Beginners
Many people are drawn to the idea of hanging upside down to relieve back pain or improve posture, which it can. However, inversion or hanging upside down should be eased into. Inversion tables allow you to control the degree to which you invert. You can lie horizontally, at zero degrees, or go all the way upside down to 90 degrees. Different people will have different results. If you feel any uncomfortable side effects, such as headaches, invert at a lower angle or discontinue use. The first time you use the table you should try only inverting to 20 to 30 degrees. You may wish to remain at this slight angle for a couple of weeks. You should feel completely at ease before trying a greater angle of inversion. You will be able to get benefits from even this mild angle. A total body stretch, increased blood circulation, and more oxygen getting to the head are positive effects from hanging at even this mild angle. Because the body is upside down the blood flow is reversed, which according to a "Los Angeles Times" article will counteract the effect gravity has on circulation and blood flow.
Intermediate
After you become accustomed to being at an angle with your head below your feet at a 30 degree angle, you can double the degree and invert to 60 degrees. Most people will get everything they need by hanging upside down at this angle. Hanging upside down is good for your spine, as it allows gravity to gently pull and create traction. Traction is something chiropractors do to decompress their clients' spines and create space between the vertebrae. When a person lies on the inversion table, and is two-thirds of the way upside down, gravity can naturally allow the spine to decompress, if you do not resist. The more comfortable you become over time, the more relaxed you will be, and the more you will get from the experience. Inverted traction has been shown to be the only "effective means of achieving pelvic traction at home," according to a study published in "Archives of Physical Medicine and Rehabilitation." This means the vertebrae in the lumbar or lower region of the box were pulled away from each other, so they were a healthy distance apart.
Advanced
Hanging completely upside down will give you all the stretching and spinal benefits as inverting. Anyone with a lot of muscle or tension, such as people who exercise frequently, may need to hang completely upside down so gravity can work harder to stretch the stronger muscles and soft tissue.
Your best results will likely come from alternating between full or partial inversion and returning to an upright position. This back-and-forth method will increase your circulation more than remaining in one position. You can try hanging for 30 seconds and then returning to standing for 30 seconds.
This is referred to as intermittent traction. Gently rocking up and down is another option called oscillation intermittent traction. Oscillating was shown to be present "no risk to normotensive healthy subjects" in a study published in "The Physician and Sportsmedicine."
You can also hang upside down at 90 degrees by using gravity boots hooked into a metal bar stuck in a door frame. This will not allow you to control your angle; you can only do hanging straight upside down. You will still get the benefits of a stretched and decompressed spine this way.
Inversion has been shown to reduce instances of lower back pain. In a study done by Dimberg, L, et al on 116 people with chronic lower back pain, it was concluded that doing inversion as little as ten minutes once a day decreased participants needing to miss work because of lower back pain by 33 percent.
Warnings
According to an article in the "Los Angeles Times," inversion can be risky for people with certain conditions because the blood flow to the head increases and the body is put in an "unnatural inverted state." Anyone with high blood pressure, glaucoma, weak bones or with heart or circulatory disorders are discouraged from being inverted. Women who are pregnant or who are obese should also be wary.
