Mechanics of shoulder locomotor system during exercises resisted by weight-and-pulley-circuit.

The aim of the present study was to investigate how different ways of using a weight-and-pulley-circuit (wpc) influence the mechanics of a joint with adjacent muscles. A formula for the resisting moment with respect to a joint was developed and used in a computer model. The resistive effect of various modes of application of the wpc was calculated. It is shown how the resisting moment is influenced by changes of the following factors: 1) Angle between the horizontal plane and a line between joint and pulley (height of position of pulley); 2) Distance between joint and pulley; 3) Weight applied to the rope of the wpc; 4) Weight of the limb.