MEET YOUR MUSCLES
Hamstrings (posterior thigh) are effective at both extension of the hip-joint and flexion of the knee-joint. The hamstrings are active during normal walking.
Tight hamstrings (reduced hamstring stretch) limits hip flexion.
Three muscles make up the hamstring:
A. biceps femoris
Standing/Kneeling Hamstring Stretch
This stretch stretches your hamstrings from both your hip and knee. By bending the knee, you will feel the stretch more at the hip. When you keep your knee straight, you will feel the stretch more towards the knee.
Rotating your toes outward emphasizes the inner portion of the hamstring (semimembranosus), while rotating your toes inward emphasized more of the outer portion, or the biceps femoris.
See also: Stretches for the back