Inversion tables can be used those who want to ease tension from their back. However the advice of the doctor is needed before you can use an inversion table. An inversion table is meant to relieve stress and back pain. In fact it's believed that the practice has been used as early as 400 BC. Now many physical therapists, medical doctors use the same technique of gravity-assisted inversion. It's actually a gravity assisted traction exercise. Our body is made in such a way that every vertebrae in the spine and every disc is made to support the weight. Therefore to start with you should only 20 - 30 degrees for a few weeks before you invert at 60 degrees and finally at 90 degrees. The lower discs in our body are made to support the 60% of the weight above them while those in our neck are meant to support the weight of our head. Tables can be locked at a 90-degree angle for the full inversion. There are adjustable roller hinges. These adjustable roller hinges allow you to control the aggressiveness of the rotation. In this position you can do sit ups as wells as squats. You can even do inverted crunches in this position. A word of caution, don't overdo the exercises. If you feel too much pain, then you should stop doing the powered inversion table and seek medical advice before proceeding further. Your arm movements control the movement of the inversion table. The tether straps will lock your ankles while you are on the inversion table and in most cases the nylon mat will be washable. Most inversion tables come with a five-year warranty and some companies will also provide free shipping. Gravity boots can also be used with the inversion table to provide a better support to the ankles while exercising on the inversion table. There are many options available in the market. They can cost approximately upto $500 and the starting range starts at $300. Doctors for those who experience back pain and may have had problems in their back recommend them.