Neck pain and monitor height

Computer use is commonly associated with neck, upper back, and shoulder symptoms.

This association makes sense to all of us that sit too much and spend too much time in front of computers.  It also plays out in the occupational medicine literature in terms of high prevalence rates of neck/shoulder symptoms in modern working life.

There are several factors that feed into this connection of neck and upper back pain with computer use.  The most prominent factors are (1) monitor height and (2) sitting position.

PART 1: ‘THE CINDERALLA HYPOTHESIS’ AND THE ASSOCIATION OF MONITOR HEIGHT WITH NECK PAIN:

Studies have suggested that the position of the head is critical to setting the preferred viewing angle for a computer monitor.  It has been shown that “forward flexion of the neck creates an increased moment of the head weight that can produce significant contraction of the muscles to achieve equilibrium.” [Ind Health. 1997 Jul;35(3):330-6.]  That is, if we have a stooped posture with a forward flexed neck (see picture below) then the muscles have to work harder to keep our heads from falling forward onto our chest.  As a result, the muscles tend to get tight, to get overloaded and can be a source of pain.

Poor posture with forward flexed neck

A theory has been proposed for the pathological mechanism causing muscle pain is the ‘Cinderella Hyopothesis’ which “claims that only a few motor units are involved in muscle activity at low static levels… leaving those active units susceptible to fatigue.” [Ind Health. 1997 Jul;35(3):330-6.]

A study by Ostensvik et al. showed that sustained low-level trapezius muscle activity in periods longer than 8 min in an hour constituted a risk for neck pain symptoms. [Ergonomics. 2009 Dec;52(12):1556-67.]

So how does this relate to monitor height?  Studies have shown that neck angle and trunk inclination are significantly affected by changes in screen height [Ind Health. 1997 Jul;35(3):330-6.]  Villaneuva et al. in their study found that “the neck became more erect [i.e. less flexed forward] at higher screen positions.”  What is more, “the trunk was also noted to be more backward-leaning [or the upper back was less forward bent] as the screen height was increased.” [Ind Health. 1997 Jul;35(3):330-6.]

These investigators found that the level of trapezius activation decreased with monitor heights at 100cm or 120 cm from the ground.  Based on the above referenced ‘Cinderella Hypothesis’, lower levels of trapezius activation theoretically should correlate with less neck and upper back symptoms.

Other studies have shown that a reclining posture reduces the load on the vertebral disc and back muscles.  [Colombini et al. A (1986) biomechanical, electomyographical and radiological study of seated postures]  Villaneuva et al. conclude, then, that “It can be predicted that the load [on the spine] is significantly reduced at [a monitor height of] 100cm when the frequency of forward leaning was decreased.” [Ind Health. 1997 Jul;35(3):330-6.]

EVIDENCE-BASED RECOMMENDATIONS FOR MONITOR HEIGHT:

Generally I recommend having people move their monitors higher.  I thought I was doing a good job with my monitor on a stand on top of my desk.  It sits, though, at 95 cm above the ground which I guess is less than ideal.

The other issue is that laptops create their own set of issues.  Laptop users often sit at a couch or at whatever table is convenient.  The screen for a laptop is naturally, then, going to be a lot lower than the idealized levels.  So what can be done?  Laptop stands can remedy this to a degree by bringing the screen upwards. 

For those of us that spend a lot of our time in front of a computer, it is worth considering ergonomics generally and in this context specifically considering monitor height.

Below is a link to a monitor stand that I like found on Amazon.com:

PART 2: PROLONGED SITTING AND ITS ASSOCIATION WITH LOW BACK PAIN.  DISCUSSION OF WHAT TYPE CHAIR IS THE MOST HELPFUL FOR LOW BACK PAIN AND OTHER POTENTIAL FIXES FOR THIS ASSOCIATION: http://digg.com/d31MSNP 

Comments

[Catherine Chu]

One of the difficulties of working on a laptop means a compromise between proper height of keyboard for elbow and wrist alignment vs. screen height. My laptop screens sits only 80cm off the ground and some days I do stack it on books but that of course brings my keyboard up into an awkard position of elbow and wrist flexion. Best option, keep off the computer. Easier said than done.

Thanks for the article Dr, Mangrum

[chiropractor suwanee ga]

I have to say, every time I come to your blog there is another interesting post to read. I know chiropractic care for Suwanee, GA residents since 1996.

[neck pain symptoms]

I am a desktop user and i have a huge problem of neck pain. Sometimes i find it very difficult to sit even for an hour.I was looking for something which could help me solve my problem regarding the neck pain and i stopped at you.
You have provided really a very valuable information about this.Thanks for sharing.