The sartorius muscle — so named because, when fully flexed, one end of the muscle is at the point in the leg where a tailor would measure one's inseam — is the longest muscle in the human body. It originates on the outer hipbone and inserts at the inner front of the tibia. Stretching this muscle, like any other muscle, should be done after a brief warm-up; you should hold the stretches for 30 seconds before slowly coming out of them.
Lying Quadriceps Stretch
Because the sartorius performs actions similar to those performed by the quadriceps, stretches that target the quadriceps group —such as the lying quadriceps stretch — will also stretch the sartorius muscle. Lie face-down on the floor and bend your right knee, grasp your foot with your right hand, and gently pull back on the foot while keeping the hip down on the floor. If you cannot reach your foot, use a towel to wrap around your foot. Hold the stretch for 30 seconds and repeat on the left leg.
Kneeling Hip Flexor Stretch
Since the sartorius also acts as a hip flexor, the kneeling hip flexor stretch will also work on the sartorius. Kneel on your right knee, with the left foot out in front so both legs are bent to 90 degrees. Slowly shift your weight forward while keeping your back straight and your chest up. Lean forward until you feel a stretch on the front of the right hip. Hold for 30 seconds before coming out of the stretch, then repeat on the left side.
Internal Rotation
One of the motions the sartorius performs is external rotation of the leg. Therefore, rotating the leg internally will stretch the sartorius. Stand tall and turn the foot as far inward as you can, hold for 30 seconds, and repeat on the other leg. If you do not feel the stretch very much, advance it by crossing the left leg over the right leg (while it is still rotated inward), and bend forward at the waist. This will straighten your right leg and stretch the sartorius more than the simple internal rotation. Repeat the stretch for the left leg before finishing your stretching routine.
