“Sit up straight, it's good for your back!”
Okay, teachers, I get it. If I were in front of a room full of unruly third-graders, I too would want them to be sitting at ramrod-straight attention, like the kids at a Japanese cram school. Nothing would make me want to head to the break room for a quick cigarette like a few rows of hunched-over Quasimodos, or kids leaning back lazily like Judd Nelson in The Breakfast Club.
But if I were a chiropractor, not a third-grade teacher, I would know to reserve judgment. Doctors and fitness experts now know that the posture that's best for the back is what's called a "neutral spine," which is relaxed and slightly curved, not the 90-degree 'L' sought by Victorian nannies. The latest OSHA guidelines for computer workstations allow that healthy sitters can choose freely from any of three positions: "upright," "reclined," or "declined." In other words, the exact angle of the back is less important than ergonomic details like keeping your head level and your feet flat on the floor.
A 2006 study at an Aberdeen, Scotland hospital would go even further than that. Doctors there took MRI images of healthy patients in three different sitting positions: hunched over, sitting up straight, and leaning back a full 45 degrees. The upright posture actually caused the most spinal disc movement, which leads to strain on the back. The radiologists who ran the study ended up endorsing the 135-degree angle (i.e. leaning so far back you look like a sitcom dad watching TV) as the healthiest posture.
Granted, elementary school chairs may not support that level of recline, but it.s a good habit for kids to get into if they ever manage to land an office job where the chairs are a little more ergonomic than the blue plastic monstrosities they have to sit on now. In a classroom setting, the best advice is probably for kids to sit at whatever angle of recline keeps the back feeling relaxed and supported, to take breaks for standing and walking as much as possible, and never to sit hunched forward. Hunching puts pressure everywhere from your jaw to your ribcage and, according to a 2009 Ohio State study, actually makes students feel less confident about themselves and their work.
A 2010 MRI study by some orthopedic surgeons at the University of California, San Diego found another growing menace to the vertebrae of the nation's youth: the school backpack. When kids wore heavier backpacks, the study found, their spine curved and discs in their lower back became compressed. Even when the backpack was only 20 percent of the kid.s body weight, it caused spinal curvature in about half the subjects. A ten-percent backpack (about nine pounds for the 11-year-olds in the study) turned out to be much safer.
Don't worry, kids. You're going to hear a lot of crazy stuff about the importance of "posture" for the next few years, but relax. I've got your back.