It’s interesting how many patients I see who are conditioned to sit all day during work or they have jobs which require them to be in flexed or stooped positions for the majority of the day. They then go home and once again sit for a couple of hours, have dinner with their family, help their kids with their homework, then they go and sit for a couple more hours watching television or surfing the internet. We’ve already discussed how this constant trunk flexion turns off trunk muscular stabilization, segmental control, trunk extensors, etc. Research has shown that after just 20 minutes of sitting it took 2 minutes of standing for the facet joints to regain only half of their joint stiffness. This has implications which are important for example for workers who sit prolonged but periodically have to get up and perform trunk intensive activities, they are at a greater risk. How about something as simple as a parent who is sitting for 20 minutes and has to get up quickly and lift their child from the floor? Real world examples such as these illustrate some of the origins of low back injury.
Prolonged sitting can also push disc material backwards causing exacerbation of herniated and bulging discs and creating pressure in healthy discs which may predispose those healthy discs to disc damage, we will discuss this more in a different section on extension exercise and the disc. This posterior migration of the disc material also is significant in those of us who sit prolonged but then get up and perform a trunk intensive movement. Now we are getting up with a severely decreased facet joint stiffness, decreased core and trunk extensor stiffness, a delayed feed forward mechanism, and on top of that the possibility that our disc material has migrated posteriorly. This is just a recipe for disaster, and has been.