THE EFFECT OF BODY ROLL ON HAND SPEED AND HAND PATH IN FRONT CRAWL SWIMMING - A SIMULATION STUDY

The aim of this study was to predict the effect of body roll on hand s peed and hand path during the pull phase in front crawl swimming. An e arlier three-segment model (Hay, Liu, & Andrews, 1993) was developed t o enable the hand to move out of the plane through the shoulder parall el to the sagittal plane of the rotating trunk Elbow flexion, shoulder abduction, and body roll angular velocities were modeled as sine or c osine functions. For a given elbow flexion, an increase in maximum bod y roll from 45 degrees to 60 degrees produced a marked increase in med ial hand motion. For a given body roll, an increase in maximum elbow f lexion from 60 degrees to 90 degrees increased medial hand motion and reduced downward hand motion. An increase in body roll increased hand speed in the plane perpendicular to the swimming direction, thus incre asing the potential of the hand to develop propulsive lift forces.