“To Arm Rest or Not to Arm Rest… This is the Dilemma!”WIN NEWS: Sign up Now
November 2015: Ergonomic chairs
During my presentation last week at the National Ergonomics Conference and Exposition where I presented “Chair Fit or Failure”, an audience participant asked me what my opinion was on the use of armrests while I was demonstrating how to measure a person in a chair for best fit. Before I could answer, he gave his opinion. “I usually remove them. Don’t they encourage leaning on them and isn’t that unsafe?”
I wasn’t surprised by his comment because many people think the same way and I have heard this from others over the years. But is this really true? Is it bad to use your armrests? I call this an “ergonomic myth or half-truth”. Let’s break down the history and research on chair armrests and the validity on whether they are good to rest on and use or not.
Historically, armrests have been on chairs for hundreds of years. Think back to the King and Queen’s throne where their typical sitting posture always included the use of armrests to rest the upper extremities. Typically, the Board of Directors all sit at the board room table in chairs with armrests. Or the chair at the head of a table often has armrests. In these cases, armrests act as status symbols for executives or the head of the household. So, if they are bad for us, why would we be using them for so long for hundreds of years ingrained in our culture?
Recent research in the last 25 years has validated the importance and use of armrests at a computerized work station. The research is quite clear on the value of armrests and in my clinical ergonomics experience, they are critical and important in the prevention of musculoskeletal disorders to the upper extremities. But there is one caveat… THEY MUST FIT TO BE BENEFICIAL!
The research cites a number of studies justifying the benefit of armrests with computer use.
Peter Opsvik, a Norwegian industrial designer best known for his innovative and ergonomic chairs and author of “Rethinking Sitting” articulates in his book, “ how when we are seated, our arms require both freedom to move and lots of opportunities for support”. He further states three primary reasons why our arms need support:
1. To ease the load placed on the back by the weight of our arms and hands.
2. If we are to use our hands to carry out an activity, some form of support can in many cases reduce the strain on the muscles that results from holding our hands in the area where the activity is to be carried out.
3. Having support for our hand and underarm can also provide more strength and precision for the work that is to be done.
Mr. Opsvik also states too much support can also lead to passivity and can be detrimental. “When we sit we instinctively try and find a place to put our arms and if we don’t have armrests, we use our laps. But if the chair has armrests, these are a natural place to find support”. He recommends the support be vertical beneath our shoulders to take body weight off of our backs.
In another study by Rani Lueder, “Impact of New Input Technology on Design of Chair Armrests: Investigation on Keyboard and Mouse”, from the 1996 Proceedings of the HFES Annual Meeting, the study investigated the effects of a mouse input device on the design of chair armrests. This study found height and rotational adjustable armrests provide superior forearm support during mouse use. For keyboard work, armrests reduced neck and shoulder fatigue. This finding validates Mr. Opsvik’s findings above in statement #2 and #3. Mouse use is a precision task and benefits from forearm support for better hand accuracy.
In 1999, Ms. Lueder also wrote with Paul Allie in “Chairs with Armrests: Ergonomic Design Issues”. In this review, Ms. Leuder identifies a number of important reasons to use armrests.
1. Armrests relieve loads on the neck, shoulders and arms.
2. Armrests may help promote good postures.
3. Armrests alleviate stress on the back by reducing about 10% of user’s body weight.
4. Armrests alleviate stress on the lower limbs and help to facilitate rising from a chair cutting hip forces in half.
5. Armrests help prevent excessive pressures on the seat.
6. Armrests stabilize posture and help us do our work.
Dr. Alan Hedge of Cornell University wrote in 2002 for “Work Healthy” online newsletter further reiterating the benefits of chair armrests by noting how armrests can reduce the static loads on muscles of the neck, back, shoulders and arms especially when the arms are extended forward or abducted sideways. He also states that finger forces are lessened when a user’s arms are supported while keying. Dr. Hedge concurs with Lueder’s findings that chair armrests help to stabilize the body when seated and are critical in rising from a chair to reduce knee and hip joint muscle forces.
Dr. Hedge also suggests with keyboarding and mouse use, armrests are not a substitute for a good quality keyboard tray system. It is acceptable to occasionally rest the arms at the elbows but be cautious of resting the forearms on the armrest for any prolonged period of keying and mouse work because this can compress the finger flexors or ulnar nerve. Armrests should be used for intermittent, light support with these tasks.
In one final study I want to point out by Fred Gerr in 2004, “Epidemiology of musculoskeletal disorders among computer users: lesson learned from the role of posture and keyboard use” states, “It appears that lowering the height of the keyboard to or below the height of the elbow and resting the arms on the desk surface or chair armrests is associated with reduced risk of neck and shoulder MSDs”.
Now that you know the facts on armrest use, I’ll return back to the comments from the audience last week. It might be the person asking me about armrests had not been exposed to a chair with good fitting armrests. That’s because, in my opinion and experience, most employers aren’t buying chairs with armrests that fit even 50% of their workforce. So they remove them. If armrests are fixed in position or limited in height, width, and/or pivot, then they most assuredly won’t fit correctly and can’t be used properly by a majority of employees resulting in awkward side leaning or interference so often reported. When this happens, the most reasonable action is to remove them eliminating any possible benefits reported.
The bottom line is fully adjustable armrests (height, width, pivot and forward/back glide) on a good ergonomic chair are an important part of an ergonomically correct work environment promoting a healthy and productive workforce.
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