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배영 Backstroke
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Each frame is .1 seconds apart. Aaron Peirsol's time for this 200-m backstroke race was 1:57.13.

This stroke analysis includes a moving sequence in real time, a moving sequence where each frame is displayed for .5 of a second, and still frames.

The following image sequence is in real time. It will play through 10 times and then stop. To repeat the sequence, click the browser's "refresh" or "reload" button.

The following image sequence shows each frame for half a second. It will play through 10 times and then stop. To repeat the sequence, click the browser's "refresh" or "reload" button.

At the end of the following narrative, each frame is illustrated in detail in a sequential collage.

Notable Features

  • Frame #1: The swimmer has good streamline. The lumbar curvature of the back is pronounced as the stomach and hips are held to the surface. The left leg has sunk to below the shoulders-hip cross-sectional profile. The right arm is deep and preparing to execute an inward and upward sweep (a sculling movement).
  • Frame #2: The left arm enters long and behind the shoulder. It is not exaggerated (not behind the head). Streamline continues to be very good. The left leg kicks. The position of the left leg is such that a propulsive horizontal force component can be created. The amount of knee bend and some hip flexion is something that cannot be achieved in crawl stroke swimming. Good backstroke kicking is not "upside down crawl kicking". The right arm is fully extended with the hand beginning its sculling movement to add to its role of counterbalancing the entering left arm's vertical force production.
  • Frame #3: The left arm bends immediately to orient force application backward. Bending early will produce a long impulse force that will minimize or prevent any drop in propulsive application. No downward movement to start a vertical "S-shape" pull occurs. There is an overlap between the right arm upward sweep and the left arm propulsive phase that negates any major inertial lag. This type of stroke suggests that backstroke can allow almost constant force production, with fluctuations only in the magnitude of developed forces. The left leg performs a minor corrective movement (probably to "steer" the swimmer) and the right leg drops down. The swimmer's streamline is obvious here.
  • Frame #4: The left arm bends at the elbow and medial rotation of the upper arm occurs. This positions the hand and forearm to be the primary propulsive surface. Abduction of the upper left arm provides power to the pull. Here it is obvious that the pulling action of the arm in this early stage is very similar to that of correct crawl stroke. The right leg kicks to counterbalance forces created by the pulling left arm. The left leg drops down preparing to kick. It is hard to imagine the streamline of the swimmer being any better.
  • Frame #5: Abduction of the upper left arm powers the pull. In this position, the propelling surface has increased to include the upper arm. With the arm well to the side and creating a considerable lateral force, a corrective steering action is performed by the left leg. The arm-pull mechanics here are very similar to desirable crawl stroke. The hand is travelling almost directly backward putting to rest the erroneous concept of a down-up-down or S-shaped pulling path.
  • Frame #6: The left arm is at right angles to the body. The hand-forearm propelling surface is orthogonal to the line of horizontal movement. The legs are executing minor movements to steer the swimmer and to produce some counterbalance to the later forces created by the pulling arm. It should be noted that the rapid 6-beat leg movements do not allow the hips enough time to roll. They remain relatively flat throughout the stroke. Also, so that six leg movements can be completed, the depth and magnitude of the leg and foot movements are relatively small. That facilitates completing them in the 1.3 seconds of the total stroke cycle.
  • Frame #7: The left arm continues to push directly backward.
  • Frame #8: As the long straight right arm approaches the water, it creates considerable vertical force. To counterbalance that relatively large force, not only does a left leg kick occur (it is being prepared here) but the left arm begins to push down and backward.
  • Frame #9: The action of the left arm in the pull is distorted by the angle from which the sequence was photographed. It is not possible to be as accurate or detailed in describing its movement pattern. As soon as the left arm enters the wrist bends to orient the hand backward. The left leg has kicked to counterbalance the vertical force developed when the water was contacted. The left arm is deep, relative to the left shoulder, and is positioned to execute an inward and upward scull.
  • Frame #10: The right arm bends to present the hand-forearm propelling surface to create direct force. The "milky" drag turbulence at the back of the arm can be seen. The amount of shoulder and hip roll is distorted because of the angle of photography. Some rotation does occur, but not a great amount.
  • Frame #11: As with the left arm pull, the right arm produces primarily horizontal forces for a long period in the stroke. Streamline is maintained as it has been throughout the whole stroke.
  • Frame #12: The whole right arm is creating a large drag force to propel the swimmer forward.
  • Frame #13: The right arm is in the last stage of thrusting backward. Here, most of the thrust occurs with the hand, the upper arm being taken out of a beneficial position, and the forearm rapidly losing a position of advantage as it adducts inward.

This stroke is characterized by excellent force production. Propulsion begins almost immediately upon entering. From there, forces are generated horizontally with almost an absence of vertical movements of the hands. This stroke is very different to what is described by "lift" theorists and those who advocate "sweeping" phases in the stroke. Stroking power comes from abduction and adduction of the internal and external rotator muscles of the shoulders.

Aaron Peirsol's stroke has characteristics that should be used as teaching cues for backstroke instruction.

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