In the vast majority of cases, wrist rests do not provide
any significant ergonomic benefit and in fact will usually increase
the number of risk factors for injury in your computer workstation.
The reason is that if you 'rest' your 'wrist' on any type of support,
be it foam, gel, webbing, cloth, etc. you are applying pressure to the
underside of your wrist which will compress the tissues, resulting in
decreased blood flow. More specifically, you can compress the carpal
tunnel and possibly pinch the median nerve, which can lead not only
to long term injury, but short term symptoms such as tingling, numbness
or coldness in the hands, and finger muscles which fatigue quicker due
to reduced circulation.
Are Palm Supports Ergonomic?
Palm supports are usually ergonomic in that they provide
support for your palm during periods of inactivity (i.e. when you are
not typing or mousing), which assist in reducing the tendency to 'drop'
your hands, which can lead to a position of wrist extension (or dorsiflexion).
However it is critical that the support has a low enough profile so
that your wrist does not get 'caught' on the rest when you move the
mouse forward (i.e. move the cursor up) or reach for the upper rows
on the keyboard. In other words, the palm support when uncompressed
should be level and not be higher with the front edge
of the keyboard housing or the mousing surface to prevent any pressure
on the underside of the wrist.
Here is an example of Wrist Extension (Dorsiflexion)
caused by the dropping of the palm / hand while keyboarding.
With the use of a palm support, the Wrist
Extension has been prevented. However if you look closely you
will see that when the user reaches for the upper rows of keys
on the keyboard their wrist will catch on the wrist rest. If the
front edge of the keyboard was raised (for example by placing
erasers at the front) this would likely reduce the risk factors
associated with using the palm support further.
So What Is the Difference Between Wrist Rests and Palm
Supports?
The physical product is the same - what determines whether
is different is the usage of the product.
BAD - Resting Your Wrists ( =
Wrist Rest ) or Putting Any Type of Pressure on the Underside of your
Wrist
GOOD - Supporting Your Palms
( = Palm Support) which Reduces the Possibility of Wrist Extension and
Reduced Blood Flow
What About Wrist Rests / Palm Supports on a Keyboard?
Many people argue that a palm support which is attached
to the keyboard will increase the distance that the user has to 'reach'
to get to the keyboard. This is not the case as the position of the palm
when typing is typically 1-3" in front of the keyboard (depending
on which row of keys you are typing on). The presence (or absence) of
a palm support will not increase the distance you are having to 'reach'
to get to the keyboard. The only exception would be for individuals with
very small hands or extremely limited reach (i.e. atrophied limbs) in
which case the palms of their hands are likely over the keyboard at all
times when typing as the traditional typing posture is not an option for
these individuals.