HOW MODELING SWIMMING MOVEMENTS CAN LEAD TO DUBIOUS CONCLUSIONS
Payton, C. J., & Mullineaux, D. R. (1996). Effect of body roll on hand velocity in freestyle swimming. In J. P. Troup, A. P. Hollander, D. Strasse, S. W. Trappe, J. M. Cappaert, & T. A. Trappe (Eds.), Biomechanics and medicine in swimming VII (pp. 59-63). London: E & FN Spon.
This article used a mathematical model to evaluate the contribution of body roll to medial-lateral and vertical hand velocities in crawl-stroke swimming. It was assumed that propulsion in swimming is developed through lift forces. There are inherent difficulties with modeling. The models usually are incomplete, assume that all swimmers swim the same way (a false premise), and do not account for individual differences in stature or physical capability. Thus, research articles that use "modeling" should always be considered with extreme skepticism.
As justification for this warning this paper found that body roll does contribute to vertical and later arm movements and that lift is maximized when the arm is straight. For those who do not know the history of swimming, straight-arm swimming was debunked in the mid-1950s by swimmers even though several engineers at that time advocated straight arm pulls in crawl and backstroke.
It was also concluded that bending at the elbow was detrimental to generating lift forces because it reduced the hand's radius of rotation and created a hand velocity component that opposed that resulting from body roll. This finding is despite the fact that all world champion crawl-stroke swimmers bend the arm considerably and instead of using the hand for lift propulsion use the hand/forearm surface to generate mainly drag forces.
"It was concluded that body roll makes a substantial contribution to medial-lateral and vertical hand velocities in freestyle swimming and may therefore play an important role in the generation of propulsive lift forces." (p. 53). This ridiculous statement displays a total lack of awareness of what actually happens when the best swimmers perform crawl stroke.
Implication. This is an article that should not be heeded. It is based on false premises that lead to false conclusions. That it has been published is cause for concern about the review process for this particular volume.
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