When the hip-bones tilt forwards, creating an arch (lordosis) in the lower back, you have anterior pelvic tilt, one of the main causes of lower back pain. Some people, mainly women, have a lower back that is naturally lordotic. This is due to the shape of their Sacroiliac joints, and is not necessarily painful or problematic.
Anterior pelvic tilt is extremely painful when it is caused by muscle imbalance, mainly weak gluteal muscles. Some other symptoms of hip muscle weakness in yoga are
- Limited flexibility in forward bending
- Sacroiliac pain and instability
- Pain at the outside of the hip (Greater Trochanter of the Femur)
- Pain in the abdominal wall at the front of the hips or the pubic bone
If the Gluteus Maximus (buttocks) is weak, the Iliopsoas and Quadriceps are tight. If the Gluteus Medius (Hip Abductor muscle) is weak the Tensor Fascia Latae is tight. All of the tight muscles are hip flexors and so the pelvis will tilt forwards. Because of the forward tilt, the lower abdominal muscles – mainly the internal obliques – become weak.
Back bending in yoga practice is not the same thing as arching the lower back with the pelvis tilted forwards and the stomach muscles hanging out. Back bending should be done with a focus on using the abdominal muscles to pull the pubic bone up.
If you always allow you pelvis to tilt forwards during yoga practice, especially in standing asanas like Utkatasana and Virabhadrasana, these muscle imbalances perpetuate themselves. This is particularly problematic in lunge–asanas, because tight hip-flexor muscles exaggerate the curve of the lower back, causing lower back pain.
Anterior pelvic tilt occurs from practising carelessly but yogis can practise as mindfully as possible and still end up with anterior pelvic tilt because of unbalanced sequencing which tightens up Quadricep muscles – a major cause of anterior pelvic tilt and Gluteus Maximus weakness.
In yoga, Quads become tight from a preference for hamstring strengthening asanas involving hip extension – Ardha Chandrasana, Dighasana, etc. Many teachers put a sequence together involving a lot of hip extension and neglect to balance it out with hip-flexion and knee-extension asanas like Utthita hasta Padangustasana (with hands on hips) or Titthibhasana. Teaching students to engage the Quads by pulling up their kneecaps at all times is insufficient to balance the legs.
Yogis who practice a lot of these kinds of asanas are surprised to find that they become unable to do forward bends. Attempting to forcibly stretch the Hamstrings which have been over-strengthened in this manner only causes pain and injury.
Quadricep muscles are stronger than Hamstrings in healthy legs and hips. Many yoga practitioners seem unaware of this basic principle and think that the more they stretch their hamstrings, the more they should strengthen them. This is the starting-point of much pain and injury in yoga
Reading Sources: De Franca, 1996, Pelvic Locomotor Dysfunction Kendall, McCreary, Provance, 1993, Muscles, Testing and Function