Standing Knee Flexion (Hamstring Curl) Machine
An isolation movement for hamstring muscles, which help support the knee joint. Keep your knee aligned with the axis and adjust the lever roller pad so that it is just above your heel. Try to curl the pad all the way up to your butt, pause, and lower slowly. As this machine allows you to work unilaterally, you can discover which side is weaker and give it additional emphasis.
A non-machine (and more functional) variation on this movement can be done with the Swiss Ball either with one leg or two(easier):