The impact of tight hamstrings on the lower back
The majority of lower back problems I see in my back classes results from compression of the lumbar discs. Therefore, I focus on three main areas to reduce compression and to increase space in the lumbar region.
The first main area is on abdominal strengthening, and I draw particular attention to stabilizing the lumbar vertebrae during abdominal strengthening here
. The second main area is on lengthening tight hamstring muscles.
The hamstring is composed of three distinct muscles that originate together on the hip at a landmark called the ischial tuberosity. The muscles continue along the femur before the different muscle bellies branch off, cross the knee joint and insert onto the tibia and fibula bones of the lower leg.
As the hamstring crosses two joints (the hip and knee), it has an effect on both. The primary action of the hamstring muscle when it contracts is to bend the knee. A secondary action is to assist in extending the hip. Below is an illustration of the left hamstring muscle contracted to its shortest length, with flexed knee and extended hip.
Impact of tight hamstrings on the lower back
In forward bending, the pelvis (two hip bones and sacrum) begin to tilt forward, but tight hamstrings limit the range that the pelvis can tilt forward, because the tight hamstrings attach to the hips. Bending further forward (without bending the knees) immediately puts undue stress on the lumbar vertebrae (as illustrated in the image below):
We want the hips and pelvis to have more range to tilt forward thereby reducing the load on the lumbar vertebrae. This is why we lengthen the hamstrings. Notice the difference in the range that the whole pelvis can tilt in the image below where hamstring length is considered normal.
In the leg sequence of lower back yoga, we aim to lengthen the hamstrings in as safe a manner as possible. We start with practices (not pictured) that warm up the hamstrings before stretching them fully and in a supine position to limit risk of compression to the lumbar discs.
In both examples above, the hips are flexed, not extended, and the knees are straight, not bent, thereby lengthening the hamstring muscles all while the lower back remains in a safe supine position with floor support. These simple stretches will enable freer movement in the pelvis, thereby reducing stress on the lumbar vertebrae in forward bending.
Bending forward with knees bent
In forward bending, once the pelvis tilts as far forward as possible, always remember that bending the knees will give slack to the hamstrings and allow the pelvis to tilt even further forward without putting undue stress on the lumbar discs. Without bending the knees, once the pelvis reaches its maximum tilt, the hamstrings are at their greatest length, so one begins to stress the lumbar discs in bending any further forward.
A note for those with knee problems
During the hamstring stretches, if you can straighten the knee, please do so, but the knee should not be locked nor hyperextended. In the first practice above, you can keep the knee “soft” while the femur and tibia form a straight line.
Some people have difficulty straightening the knee. Straightening should not be forced as one must honor the limitations within the joint capsule. For the first practice above, a cloth belt or elastic band is used to allow the leg to remain further away from the body which makes it easier to straighten the knee. However, if straightening is not possible, continue with the knee slightly bent. No problem. For the second practice above, one is directed to lie right against the wall with a pleasant passive stretch on the hamstrings. However, if the knees cannot straighten, one can simply move some distance from the wall to allow the knees to straighten a bit more. The idea is to remain comfortable while gently lengthening the hamstrings over an extended period of time.
Take a class
This breathing stretch is one of twenty-eight practice videos for the lower back now available as an iphone app. See a preview.
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