The first thing to ask yourself is do you have unexplained foot\ankle, knee or lower back pain. There is some debate over the need for orthotics. One school of thought is that your lower extremity and hips may have some weak muscles that are not helping your body maintain your arch and or avoid what is termed pronation or pes planus of the foot and ankle complex. This change in foot position effects the knee, pelvis and spinal function. Many times orthotics are needed to while rehabilitating or correcting imbalances your muscles to support joints and body position until such a time you can do it for yourself. A simple self assessment of your foot position is to take two paper towels (preferably brown), step into water ( into a tray or dish tub) and step on the towels. If your pattern is more box like you may have some pronation going on. If your outline on the paper is more concave on the inside and straight on the outside you may not have this condition. Ultimately, if ther is pain involved, you should be evaluated by a qualified therapist, podiatrist, chiropractor etc..
More Answers from Brian Waldo , NASM Elite Trainer