Forearm rests not recommended

Occasionally when I’m doing an assessment at a computer workstation, I’m asked if forearm rests would be a good idea.  Forearm rests attach to the desk and provide a support surface for your forearms.

I do not recommend the use of forearms rests because they result in contact stress to the forearms.  If the forearms are constantly in contact with a surface – not matter how cushy – it is defined as contact stress and this is an ergonomic risk factor. Contact stress reduces blood and nerve supply to the hands and wrists, which will set up the path of injury as described in my post in December “How do I know if I’m getting injured?”

Instead, I recommend that people place their keyboard tray so their elbows are at right angles – 90 degrees of flexion.  Then I recommend pulling their keyboard tray so that their elbows rest comfortably alongside their torso on each side of their body.  In this posture, there is no strain being placed on any muscles because everything is in neutral posture – the upper arms hangs loosely from the shoulder joints and the forearms are in-between flexing and extending which is considered neutral posture.  Neutral posture is the goal of all postures in ergonomics because it provides the least amount of muscular strain to the body.


How to choose a keyboard (or not)

Keyboards are a key piece of equipment to consider when you are experiencing finger, hand, wrist, and arm pain.  But different keyboards are going to be better for different types of discomfort – and one is not necessarily better than the other.  Here is a review of three main types:

1. Split keyboards – These are keyboards that come in two pieces or have a large space between the middle of the keyboard effectively splitting the keyboard in two.  The biggest advantage of split keyboards is that they place the wrists in a neutral posture, rather than radial deviation with standard keyboards.  The disadvantage is that people find them to quite wide requiring them to raise their elbows slightly rather than keeping them close to their torso.  This increases muscle activation in the deltoid muscle and can cause fatigue in the shoulder.

2. Natural keyboards – These keyboards rest on the same premise as split keyboards with a more natural curve as opposed to a complete split.  These seem to be a good middle ground for alleviating wrist deviation while keeping the elbows down.  But studies have not shown that natural keyboards significantly reduce the chance of work-related injury.  And these keyboards usually come with a wrist/palm rest making it harder to reach the keys and increasing the risk for injuries caused by prolonged contact stress.

3. Non-numeric keyboards – These keyboards are made without a numeric keypad on the right side of the keyboard or the numeric keypad is on the left side of the keyboard.  These are my favourite keyboards of the bunch because they significantly reduce the reaching required when mousing.  Being able to eliminate 5-6 inches of reaching really makes a difference in all areas of the right arm.  Deltoid activation is reduced, weight on the palm/wrist is reduced, and elbows have a more neutral posture.

However, despite the wide array of keyboards available, the standard keyboard will suffice for most people.  More often than not, the most effective way to reduce hand/arm discomfort is to change your postures and working habits, not your keyboard.  Here are some tips:

1.      Adjust height of keyboard tray to ensure elbows are at 90 degrees of flexion (to eliminate the constant need for the neck and shoulder muscles to raise the arms)

2.      Ensure the keyboard tray is parallel to the ground or at a negative tilt (the back of keyboard is lower than the front).  The keyboard tray should not be tilted positively (the front of the keyboard is lower than the back).

3.      Ensure both keyboard and mouse are on the keyboard tray (to reduce shoulder and arm strain)

4.      Keep wrists neutral when keyboarding and mousing, i.e. keep wrists straight (to reduce wrist strain)

5.      Do not rest wrists on wrist rests while keyboarding.  Wrist rests are for resting wrists during pauses from keyboarding.  Consider removing wrist rest completely (to reduce wrist compression)

6.      Move your keyboard and mouse to very edge of keyboard tray closest to you so that your wrists are free floating and cannot rest on the tray (to eliminate wrist and forearm compression)

7.      Try to mouse with the right side of the palm resting on the mouse pad, not the inside of the wrist (to reduce wrist compression)

8.      Try to use your left hand for mousing (to give your right hand a break). To change your mouse to a left-handed mouse – go to Start, Control Panel, Mouse.

9.      Use keyboard keys to reduce mouse use and eliminate scrolling (to reduce strain placed on wrist extensor muscles):

§  Page Up and Page Down

§  Arrow keys – up and down

§  Ctrl+Home – straight to top

§  Ctrl+End – straight to bottom

§  Click Vertical Scroll Bar

§  Drag Vertical Scroll Bar

10.     Take breaks from keyboarding and/or mousing frequently (to give your body a break)

11.     Alternate tasks every 15-30 minutes throughout the day (to reduce prolonged exertion on one set of muscles)