THE LIFT COMPONENT PRODUCED BY THE UPPER LIMBS DURING THE BREAST STROKE

Abstract

It is known that a breaststroke swimmer's speed varies during a stroke cycle. Immediately after the leg drive (see Figure 1) the swimmer experiences a negative acceleration (-a) phase because the water resistance (R)is temporarily greater than the propulsive forces generated by the swimmer. This is followed by a phase of positive acceleration produced by the forces generated by the upper limbs. The purpose of this study was to determine the relative contributions of the lift and drag components of the forces produced by the upper limbs in causing the observed positive accelerations of the body. It was assumed that the lift component would be the greatest during lateral limb movements and that the drag component would be the greatest during backward limb movements. It was also assumed that the greatest positive acceleration of the swimmer would occur during the time of greatest positive tangential force production by the limbs (re. Newton's Second Law). A positive tengential force is one that acts in the same direction as the movement of the SWimmer's bedy and that has a magitude greater than that of the resistive forces opposing the body's motion.