The rectus femoris is located to the centre of the thigh, and is one of the four muscles which collectively compose the quadriceps.
As with the other quadriceps muscles, the rectus femoris is actively engaged during the extension of the knee. The muscle can therefore be targeted with squat variations, as well leg extensions.
Strong quadriceps are not only important to improve performance for athletes and sportspeople, but are also vital for taking stress away from the knee joint during sporting activities.
Sitting beneath the rectus femoris, the vastus intermedius is one of the four muscles which compose the quadriceps.
Like the other quadriceps muscles, the vastus intermedius is successfully exercised with squats and leg extensions. Other exercises which incorporate the extension of the knee will equally recruit the muscle, such as cleans and snatches.
Being deeper within the quadriceps structure, the vastus intermedius can prove more difficult from a therapeutic stand point. Tissue manipulation, releasing, and stretching are more challenging for the muscle compared to the other, more superficial, quadriceps muscles.