An arabesque panche (definition): in which the raised leg is at an angle much greater than 90 degrees. The body bends forward to counterbalance the back leg. This ballet pose requires tremendous balance as well as flexibility.
When putting these two exercises together on the reformer focus is on coordination, balance and strength. At the top of the extension on the arabesque panche I bend my knee to enhance the stretch on the hamstring of the supporting leg as well as to increase the flexibility on the hip flexor of the opposite leg.