Each frame is 0.1 seconds apart. Kirsty Coventry's time for this event was 2:04.81.
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.
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At the end of the following narrative, each frame is illustrated in detail in a sequential collage.
- Frames #1 and #2: The left arm enters with the hand behind the head. The arc of the arm causes unnecessary drag as is evidenced by the large amount of turbulence streaming rearward in Frame #2. The right hand is deep at the end of its propulsive phase, the vertical force component serving to largely counterbalance the entering arm. Finishing with a deep pull like this in backstroke is equivalent to a crawl stroke swimmer swimming with the propulsive arm mostly under the body's centerline. Kirsty Coventry is very well streamlined.
- Frame #3: As the right arm rounds-out and sculls upward to initiate the exit, the left arm repositions to orient the hand directly backward. This occurs as the elbow bends and the upper arm abducts. The good feature about this frame is that it illustrates the lack of any appreciable inertial lag, that is, it conforms to Newton's First Law which when applied to swimming implies that swimmers should find ways to minimize any loss of propulsive force when progressing through the water (i.e., as one arm-stroke finishes, the next should start). When this application is contrasted to the excessive inertial lags demonstrated in crawl stroke (see Paul Biedermann's analyses) one has to question why Newton's First Law is so important for backstroke but flaunted in crawl stroke. The left leg kicks to counterbalance the vertical force components of the exiting right arm.
- Frames #4 though #7: The left arm's direct horizontal force production can be seen in this sequence. The right leg kicks to counterbalance the lateral force component (twisting force) that cannot be avoided with the left arm off to the side. This is an excellent example of positioning the propelling surface of the total arm and powering the force application with abduction that phases into adduction. The swimmer's excellent streamline assisted by the head being well back in the water is worthy of note.
- Frame #8: The left arm accelerates with adduction and elbow extension producing both horizontal and vertical force components. The amount of drag-pocket turbulence created indicates the degree of power exerted in this position. The vertical force counterbalances the recovering left arm and reduces the need for a kick. The extent to which the head is held in alignment with the straight spine is obvious.
- Frame #9: The left arm continues its adduction, elbow extension, and thrush back and down to counterbalance the just-entered right arm. The head remains well back in the water.
- Frame #10: The left arm completes its full extension to below the buttocks. The right arm is oriented backward. It is worthy to note the absence of any deep dive on either arm's entry. In contrast to the emphasis on entering the water "little finger first", which resulted in the hand and arm plunging deep before developing propulsion (the "S-shaped" pull that often is still advocated), Kirsty Coventry's propulsive arm-path, as well as that of Aaron Peirsol, does not compromise on developing direct backward thrust immediately upon entry. This valuable point cannot be over-emphasized.
- Frame #11: The upper body and hip roll to the right are clearly seen here. They occur as the left arm exits the water. The right arm immediately repositions to produce propulsion backward by flexing at the wrist and elbow and adducting the upper arm. The right leg kicks to counterbalance the left-arm recovery.
- Frames #12 and #13: The right arm continues to develop power. In Frame #13, the drag pocket has developed from the shoulder to the fingers and is quite sizeable. The swimmer remains rotated to the right which puts the line of right-arm force closer to the mid-line of the swimmer and allows the recovery to also be made closer to the mid-line. Both actions serve to reduce the size of lateral force components. The head remains well back.
- Frames #14 and #15: The powerful contraction of the external and internal shoulder rotators is responsible for the direct powerful arm pull. Frame #15 marks the end of the body rotation because the recovering arm has passed the highest point in its movement path.
- Frame #16: As the recovering left arm stretches backward and approaches the water, the right arm adds vertical thrust to counterbalance the left arm entry.
- Frame #17: The stroking sequence begins again.
Kirsty Coventry displays a very efficient form of backstroke. The almost constant application of emphasized horizontal propulsive force is especially impressive. The immediate reposition of the hand/arm on entry to begin applying force puts to bed any consideration of an S-shaped pull in backstroke. Much of what this swimmer does is worthy of emulation.
The entry into the water of possibly each whole-arm is the only alteration that is recommended.