HOW CHAMPIONS DO IT
Researched, produced, and prepared by Brent S. Rushall,
AMY VAN DYKEN'S FULL ARM ACTIONS AT 35 m OF HER 50 m GOLD MEDAL RACE AT THE 1998 PERTH WORLD CHAMPIONSHIPS
The time base of this sequence is not known as it was downloaded from a slow-motion video clip. However, the duration between each frame is constant.
- Frame #1: The left arm enters, as the right arm is in mid-pull. The almost flat surface of the combined upper and lower arm and hand demonstrates the application of maximum drag force. As is usual with sprinters the elbow angle is not as sharp as that demonstrated by most distance swimmers. This presumably optimizes lever effectiveness in this facet of the stroke. Power for the right arm is applied through adduction of the upper arm. The shoulders are rolling to position the entering left arm. The head is well down with the face-profile parallel to the surface.
- Frame #2: Right arm propulsion continues powered by adduction. The principal propulsive surface of the hand/forearm is quite evident as it remains almost at right angles to the direction of progression even though the upper arm begins to rise. The left arm enters with the wrist slightly flexed, the hand flat, the elbow extended, all on a fully elevated shoulder. The shoulders are flat.
- Frame #3: Right arm propulsion continues as adduction is completed (the upper arm is virtually at the swimmer's side). Propulsion still continues with the hand/forearm surface. As the right shoulder is depressed in the final stages of adduction, further left-arm forward reach is attained by elevating the left shoulder as a counter-balancing movement.
- Frame #4: Right arm propulsion is completed and the extraction phase begins. It should be noted that in these first four frames, the path of movement of the right hand is back and up, suggesting that it has been too deep in the middle of its pull. Vertical movement components such as this produce slip and reduce effective propulsion while still requiring effort. In concert with loss of right-arm propulsion, the left arm begins to create its propulsive force. By medially rotating the upper arm and bending at the elbow while maintaining slight wrist flexion, the left arm starts to build propulsive force. This is a good mechanical feature. There is possibly a reduction in propulsive force for the total swimmer's system but the continuity of force production reduces any drastic inertial lag. The swimmer's streamline is well demonstrated and maintained as the shoulders and hips roll together to the left.
- Frame #5: The left elbow remains high due to continued medial rotation of the upper arm on an elevated shoulder. Propulsion increases as the hand/forearm propelling surface progresses towards an optimally effective position for force production.
- Frame #6: The left hand/forearm continues to be positioned through further elbow flexion and upper arm medial rotation. The left upper arm begins to adduct. At this position, the shoulders and hips have achieved maximum rotation. The amount of rotation is possibly less than the amount demonstrated by distance swimmers. This is because rotation takes time and to turn any more would require extra time that would delay or stall the opportunity to produce arm propulsion.
- Frame #7: Violent upper-left-arm adduction occurs creating force with the whole arm. The degree of force is demonstrated by the white-water/eddies that trail the whole arm. This frame is well into a very effective propulsive phase of the stroke. The shoulders have already begun to rotate back to the other side.
- Frame #8: Emphatic adduction of the left arm occurs and large propulsive forces are created. It is interesting to note from a theoretical viewpoint that the trailing white-water eddies indicate the swimmer is generating large drag forces. Such eddies are telltale signs that large drag forces are in effect. If propulsive lift forces were created then those obvious eddies would not exist. The head is turning to the left preparatory to breathing.
- Frame #9: Powerful left arm propulsion continues as adduction nears its effective limit. The right arm enters fully stretched forward eliminating any time required for repositioning. The head continues to turn. In frames #7-#9 the path of the hand/forearm is almost directly backward indicating the production of very direct propulsive forces.
- Frame #10: Left arm adduction is completed and the hand/forearm propulsive surface is at the end of its maximal effectiveness. From this position on, the left arm will extend at the elbow to eke-out more, but diminishing, propulsion. The right arm begins to bend at the elbow and the upper arm commences to medially rotate. The shoulders and hips rotate to the right more at this time possibly contributing to the creation of a better breathing "pocket" on the left side.
- Frame #11: The left arm completes its propulsive phase as the right arm begins to create propulsion (eddies can be seen developing on the back of the right hand). Inhalation begins. Because the swimmer is moving fast through the water a bigger bow wave is created resulting in a deeper breathing pocket. Consequently, sprinters do not turn their heads as much to breathe as do slower-moving distance swimmers.
- Frame #12: Right arm propulsion is well underway as the left arm is extracted. The swimmer does not demonstrate the same degree of upper-arm medial rotation as was shown with the left arm. Propulsion comes mainly from the hand and lower-forearm as the path of movement is both down and back reducing the economy of energy use and effective force production. This contrasts markedly to the direct propulsion of the left arm as demonstrated in frames #7 through #10. Breathing is completed and the head begins to return to its facedown position.
- Frame #13: The right arm continues to press down and back. This action is not as powerful as that of the left arm. The absence of telltale eddies indicates the size of the developed drag force and supports this interpretation. As well, the length of time (i.e., the number of frames) for completion of right arm propulsion is longer than that for the left arm. The head has returned and looks forward and down.
- Frame #14: Right arm propulsion continues down and back.
- Frames #15 and #16: The movements in frame #1 and #2 are replicated.
Amy Van Dyken displays an arm-stroking pattern that produces large and relatively continuous propulsive forces. It would seem that the left arm pull has better movement characteristics than the right arm. It would be interesting to see what performance changes would eventuate if the right arm kinematics were more direct than that exhibited here.
It would seem that the left-arm pulling pattern is one worthy of emulation by female sprinters.
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