In short: head-to-knee pose is a one-legged seated forward bend. One leg stays straight, the other knee bends out to the side with the sole of the foot against the inner thigh, and you fold over the straight leg. It stretches the hamstrings and back of the straight leg and opens the hip of the bent one. Because you work one side at a time, it is often easier than folding over both legs.
The pose is taught in most schools: Iyengar, Ashtanga (where it comes in three versions, A, B and C), hatha and vinyasa classes. Below we explain the name, the cues behind the steps, the knee precautions and the three Ashtanga versions, each in its own section.
What the name means
The Sanskrit name is Jānu Śīrṣāsana (often written Janu Sirsasana or Janu Shirshasana): jānu means knee, śīrṣa means head and āsana means seat or posture. “Head to knee” describes the idea more than the goal; in practice you reach the chest along the thigh, and the head arrives near the shin only when the hips and hamstrings allow it. It is a 20th-century posture as far as the written record shows: it is described in Krishnamacharya’s teaching and by his pupils B.K.S. Iyengar and Pattabhi Jois, not in the medieval hatha texts. Do not confuse it with revolved head-to-knee pose, which uses the same legs but is mainly a side bend.
Making the pose work
The bent leg does most of the hidden work. Its thigh rotates outward at the hip, much as the front leg does in warrior II. Let that thigh relax outward and down; if the knee floats high, put a block or folded blanket under it. If the inner knee complains, bring the bent knee a little closer to the straight leg: Yoga Journal notes that a wide angle can strain the inner thigh, and AshtangaYoga.info warns that forcing the fold while the bent thigh turns inward can press on the inner meniscus of the knee.
Turn the torso slightly so the breastbone lines up over the straight leg, sit on a folded blanket if the lower back rounds, and hinge from the hips. Keep the straight leg active with the kneecap pointing up and, if the knee tends to lock, a rolled blanket under it. Inhale to lengthen, exhale to fold a little further, and never pull yourself down with the arms. Ashtanga holds each side for five breaths; in slower classes you may stay for a minute or longer on each side.
Precautions in plain words
Watch the bent knee. Pain on the inside of the knee is a signal to support the thigh, narrow the angle or straighten the leg out of the pose. Lower-back problems, sciatica and hamstring injuries call for the same care as any forward fold: bent straight leg, long spine, no pulling. If you have a knee, hip or back condition, ask your doctor or physiotherapist before practising. This page is general information, not individual advice.
Preparation and what comes next
Downward-facing dog, bound angle pose and reclining hand-to-big-toe pose prepare the hamstrings and hips. Afterwards, open the front of the body with upward plank or fish pose, or rest in hero pose. From here, seated forward bend works both legs at once, and revolved head-to-knee adds a side bend. The yin version of this shape is half butterfly, held for several minutes with the muscles soft.
Head-to-Knee Pose A (Janu Sirsasana A)
Version A is the shape described above and the one most classes teach. In the Ashtanga primary series the sole of the bent leg rests as high as possible on the inner thigh of the straight leg, the bent thigh relaxes outward, and the hand on the straight-leg side holds the opposite wrist beyond the foot. You fold on an exhalation and stay for five breaths, then repeat on the other side, right side first. Level: beginner with props.
Head-to-Knee Pose B (Janu Sirsasana B)
In version B the foot of the bent leg keeps the same placement, but you lift the hips and sit with the perineum on the heel, the outer edge of the foot on the floor and the toes pointing forward under the straight thigh. You then fold as in A for five breaths. AshtangaYoga.info points out that sliding the foot under the thigh with the top of the foot flat is easier but is a different pose. Sitting on the heel loads the ankle and knee, so treat B as an intermediate variation and come out if the ankle or knee hurts.
Head-to-Knee Pose C (Janu Sirsasana C)
In version C the toes of the bent leg are turned under: the ball of the foot is on the floor, the heel lifts toward the groin and the foot is held between the two thighs, with the bent knee angled forward at about 45 degrees and drifting toward the floor over time. It asks a lot of the knee and ankle and is an advanced variation. Learn it with an experienced teacher, never force the knee down, and skip it if you have any knee injury.
You will meet head-to-knee pose in hatha, Iyengar, Ashtanga and vinyasa classes, usually in the seated, slower part of the practice.
