Lower back pain in Savasana can be caused by tightness in the Hip-flexor muscles – mainly the Iliopsoas – that causes the pelvis to tilt forwards.
Hip-flexor muscles are found in the front of the body and are active in forward bending (bringing the head closer to the feet) and in any kind of leg-lifting (bringing the feet or knees closer to the head). One of the functions of the Iliopsoas is to maintain the natural curve (lordosis) of the lower back and if there is excessive tension in this this muscle, the lower back curves inwards more than it should. When someone lies on their back, it’s natural for the pelvis to tilt backwards and for the curve of the lower back to flatten but if the Iliopsoas is tight, the lower back will be painful.
If the pelvis isn’t tilting forwards, a tight Iliopsoas tends to cause pain and tightness in the mid-back. If it does tilt forwards, then the lower back hurts instead.
One of the major causes of hip-flexor tightness is sitting all day, which is why physical therapists encourage office-workers to stand up, stretch and move around regularly during the day. Yoga and exercise in general usually helps this kind of pain if the Iliopsoas is stretched and strengthened in a balanced way but yoga practice can make the Iliopsoas overactive and worsen lower back pain:
- The Iliopsoas is an antagonist of the Hamstrings – these two muscles are the main determinants of pelvic tilt: if the hamstrings are tighter than the Psoas, the pelvis tilts backwards but if the psoas is tighter, the pelvis tilts forwards. Too much focus on asanas that extend the leg backwards causes muscle imbalance in the legs and makes the lower back tight and the hamstrings inflexible. Forward-bending also becomes difficult and painful
- Core strengthening focused on abdominal exercises that involve lifting and lowering the legs with the knees extended strengthens the Iliopsoas considerably and if such abdominal strengthening isn’t balanced by also practising
- bridging – Setu Bandasana, Eka Pada Setu Bandasana or Purvottanasana
- back strengthening – Salabhasana
- oblique abdominal strengthening – Vasistasana and twisted inversions
the Iliopsoas becomes the dominant muscle in the lower back. Although most people understand that sit-ups make the psoas tight and doesn’t really strengthen the deeper abdominals (Transverse Abdominis and Internal Obliques) that are important in lower back and pelvic stability, so does lifting and lowering the legs, especially for people who can’t maintain a contraction of the deep abdominal muscles
- In Ashtanga Primary series, regular practice of large numbers of forward-bends with 5 repetitions of Navasana can make the pelvis tilt forwards after a while – the Hamstrings get stretched in forward bends and the Iliopsoas gets strengthened in Navasana. A forward-tilting pelvis is one of the causes of Ischial Tendinitis, which is common in Ashtanga practitioners. Movement habits like Hinging from the hips from Uttanasana to Tadasana also contribute to Iliopsoas overactivity because the gluteal muscles become less active, allowing the pelvis to tilt forwards
An overactive psoas can also cause lower back pain via the Quadratus Lumborum – if there is tension in the Iliopsoas, all the lower back muscles become tense and because the Quadratus Lumborum attaches to the lumbar spine and the hips, alignment problems with the hips causes misalignment of the vertebrae and lower back pain. Stretching the Iliopsoas doesn’t correct overactivity in this muscle; muscle balance needs to be restored in the lower back and hips to relieve lower back pain that is caused by pelvic tilt
Although ‘Decompressing the spine’ with abdominal contractions is often suggested as a way to relax the Iliopsoas and supine twisting at the end of class has a similar effect, it makes more sense to get pelvic tilt assessed by a trained professional and corrected as necessary. Looking at how a yoga practice contributes to the problem and changing it is the key to lasting relief of lower back pain of this kind.
Kendall, Mc Creary & Provance, 1993, Muscles: Testing and Function
Boyle, 2004, Functional Training for Sports
Cook, 2003, Athletic Body in Balance