Can hip rotation increase hand force in freestyle?
No. In freestyle, the torso rotates about the polar axis (a reference axis through the center of the body from head to feet). Summation of forces (See Francis, 2007, Chapter 4) requires that successive body segments (torso, upper arm, lower arm, hand) rotate in the same direction (as in throwing). The freestyle arm motion is perpendicular to the torso rotation and the hand force cannot be increased by the force of hip rotation. Although the timing of the push phase in freestyle is usually simultaneous with torso rotation, rotating the hips harder or faster will not increase hand force. Prins (2007) described how exaggerated torso rotation is even associated with counterproductive motions.
