Leg Extensions for Stability & Control: Short Arc Quads involve a controlled, mindful movement that helps activate the vastus medialis (the inner part of your quad), which plays a huge role in knee stabilisation. Progression: The Long Arc Quad is done lying down and focuses on working the quadriceps through a full range of motion, typically from 0-90 degrees. In contrast, the Short Arc Quad exercise focuses a smaller range of motion, particularly targeting the last 15-20 degrees of knee extension. Both exercises serve a similar purpose in strengthening the quadriceps, but the Long Arc Quad allows for a more extensive workout of the muscle group.