Paścimottānāsana (Seated Forward Fold) is the signature āsana of the Primary Series and one of the most important postures in all of yoga. In Sharath's Anuṣṭhāna it is given as A and then “B or D”, a choice of grip by ability. In the Ashtanga system it directly follows Daṇḍāsana and represents the quintessential expression of the 'western stretch' — the lengthening of the entire posterior body.

From paścima (west, referring to the back of the body), uttāna (intense stretch), and āsana (seat). In traditional Indian practice, one faces east during sādhana, so the back body is the 'western' side. The name thus means 'intense stretch of the west (posterior) side.' It appears in the Haṭha Yoga Pradīpikā as one of the foremost āsanas.

Paścimottānāsana has a 16-vinyāsa count (Anuṣṭhāna, pp. 48–49). Vinyāsa 7 (Saptaḥ): jump through to Daṇḍāsana. Vinyāsa 8 (Aṣṭau, inhale): catch the big toes and look up. Vinyāsa 9 (Nava, exhale) is the state: fold, head and chin toward the knees, held for five breaths. Vinyāsa 10 (Daśa, inhale): head up, then exhale. The practitioner then lifts up and jumps back (vinyāsas 11 to 14 in the book's count for the second version). The book gives A, and then “B or D” as a choice of grip by ability (the sides of the feet, or the hands locked around the feet); the choice of grip changes the hold, not the count.

From Daṇḍāsana, inhale and raise both arms overhead, lengthening the spine. Inhale at vinyāsa 8: catch the big toes with the first two fingers and thumb (padāṅguṣṭha grip) and look up. Exhale at vinyāsa 9: fold, and hold for five breaths. Inhale at vinyāsa 10: head up. The alternative grip (“B or D” in the book) takes the sides of the feet or locks the hands around the feet; it replaces the toe grip within the same count.

In every grip, the objective is to lengthen the spine along the legs rather than simply rounding toward them. The belly draws toward the thighs first, then the chest toward the knees, and finally the chin beyond the shins. The legs remain straight and active with kneecaps pulled up. In the full expression, the torso lies flat along the thighs with the face resting on the shins and the breath remains steady and even despite the depth of the fold.

After the five-breath hold, inhale lift the head and lengthen the spine (vinyāsa 10). Exhale release the hands, press the palms beside the hips. Inhale cross the ankles and lift up (utplutiḥ), exhale jump back to Catvāri. Continue through upward dog and downward dog to set up for Purvottānāsana.

Pādayoragra dṛṣṭi (toes). The gaze rests on the tips of the toes throughout the fold. This dṛṣṭi encourages the forward extension of the spine and helps maintain the internal focus of the fold.

Uḍḍīyāna bandha is paramount in Paścimottānāsana. On each exhale, the lower abdomen draws in and up, creating space for the torso to move deeper toward the thighs. Mūla bandha stabilizes the pelvic floor and helps tilt the pelvis anteriorly. The interplay of both bandhas prevents compression in the lumbar spine and supports a long, even fold.

The fold initiates from the hip joints, not the waist. The pelvis tilts anteriorly as the sit bones spread apart. The spine remains long — imagine reaching the sternum toward the toes rather than pulling the head toward the knees. Shoulders draw away from the ears, and the elbows bend outward and slightly upward. The legs are fully engaged, feet flexed and together.

Rounding the upper back excessively while the hips remain static — the fold must come from the hips. Pulling aggressively with the arms rather than using the breath and gravity to deepen. Bending the knees to reach the feet instead of maintaining straight legs and accepting the current depth. Holding the breath or tensing the neck and jaw.

Paścimottānāsana intensely stretches the entire posterior chain: gastrocnemius, hamstrings, gluteus maximus, and the erector spinae group. The hip flexors (iliopsoas) and quadriceps contract to tilt the pelvis and maintain leg extension. The thoracolumbar fascia is mobilized as the spine lengthens. Deep folds also stretch the plantar fascia and Achilles tendon when the feet are properly flexed.

As the namesake of 'Yoga Cikitsā,' Paścimottānāsana is considered one of the most therapeutically potent postures. It calms the nervous system by stimulating the parasympathetic response through the forward fold. It is traditionally said to stoke the digestive fire, aid digestion, and reduce abdominal fat. It is therapeutic for mild anxiety, insomnia, and hypertension. The Haṭha Yoga Pradīpikā (1.29) calls it the 'foremost of āsanas' that causes prāṇa to flow through the suṣumnā.

For tight hamstrings, bend the knees slightly to maintain a long spine and anterior pelvic tilt. A strap around the feet can replace the hand grips while maintaining proper spinal alignment. In Mysore style, the teacher may provide adjustments by pressing gently on the back to help deepen the fold, always respecting the student's breath and comfort.

All of the standing forward folds (Pādāṅguṣṭhāsana, Pāda Hastāsana, Uttānāsana within Sūrya Namaskāra) prepare the hamstrings and posterior chain. Daṇḍāsana immediately precedes and establishes the seated foundation. The standing sequence systematically warms the body for this deep forward fold.

Purvottānāsana (Upward Plank) is the direct and essential counterpose, practiced immediately after Paścimottānāsana. It extends the entire front body and strengthens the posterior chain, perfectly balancing the deep flexion of the forward fold.

The Haṭha Yoga Pradīpikā (1.29) states that Paścimottānāsana is 'the best of āsanas' and that it 'makes the breath flow through the suṣumnā, stimulates the gastric fire, makes the loins lean, and removes diseases.' Symbolically, folding forward represents surrender (praṇidhāna) and turning inward (pratyāhāra). The western (posterior) body represents the unconscious — stretching it brings awareness to what we cannot see.