Swimmer's Hand Movements in Water Create Resistance

[Barry1492]

I'm a competetive triathlete (and an engineer) and took a swim clinic last week. One of the things I was taught was that by making little "S" patterns with my hand as I pull myself through the water, I can create more resistance with which to pull me through. I tried this and noticed that the instructor was, in fact, correct.

Background: For those of you who don't swim, the idea is that you DON'T want your hand to slip in the water. If you use a reference point on land and observed a novice swimmer, you would notice that his hand exits the water behind the point where he put it in. In otherwords, he reaches a head of himself and it slips through the water as he pulls and exits at his hip. If you would observe an elite swimmer, the hand does not slip in the water. Instead, the hand remains static as he pulls his aerodynamic body through the water and the hand exits IN FRONT of where it entered.

Question: What causes this?
I spoke with a fluids professor today and he has some ideas, but admitted that it is mainly based on conjecture. I'd like to see what you think before I post what he had to say.

-Barry

 

[MikeHalloran]

Related questions arise w.r.t. rowing. Bill Atkinson has published some material that may be of interest. See

http://www.atkinsopht.com

Mike Halloran
Pembroke Pines, FL, USA

 

[BRT549]

There was an article in a recent "Chemical & Engineering News" about a test whereby about 300 kg of guar gum was added to a pool to increase viscosity. The theory to be tested was that the increased drag would be offset by the increased force the swimmer could exert. Elite swimmers were able to get within 4% of their times in water when swimming through the snot.

I'm not sure how making S-wiggles with your hand would exert more force. Maybe the s-shape keeps your hands perpendicular to direction better. Other than having bigger hands or webbed fingers, how else would you maximize surface area of your hands?

 

[eric1037]

As a former competitive swimmer, I can tell you that using and "S" stroke does keep your hand perpendicular to the water. Also, the last third of the stroke is where you really get your power. This is because you are pushing your self rather than pulling and your tricep is a stronger, larger muscle.

Many novice swimmers pull their hand out of the water before they ever get to the most powerful part of their stroke.

Another thing about elite swimmers that you will notice is their long, lean body shape. They are more hydrodynamic. Swimming is much more about technique and body shape than it is about strength.

When I was swimming competitively, I noticed that many girls were better in their freshmen or sophomore years of high school, before they were fully "developed". When they grew, their bodies quite often became less hydrodynamic.