From the moment we are born, and throughout our lifetime, we fi ght a constant battle against a downward compressive force of nature – the force known as gravity. It is a force that we can’t live without, but a force that we can do something about. You may be asking yourself; what can I do to fi ght the negative effects of gravity? HISTORY OF INVERSION This same question was asked nearly 2,500 years ago when, in 400 BC, Hippocrates used a complicated system of ladders and pulleys in order to remove weight from his patients’ spine in an attempt to reduce the effects of gravity. In the 1960s Dr. Robert Martin, a California-based chiropractor, osteopath and medical doctor, developed the “Gravity Guidance System.” His ideas, and use of inversion therapy, stemmed from 15 years of research on common activities such as standing, sitting and lying down, as well as more uncommon actions such as extended, brachiated and inverted postures. He took inversion therapy into the mainstream and challenged physicians and therapists to look at these uncommon postures as ways to counter the adverse effects of gravity. By 1980, inversion had begun gaining popularity as a therapy. As inversion grew in popularity, Drs. Klatz and Goldman1 in 1983 published a study that all but eliminated inversion as a way to combat the negative effects of gravity. Their study concluded that there was “concern” with the use of full static inversion in individuals with a history of hypertension, cardiovascular disease and stroke. They recommended that general caution be observed among the elderly, who are at an increased risk for a cardiovascular accident. The media misinterpreted these fi ndings, stating that inversion causes strokes, which all but destroyed inversion’s chances for existing as a therapy. In 1985 Dr. Goldman2 published a second study to help clarify what had been previously stated. Dr. Goldman’s second study led to the conclusion that the risk of stroke in previous studies appeared to be greatly exaggerated and that there have been no reports of stroke, cardiovascular accident (CVA) or serious injury with inversion. Furthermore, Goldman stated that there is more risk of CVA in standing posture and while weightlifting. With the “scare” lifted, an increasing number of health-care providers began to use inversion as a form of treatment for a multitude of spinal health issues. THE EVIDENCE FOR INVERSION THERAPY As the popularity of inversion has grown, so, also, has the body of research to help validate the use of inversion as a clinical treatment. Some of the main areas of interest for researchers have been the reduction of back pain, decrease in lost work time and avoidance of surgery. The following is a summary of the more prominent studies in this area – references can be found at the end of this article, if the reader is interested in pursuing more detailed information. The Nachemson study3 measured internal disc pressure – in the third lumbar space – through a range of activities, including standing, sitting, bending, along with vertical and supine traction. The study demonstrated that, when lying down, there is a residual pressure inside the discs equal to 25 per cent of standing pressure. In a separate test, this study indicated that traction equal to 60 per cent of body weight was required to reduceThe standing body pressure by 25 per cent, suggesting that the pressure inside the disc could be reduced to, at, or near zero by applying traction equal to 60 per cent of body weight while in the supine position. This amount of traction is effectively applied by inverting to 60 degrees, or more, thus substantially reducing low back pain. The Kane study4 demonstrated that gravity-facilitated traction produces signifi cant intervertebral separation in the lumbar spine. The study concluded that gravity- facilitated traction may be an effective modality in the relief of low back pain. The Nosse study5 found that EMG activity (an indicator of muscle pain) declined by 35 per cent within the fi rst 10 seconds of inversion. The study also found that inversion increases spinal length, concluding that there seems to be a correlation between a reduction in EMG activity and an increase in spinal length. The Dimberg/Volvo study6 evaluated 116 people in a randomized controlled trial that lasted for 12 months. Three training groups were studied, and after 12 months, the researchers showed a decrease in sick days due to back pain by 33 per cent. The average sick days lost to back pain fell by eight days per individual in the treated group. The study concluded that inversion is an effi cient and inexpensive way to improve employee health and possibly reduce sick day costs to the employer. The Sheffi eld study7 evaluated 175 patients who were unable to work due to back pain. After eight inversion treatments, 155 patients were able to return to their jobs full time. AVOIDING SURGERY THROUGH INVERSION THERAPY One area of concern for today’s patients, health-care providers and payers is the avoidance of surgery. The cost of back surgery is staggering in dollars and cents as well as lost time on the job, not to mention the percentage of failed surgeries that can compound the problem for both the patient and the physician. A preliminary study, from Newcastle Hospital,8 shows evidence that regular use of an inversion table may signifi cantly reduce the need for back surgery. In this study, patients who were told that they needed surgery to relieve sciatica were divided into two groups. One group regularly practised inversion along with traditional physical therapy, while the other group received physical therapy only. The results showed that the patients in the inversion group were 70.5 per cent less likely to require surgery. The effi cacy and benefi ts from inversion defi ne a broad spectrum of patients and conditions. Patients who present with numerous conditions such as herniated or bulging discs, sciatica, spondylolisthesis, scoliosis, muscle spasm and even lymphedema, can benefi t from inversion. Inversion therapy can result in a reduction of pain, realignment of the vertebrae, rehydration of the intervertebral discs, relaxation of the muscles and reduction of recovery time. In addition to these direct benefi ts, the use of inversion also has beenShown to stimulate venous return and the lymphatic system; stimulate the autonomic nervous system and its baroreceptors; increase oxygen fl ow to the brain; help maintain our original body shape and avoid prolapsed internal organs; help maintain correct posture; and contribute to overall general good health. With such wide-ranging effects on such diverse patient populations, why wouldn’t a practitioner offer inversion in the clinic? The answer may be as diverse as the benefi ts of inversion itself. It is surely not due to the complexity of the treatment. Inversion is a relatively simple, cost-effective treatment that does not require highly expensive equipment or lengthy staff training. A comprehensive and effective inversion treatment program can fi t into almost any type of offi ce or clinic setting. If more health-care providers were educated on the benefi ts of inversion, many patients could receive the lifelong benefi ts of this therapy and the cost savings to both patients and practitioner can be substantial, as we start to equalize gravity’s negative effects one patient at a time.