There are two different ways that we can measure our flexibility in any joint: active flexibility and passive flexibility. It is important to know the difference between them and how to use them to achieve your flexibility goals. Active Flexibility Active flexibility is the amount that we can use our own muscles to move into an end range position. So if I want to lengthen my hamstrings and the back of my leg, my active flexibility would be the amount that I could use my hip flexors to bring my leg closer to