The sliding backrest motion invented by Mastercare is unique to their Back-A-Traction gravity inversion units. This feature exerts a force that greatly magnifies the degree of traction force applied to the lumbar spine. In practice, as the unit inverts beyond horizontal, gravity causes the sliding, spine-supporting-surface (actually the tabletop) to move the torso away from the pelvis, while the legs and pelvis are held comfortably in place because of the locked-in feet and ankles.
A greater degree of useful therapy (traction force) is applied without the likelihood of adverse side effects possible with full vertical inversion utilized with sling-type inversion brands. As one of the participating clinicians for development of gravity inversion systems almost 40 years ago, Dr. Brad Lustick (Back Be Nimble's medical editor and CEO), has the clinical research experience to understand and endorse Mastercare's 'Sliding Backrest' as a safer and more effective alternative when utilizing gravity-based inversion traction therapy.
Dr. Lustick explains: "after many years of touting the use of inversion therapy as a beneficial adjunct to spinal manipulation and rehabilitative therapy, I had the opportunity to infer from my clinical observations, that the use of "sling type" full inversion units and/or use of 'gravity inversion boots' often resulted in repetitive stress injuries related to the hips, knees and ankles". Additionally, full inversion certainly presents more of a risk for those patients known to have glaucoma, hypertension or family history of stroke.
Dr. Lustick noted a secondary finding to be a less than desirable result noticed when patients used inversion units or gravity boots that position the body with the legs straight vs. a bent knee position. One unique feature of Mastercare inversion is the 'optional and adjustable knee bending attachment (K3)'. This option helps eliminate the undesirable pull of the hip flexor muscles on the lumbar spine during traction. Most knowledgeable physicians prefer to prescribe gravity inversion using the positioning and methods only offered by Mastercare Back-A-Traction tables.