Why would Heros pose or Virasana will help with lower back pain? You have 11 hip flexors with varying attachments at the hip to the knee or from the vertebrae to the femur. When one or more of the hip flexors begin to become chronically short and tight it will begin to take the pelvis in to an anterior pelvic tilt and this can begin to place pressure on L4L5 L5S1 area of your back. The lumbar erectors and other back muscles then have to over work. Glute max then gets put into and lengthened position which is not an ideal place for contracting or engaging so they become inhibited. This is a common problem for people who sit for long periods of time or sit more than they move. When you open not only the quadriceps and hips flexor area but the shin area (anterior tibialis) and the top of the foot. This is a challenging pose for people who have a lot tension on the top of foot/ankle area. If this is you, you will need to have a towel, blanket, bolster or block under the hips to help ease you way into just being able to sit on the block/blanket. It's critically important to ease very gently back and forth in and out of the pose to help with the release of tension. If you sit back and its painful, you having a hard time breathing through it the body simply will not release for you. It will simply hanging onto the tension and create tension in other places. The same will hold true for finding depth in the pose. If it's the position is too much for the body, give it some space and back out; take a breath; and move back into it. You will get a release. Keep doing this until the body quits releasing and then your static stretch will be more effective and powerful. It's like cleaning out the junk drawer; you have to keep going back and forth until we get to the good stuff. Tucking the tail is important here b/c in order to stretch the hip flexor portion you need to do this; as this will protect the back and L4L5; L5S1 area. While this can be done as a back-bend variation you need to make sure you are not hinging at these 2 segments. My intention here is to not make it a back-bend. I do sometimes but doing it this way also allows the back-bend option to be more open. I hope this helps and if any questions message me.