant feedback to determine exactly what stroke technique works best for any swimmer. We no longer have to wait until the next race to find out if some change improves our speed or not, and even then, we are never sure. Until now, we have been working off of experience and good hunches; not too scientific.

What kinds of questions about your stroke can the Velocity meter help you answer? Here are some examples:

  1. How many dolphin kicks should I take under water off each wall and the start? Or should I even use a dolphin kick?
  2. What breathing pattern should I be using in freestyle or butterfly? Every stroke cycle, every other, every third?
  3. Why am I coming out a half body length behind on the breaststroke pullout?
  4. Should I front-breathe or side-breathe in fly?
  5. How much faster will I swim in freestyle if I put my elbows very high underwater?
  6. What is my ideal stroke rate for 50, the 100 the 200, 400, 1500, 2 ½ mile ocean swim? For any stroke?

All of these questions and many more are now more easily answered with the objective data from the Velocity meter. With this exciting technology, careful stroke analysis is the new ‘swim suit technology’. But it is perfectly legal. It is called smart swimming.

Yours in swimming,

Gary Sr.

2 Responses to A Lesson Learned

  1. Scott Holtz

    Gary,

    Excellent read…. Wish I was down there for more excellent Tri pool training.

     
    • Gary Sr

      Congrats again, Scott, on a great Tri performance this summer. Look forward to seeing you down here again, soon! Gary Sr.

       

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