Passive stretching
Passive stretching is a form of static stretching
Static stretching
Static stretching is used to stretch muscles while the body is at rest. It is composed of various techniques that gradually lengthen a muscle to an elongated position and hold that position for 30 seconds to two minutes...

 in which an external force exerts upon the limb to move it into the new position. This is in contrast to active stretching
Active stretching
Active stretching eliminates force and its adverse effects from stretching procedures.Before describing the principles on which active stretching is based, the terms agonist and antagonist must be clarified...

. Passive stretching resistance is normally achieved through the force of gravity on the limb or on the body weighing down on it. It can also be achieved with the help of a partner, stretch bands, or mechanical devices. The more force exerted on the limb, the less time it will take to drop lower into the stretch.
It is a fallacy that passive stretching will lead to 'an increase in injury risk'. As long as you gradually go into a stretch instead of a sudden stretch the risk of injury is no more than relaxed stretching.
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