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Dear Lucy: I am really confused about the correct posture for sitting. The data on the web seems contradictory. For instance, some sources advise keeping the knees below the level of the hips; others advise the opposite. Can you clarify? —Flying by the Seat of my Pants

Dear Flying: Your excellent question made Lucy sit up and take notice! Fortunately, she knew just where to turn—Associate Medical Director David Diamond, M.D., a specialist in occupational and environmental medicine and MIT Medical’s resident expert in repetitive strain injury (RSI).

Unfortunately, Diamond tells Lucy, there’s no definitive research that answers your specific question about relative level of knees and hips. “In general, however, we recommend feet on the floor,” Diamond says. “Your seat pan, the part of the chair you sit on, should be well cushioned and should extend to within a few inches of the back of your knee.” The tilt of the seat pan—forward, flat, or slightly back—is a matter of personal preference, but, Diamond emphasizes, back support should fit the shape of your spine. “Most people need lumbar support with back angle somewhat greater than 90 degrees. That way, when you lean back slightly, it supports your back as well as some upper body weight.”

Diamond pointed Lucy to several excellent MIT resources. For example, MIT’s Environmental Health Service (EHS) ergonomics page offers links to useful information as well as a form you can use to request an individualized computer workstation evaluation. Diamond also suggests checking out the extensive information on RSI prevention from MIT’s Adaptive Technology Information Center (ATIC). “Proper seating is only one factor contributing to RSI prevention,” he emphasizes. “In many cases, pacing, typing technique, and exercise may be equally important.”

Lucy hopes this answer is helpful, and she thanks you for giving her the chance to share this important information and these excellent resources with her readers. —Lucy

Information contained in Ask Lucy is intended solely for general educational purposes and is not intended as professional medical advice related to individual situations. Always obtain the advice of a qualified healthcare professional if you need medical diagnosis, advice, or treatment. Never disregard medical advice you have received, nor delay getting such advice, because of something you read in this column.