Lift or Drag? Let's Get Skeptical About Freestyle Propulsion

Submitted by marcrandell on Tue, 10/19/2010 - 20:51

Swimming

Airfoil Here's an interesting article about freestyle swimming. I still hear this debate in forums. It seems that the 'elite' swimming community has accepted that the 'S' curve / Counsilman theory on lift was not quite scientifically sound. I still hear swimming vigilantes advising folks to apply this technique.

The point of the article, of course, is that a healthy bit of skepticism is important. In a few years, we may find that we did not really understand the stroke in 2010.

Here's a great clip from the article. It really gets to the point of how easy it is to be tricked by our eyes, and believe in a hypothesis without real proof.

"Through a combination of experiment and simulation, Liu et al. (1993) and Hay et al. (1993) showed that the curved path of a swimmer's hand is due to body roll. In fact, when the arm is simulated to move directly backwards with respect to the swimmer's reference frame, the path of the hand in the external reference frame is more curved than in actual swimming. This means that swimmers actually straighten the curve somewhat. This has important implications. It means that the curved hand path is not deliberate. Rather than swimmers adducting the arm to produce the "insweep" and then abducting to produce the "outsweep", as is commonly demonstrated by coaches when instructing on poolside, the swimmers are actually reducing the curve by abducting in the early part of the pull and adducting during the latter part of the pull. The fact that swimmers attempt to straighten the path rather than to use sculling actions is strong indirect evidence that swimmers rely on drag forces rather than lift forces."

Read the entire piece at Sprtsscience

Comments

Anchoring

Submitted by coacherik on Thu, 10/21/2010 - 11:35.

Kids often think too much about moving their hands and arms because it is right in front of their eyes. At a certain point the light goes on and they see their times drop considerably after they adapt to the added muscle recruitment that comes with anchoring (using the bigger muscles in the back versus the shoulders and arms) versus pulling.The biggest thing with this is convincing them that the "slower" pull is better. The hands used to slip through the water feeling faster (which is true in a way).

Another thing that is often taught and blows my mind is the high elbow recovery. It is not taught in conjunction with the rest of the body at times, resulting in a flat body position and compromised shoulder (I hate fingertip drag as a result and don't use it unless a swimmer sweeps really wide on their recovery).

Too often it is told as the only way to swim/recover the arm forward. As we have seen, that is both true and untrue. In straight arm recovery or the classic high elbow recovery (I try and teach a hybrid middle ground), the elbow is in fact high in both, but may not be the highest point. As long as the recovery elbow stays inside the scapular plane and is serving its purpose of the hand getting out front quickly with out effecting the path of the body down the pool, it should not matter if the elbow is highest or not. if you have a high elbow recovery, you have to roll the body that much to keep the shoulder from being compromised.

I teach my kids several key points. #1- The recovery must be relaxed and guided towards the front of the stroke. #2- The fingertips should lead the recovery forward, with the palm slightly inward. (Kids have tendancy to lead with the back of the elbow and hand, putting a ton of stress on the shoulder joint). #3- The shoulder/hip of the recovering arm is driven into the stroke (proactive) versus clearing the hip out of the way of the recovery, which often times is not done far enough (reactive). #4- The hand enters in front of the shoulder, anchors under the shoulder (solid line from elbow to fingertips, elbow bend depends on length of race and strength of swimmer) and the body goes past that point. #5- The hand is released early to get into the recovery faster and out in to the more powerful part of the stroke (Quick/Faster Fast).

I think we need to rely on what the body gives us more, especially the comfortable positions (anatomical position) during recovery (specifically BK, Fly & Free) to avoid overuse injuries.

Good comment

Submitted by Anonymous Athlete on Fri, 10/22/2010 - 13:57.

Good Comment coacheric.

It seems to me that a high elbow or straight arm recovery are both good ways to swim. The reason that we teach the high elbow is that for most swimmers, this corrects other body line issues, and gets the hand into the proper position for the catch. I can see the validity of fingertip drag, but I would also agree that if a swimmer is successfully using a straight arm recovery, not to 'fix it'