HOW CHAMPIONS DO IT
Researched, produced, and prepared by Brent S. Rushall,
DANA VOLLMER AT 40 m OF HER GOLD MEDAL WORLD RECORD 100 m BUTTERFLY RACE AT THE 2012 LONDON OLYMPIC GAMES
Dana Vollmer set a world record of 55.98 in this 100 m butterfly race. Each frame is .1 seconds apart. This analysis is of a breathing stroke in the swimmer's cycle of breathing once every two strokes.
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: Coming off a non-breathing stroke, the swimmer's body is flat with the head well down. The arms have just entered and the legs are kicking to counterbalance that entry.
- Frame #2: The arms have entered and are pressing down. The kick is near completion and its developed force is in excess of that needed to counterbalance the entry. That extra force pushes the hips up. Whether the hip elevation is or is not deliberate cannot be determined. The excessive kick force could be part of an attempt to develop a total body wave-like movement that is often learned when using a kick board. It may be unnecessary.
- Frame #3: The vertical force developed by the arms continues. The arms spread further not from a deliberate movement but as a result of the upper arms rotating in the shoulder joint as part of abduction. The kick is completed and the hips are in their highest position. The head begins to rise. The back hyperextends which may be an artifact of trying to develop a wave-like "dolphin" action.
- Frame #4: The feet rise as the hips are depressed. Drag resistance begins to be created by the legs and is indicated by the milky pocket of water on the front side of the legs. The arms begin to bend at the elbows making them capable of greater force production, although little of that force will contribute to propulsion. The head rises through the surface. The head and torso position create resistance, which can be seen as a milky covering from the chest up between the arms to the chin.
- Frame #5: The feet are close to the surface while the hips are lowered further. Drag resistance created by the leg action increases and now covers the legs from above the knees to the toes. The head breaks the surface. The resistance created by the leading surfaces has increased as the stream of turbulence now extends to the waist. The arms are creating considerable force through abduction of the upper arms. A large component of that total force is still vertical although that which would contribute to propulsion has increased.
- Frame #6: In one tenth of a second much happens in this stroke. The upper arms move very quickly from abduction to adduction. The elbows travel faster than the hands to position the lower arms to mostly apply force backward. The sudden creation of substantial propulsive force can be seen by the large pocket of drag-force turbulence (milky water) that is in front of the arms. The head is out of the water. The milky water on top of the body is evidence of resistance created by the swimmer's position. The feet break the surface, the knees bend, and the knees and hips are lowered further. The position of the lower legs creates substantial drag force.
- Frame #7: The upper arms have finished their adduction and the elbows begin to rise preparatory to exiting the water. The lower arms and hand surfaces continue to push backward possibly sustaining the force developed in the previous frame. The feet kick to counterbalance the vertical forces being created by the upper arms and primarily to support the head out of the water and the shoulders emerging from the water.
- Frame #8: The arms have exited, the legs have kicked to counterbalance that action, and the hips have risen to straighten the swimmer's body alignment. It can be inferred that breathing is occurring.
- Frame #9: The legs begin to move vertically in preparation for the next kick. The hips sink as the back hyperextends to facilitate the elevation of the feet. The upper body begins to be lowered into the water as the arms are about half way through the recovery.
- Frame #10: The head begins to be covered and the shoulders sink into the water. The recovering arms are in the forward sector of that total segment of the activity. The hips sink as the legs rise. The resistive drag off the legs can be seen with the large pocket of turbulence below the legs. The trailing edge of that resistance pocket is just off vertical.
- Frame #11: The head and shoulders are now covered. The arms are reaching forward over the water. This position shows why flexible shoulders are an asset, but that does not mean that all swimmers should go through extreme programs of flexibility development (and incur the associated injuries). Rather it shows why swimmers with the natural endowment of flexible shoulders have an advantage over others not as flexible when swimming this stroke. The drag pocket off the front of the legs (lower shins and feet) is more obvious than in the preceding frame.
- Frame #12: A position similar to that illustrated in Frame #1 is attained. As the legs kick down, the hips rise and the shoulders/head sinks further. Those notable movements in the head and shoulders result from the vigor/size of the kick. Those movements transfer considerable amounts of energy to the water as it is moved out of the way. With these data it is not possible to determine how much these movements detract from the swimmer's capacity to complete a 100 m swim or if they are absolutely necessary for this swimmer to perform as well as she does.
This analysis illustrates just how poorly the human body is constructed for propulsion through water. Much movement is required to develop a short-lived propulsive phase against a backdrop of many movements that create substantial resistance. From the supposedly unnecessary movements that are created in this sequence, it is prudent to ask:
- Do the legs and hips need to travel so far vertically when those movements only create drag resistance? Would the swimmer benefit more from a smaller kick and hip action which would increase streamline, reduce drag, and place the swimmer closer to the surface?
- It appears that the breathing action largely involves the upper body and shoulders. Could that amount of movement be reduced, possibly by limiting the height of the head when breathing and extending the chin forward through the bow wave?
- It is hard to discern any movement in the legs that would produce forward propulsion. They certainly develop considerable vertical forces that counterbalance the arm movements but are never in a position where any force that would contribute to forward propulsion exists. The leg actions do produce significant drag forces which would be contrary to propulsion. The question has to be asked: If the kicking action was made smaller, would the reduction in resistive drag forces contribute to more efficient movement through the water?
Since a large portion of the kicking movement occurs to support the amount of the swimmer that is above the surface in breathing and the recovery, those movements would have to be reduced to facilitate a less resistive kick. It is not possible here to determine if that could be done.
Butterfly stroke is the second fastest of the four competitive swimming strokes and yet in this world-record holder many features that are not conducive to fast swimming are exhibited. It appears that the brief propulsive phase (Frames #4 through #7) generates forces that are huge when compared to the propulsive phases of the other strokes. Cappaert and Rushall (1994) calculated the forces produced by the arms in the four strokes in Olympic Gold medalists in their final races in Barcelona. As a rough estimate, the effective forces for the two arms in butterfly are at least three times the forces developed for the single arms in sprint crawl-stroke swimmers. It is a reasonable to assert that butterfly swimmers obtain propulsion from very large short-lived propulsive phases in the stroke whereas crawl stroke and backstroke generate propulsion through more sustained but much lower forces.
Cappaert, J. M., & Rushall, B. S. (1994). Biomechanical analyses of champion swimmers. Spring Valley, CA: Sports Science Associates. [http://brentrushall.com/#books]
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