Psoas Muscles Hurt Using Exercise Ball for a Chair

Question

Will my psoas muscles stop hurting after using an exercise ball for a chair for a while?

I've been using the exercise ball as a chair for about a week now 4 hours a day at work, and it seems that the muscle it effects the most is my psoas muscles. This is mostly due to the fact that I'm used to slumping in my chair for 8 or 9 hours a day, and using the exercise ball I'm having to make a concentrated effort to sit up straight.

How long will it take for this to stop being so painful, and is it possible that I'm overdoing it with 4 hours a day?

Answer 1

There is some evidence that using an exercise ball as an office chair may do more harm than good (source: PubMed). This study found that there was a higher level of activation in the low back muscles on an exercise ball than on an office chair. This doesn't sound like such a bad thing, but according to the authors:

It seems ... that low-level activations can lead to enhanced development of muscle fatigue. Higher muscle activation would also cause higher forces on the spine and consequently enhanced fluid loss from the intervertebral discs.

Accordingly the study found that sitting on an exercise ball instead of a chair was related to spinal shrinkage.

Since the psoas major originates from the lumbar vertebrae, it may be compensating for the extra strain on the low back. My advice would be to nix the exercise ball and go for an office chair designed by ergonomic specialists, but if you want to keep using the ball, this article offers some decent tips, such as:

• Develop good sitting posture on a normal chair before moving to an exercise ball. If you have bad posture, sitting on an exercise ball could just make it worse.
• Start with only 15-20 minutes per day on the exercise ball, and work your way up. Don't push through discomfort to keep sitting on it, that's your cue to get off.
• Do core strengthening and stability exercises on the side.

Answer 2

Based on Barbie's excellent answer, I suspect we should view the exercise ball exactly for what it is: a ball to exercise on. It might help you train to get a better posture, which is useful for when you sit in a regular chair, but it isn't meant as an alternative for your permanent seating.

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In your specific case: pain while sitting is never a good sign, especially since these muscle are very strong and used very often. I therefore suspect that you overdid yourself and should either built it up more gradually or use the ball and chair in an alternating fashion.

Try building it up with 1 hour incremental steps to see how long you can maintain it or alternate in one hour long intervals. If it starts to hurt, be sure to give your muscles rest before trying the ball again. This might mean not using the ball for a day. The pain doesn't have to be completely gone, but you should give your muscles sufficient time to recover.

The idea is to gradually built up the strength required, so while it may be slow, keep in mind you're coming from hunchbacking 8-9 hours a day!

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Another option is to slightly change your position, so that while you still need your iliopsoas to remain upright, other muscles take up part of the load. While you might not be maintaining your perfect upright posture, it's probably still better than slacking in a chair.

Here's a small schematic image of what I mean:

By moving more forward and flexing your hip differently, your iliopsoas will be stressed differently and your rectus femoris (part of the quadriceps femoris) can aid you more.