T: You also talk about our increased risk in the morning hours after waking. Can you explain this?
SM: As you know, you’re taller when you wake up in the morning than when you go to bed at night. This is because the discs are hydrophilic, that means they suck up water while you sleep and when there are no stresses present.
After rising, hydrostatic stresses of just walking around and using the muscles during the day compress your spine and the fluid is squeezed out, decreasing the anular tensions in the disc. So, when you wake up the extra height in the discs are analogous to a full water balloon ready to burst and if you bend, you build up much higher stresses in the disc. In fact, the stresses are three times higher than when you perform the same bend two or three hours later.
Now I’m not talking about getting up and going for a walk or perhaps a boxer going for a jog first thing in the morning. I’m talking about heavy bending exercises, like for example the good-morning exercise or doing sit-ups. Somehow people thought that this would be a good thing to do in the morning. It’s the worst possible thing you could do for the back first thing in the morning. I personally have a more favorite morning exercise, it’s what I like to call a "great-morning," but I don’t think my wife would appreciate me talking about it! Full spine bending first thing in the morning is a great way to damage your back—an unwise thing to do.
