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배영 Backstroke
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Ryosuke Irie's time for this event was 1:52.86. Later in 2009, Irie improved on this time while Aaron Piersol established a new world record with a time of 1:51.92.

This analysis features only a frame-by-frame analysis of the swimmer at 140 m (1:18.2 into the swim) in the race. Each frame is .0833 seconds part. The frames captured here do not lend themselves to making a continuous repeating sequence as included in many previous analyses.

This performance was more than one second faster than the existing world record at the time. Such an improvement warranted some investigation. While features that could signal advances in the backstroke technique are discussed, other features of the swim, such as the swimmer's not-so-exact streamline, underwater kicking, and handling of the start and turns leave much to be desired. It is suggested that the reader does not assume that Ryosuke Irie has perfect backstroke racing techniques. Only the features that contribute to his high-level performance should be considered.

Although it is not obvious in the analysis frames, Ryosuke Irie is renowned for the stability of his head, which is impressive in the YouTube video. The commentator on the clip states that he trains with a half-filled water bottle balancing on his head. That is difficult at any time but with the amount of shoulder and hip rotation which is a marked feature of his swimming, it would be extremely difficult to produce the level of stability he exhibits without a great amount of practice.

Some of the general features Ryosuke Irie's stroke are as follows:


  • A large rotation of the shoulders and hips is exhibited, much more than in any other swimmer analyzed on this "How champions Do It" section of this web site. In crawl stroke, the case has been made that rolling the shoulders and hips to the same degree in unison reduces frontal resistance (CRAWL STROKE BODY DYNAMICS IN MALE CHAMPIONS ), which is a major form of resistance in swimming. There is no reason why unified rotation should not occur in backstroke although it is rarely displayed. It is likely that the swimmer's rotation and reduction in resistance is one of the major contributions to his high-level performance.
  • Combined with the marked shoulder and hip rotations, is the deep pull and deep kick. The depth at which these occur, is such that better propulsion is effected. The changes in hydrodynamic resistance with water depth were discussed in a research article by Marino et al. (2010) in the Hydrodynamics Abstracts section of this web site, However, one should understand just how this occurs. There is no attempt to pull or kick deep by this backstroker. It is the high degree of shoulder and hip rotations that places the arms and legs in deeper, more stable water. If the same arms and legs actions were to occur in a flatter swimmer, they would occur closer to the surface (in less stable water). If one coached this, the depth of both actions would be achieved by instructing rotation with no mention of altering the arm or leg movements.
  • From an above the water view, it seems that Ryosuke Irie slows his right hand just as he enters the water at the end of the recovery. It is doubtful that a significant slowing occurs. The impression is likely an optical illusion prompted by the alteration of the hand position as the water is entered. That alteration promotes a "grab" of the water right from the start of the stroke, with the left hand appearing more effective than the right hand.


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

Notable Features


  • Frame #1: The left arm enters. The swimmer could improve his streamline by raising his stomach and hips closer to the surface. The right hand has completed its propulsion and prepares to exit. The left leg is very deep and prepares to counter-balance the right-arm exit. In this position, the leg should be able to produce some propulsion in the early stage of the kick. However, to get to this position, the lower leg would have created considerable drag. It is doubtful if the amount of propulsion that results would exceed the amount of drag created. [At the Western Australian Institute of Sport, it has been shown that in underwater kicking it is better to kick small and fast rather than big and powerful. To get to a "powerful" position, the drag created exceeds the propulsion generated. The same implication exists for this swimmer's right leg kick.]
  • Frame #2: The left arm enters and the hand rolls to produce a grab on the water. The left leg kicks to counter-balance the vertical force created by the backward and upward sweeping right arm exit. The hips rise slightly.
  • Frame #3: The right shoulder and hip rotate upward while the right hand remains low although the upper arm rises. This completes a longer-than-normal push back with the right arm. The left leg kick is completed. The body appears to straighten to a slight degree. The roll of the shoulders and hips places mostly vertical pressure on the left arm.
  • Frame #4: The body continues its rotation to the left. It appears to have improved its streamline than that shown in Frame #1. [However, one cannot be sure of this because of the lateral view possibly obscuring any lateral bend at the hips.] The left arm remains straight and presses down. The right arm has exited the water. The positions of both legs provide a momentary improvement in streamline although the right leg begins to be repositioned for the next kick. The right leg kicks under the left leg (the backstroke equivalent of a crawl stroke cross-over kick).
  • Frame #5: The hips and shoulders have almost completed the rotation to the left. The right leg continues to be repositioned. At first glance, it seems that the leg will not kick deep but the hip rotation means the foot is moving to the side and down. The left arm is increasing in its force and is producing considerable drag force (see the amount of turbulence following the upper arm surface) although only a small portion would be a horizontal force component.
  • Frame #6: The left arm is very deep for a backstroker. The shoulder rolls a little more so that the swimmer leans a large amount of bodyweight on his arm. The size of the horizontal force component produced by the left arm increases. The right leg still is repositioning preparatory to kicking.
  • Frame #7: Possibly in this position, the horizontal and vertical force components of the left arm are similar. The recovering right arm has just passed vertical. The right leg prepares to kick.
  • Frame #8: The left shoulder and hip and the body rotation are at their maximum. The right foot kicks to counter-balance the left arm pulling action's tendency to roll the shoulders and hips upward. Some propulsive force is produced by this foot action. The left leg is repositioning preparatory to kicking. The left arm is deep and propelling mainly backward (drag turbulence is on the front side of the arm). There is an elbow bend in this arm that places it in a propelling position for the rest of arm action. The recovering arm is about 45� to the surface.
  • Frame #9: The hips and shoulders begin to rotate to the right. The right leg kicks and assists the body rotation as well as counter-balancing the vertical component of the latter part of the left arm pull. The left leg appears to be approaching a position of exaggerated drag resistance production. The hips appear to be low, which suggests throughout the stroke, maximum torso-hip streamline is not be attained. The right arm nears entry.
  • Frame #10: The shoulders rotate rapidly, with the hips slightly behind, to accommodate the right hand that has just entered the water. The right leg completes its kick. The left arm/hand continues to push backward although exactly how that is done is obscured by the swimmer's hips.
  • Frame #11: The right arm has entered but does not appear to be straight. The left leg kicks. The body seems to have a slightly improved streamline when compared to the position in Frame #1.
  • Frame #12: The more streamlined body position is maintained. The left leg begins to kick under the right leg (a "cross-over kick" again). The left arm continues the very latter stage of propulsion. The right arm begins to reposition, having to straighten first.
  • Frame #13: The shoulder and hip rotations to the right become more obvious. The right arm is being repositioned although it is still not straight and capable of producing propulsive force. The legs cross-over at the end of the left leg kick. It is not possible to tell what the left arm is doing.
  • Frame #14: The right arm has been straightened and begins to bend in a preparatory propulsive manner. The right leg kicks and the left leg is lowered preparatory to kicking.
  • Frame #15: As the right shoulder and hip rotate to the right, the right arm begins to bend at the elbow producing a propulsive force, although it is not that substantial at this stage. Abduction of the right shoulder provides arm force. [The asymmetry of both arm actions is notable, although not worthy of emulation.] The right leg continues kicking and the left leg nears a position to begin kicking.
  • Frame #16: The right arm is in a good propulsive position. The right shoulder and hip are almost finished their rotation. The right leg finishes its kick. [The cross-over actions and irregular rhythm of the kicking action indicates that unusual and asymmetrical actions of the arms occur.]
  • Frame #17: The right arm continues to bend at the elbow. The left leg kicks as the right leg is drawn away from it and sinks lower in the water.
  • Frame #18: The right arm bends rapidly and adduction of the upper right arm occurs. The left leg kicks high toward the surface and the right leg sinks lower.
  • Frame #19: The right arm pushes back and slightly down. The width of the kicking left foot and preparatory right foot kick is very notable, and possibly undesirable.
  • Frame #20: A position similar to that exhibited in Frame #1 is attained.
  • Frame #21: A position similar to that exhibited in Frame #2 is attained.


Ryosuke Irie was the best male backstroker over 200 m in the world at the time of this swim. However, his technique leaves many aspects that if corrected, should lead to faster swimming times. It is somewhat difficult to understand how he could be so good in terms of performance with unsymmetrical actions, a non-streamlined body position, and poor overkicking in his technique. The major strength of his swim is the combined shoulder and hip rotations to both sides. The reduction in frontal resistance and probably the better use of the internal and external rotator muscles of the shoulders that could produce greater and more enduring forces could contribute to better swimming.

It would be very interesting to see what performance changes would result if the critical-fault features of Ryosuke Irie's technique mentioned here were changed.

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