by Christy Lotz, CPE
Thank you to those of you who attended our Office Ergonomics Assessment web course this week. We hope you enjoyed it and if we missed any questions, please feel free to add a comment on this blog and we’ll respond. Here are some answers to questions that were posed during the event.
Q: What has been your experience with the swiss ball/balance ball as an office chair? What are the main concerns and benefits?
A: Sitting on a swiss ball at the office is believed by some to be better than a regular office chair because it increases low back muscular activation. The fact is, however, that in a recent 2006 study (Gregory et al.), researchers did not observe a significant difference in muscle activation between sitting on the ball and a regular office chair. If you do not already have a strong core, prolonged core, you will inevitably move from activating the core muscles to using the passive tissues of the back which may result in low back pain. Think about holding an isometric contraction for 8 hours in the gym – impossible. The support of the backrest in a chair will allow users to release the contraction of the core and hold the back in the “s” shape curve. In addition, the instability of a stability/swiss ball is more likely to cause an injury in the office.
Q: What is your view of “computer glasses” compared to others, such as progressive glasses.
I’m definitely not an optometrist or an optician, but my understanding of computer glasses is that they’re designed to address the symptoms of computer vision syndrome (eye strain, headaches etc.) and put the lens power within the optimal viewing area for looking at a computer screen. This is usually farther away than you would hold a book for reading, but too close to be considered “driving” distance, so it’s referred to as “intermediate”. Using computer glasses allows people to see that intermediate distance without having to tilt their head back if wearing standard bifocals, or lean forward if the prescription is not strong enough. Progressive lenses (as far as I know) have different levels of power, however, sometimes they don’t have a large enough zone to view a monitor. From an ergonomic standpoint, I would say that whatever method will allow users to keep a neutral neck and back posture is going to work best for them. It will be dependent on the individual and his or her prescription power.
Q: Explain the “o.k.” example representing less strength in an awkward posture position.
To let people feel how much stronger they are in a neutral wrist position, have them keep one wrist straight and put their index finger and thumb together and squeeze tight (‘O.K.’ sign). Have them try and break those fingers apart with one finger on the opposite hand. It is very difficult to do because you are strong in a neutral position. Then have them flex that wrist but still keep the index finger and thumb together. Now try to break through with the opposite hand. They’ll see it’s much easier. Just changing the posture can have a huge impact on the amount of force you can generate.