Diaphragm lock is applied by lifting the diaphragm up high into the thorax and pulling the upper abdominal muscles back toward the spine. It gently massages the intestines and the heart muscle. The spine should be straight and it is most often applied on the exhale. Applied forcefully on the inhale, it can create pressure in the eyes and the heart.
It is considered a powerful lock because it allows the pranic force to move through the central nerve channel of the spine penetrating the neck region. It also has a direct link to stimulating the hypothalamic-pituitary-adrenal axis in the brain. It stimulates the sense of compassion and can give a new youthfulness to the entire body.