Bandhas are the part of yoga that sounds most esoteric and turns out, on inspection, to be surprisingly concrete. A bandha is a lock, a deliberate muscular contraction that contains and redirects energy. It is not strictly "science," but it has effects the body can feel, and increasingly ones physiology can describe. Its gentler partner is the seal (mudra), a light gesture of the hands or face, which has its own page.
They belong with Pranayama because they are applied through the breath (most often during retention) to direct what the breath has gathered. How comfortably you hold a breath is itself concrete, a number you can take with a timer, and Measuring a practice shows how.
Bandhas: the locks
Energy locks: directing, containing, and redirecting prana.
In one line: Bandhas are small, deliberate muscle contractions that, in the yogic map, "lock in" energy, and in modern anatomy do real work on the core, pelvic floor, and nervous system.
From tradition
Bandha means lock or seal. Bandhas are specific contractions of muscle groups that, in the yogic framework, create energetic seals within the body, preventing the dissipation of prana (life force) and redirecting it upward through the central channel, Sushumna.
Along that central channel sit three granthis, psychic "knots" that the locks, and Maha Bandha especially, are said to help loosen and pierce. → See The three granthis in Subtle Anatomy.
From science
From an anatomical perspective, bandhas work on the pressure inside the abdomen, engage deep core stability, and appear to influence the autonomic nervous system through their action on the pelvic floor and abdominal muscles. Which way that pressure goes depends on the lock: the root and throat locks contain it, while the abdominal lift (Uddiyana Bandha) lowers it, drawing the organs upward into the space that opens.
The clearest evidence is for the abdominal lift. A 2024 randomised controlled trial in sixty people with high blood pressure found that a single session measurably shifted heart-rate variability toward the rest-and-recovery side straight afterwards. That is one trial, and later work suggests the picture during the lift itself is more mixed, with both branches of the nervous system active at once and the calming shift arriving in the minutes after. Real evidence, then, where there used to be none, but not a closed case.
The contraction of the perineum corresponds to the sacrococcygeal nerve plexus, the bundle of nerves at the base of the spine, a region rich in the parasympathetic fibres that turn the body toward rest.
The bridge
The traditional and the anatomical descriptions are not the same thing, but they resonate with each other. What the tradition calls "redirecting prana upward through Sushumna" lines up with what anatomy describes as creating internal pressure and engaging the deep core to support and lengthen the spine. The yogic map names regions and effects that modern physiology is still catching up with, without claiming one framework proves the other.
"The bandhas induce pratyahara (sense withdrawal) and are preliminary techniques for meditation." — Bihar School of Yoga, Asana Pranayama Mudra Bandha
The three main bandhas
Mula Bandha (Root lock) Contraction of the perineal body, the point midway between the anus and the genitals. In women, the equivalent contraction is around the cervix and upper vaginal muscles. This is distinct from the full pelvic floor squeeze or anal contraction (Ashwini Mudra), though those are useful preparatory practices. Mula Bandha is subtle and central. It stimulates the base of the spine, integrates the pelvic floor into the breath cycle, and, in the yogic framework, awakens the dormant energy at Mooladhara chakra. It is practised in three stages: the physical squeeze, then the squeeze held with focused attention, and finally the contraction made with intention alone, barely moving the muscle. The schools agree on where it sits and differ on when in the breath it applies: classical hatha applies it during the held breath alongside the other locks, some lineages engage it on the exhale and release it on the inhale, and Ashtanga vinyasa holds it lightly throughout the whole practice, tied to no beat at all. So a drawing of the breath can honestly mark its place, but never its moment.
Uddiyana Bandha (Abdominal lift) Practised on a full exhale with the breath held outside. The abdomen is drawn sharply back and up toward the spine and under the ribcage, creating a powerful vacuum in the abdominal cavity. This massages the abdominal organs, fires the deep core, and, in the energetic model, stimulates Manipura chakra at the solar plexus. It is an advanced practice, always taught after Mula Bandha is established. Never practise on a full stomach.
Jalandhara Bandha (Throat lock) The chin is drawn down to meet the sternum, lengthening the back of the neck and sealing the throat. Applied during breath retention, particularly after a full inhale, it prevents the premature release of air and regulates the pressure in the chest. In the energetic map it corresponds to Vishuddhi chakra at the throat, and is said to contain the prana gathered on the inhale.