So what is it now, you medical experts? </p><p>We need to learn how to sit? </p><p>Oh, puhleeze. We&rsquo;ve been doing it all our lives. For many, sitting for eight hours straight is pivotal to the job, not to mention that post-work leisure time plopped on the La-Z-Boy watching TV or playing video games. Oh, occasionally we&rsquo;ll get up to go sit in our cars in order to sit in restaurants and eat. </p><p>You&rsquo;d think, therefore, we&rsquo;d have this sitting thing down by now, that we&rsquo;d be no slouches when it comes to taking a load off. </p><p>Right? </p><p>Not so. </p><p>Turns out, we literally are slouches. Doctors, chiropractors and ergonomics experts, who make a nice living off our backs, say poor posture while sitting is something of an epidemic. </p><p>Eighty percent of Americans will cringe with back pain at some point in their lives, and back injuries prove the top reason for missed work, according to the National Institutes of Health. </p><p>This is something San Francisco chiropractor Gregg Carb, for one, just won&rsquo;t stand for. </p><p>Carb has written a book, &ldquo;The Science of Sitting Made Easy,&rdquo; to address the problem. Boiled to its essence, Carb&rsquo;s message is the same as Mom hectored you with for years: Sit up straight, will ya? </p><p>Our spines are strong and resilient, Carb says, but not impervious to the deleterious effects of slouching, craned necks, twisted trunks. </p><p>&ldquo;When you hold any body position for long periods of time, your spine is gradually reshaped into that very position through an adaptation of the connective soft tissues,&rdquo; Carb says. </p><p>Years of improper sitting can lead to disc degeneration, which is permanent. But, Carb says, mobility and comfort can be restored through rigid adherence to, well, sitting rigidly. </p><p>&ldquo;You will get some actual form changes over time if you improve your posture,&rdquo; Carb says. &ldquo;It&rsquo;s almost like having braces (on your teeth). But we&rsquo;ve found we can loosen people up in a matter of weeks.&rdquo; </p><p><strong>What not to do while sitting:</strong> Roll your shoulders inward, jut your head forward, round out your lower back, sink your chest. </p><p><strong>What to do to avoid those bad habits: </strong>Set your seat back to a nearly upright position and sit as far back into the seatback as you can, keeping your rib cage and trunk upright and your head aligned directly above your shoulders. </p><p>George D. Picetti III, a spine surgeon in Sacramento, Calif., recommends lumbar support &mdash; usually a molded foam pad &mdash; to promote the natural forward arch of the lower back, called lordosis. The support should be placed around the belt line, &ldquo;but some people have more swayback, so you&rsquo;ve got to fit yourself for it.&rdquo; </p><p>The other option is to spring for a high-end, ergonomically designed office chair, such as the Herman Miller Embody at $1,600. </p><p>Paying close attention to your breathing &mdash; deep breaths that expand the rib cage &mdash; is another key, Carb says. </p><p>&ldquo;Patients are always worried about their head and shoulders being in the wrong position,&rdquo; Carb says. &ldquo;But if you keep your rib cage up, the other parts will follow. That&rsquo;s how to do it without overwhelming yourself doing too many things at once.&rdquo; </p><p><hr class="infobox-hr-separator" /> <div class="infobox"> <strong><span class="infobox-head">THE BOOK </span></strong><br /> <strong>&ldquo;The Science of Sitting Made Easy&rdquo; </strong>by Gregg Carb (176 pages, Posture Press, $14.95)</p><p>Available at Amazon.com or <a href="http://www.posturepress.com">www.posturepress.com</a></p><p></div>