Full arc extensions are early rehabilitation exercises to strengthen the quadriceps and improve range of motion.
Slowly lower the leg and repeat on the other side. Repeat this whole sequence several times. Add ankle weights if it is too easy.
Why is knee extension important?
Proper knee function demands a strong quadriceps muscle which can support the body's weight when walking and running. This particular exercise is an open chain exercise - where the foot is free during the exercise, and should only be included once the patient is confident with closed chain exercises of the quads, such as mini-squats, where the foot remains in contact with the surface throughout the procedure.
How can we strengthen the quadriceps femoris in patients with patellofemoral pain syndrome?. Kaya D, Doral MN and Callaghan M. Muscles Ligaments Tendons J. 2012 Jan-Mar; 2(1): 25–32.