When walking the range of movement available at the ankle joint is so important. Whenever we put the foot on the floor the body above is required to move forward over that foot. That forward movement occurs at the ankle joint, therefore it ought to be apparent that there really should be nothing that prevents that forward movement at that joint. Problems such as osteoarthritis in the ankle joint may affect that forward motion. Another frequent problem that can hinder that forward movement are tight calf muscles. They stop the leg moving the desired range of motion above the foot. If that motion is restricted than a number of things can happen. Firstly, walking is a lot harder. It is more fatiguing as more efforts are needed to walk. Secondly, the body has to obtain that motion from someplace. If it can't get that movement at the ankle, then it could possibly get it in the knee and if that happens we then walk with a more flexed knee that is a difficult way to walk. If the body doesn't compensate at the knee, then it gets the movement at the midfoot. In the event that happens then the arch of the foot flattens which can result in a variety of clinical disorders.

For these reasons, clinicians want to assess the mobility at the ankle joint as part of a biomechanical examination. There are many ways of doing this. One way is a non-weightbearing examination with the foot and leg up in the air and the feet are just moved on the leg and the range of motion is tested. Another, probably better approach, would be to do what is called a lunge test. This is a weightbearing measure of the ankle joint range of motion and in that position it is probably a better representation of the reality of the way that we walk.