This section is from the book "Holistic Medicine", by Shriniwas J. Kashalikar.
Bandha means tying or closing tightly This apparently is to close the leakages of the vital or life energy' Actually band has are, contracting anal sphincter (mulabandha) or closing tightly the laryngo pharynx from oropharynx Jalandharab and ha) or contracting abdominal muscles (uddiyana bandha).
It is essential to understand the nature of life force to understand various changes/benefits associated with band has Hathayoga revolves around the primal force or life force and its sublimation into subtler force of higher consciousness It is known that this life force does not obey and is independent of the laws of physics. This life force is named kundalini, and as seen earlier, is associated with germinal epithelium. It seems this life force is associated in the Irving being with germinal epithelium not as a coincidence Actually this life force is responsible for sexual behavior of would be parents. The life force is responsible for selection of a specific sperm for fertilisation with the ovum This selection of sperm depends on the S ANKALPA* of the life force, and the purvasanchita' of previous birth The zygote m this way is a function of non random choice of sperm with the ovum This explains the peculiar constitution of the person who is to be bom. The person thus bom therefore can manifest many phenomena both explainable by genetics because the genetic constitution itself is the result of SANKALPA' of the life force. This life force it seems is beyond four dimensions which I tend to understand or believe Coming back to band has they cease to remain mere physical or physiological closures or contractions They seem to influence through, a yet un-understood connection, the life force.
But this all needs further exploration The point is, the band has assist in channelization of the primal force to be sublimated and merged into cosmic consciousness.
The mudras' are peculiar arrangements of toes, fingers, limbs etc Thus, brahmamudra, dronamudra, yonimuolra and yogamudra seem to influence the life force.