Did you know that there are three muscles that form the hamstring muscle group? The semimembranosus and semitendinosus attach to the medial (inside) area of the knee and the bicep femoris attaches to the outside of the knee. All three muscles attach into the sitting bone. The hamstring functions to extend the hip and flex the knee.
Signs that your hamstrings are grumpy, tight and full of trigger points include pain that can be felt in the back of the thigh and refer into the buttock and lower glut area as well as referring down into the knee and occasionally the calf as well. Referred pain in the back of the leg can often be confused with sciatica. Hamstring pain may be increased from sitting or walking and that can disrupt sleep.
There is a tendency for the hamstrings to get tight and over active when the gluts becoming weak and lazy (this often occurs with long periods of sitting). Tension in the hamstrings can start to pull on the pelvis and lower back causing a posterior pelvic tilt, straightening of the lumbar spine and compensatory anterior head tilt in the upper body. So tight hamstrings not only cause pain in the in the sitting bone, back of the knee and thigh but also into the upper body when looking at the impact they have on the body as a whole.
The best thing you can do to prevent tight hamstrings causing trouble is to make sure you stretch them regularly. Below is a good hamstring stretch, make sure you hold the stretch for at least 2 minutes each side and try use PNF stretching where you contract then relax the muscle which will allow for a much deeper stretch.