After you have mastered the energy locks you are ready to incorporate them into more complicated techniques that are the core of tantric practice: Aswini Mudra and Vajroli Mudra.
These practices both generate intense energy in the lower body while keeping it contained. This builds up pressure in the energy channels. Once the containment is released, that pressurized energy shoots up the spine, breaking through any blocks or restrictions.
Vajra means thunderbolt in Sanskrit. Vajroli Mudra (the thunderbolt) stimulates the genitals with prana activated blood. Vajroli is simply the constriction of the urethral muscles in the lingam -- the same muscles used to cut off the flow of urine. This mudra strongly influences the nadis that supply the sex organs with spiritual energy. After some practice a man can retain the energy from the semen even when ejaculating. That energy can be used for his health and spiritual growth instead of being wasted.
Position of Readiness
Sit in an easy pose(sukhasana) or in padmasana. Put palms upon thighs. Close your eyes and relax.
Focus your attention on the sphincter muscles involved, near the pubic bone at the base of the lingam.
Inhale through the nose as you pull energy up the spine. Hold the breath at the Third Eye (Ajna Chakra). Pull up the sexual organs by contracting the muscle you would use to stop the flow of urine and the lower abdomen muscles.
Continue to hold the breath as you relax and contract ten times.
On the tenth relaxation, exhale through the nose and experience sexual energy rising from the sex center to the brain (or whatever body part needs energy).
A man can make these muscles even stronger by adding more weight. Place a washcloth over the penis and lift that. Then make it a wet washcloth, which is heavier.
Benefits of Vajroli mudra
Vajroli mudra tightens vaginal walls which were stretched out during childbirth that gives more pleasure, for both partners during intercourse .For most men this exercise is the solution to the problem of premature ejaculation. Vajroli awakens the Swadisthana Chakra , and encourages potency. Mastery of this exercise allows you to experience longer and more intense orgasm.
Vajroli mudra is described in the Siva Samhita, with two methods: 1. Sahajoli, where the yogi is able to restrain his ejaculation while still experiencing the bliss of orgasm; 2. Amaroli, where ejaculation takes place, and the Amrita , ie, the conjoined male and female sexual fluids, are drawn back up through the lingam.Bandhas are necessary for practice of Pranayama, Bandha means energy lock. There are main 3 types of locks, first is Jalandhar Bandha or Chin lock, second is Moolabandha or anus lock and third is Uddiyan Bandha or abdominal lock. These locks are essential while doing the Kumbhaka that is retaining the air inside or outside of the lungs.