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  #31  
Old 06-22-2012
RodHavriluk RodHavriluk is offline
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Suzanne,

I’m glad you’re enjoying the discourse as well. My participation in this forum was prompted by someone citing information from my website (swimmingtechnology.com). My goal was to address the comments with science and I’m fine with expanding the discussion.

I’m also glad to hear that you don’t teach catch-up stroke. However, the swimmer in the logo image at the top of this page has a negative IdC (Index of Coordination). There is a gap in propulsion. The submerged arm has not begun propulsion and the opposite arm (above the surface) has already completed the exit phase. A negative IdC is generally referred to as catch-up coordination. The important point is that the source of propulsion is not continuous - resulting in fluctuations in body velocity, a less efficient use of energy, and slower swimming.

Research that supports a continuous source of propulsion dates back to Counsilman (1955). Numerous studies supported Counsilman’s work. Over the past decade, Seifert and his research group showed that the IdC increases with performance level and swimming velocity. A negative IdC limits performance at any ability level.

To clarify the issue about stroke rate - the arms do not have to move faster throughout the stroke cycle because of a steeper arm entry angle. The stroke rate does increase, however, when wasted time is eliminated by completing the arm entry with the hand deeper than the shoulder – and not parallel to the surface as shown in the image above.

In addition to wasting time, a parallel arm position stresses the shoulder. (A US Olympic Swim Team physician and trainer, and a USA Swimming national team physician co-authored a paper explaining the risk of harmful technique- http://www.swimmingworldmagazine.com...tary/30442.asp.)

In response to Hashu's comment, moving the arm slowly from parallel to the surface to a position where propulsion can be generated lengthens the “time of exposure” to the arm position that stresses the shoulder (as explained by Becker). I hope it’s also obvious that moving the arm slowly through that range of motion (to minimize force) is inconsistent with fast swimming.

Swimmers at all levels can learn to swim with the arms opposite in synchronization (an IdC = 0). Initially, the arms can be moved slowly through the stroke cycle to maintain a body position that minimizes resistance. As stroke rate increases, the recovery arm can move through the air slightly faster than the submerged arm moves through the water, which increases the IdC to a positive value. Seifert’s research also supports the fact that a positive IdC is necessary for the fastest swimming.

Rod
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  #32  
Old 06-22-2012
CoachSuzanne CoachSuzanne is offline
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Quote:
Originally Posted by RodHavriluk View Post
Suzanne,

I’m glad you’re enjoying the discourse as well. My participation in this forum was prompted by someone citing information from my website (swimmingtechnology.com). My goal was to address the comments with science and I’m fine with expanding the discussion.

I’m also glad to hear that you don’t teach catch-up stroke. However, the swimmer in the logo image at the top of this page has a negative IdC (Index of Coordination). There is a gap in propulsion. The submerged arm has not begun propulsion and the opposite arm (above the surface) has already completed the exit phase. A negative IdC is generally referred to as catch-up coordination. The important point is that the source of propulsion is not continuous - resulting in fluctuations in body velocity, a less efficient use of energy, and slower swimming.

Research that supports a continuous source of propulsion dates back to Counsilman (1955). Numerous studies supported Counsilman’s work. Over the past decade, Seifert and his research group showed that the IdC increases with performance level and swimming velocity. A negative IdC limits performance at any ability level.

To clarify the issue about stroke rate - the arms do not have to move faster throughout the stroke cycle because of a steeper arm entry angle. The stroke rate does increase, however, when wasted time is eliminated by completing the arm entry with the hand deeper than the shoulder – and not parallel to the surface as shown in the image above.

In addition to wasting time, a parallel arm position stresses the shoulder. (A US Olympic Swim Team physician and trainer, and a USA Swimming national team physician co-authored a paper explaining the risk of harmful technique- http://www.swimmingworldmagazine.com...tary/30442.asp.)

In response to Hashu's comment, moving the arm slowly from parallel to the surface to a position where propulsion can be generated lengthens the “time of exposure” to the arm position that stresses the shoulder (as explained by Becker). I hope it’s also obvious that moving the arm slowly through that range of motion (to minimize force) is inconsistent with fast swimming.

Swimmers at all levels can learn to swim with the arms opposite in synchronization (an IdC = 0). Initially, the arms can be moved slowly through the stroke cycle to maintain a body position that minimizes resistance. As stroke rate increases, the recovery arm can move through the air slightly faster than the submerged arm moves through the water, which increases the IdC to a positive value. Seifert’s research also supports the fact that a positive IdC is necessary for the fastest swimming.

Rod
We don't teach parallel arm either.The logo is a logo...perhaps misleading. I've thought that it needs updating for awhile.

Anyway, we can go in circles with this discussion. on one hand you are saying that swimmers should learn an IDC of 0, but then that a postitive IDC is needed for fastest swimming. So if that's valid why is it any less valid to learn a "more positive" IDC first and then migrate to a slower one as your technique and form develops?

Changes in speed throughout the stroke cycle are a given...they are never going to go away even if you swim like Janet Evans, it's not possible.

instead, learning to minimize resistance in-between propulsive elements will result in a net higher velocity by raising the lowest point of the velocity cycle..even if the highest point stays the same (propulsion isn't increased).

Durign the most propulsive part of your stroke, I also believe that you should be in the most strealined part of your stroke which is with the lead arm extended...a longer body in the water AND a more tapered leading point. it may not be perfect but a tapered lead point (the hand & arm) allowing water to part around the body is still more tapered than the top of the head.

My proposal is that the streamlining and drag reduction benefits with one arm leading as the other arm has reached it's most propulsive point far outweigh the energy costs of trying ot add propulsion throughout the stroke cycle.

as a swimmer develops the propulsive stroke can begin prior to the point where diminishing velocity becomes an energy cost itself. This is part of the fun of developing into a faster swimmer.
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Suzanne Atkinson, MD
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USA Paralympic Triathlon Coach
Coach of 5 time USA Triathlon Triathlete of the Year, Kirsten Sass
Steel City Endurance, LTD
Fresh Freestyle

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  #33  
Old 06-22-2012
CoachSuzanne CoachSuzanne is offline
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I state my case, noting that this is a typical adult learner. It's VERY difficult to create the type of propusive, fast, efficient, fluent streamlined stroke that Rod & Terry are both promoting for a swimmer like this by focusing on oppositional stroking. He has to get to the point where he can feel a streamlined glide through the water with drag minimized before any propulsive element of his stroke will make a significant contribution

http://www.youtube.com/watch?v=T8lLA...ature=youtu.be

(This video was posted on beginner triathlete...advice received was both good and bad but among them included stroke faster and get in better condition)
__________________
Suzanne Atkinson, MD
Level 3 USAT Coach
USA Paralympic Triathlon Coach
Coach of 5 time USA Triathlon Triathlete of the Year, Kirsten Sass
Steel City Endurance, LTD
Fresh Freestyle

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  #34  
Old 06-27-2012
RodHavriluk RodHavriluk is offline
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Suzanne -

That’s a really good point that you brought up about the IdC shifting to positive values for faster swimming. Keeping the arms opposite is a relatively simple coordination exercise that accelerates the learning process for other key technique elements, such as complying with the four critical arm checkpoints. Once a swimmer learns an arms opposite synchronization (IdC = 0), increasing to positive IdC values is fairly naturally with an increase in swimming speed (as Seifert has repeatedly shown).

If the arm is parallel to the surface so that it is in line with the body, there is less than a 3% overall decrease in resistance (based on data in Vorontsov’s book chapter). If the arm is maintained motionless and not parallel to the surface, the body cross-section (and resistance) will be increased. Immediately beginning the pull instead of keeping the arm motionless can increase propulsion by more than 25%. The trade-off is heavily weighted in favor of continuous arm motion.

Haschu -

The “catch” is the transition “point” between the entry and pull (when the hand changes direction from forward to backward). Vertical or lateral hand motion between the entry and pull (i.e. a catch “phase”) is wasted time and effort.

Good question about a study on entry angle. See if this helps - http://www.swimmingtechnology.com/in...-in-butterfly/

Rod
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