Bandha is a Sanskrit word that refers to a “lock” or “stabilizer.” You can co-contract muscles to create locks or bandhas throughout the body in yoga poses. For example, in Parivrtta Parsvakonasana we turn the upper body in one direction and the lower body in the other.
Consciously engage the muscles that turn the trunk, such as the latissimus dorsi, posterior deltoid, and supraspinatus and infraspinatus muscles of the shoulder. Do this by pressing the elbow onto the knee to rotate the chest. Then at the same time, contract the gluteus maximus of the back leg to externally rotate the hip. Feel how these two actions combine to form a wringing effect across the torso, deepening and stabilizing the pose. This is an example of a bandha.