Salabhasana (Locust Pose)

Salabhasana, Locust Pose, is a prone back strengthening pose. Salabha means a locust or a grasshopper, and the shape, with the legs lifted behind and the chest raised, is where the name comes from. In the half version, Ardha Salabhasana, one straight leg lifts at a time. In the full version the legs, chest, head and arms all leave the floor together and only the abdomen and the front of the pelvis stay down.

It is not a deep backbend, and calling it one sets people up to make it badly. The range of movement is small. A well made locust often lifts the legs by five or ten centimetres, and that is the whole pose. What it is, is a strength pose for the back of the body, held against gravity, in the one position where there is nothing to balance on and nothing to fall off.

It is not Bhujangasana, although both are done face down. In Cobra the legs stay on the floor and the arms press the mat to help the chest rise. In the locust the arms are given nothing to push against and the legs lift too, which is why it is a good deal harder work and a good deal less impressive to look at.

It is also the substitute for Dhanurasana. If your shoulders will not reach back to your ankles, or if reaching them rounds the chest and slides the hips, the locust gives you the same back and buttock work without any of that. In a practice it sits with the prone poses: after the standing work, alongside Cobra, and before the finishing sequence. It is one of the poses I would keep in a short practice for anybody working through yoga for back pain once the acute pain has gone.

The instinct in this pose is to get the legs as high as possible, and the two ways of doing that both spoil it.

Bending the knees. A bent knee shortens the lever, so the leg comes up further with less work. It looks like progress and it removes most of the training effect, because what should be working is the hamstring and the gluteal on the back of the thigh. Keep the knee straight and let the lift be small.

Tilting the pelvis. If one hip bone leaves the floor, the leg is being lifted by rotating the pelvis rather than by extending the hip. That is a twist wearing the clothes of a backbend, and it concentrates the load into the joints at the base of the spine. Both hip bones stay down. Lower the leg until they do.

The third check is the neck. Look at the floor a little in front of you. Looking up adds nothing and compresses the back of the neck, which matters more than usual because cervical spondylosis is common in adults and the position is held rather than passed through. The rule is the same one that runs through yoga for neck and shoulder pain: never buy height at the cost of the neck.

The reason to be this careful about a modest pose is that back strengthening work is the part of yoga most likely to be reported as a harm. The Cochrane review of twenty one trials and 2,223 participants found small improvements in back related function from yoga compared with no exercise, and found the most commonly reported harm to be increased back pain, with no serious side effects reported in any of the trials. Small lifts, straight knees and a level pelvis is what keeps this pose on the useful side of that finding.

The erector spinae run the length of the spine and are the main workers here, together with the multifidus in the deeper layer and the quadratus lumborum at the sides of the lower back. The gluteus maximus and the hamstrings lift the legs. The middle and lower trapezius and the rhomboids draw the shoulder blades together and lift the chest. The deep neck muscles hold the head steady. Almost nothing at the front of the body works, which is exactly why the pose is paired with an abdominal pose in a sensible practice.

These are endurance muscles, not power muscles. They are meant to hold a position for hours, and in most modern adults they fail from disuse rather than weakness: a person who sits eight hours a day has spent eight hours letting a chair do their spine's job. That is why the prescription here is short repeated holds rather than one maximum effort, and why ten seconds three times is a better dose than thirty seconds once.

The pose also belongs to the group of chest opening postures that appear in modules with measured effects on breathing. In the sixteen week trial of forty eight men described above, the yoga module included Shalabhasana alongside Dhanurasana, Ushtrasana, Bhujangasana, Ardhamatsyendrasana, Gomukhasana and Paschimottanasana, and lung function improved substantially in the yoga group while declining in the control group. That is a result for the whole module and its breathing practices rather than for any single pose, and it is worth stating that way round. If breathing is your reason for practising, add an actual breathing practice such as Anulom Vilom rather than relying on the postures.

Short holds, repeated, with a real rest between them. This is endurance training for the muscles that hold you upright.

Three or four days a week. A back worked properly is mildly stiff the next day, which is normal, and the way to tell the difference between that and an injury is that stiffness eases as you move and an injury does not. If it does not ease, stop and read the guidance on how often should you do yoga about recovery days.

The locust goes with the prone group, once the body is warm. The order I use is Marjariasana for the spine, then Cobra, then the half locust, then the full locust, then the bow if the shoulders allow it. Every one of those is done face down, so there is no getting up and down between them, which matters more than it sounds when you are teaching people in their seventies.

Afterwards, rest and undo. Balasana is the counter pose and forty seconds of it returns the lower back to neutral. Then, because this pose has worked only the back of the body, add something for the front: an abdominal pose such as Naukasana, or simply lying on the back and hugging the knees in.

The pairing worth building a short practice around is the locust and the boat, one after the other, twice each. Together they cover the front and the back of the trunk, they take about four minutes, and they need no props and no space. That combination plus a fold and a rest is a genuine practice on a day with no time, and it fits the shape described in how to start yoga at home.

The locust is easy to modify because there are so many degrees of it.

• An active back problem. Leave it out while there is pain. When you come back, chest and arms only, or one leg at a time, and only with your doctor's agreement. This is the pose I use for that return, but the timing is a medical decision and not mine.
• Pregnancy. Leave it out. Lying face down is not appropriate after the first weeks.
• Abdomen. A hernia, an ulcer or recent surgery rules it out, because the whole pose rests on the belly.
• Blood pressure. The half locust for a few seconds, or nothing. The full pose with a held breath is a real rise in pressure, and the high blood pressure page is the place to start.
• Cannot lie face down. Use the chair version: sitting tall and lifting the chest ten times slowly works the upper back muscles, which is the part most people are missing anyway.

Anyone over forty coming back to movement should spend a month on the half locust before attempting the full pose, and the reasoning behind that patience is in yoga for beginners over 40. If you want somebody to check whether your hip is lifting, come to a class, or start with a first class and have it looked at.