WFH and Ergonomics

by Zoja Savkovic

With 2020 having so many people working from home, a post about ergonomics makes sense. One specifically about computer use, for the keyboard and mouse! This post is about that.

Disclaimer: this post is interesting information that has been collected from various sources, with links throughout - always talk to health professionals if you have any issues!

"Evolution" of the Hand

The hand is pretty complex. From that link, it is also unique and different to.... yep, paws!

"A hand is a prehensile, multi-fingered appendage located at the end of the forearm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs. A few other vertebrates such as the koala (which has two opposable thumbs on each "hand" and fingerprints extremely similar to human fingerprints) are often described as having "hands" instead of paws on their front limbs. The raccoon is usually described as having "hands" though opposable thumbs are lacking."

Hands really allowed humans to throw weapons and make things very efficiently. Some people think the hand is a marvel of the body!

There is  even a muscle visible as a small tendon in the wrist that is not present in 14% of the population! The palmaris longus. It might have been used by ancestors for climbing! You can check if you have it by touching your smallest finger to your thumb and checking the palms side of your wrist for a obvious tendon - some people may not have it in both hands - so be sure to check both hands!

Anatomy

Anatomy can get pretty complicated - and you would think that muscles in the hand control the hand, and some do. But basically, muscles in the forearm, control lots of finger movement!  

There are muscles, tendons, ligaments, pulleys (more like eyelets on a fishing rod, often injured by rock climbers), nerves, etc, all of which deserve a lot of study and detail in their own right.

Nerves

Nerves deserve a special mention on the anatomy side of things, because they are what we feel, when they sense things, and they help us move too, when they send out signals. They are also made up of neurons which are the longest cells in the body - some are longer than a metre! But some are less than a millimetre.

Nerve conduction studies can measure how much of a signal is going to and from a nerve - a pinched nerve will be damaged, and less signal will be able to pass to or from it.

But why does this matter?

  • A group of neurons form a nerve.
  • A nerve is a cable-like structure within the body designed to conduct nerve impulses that relay information from one part of the body to another.
  • Nerve pain is neuralgia.
  • Peripheral neuropathy is weakness, numbness and pain from nerve damage, usually in the hands and feet.
  • Most peripheral neuropathies are the result of damage to either the message-carrying axons or to the insulating sheath of myelin, although sometimes both occur.
  • Carpal tunnel syndrome is a localized peripheral neuropathy that affects the hands.
  • Unlike nerve cells in the central nervous system, peripheral nerve cells continue to grow throughout life.
  • The pins-and-needles people often get from sitting in one position go away after we change position so blood vessels open up and the pressure is off the nerve – unless you suffer from peripheral neuropathy.
  • Sensory fibers are more prone to damage from nerve compression compared to motor fibers; thus, paresthesias and numbness and tingling are often the first signs of carpal tunnel syndrome. Motor fibers are affected as the severity of carpal tunnel syndrome progresses.
  • Nerve impulses are extremely slow compared to the speed of electricity (3*10^8m/s), where the electric field can propagate with a speed on the order of 50–99% of the speed of light; however, it is very fast compared to the speed of blood flow, with some myelinated neurons conducting at speeds up to 120 m/s (432 km/h or 275 mph).

So basically, the consequences of nerve damage are pain, the inability to sense, and ultimately even the inability to move.

What Can Go Wrong and Pain

Many things can go wrong with such a complex thing.

Causes are many and varied but are generally things go wrong due to:

  • repetitive stress, which may cause tendon swelling, but many sources say we are still not sure of exact causes.
  • swelling of something in the wrist due to some other medical condition eg arthritis, diabetes.
  • many other things, such as those involving the hand, arm, neck or some other medical condition.

The effects of these thing can include:

  • tendonitis
  • tenosynovitis
  • nerve compression such as carpal tunnel syndrome

Usually these all cause pain in some form. Pain is a topic in itself. But hand pain can also be very mysterious as it might not be obvious to other people - there are no bruises, bandages etc. The pain may also not be present when not say typing or starting to type, but come on gradually. Which can be confusing for onlookers, as one minute someone may not be in pain, the next they are. The pain may also be delayed, for example needlework such as knitting and crochet can bring on pain hours or days after the task.

Once there is pain, normal tasks that did not used to cause pain, may be painful, like doing chores.

The other mysterious thing here is that this pain that comes and goes may take months to heal. It is just not intuitive that something that you cannot see and cannot feel all the time, will take months to heal.

Hand Exercises

There are tendon and nerve gliding exercises that physios can prescribe. There are also lots of products and opinions online - hopefully everyone will find something that works for them.

There are lots of tests for various things, such as testing grip strength and the Roos stress test for thoracic outlet syndrome.

What Hand Position is Best for PC Use?

Some people get no pain in the hand, arm and neck when using a PC. For those that do, keeping things "straight" at the wrist seems to avoid pinching nerves and inflaming tendons and things.

The main things to keep in mind to avoid, specifically related to the wrist are:

  • pronation - which is when the palm faces downwards. Keyboards and mice that are vertical avoid this by keeping your hand not facing downwards entirely.
  • extension - this is the bending of the wrist as you raise your hand back towards the forearm. Arm rests try to avoid extension, by placing the wrist higher, in line with the keyboard.
  • ulnar deviation - this is basically the movement of the hand left to right as though you are waving your hand while keeping your wrist in the same position. This is hard to avoid even during any ergonomic keyboard use, as you move your hand around to reach certain keys. The best keyboards therefore tend to be small, so that the hand does not have to move around so much.

Ergonomic Things!

Following on from the above where keyboards and mice were already mentioned, there is a huge range of ergonomic things out there. The choice can be overwhelming, and the various keyboards and mice can look strange at first.

It may sound extreme, but using a foot pedal for some keyboard and mouse inputs can take repetitive strain out of the hands, and is a great idea - after all, we use foot pedals for driving cars.

Some trends and things easily found online seem to be:

  • keyboards that follow the shape of your hand, that link has a triple foot pedal too
  • keyboards that are vertical, or use gestures
  • keyboards that are "tenkeyless" which means they do not have the 10 numbers to the side of the keyboard, but they are usually built in to other keys with a function key - this reduces hand movement and makes for a smaller keyboard
  • some people make their own keyboard by 3D printing it!
  • vertical mice
  • trackball mice (either a finger trackball or a thumb trackball)
  • hand held mice

Medical professionals may also prescribe splints (a wrist glove) to keep the wrist straight - but these may not be for everyone, and custom made ones can be better. There are splints where the splint is on the top, side or bottom of the wrist.

Physios do say that variety is key, so changing up keyboard and mice use can help. There are also alternative keyboard layouts like Dvorak that are meant to be more ergonomic. Breaks, stretches and varying sitting, standing and walking can also help.

So that is the end of the post - a collection of various entertaining and detailed information about hand ergonomics!