As simple as it seems, many people with chronic low back pain can improve and even fully heal their backs by doing one simple thing: stretching their hamstrings.
Your hamstrings are the muscles that run along the back of your thighs, from behind your knees to the bottom of your pelvis. If your hamstrings are tight, they are causing a constant downward pull on your pelvis. Since your pelvis is the foundation of your lower back and spine, having tight hamstrings contributes to an unstable lower back and a greater chance of intermittent sprains and strains.
In my chiropractic practice, I estimate that at least 80 percent of people who present with lower back pain have tight hamstrings as the root of their problem. Even if these people have their lower backs treated on a regular basis, they will continue to suffer from intermittent lower back pain if they do not address their hamstring tightness.
How do you know if your hamstrings are tight? The best way to assess hamstring length is to lie flat on your back and have someone slowly raise one leg. Your leg must be completely relaxed, and you must not help lift the leg with your own muscles. If your hamstrings are at an appropriate length for your body, your leg can be raised to 90 degrees off the ground (straight up towards the ceiling) without any significant tightness anywhere along your hamstrings from behind your knee to your sitting bone (pelvis). If you start to feel tightness before 90 degrees, you know it’s time to stretch!

A simple and effective way to stretch your hamstrings is to sit in a hurdler’s stretch – with one leg tucked behind your bum, and one leg flat on the ground, outstretched in front of you -and to lean forward slightly until you feel a stretch anywhere along the back of your thigh or knee. It is important to keep your back straight, and to only go to a point where you feel a comfortable stretch. If you experience pain, ease back until you are comfortable. Some people find that slinging a towel around their outstretched foot and holding onto both ends with their hands is more comfortable than bending forward without a towel. Be sure to breathe while you stretch, and to do the same stretch for your other leg.
It is best to stretch your hamstrings later on in the day, or after a good warm up such as after a brisk walk or jog. The key is to get lots of blood going through your muscles before you stretch. Alternating between legs for a few minutes each day is enough for most people.
Many people with chronic lower back pain can experience dramatic improvement after stretching their hamstrings on a daily basis for 1-3 months.

 

You can probably feel the difference in length of your hamstrings when you sit down.  When you stand, the muscles are lengthened.  Sitting even in good posture shortens your hamstrings.  If you sit for prolonged periods of time, you will be prone to chronic hamstring tightness. 
There are a few posture problems associated with tight hamstrings.  If the hip flexors (above) are tight, the hamstrings will become your primary hip extensor.  The hamstrings are supposed to be the synergist but become the prime mover.  This is called synergistic dominance which increases the chances of injury.
It is easy to see why synergistic dominance increases the chances of injury.  The gluteus maximus the largest muscle in the body.  If the gluteus maximus cannot extend the hip, the hamstrings which are not as powerful as the glutes are forced to do more work than they are designed for.
If you have tight hamstrings you will find it difficult to work and get results with your legs and butt exercises.  Hamstrings tightness can make you prone to pulled hamstrings, and sciatica.


A lot of pain that occurs due to muscles becoming too tight. The tight muscles do not allow as much blood into them as is needed and therefore they do not get the energy and nutrients they need to stay healthy. Therefore tight muscles weaken and then tighten up further, so a viscous circle has begun.