Description: The hamstrings attach to the ischial tuberosity at the back of the pelvis and run down the back of the leg.
Actions: These muscles flex the leg at the knee joint, extend the thigh at the hip joint, and medially rotate the leg at the knee joint.
When tight, these muscles can pull and stress the low back.
The hamstrings can limit forward bending because they keep the pelvis from rotating forward.
These muscles are stretched by hip flexion, including forward bends such as Paschimottanasana in which the knee is straightened while the hip joint flexes.
Abductors / Gluteus Muscles
Muscles: Gluteus Maximus (the largest, most posterior and most superficial), Gluteus Medius (medium-sized, fan-shaped partially covering the glute maximus and covering the glute minimus), Gluteus Minimus
Description: These muscles run from the outside of the pelvis to the outside of the femur; they work opposite the adductors. The gluteus maximus externally rotates the hip and assists in knee extension. It attaches along the outer portion of the femur and connects through fascia to the iliotibial (IT) band of the tensor fascia lata (TFL).
Actions: The abductors are responsible for lateral rotation of the thigh at the hip joint, extension of the thigh at the hip joint, and abduction of the thigh at the hip joint.
Tightness in the glute maximus limits forward bending at the hips.
Abductor weakness limits backbends.
These muscles are strengthened during hip extension against gravity.
Bringing focus to the engagement of the glute maximus will keep the femur more centered in the hip socket, reducing overall wear and tear on the hip joint. (Doug Keller)