Extension When Using the Keyboard
is Wrist Extension?
The natural position of the hands with respect to the relative
vertical position at the wrist is along the plane or below it
(i.e. one should attempt to have the tips of the fingers at the
same height as the wrist or preferably slightly lower). When the
hand rises above this plane (i.e. making the hand signal for
'STOP'), this is called wrist extension
greatly reduces blood flow through the wrist and can quickly
cause pain, fatigue and numbness.
Most keyboards have a built-in positive inclination (i.e. the
Function row is higher than the space bar). In addition,
there are often 'feet' at the back of the keyboard which further
increases this positive incline, forcing the user into a posture
of Wrist Extension.
Why is Wrist Extension a Risk Factor?
When adopting this position, blood flow is constricted through
the wrist and this posture also requires sustained muscle
tension which further reduces blood flow to the muscles. The median
runs through the carpal tunnel
the wrist, and when adopting a position of Wrist Extension the
span of this tunnel is compressed and pressure on this nerve can
lead to Carpal
How Much Wrist Extension is 'ok' and not a Risk Factor?
For most individuals, even a minimal amount of Wrist Extension
will cause some discomfort and is a potential risk factor.
What are the Symptoms of 'too much' Wrist Extension?
Symptoms of excessive Wrist Extension include pain in the top of
the forearm and to a lesser extent in the wrist itself. In
more significant cases, this can include pain, numbness or
tingling in the fingers and weakness in the hand and fingers.
How can the Choice of Keyboard Help to Reduce Wrist
and Negatively Inclined Keyboards
feature an architecture
and housing which is either neutral or even negative (i.e. the
plane of the keys is level or declines when moving from the
front (space bar) of the keyboard to the rear (function keys) of
What Other Strategies can be used to Reduce Wrist Extension?
offer the option of a negative inclination,
which will make the entire work surface slope away from the
individual, ensuring that the hands are not bent upward at the
wrist, even if the keyboard has a positive inclination.
Ensuring the proper height of the workstation i.e. that it
should be slightly lower than the underside of the forearm /
elbow is critical in prevention Wrist Extension.
Often individuals will adopt positions of Wrist Extension while
they are asleep (without realizing it). The wearing of a
wrist brace or support while sleeping can prevent accidental
adoption of a position of Wrist Extension when one is supposed
to be at rest.