Bridge pose
Setu Bandha

 
 The main thing that helps you in the hip extension is your gluteus muscles. So how can one reach a complete extension in the bridge pose without having to fight with your gluteus maximus and hurting the lower back?
The gluteus muscles help in creating a backbend as well as they grab onto the tendoneus portion of our upper thighs, and spin your thigh bones outward causing an external rotation. See how the feet try to turn outwards when the gluteus muscles contract during the wheel or bridge pose, the more the gluteus muscle contracts, the higher the hips go up and the more your feet turn outwards; what might cause a problem in the lower lumbar vertebrae as well as in the sacrum leading to lower back pain and strained muscles if you do it for a long period of time.
To avoid theseproblems you should do two things:
  •  Contract your inner thighs to prevent the rotation outwards by putting a block between your knees.
  •  As you raise your hips, turn your tail bone inwards firmly and push the floor with your heels what helps move the sacrum away from your lumbar bones and allow you to go deeper in your pose.    

 
The Benefits
Stretches the chest, neck, and spine
Calms the brain
Stimulates lungs, and thyroid
Reduces anxiety, fatigue, backache, headache, and insomnia