The time between each frame is not known (this analysis is from a slow motion clip). Because of the quality of the video, it is only possible to view Jodie Henry's right arm pull. Jodie Henry's time for this event was 53.84 seconds.
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.
- Frame #1: The right arm enters and stretches fully forward while the left arm continues to propel. The entering arm develops a considerable amount of drag. The depth of the kick of the left leg is no lower than the body + thigh profile. Streamline appears to be less than optimal.
- Frame #2: The left arm begins to exit the water. The upper right arm begins to medially rotate at the same time as does right elbow flexion. Streamline improves.
- Frame #3: Medial rotation of the upper right arm and elbow flexion continue with the purpose of repositioning the forearm and hand that eventually will serve as a major propelling surface. Streamline is stable and good. The left arm has exited the water. A large right foot kick begins to offset the vertical force component of the exiting left arm.
- Frame #4: Right arm repositioning continues. The upper right arm is still extended fully forward. This position contrasts with the common "American crawl stroke style", which at this time would have abduction of the upper arm well under way.
- Frame #5: Right arm medial rotation continues as does elbow flexion. Upper arm abduction begins. The developing drag force pocket of turbulence can be seen off the lower right arm and hand.
- Frame #6: Right arm medial rotation and elbow flexion continues as abduction increases. Propulsive force increases and is indicated by the growing pocket of turbulence of the hand and lower forearm. The left foot is near the surface being preparatory to kicking.
- Frame #7: Very vigorous abduction of the right upper arm occurs. At this stage, the whole arm is the propelling surface, not just the forearm and hand. Because of the swimmer's velocity through the water, the drag pocket off the right arm will be small but at the same time, will be effective in generating fast swimming speed. Some unusual event that is not readily evident has caused considerable turbulence off the right hand and wrist. The left arm is approaching entry. As with most champion crawl stroke swimmers, the time that the recovering arm spends out of the water is minimized.
- Frame #8: The angle from which this video clip was taken does not show the amount of shoulder roll that has occurred. In this frame, the right shoulder is lower than the left. However, the six-beat kick requires the hips to remain relatively horizontal throughout most of the stroke. Thus, this stage of the stroke demonstrates torso roll (twist) with stable hips. The depth of the right shoulder would not match that of a distance crawl stroke swimmer performing at race pace. Abduction of the right upper arm is almost complete with the hand, forearm, and upper arm positions being essentially the same as in Frames #6 and #7.
- Frame #9: The upper right arm is now adducted with the whole-arm-propelling surface maintaining its position. The right leg prepares to kick.
- Frame #10: Right arm adduction continues. The right leg kicks causing the right hip to rise and the left hip to dip. This is important. It moves the right hip out of the way of the path of direct propulsion of the right arm. If the hip were not rotated up, the hand would have to sweep more to the side. In this swimmer, shoulder and hip rolls are more complex than in champion distance swimmers who usually use a coordinated hip and shoulder roll (see Crawl stroke body dynamics in male champions).
- Frame #11: Right arm adduction is complete. The right elbow is close to the water surface but the lower arm and hand are vertical and generating propulsion. The right hip has rotated upward. The left arm is pressing down, as can be seen by the drag pocket along the upper surface of that arm.
- Frame #12: The right leg has completed its kick and the hips have rotated moving the right hip out of the way of direct propulsion produced by extension of the right arm. The left arm continues to press down. [At this stage the swimmer is looking mainly forward, which could be an artifact of gauging a finish as the wall is approached.]
- Frames #13 - #19: In Frame #13, the right hand exits the water. The left upper arm medially rotates and the elbow flexes. The angle from which the video was taken obscures clear understanding of the various actions in the remainder of the pull. What is obvious is that the drag pocket turbulence of the left arm is very noticeable in this stroke. It too could be an artifact of the swimmer positioning herself for a good finish on the wall.
Jodie Henry's right arm action exhibits the good mechanics that differentiate today's swimming champions from those of yesteryear. It demonstrates one of the most misunderstood features of swimming, the concept of "stroke length".
When the coaches at Indiana University in the mid-1960s first discussed stroke length, it was conceptualized as being the length of effective propulsion achieved underwater. Over time, that was distorted to generally mean the distance from the point of entry to the point of exit of a stroke -- something easy for a coach to see but in reality, a feature that is relatively meaningless. Jodie Henry, and other champions exhibited on this web site, achieves a very long effective stroke length. The repositioning of the forearm and hand by medially rotating the upper arm and flexing the elbow while the upper arm is extended forward allows for very long and effective propulsion. The arm is repositioned and then through abduction-adduction of the upper arm, the total arm surface is used to generate drag forces that propel the swimmer forward. Rotation of the upper arm in the shoulder produces outward and inward lateral movement paths, which are largely cancelled out by appropriate shoulder and body roll (see Hay, Liu, & Andrews, 1993). This web site presents information that focuses on what happens underwater. That is where propulsive forces are developed and consequently, stroke length is considered as the length of effective propulsion developed underwater. That concept should always be understood and remembered when analyzing and reviewing the exhibits of this web site.