Brad's Iyengar Yoga Notebook
Prasarita Padottanasana is eventually a resting pose, although when learning the pose, a lot of effort is involved in achieving a good posture, especially for those of us with tight hamstrings.   But eventually the pose becomes more effortless, quieting, and soothing and is often given as a prescription for anxiety and nervousness.   Prasarita Padottanasana can also be used as a preparation or even a substitute for Sirsasana for those who cannot do Sirsasana.   The word Prasarita should be pronounced more like praSArita (though generally there is little accent placed on any syllables in Sanskrit words) -- don't mispronounce Prasarita like "margarita" with an accent on the "i."
There are several stages and variations of this pose:
Having your hands underneath your shoulders, stretching your torso forward
Having your hands in line with your feet, taking your head to the floor
Taking your hands to your outer ankles or the outer blades of your feet
Taking your hands behind your back in Paschimanamaskarasana (Anjali mudra behind your back)
This page will discuss the first two stages of the pose.
Actions of the legs and feet
When you jump your feet apart for Prasarita Padottanasana, the classical method is to keep your hands on your hips.   The same is true for Parsvottanasana.   The reason for this is that you will be doing other things with your hands immediately after you come into the pose, unlike poses like Trikonasana where you will keep your arms extended to the sides away from your chest as you enter the pose.   If you move away from the classical method, have a reason for doing so, don't just be on autopilot, not thinking.   If you decide to jump your feet apart and bring your hands to the center of your chest and then out to the sides as we do for Trikonasana, do it for a purpose, such as working on broadening your chest.   Otherwise, know that the classical way of entering this pose is to jump your feet apart keeping your hands on your hips.
The distance you take between your feet will be a matter of experience with your body.   A common error is to place the feet too wide.   The goal of this pose has nothing to do with approaching Samakonasana (full side splits).   This is a forward bend.   But do jump your feet a little wider for this pose than for other standing poses, four-and-a-half to five feet apart.   Having your feet a little too wide is better than having them too narrow in this pose.   However, remember from before that in one version of this pose, you take your hands to the outside of your feet.   Here you will want to be able to have the outer edges of your feet actually stand on your fingers curled under them.   This gives you a gauge of how far "too far apart" would be for your feet in this pose.   Your feet must not be so wide that you cannot reach both ankles (or the outer blades of both feet) with your hands.   Also, your legs should not be so far apart that your torso does not have to lengthen a little to take your head to the floor.
Balance your weight equally on both feet.   Your feet should be parallel or slightly turned inward ("pigeon toed") in this asana.   As in Tadasana, broaden the soles of your feet.   Raise your toes and reach forward with them.   In this pose you need to avoid having little "parentheses feet" -- feet that curl inward in the shape of two parentheses.   This means don't allow the distance between your inner heel and inner great toe to shorten -- lengthen that distance.   Lift your inner ankles and the inner arches of your feet slightly and press the outer edges of your feet down onto the mat, but do not overdo the outer edges of your feet pressing down so that your outer ankles do not overextend.   Have the downward force of your legs caused by the gravity of your body going straight through your shinbones and going down through the centers of your heels, not out through the outsides of your ankles.   Press the entire soles of your feet onto the mat as in Tadasana, don't be more on the inner edges or outer edges.   Once you have achieved Tadasana in your feet, plant them firmly as if you want to make an even impression in concrete.
In the concave or first stage of the pose (before taking your head to the floor), after you take your hands down to the floor directly underneath your shoulders, bring your weight forward to the balls of your feet and align your hips with your ankles.   There is a strong tendency to let the weight fall back into the heels.   A common mistake is to let the legs tilt back while lengthening the sternum and torso forward toward the front of the room.   Keep your legs aligned with your feet.   Keep your hips in line with your ankles during all stages of the pose.   Your buttocks will be in the same plane as your heels and will stay there throughout the stages of the pose.
As you press firmly into the outside edges of your feet, use that energy to lift your inner ankles and the inner arches of your feet and draw your inner thighs upward toward your pelvis and also out to the sides away from each other.   To use Mr. Iyengar's terminology, "hit" your inner ankles, lower legs, and inner thighs outward.
You will probably need to turn your thighs slightly inward to ensure that the front center line of each thigh is facing directly forward, since the thighs have a tendency to turn outward.   This involves internally rotating your legs so that you are taking your inner thighs back more than your outer thighs.   Take your mind to a spot on your upper inner thighs right below your buttocks and move that spot on each leg back and away from each other.   Another way of saying this is that the tops of the backs of your thighs should roll outward away from each other (just as in Tadasana or Uttanasana).   Turning your thighs inward also helps to spread your sitting bones (buttock bones) apart, which is an important action in many asanas.   The action of the inner thighs moving back also helps your lumbar spine to lengthen.
So you pull your inner groins toward the wall behind you and you do the same with your inner knees.   Then you will want to pull your outer calves toward the wall behind you to counteract the inward rotation of the first two.   Again, another way of stating these same actions is to turn your upper/rear thighs (at the tops of your hamstrings) outward and then take your inner calves and roll them forward to keep your knees centered (while you're rolling your thighs inward).
Observe the Tadasana of the legs.   Engage your leg muscles to the bones on all sides (and draw them into pelvis).   Tighten your quadriceps and lift your knees upward toward your groins strongly.   A common mistake is to press the knees back rather than lifting them up.   You want your legs to be "Uttanasana legs" to avoid knee hyperextension, so the tops of your shinbones have a forward moving feeling.   Lift the skin and flesh of your hamstrings up toward your buttocks and also have a lateral (side to side) spreading of the flesh of your hamstrings.   Level your pelvis and lift your pelvis off your thighs.   Raise your buttock flesh upward and spread your buttocks apart.   Also spread your lower back flesh, spread your rear thigh flesh, and spread your calf flesh.   Be aware of the horizontal intelligence of these areas.
In the concave or first stage of the pose (before taking your head to the floor), go on pulling the tops of your thighs back into the backs of your legs (making sure that your legs are not tilting backward -- pin your hips in place in line with your ankles).   As you draw the tops of your thighbones back, draw your sternum more and more forward away from your pelvis.   Stretch the sides of your torso forward toward the front of the room.   Move your shoulder blades toward your kidneys and your clavicles and armpit chest forward.   There should be a soothing sensation in your groins and abdomen.   The main action is in your legs.   Relax and "hollow" your groins -- hold no tension there.   This stage gives length to the side ribs and spine.
Actions of the torso, hips, and pelvis
Since there is a tendency to have the legs leaning forward or back in this asana, verify that your buttock bones are in line with your heels.
Before taking your head down to the floor, roll the top of your sternum forward maximally so that your buttocks and your head rise while your lumbar spine drops into its normal concavity (lordosis).   You want to take your lumbosacral spine inward into your body to concave your back but do not take your kidneys into your body -- differentiate between those two actions.   In this first stage of the pose, it is important to rotate your pelvis forward so that your lower back drops toward the floor and concaves.   Another way to think about this action is to keep your tailbone lifting strongly.   If you are not able to accomplish this well with your hands on the floor due to hamstring tightness, place your hands on blocks to raise your torso as much as necessary to extend your spine and allow your low back to concave.   You must establish this relationship in your spine and low back before you are ready to take your head down to the floor.   Equanimity in this position is crucial before taking your head to the floor.   Throughout this work, try to maintain a neutral feeling in your spine.   Although in the final pose, there will be a natural, gentle convex curve in your low back, the feeling of having your spine extended and the front of your torso long must not be compromised.
Lift your sitting bones so that your hips rise toward the ceiling.   Spread your sitting bones apart, turning your thighs and knees inward to help this action.   Rotate your pubic bone back between your thighs.   Lengthen both sides of your torso from your hips toward your armpits.
When you are ready to move into the second stage of the pose with your head on the floor, take your hands on the floor back in line with your feet, but don't allow this to change to position you have established in your feet, legs, and pelvis.   As you move your hands back, your weight will naturally move more toward your heels.   However, once you get your legs into the right position in the first stage of the pose, keep them stable as you take your head to the floor.   Lengthen the front of your torso even while taking your head to the floor.   Bend from deep in your groins as you take your torso forward and take your head to the floor.   Strive for the feeling of moving from your groin area like a fulcrum.
Keep your sternum uplifting strongly to maintain the extension of your spine and the length of the front of your torso throughout the pose.   Roll your sternum toward your chin.   Keep the front of your torso long, separating your pubic bone and your sternum as much as possible.   Strive for this front body elongation in every forward bend.
In the second stage of this pose with your head on the floor, your back should not be straight, but should be rounded or dome-shaped as in Bakasana.   You want your back to be convex, so don't make the mistake of taking a more narrow stance in this pose to give your torso more space just to get a straight spine (like a very wide legged Uttanasana with your head on the floor) -- take the proper wide stance and accept the curve that you will have in your spine.   Remember even though your spine is not straight but curvilinear in poses like Prasarita Padottanasana, Parsvottanasana, and Pascimottanasana, you can still extend both the front and back of your spine.
A very common tendency in Prasarita Padottanasana is to let the legs tilt back when you take your head to the floor.   As you come into and hold the second stage of the pose, remember even now your legs should not be tilting forward or backward.   Use your feet to feel if your legs are tilting forward or backward.   Your feet are the messengers in this pose.   How they feel, their sensation on the floor, as you gain experience, will tell you if your legs are tilting forward or backward.   When your head is on the floor, you should feel most of your weight at the front edges of your heels, as opposed to the feeling you had during the first stage of the pose which was more toward the balls of your feet.
In this second, or convex stage, draw your bottommost ribs into your back without hardening your abdomen or diaphragm.   Lift your lumbar spine into roundness -- do not drop your lumbar spine if you are very flexible in that area.   Take your thoracic ("dorsal") spine into your body, not your lumbar spine.   This is true for most forward bends, sitting or otherwise.   Lift if your sternum away from the floor.   Your abdomen should be soft and broad and your groins relaxed.   Broaden your chest and separate your collar bones.
Actions of the hands, arms, shoulders, and head
Spread your palms on the floor as in Adho Mukha Svanasana and lengthen each finger away from your palm.   No matter where you are with your torso, maintain the intelligence of your hands on the floor.
In the concave phase of the pose, have your arms straight and turning from the inside outward, drawing your biceps upward.   When coming into the second, convex, stage of the pose, walk your hands back so they are in line with your feet and try to press the heels of your palms to the floor.   Use your hands on the floor to try to maintain the length of your spine as you go down.   Use your hands to pull your torso.   Use your hands on the floor at every step of walking them back -- push with them.   You get more energy from your hands with your palms flat on the floor than you do with just your fingertips on the floor.
Exhale as you are taking your torso down, bend your arms so that your forearms are perpendicular to the floor, and take the rear of your head downward so you take the crown of your head to the floor in line with your hands and feet.   Be on the crown of your head, not your forehead.   If you cannot make contact with your head on the floor, take a support like a block for your head.   In the second stage of the pose, you have to rest your head on the floor or a prop in order to get the cooling effect of the pose, the inversion effect.   Also there is an increased intensity of stretch in the hamstrings without head support.   Being upside-down should foster equanimity, not strain.   However, if you are at the point where you are resting your forehead (rather than your crown) on a support, then you can probably lower the support or dispense with it altogether and take the crown of your head to the floor.
Remember to maintain the drawing action of your shoulder blades toward your pelvis, which will be upward if you have taken your head to the floor.   When your head is on the floor, it is important not to allow the weight of your shoulders and thoracic spine to rest on your neck.   Move your inner shoulder blades up and lengthen from the base of your neck to your tailbone.   Press your palms down and lift your inner shoulders upward away from the floor, but not so much that the muscles of your upper back harden.   Take your upper arms into your shoulder sockets and lengthen your neck and thoracic spine upward.   Your elbows should point straight back and be aligned with your shoulders and directly over your wrists.
To come out of the pose, keep your hands in place on the line between your feet and re-concave your back and look upward before raising your torso all the way straight up.
A more advanced way of entering this pose is to start from standing with your feet apart and your hands in reverse Anjali mudra (behind your back) and then just slowly, with control, take your torso forward and your head to the floor in line with your feet.
One way to make this pose even more resting or restorative, is to have your head on the floor and then take your hands behind your head and interlace your fingers as in Sirsasana.   Even if you need a few blankets folded in half widthwise from the storage fold to build more height, this principle will still work and allow you to relax more deeply in the pose.