"Don't hunch your back."
"Stand up straight."
At some point in almost everyone's teen years, a well-meaning parent or teacher tells us to correct the way we're standing or sitting. The advice comes with no explanation. And yet, perfect sponges that we are as teens, we file the criticism in the back of our memory so we can dredge it up later in life. Usually, it's in front of a mirror, when we look with astonishment at our stooped shoulders, sagging gut, and bent over-spine. What we do next is so classic that it's parodied in nearly every comedy about a character undergoing a mid-life crisis -- we suck in our gut, throw back our shoulders, and arch our back, as if to proclaim: "I've still got it."
Got what? Good posture? Think again.
We manage to hold that ridiculous stance for several seconds and then collapse from fatigue, pain or lack of air. It is not a posture meant to make you feel comfortable. It is a posture for posturing... nothing more.
It is a pose based on notions of "good posture" that are more myth than fact.
• Myth #1: Good standing or sitting posture needs to be straight.
This advice never helped anyone learn proper alignment or avoid injury. If it had, we would all be perfectly symmetrical Eliza Doolittles, because we've all been beaten up with it. When "straight" is how we think of proper alignment, we park or fix ourselves in position. The reality is that optimal posture isn't straight or fixed; it's dynamic, so we're ready to move in any direction without first having to adjust.