When a patient presents to my office with low back pain I ask them if they have done any home treatment for the pain, such as ice, heat, rest, over-the-counter medication, etc. One of the most popular responses seems to be that they did some stretching. The most common stretch seems to be for the hamstrings. Many people seem to think this is a good treatment for back pain, unfortunately it is not a good treatment and could do more harm than good.
The hamstrings is the name given to a group of muscles in the back of your thigh. These muscles are used to to flex the knee, which is when the knee is bent and the foot moves towards the back of the thigh. The hamstrings are also used for hip extension, which is when the knee/leg is moved backwards. The gluteus maximus muscle, along with some of the hamstring muscles, is also used for hip extension. These muscles also plays a critical role in pelvic stabilization.
Most people will have tight hamstrings and tight muscles in their low back, why? Poor movement patterns resulting in lack of pelvic stabilization. Once the body realizes there is not enough stability in the pelvis, it will tighten up the surrounding muscles in an attempt to increase pelvic stability. This results in tight hamstrings and tight back muscles. Stretching these muscles can result in a temporary decrease in stability, increasing the likelihood of back pain. Unless you work on strengthening the hip extensors and increasing pelvic stability, you will be fighting an uphill battle.
How do we target and strengthen the hip extensors? Squats, lunges, and deadlifts are all great exercises that incorporate hip extension. If you look for it, you can incorporate these exercises into daily life. Arising from a seated position can be performed like a squat, tying your shoes can be performed like a lunge, picking objects off the floor can be a deadlift. Every time you have to bend down,if you hinge from the hips, you will keep the core engaged, the back protected, and the hip extensors active.
With the above said, if you want to stretch the hamstrings, please do so properly. Most people will stand up, bend forward by rounding their back, and attempt to touch their toes. Another way people attempt top stretch the hamstrings is to do a sit-and-reach. Seated with their legs straight out in front they attempt to again touch their toes. These will stretch the hamstring, but they will place unnecessary strain on the low back.
A much better way to stretch the hamstrings is to lie face up, bend the hip to a 90º angle and slowly straighten out the leg, while keeping the 90º angle at the hip. You can use a towel, band, or a stretching partner to help if needed.