The legs are large muscle masses that are meant to take on a lot of weight. When the legs are strong, they are able to take on much of the weight that the back would otherwise have to carry. The hamstrings are the muscles on the back of the thigh that if tight, can actually exacerbate back pain. Elongated hamstrings allow the legs their full range of motion which allows the body to stand upright and in proper posture. Tight hamstrings can lead to swayback.
Keeping the muscles of the legs elongated and toned plays an integral part in maintaining back health. Back pain can radiate down through the buttocks and into the legs. Severe back pain can cause numbness or tingling in the legs.
The Sciatic nerve also runs through the same area of the leg as the hamstring. When the sciatic nerve is being pinched by inflammation it can radiate pain down the back through the buttocks and into the legs. When people experience sciatica, they want to overcompensate and be too gentle on the back and legs. However, once inflammation has been reduced, stretching the hamstring can relieve the tension in the legs and the back, which then eases the pressure being put on the sciatic nerve. Here is a stretch that will help elongate the hamstring and can also ease the tension on the lower back:
Lie down on your back with your knees bent and your head on the ground. Tilt your pelvis slightly toward the sky so that there is very little hollow between the low back and the floor. (You can put a small, rolled up towel under your back if it is especially tender.) Bring up your right knee and lace your fingers behind the upper middle part of your calf. Pull the leg toward your chest. Slowly straighten the raised leg. The stretch will increase as you pull back and straighten the leg. Stop the stretch if you begin to feel pain. Stretch the hamstring for 15-30 seconds trying to straighten the leg a little more every several seconds. Slowly lower the leg. Repeat on the left leg. This stretch can be done several times a day.