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90 m a s s a g e & b o d y w o r k m a y / j u n e 2 0 1 7 technique MYOSKELETAL ALIGNMENT TECHNIQUES Why We Get Shorter The Secret Life of Spinal Discs By Erik Dalton, PhD The intervertebral discs are responsible for 25 percent of our spine's overall length. Given that the average adult spine measures 24–28 inches, the intervertebral discs account for six to seven of those inches. In young individuals, the water- filled, gel-like nucleus pulposus and annulus fibrosis are both firm and flexible. However, by age 40—earlier than any other connective tissue—the vertebral discs often begin showing degenerative changes (Image 1). 1 As the discs dehydrate and lose elasticity, the length of the spinal column can shrink by 3 centimeters or more. Thus, most of us get shorter as we age. To resist gravity's compressive forces, the myoskeletal method uses graded exposure stretches to ease protective guarding, neurologically awaken antigravity muscles, and help restore lost body height. In a study titled "Nutrition of the Intervertebral Disc," a team of researchers from Oxford University found that loss of nutrient supply for the discs can lead to cell death, as well as an increase in matrix degradation and disc degeneration. 2 Oddly, vertebral discs are among the few human tissues that do not possess an independent blood supply. Even our teeth, nails, and hair have designated nutritional vessels, but the discs do not. The annular fibers require glucose for survival, and the nucleus obtains fluids and eliminates waste—primarily lactic acid—through a complicated process called imbibement. The imbibing of water occurs as individual spinal segments flex, extend, sidebend, and rotate during normal daily activities. Contrary to popular thinking, vertebral discs are not designed to act as the spine's primary shock absorber. This role belongs to a marvelously designed musculofascial spring system. Notice in Image 2 how the flexible colored bands, which represent muscles and ligaments, form a tent-like tensegrity arrangement. When healthy, these soft tissues can maintain separation of vertebral bodies even with the disc completely removed. Equipped with these facts, we're left with this question: If restoring antigravity function is the key to slowing spinal disc aging, then what's the best way to pump up those discs? FETAL POSITIONING AND IMBIBEMENT When picturing an intervertebral disc, most of us think of the outer annular fibers as circular connecting rings, similar to a radial tire, that support the gel-filled (hubcap) nucleus. However, many of the disc's concentric tree-ring fibers do not connect, nor is the disc round (Image 3). Mother Nature cleverly thickened the anterior and lateral sides, leaving the thinner posterior fibers to absorb lubricating fluids during daily activities and also during sleep. Strangely, 80 percent of this fluid imbibement occurs during the first hour of sleep. That's why researchers believe the best resting position for rehydrating discs is a sidelying fetal position with knees flexed, chin tucked, and lumbar 1 2 Disc degeneration beginning at age 40. Image adapted from Dreamstime. A tent-like tensegrity arrangement acts as the spine's primary shock absorber. Image courtesy tensegrity-model.com.