Researched, produced, and prepared by Brent S. Rushall, Ph.D., R.Psy.

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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.

Notable Features

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:

  1. 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?
  2. 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?
  3. 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?
  4. 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.

Dana Vollmer


Cappaert, J. M., & Rushall, B. S. (1994). Biomechanical analyses of champion swimmers. Spring Valley, CA: Sports Science Associates. []

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