Many yoga poses appear to be straightforward to the point of inanity; Uttanasana, or Standing Forward Bend, is certainly one of them. After all, ‘bend forward and touch your toes’ has been part of calisthenics forever, right? How difficult can it be to do this?

Actually, there’s a lot going on when we bend forward. Our alignment can make the difference between been a peaceful inversion and a back-wrenching misstep. Like many other disingenuously humble yoga moves, Uttanasana teaches us to be mindful, to be present in our movements, and to watch our alignment.

When learning or reviewing Uttanasana, it’s helpful to start in Tadasana, or Mountain Pose. Try these three micro-movements as an experiment. First, lean forward without bending your back and return to standing. Now bend your back from the waist. Coming back into Mountain, bend forward again, this time from the hips. Each of these movements demonstrates a different biomechanical marvel of the human spine. First, it’s possible to lean forward without bending anything. Second, any movement carried out from the waist or higher is done with the back muscles and the intervertebral discs in the spinal column. Bending at the hip, on the other hand, utilizes the muscles located around the lumbar, or lower spine as well as those of the hip and buttocks.

A little bit of anatomy: the spine is composed of a series of bones that are strung together tightly, with very little movement naturally occurring between them. As cushion, there are discs -- little bundles of jelly which protect the bones of the spine. If compressed on one side, the jelly can bulge in a different direction. These discs can also get torn, and they can impinge on the nerves connecting the spinal column to the brain.

The hip area, on the other hand, is composed of bones organized into ball and socket joints. This means that the bones and muscles can move in all directions. In contrast to the vertebrae of the back, the hip area is meant for deep bending movements, while the muscles and joints of the back should be moved in more limited fashion.

When practicing Uttanasana, keep this in mind. Standing in Tadasana, raise your arms out to the sides and up to point fingers towards the sky. Begin to bend – at the hips, please! Keep a bend in your knees – a slight one if you want more stretch in the legs, a bigger one if you’re looking to elongate the back and hip muscles.

At some point on your way down, you will reach the limit of your bendability. For limber people, this often means being able to touch the floor with straight legs, the belly area pressing to the thighs. For many of the rest of us, it means that at some point you will have a choice: increase the bend in your knees to allow the stomach to reach the upper legs, or round the back in an effort to continue the movement. The latter is a very bad idea, as it can do all sorts of twisty weird things to the discs and vertebrae.

For most of us, the full forward bend will involve some amount of bend at the knees to protect the tender back. If the belly starts to move away from the legs, that’s the sign that you have reached today’s maximum fold. From here, breathe and relax into the posture. When you are finished, come up carefully, with a straight back.

Those of us who are especially stiff may find that Ardha Uttanasana, or Half-Forward Bend, is enough of a stretch for straight legs. Bend forward at the hips, but keep your back flat and stop halfway down. Drop the hands to the thighs or knees, and hold, breathing. Come up slowly, keeping the back straight. This is a good strengthening exercise for the back muscles, but again should be done slowly and with caution.