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The Continuously Variable Position Pulley System (Clinical Model)- C.V.P.P. (CM) Patented
This system consists of a pulley that moves continuously with the
motion. Thus the resistance cord gives more resistance torque at most
angles and resists through a wider arc of motion. This is particularly
important for wide sweeping
PNF motions
and many sports movements. Unit may be mounted on the wall or stands
(R16230,R16232) Height is 88". Supplied with one leather handgrip and
three leather straps for ankles, wrist and thigh. Advantages of the Continuously Variable Position Pulley System
DIAGRAM AThe C.V.P.P. provides resistance over a wider arc of motion than the standard pulley systems. Diagram A shows the cord and pulley action rotating around the axis on a fixed pulley system. The fixed pulley system resists the segment for half a complete circle and helps for half a circle since the direction of the cord remains constant at any single point. R - indicates points where the pulley cord resisting its movements in a counter clockwise direction O - indicates points where the pulley offers NO resistance to the segment i.e. the force is either distracting or compressing the segment. H - indicates points where the pulley rope would be HELPING the segment turn counter clockwise DIAGRAM B Diagram B shows the relationship between the cord and pulley of the C.V.P.P.systems. In this unique system there is a resistance in a full circle. As the segment moves, the pulley moves so that the direction of the cord pull changes as the segment moves. As shown the resistance points cover three quarters of a circle on the C.V.P.P. as opposed to the 1/2 of the circle on the fixed pulley.  C.V.P.P. Rope forms a greater angle with the moving segment at most points in the arc of motion.In all Resistive (R) points except when the cord is perpendicular to the segment, the system's cord is at a greater angle to the segment (see diagram). Thus the movement arm for the resistance is greater at each R point for the C.V.P.P. system. This makes any resistance force attached to the cord more effective at providing resistance torque at each R point. R - indicates where the pulley cord is resisting the segment O - indicates where the cord's force is neither resisting or helping H - indicates where the pulley cord is helping move the segment C.V.P.P. Resists large sweeping movements over a wider arc of motion. The C.V.P.P. provides exercise where the arc of movement is greater than 180 degrees. For example, as shown in diagram B for shoulder extension the pulley continues to resist the movement to attain a greater movement. C.V.P.P. is superior PNF for diagonals. Most PNF patterns involve large arc movements. In the case where the arm starts behind the body and finishes behind the body, the C.V.P.P. pulley moves downward and keeps the cord at a better angle with the arm. In this way the C.V.P.P. system provides significant resistance all through the larger arc exercises. The C.V.P.P. system is superior when an increase in resistance with movement is desired. Standard wall pulleys are frequently used for closed chain movements. This is accomplished by the patient performing side stepping exercise against the pulley system. In this instance the resistance the patient starts with is the same as the force when the exercise movement is completed. However in some instances, the therapist would prefer to have the resistance increase as the movement is completed and then have the patient hold against the increased resistance. This movement is also possible with the C.V.P.P. exercise unit in the "bow-stringing" method (see Figure C). As with the Freedom Pulley (above) the two pulleys can be set at varying distances. When the exercise is performed with the Freedom Pulley, there is a slight increase in resistance as the pulley cords become more convergent. With the C.V.P.P. system the cords become convergent more quickly thus making the resistance increase quicker. 
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