Tag: Human Factors & Ergonomics

Critical Stakeholder Insight

January 20, 2021 / Xavier Drysdale / 0 Comments

I contacted Dan Robinson an ergonomist at Kwantlen Polytechnic University about how I could (within a short span of time) test the effectiveness of my mouse without putting any risk of injury on the users.

he said that testing for the actual injury “would need a longitudinal study that looks at injury outcomes of a large sample over several months or years.”

However he suggested that the “best approach is likely to evaluate what are called “leading indicators” (repetitive strain injury is a lagging indicator… happens later and takes time). Risk factors for carpal tunnel syndrome and hand/wrist tendonitis would be leading indicators (happen immediately and can be measured with an assumption that higher levels increase risk for injury – but without waiting for the injury). Leading indicators would include repeated or sustained awkward wrist/forearm postures (ulnar/radial deviation, flexion/extension, pronation/supination), or grip force on the mouse, or frequency of button clicking. If your design reduces the occurrence or severity of these, it likely reduces risk of injury.”

“Research the key risk factors/hazards for CTS and tendonitis associated with use of a mouse, and it will likely guide you towards what to quantify in your testing (and possibly in your design). Focus on what you believe your design will influence. For example, a vertical mouse like the Evoluent or Adesso designs claim risk reduction by eliminating forearm pronation and radial/ulnar deviation of the wrist. “

Neuropathy

November 28, 2020 / Xavier Drysdale / 0 Comments

jumping off of what I learned from tendon strength and hand position effort , I felt it could be insightful to learn about people who have conditions where their tendon strength has been injured.

Neuropathy is damage or dysfunction of one or more nerves that typically results in numbness, tingling, muscle weakness and pain in the affected area. Neuropathies frequently start in your hands and feet, but other parts of your body can be affected too.

-carpal tunnel is a type of hand neuropathy

-Hand Neuropathy can negatively effect hand manual dexterity (the ability to use your hands in a skillful, coordinated way to grasp and manipulate objects and demonstrate small, precise movements).

Indoor Rock climbing may provide some insight into what kinds of shapes and forms are easier to grip (requiring less hand dexterity and grip strength)

https://www.rei.com/learn/expert-advice/climbing-holds.html

there are many types of rock climbing hold including horns, jugs, flakes, underclings, pockets, slopers, pinches, crimps, and ledges. However the easiest of these holds are Jugs.

Normally smaller holds are considered harder and thus because of their large size, Horns can also be considered to be easier than most holds, but because they are so big (bigger than the size of your hand), it can be difficult to maintain this grip for a long time.

This is why Jugs are the easiest hold; small enough to fit nicely for the size of an average hand, yet large enough to require little grip strength.

SOURCES

C. (2019). Neuropathy (Peripheral Neuropathy). Retrieved November 28, 2020, from https://my.clevelandclinic.org/health/diseases/14737-neuropathy

A. (2015). THE IMPORTANCE OF MANUAL DEXTERITY. Retrieved November 28, 2020, from https://www.adea.org/GoDental/Application_Prep/Preparing_for_Dental_School/The_Importance_of_Manual_Dexterity.aspx

R. (2018). How to Use Rock Climbing Holds. Retrieved November 28, 2020, from https://www.rei.com/learn/expert-advice/climbing-holds.html

Hand therapy insights

November 28, 2020 / Xavier Drysdale / 0 Comments

Finger tendon gliding exercises are used in physiotherapy to rehabilitate an injured ligaments, muscles or tendons in the hand or wrist. These exercises include transitioning your hand between specific hand positions including the:

relaxed, straight, duck, hook, flat fist, and full fist, and tabletop positions.

This is important because all of these positions are used by physiotherapists because they activate the hand tendons and require a level of strength from your forearm muscles to be able to do these movements properly.

These positions require effort to hold therefore these are great for training your hand back into working condition, but I should stay away from designing any concept or form that requires the user to make any of these positions.

SOURCES

S. (2015, July 29). Tendon Gliding – Southlake Hand Therapy. Retrieved November 27, 2020, from https://www.youtube.com/watch?v=dUhjUBAQv30

Neutral hand position research

November 27, 2020 / Xavier Drysdale / 0 Comments

A study posted by the National Center for Biotechnology Information and published by the Europe PMC founders group investigates natural movements of the right hand in day to day activity. The results were as follows:

-The thumb is the most independent digit, the pointer finger is the most independent finger (meaning it is easiest to move that finger by itself without strain), and the ring finger is the least independent of all (meaning it is difficult to isolate that finger).

-it is always harder to move a finger independently from a directly adjacent finger than it is to move a finger independently from one that is farther away.

[insight: since it is more difficult to move certain fingers by themselves, if i make a design that requires the frequent use of an isolated finger (especially the ring and middle fingers), it will be likely to lead to hand fatigue]

-IDEA: what if i designed a stationary form that used direction force to move the cursor instead of designs that use the movement of fingers to do so. using pressure sensors to dictate the speed of the cursor and programming in a way where the force required to move the cursor is small enough to be usable for long periods, while being large enough to prevent accidental or unwanted movements.

IDEA: what if i created a mouse that could rotate to a neutral position for both hands.

[IMPORTANT INSIGHT: I should then also stay away from designing a form that causes one or two fingers to rest in different positions than the others (the resting position of all fingers should be the same). For example

this picture shows how the resting position of the index and middle fingers are at different heights from the ring and pinky. ]

– Steve Meagher a physiotherapist specializing in ergonomics says that the ulnar nerve and the median nerve both tend to get pinched when your wrist is sat on the edge of a desk while utilizing a mouse. further more, when you physically move the mouse around, you are rubbing and grinding into those two nerves which can cause much discomfort.

(solution is to either position the wrist and arm in a way that is not sitting directly on the base of the wrist, or to provide extra cushioning to decrease the immediate hardness of the desk being used. )

he also says that those particular nerves become aggravated when your wrist is in the extended position for long periods of time)

SOURCES

Ingram, J., Körding,, K., Howard, I., & Wolpert, D. (n.d.). The statistics of natural hand movements. Europe PMC Founders Group.

Meagher, S. (2016, November 10). Gaming- Mouse Position and Wrist Pain. Retrieved November 26, 2020, from https://www.youtube.com/watch?v=1xS7EzEKScs

Working Posture

September 24, 2020 / Xavier Drysdale / 0 Comments

Having a comfortable chair, height-adjustable screens, and wrist supports are good ways of tackling neck pain

“Some people even work from bed — ‘a terrible place to work,’ he says. ‘Even if you prop yourself up with pillows, sitting puts you at a 45-degree angle with your neck craned forward looking down at a screen.

‘This puts a significant amount of strain through your neck — your head weighs about 8kg and the muscles which support it are designed for rotational movements — not load carrying.’ So what is the best solution? ‘Reduce the amount of time you spend leaning forwards over a laptop to a maximum of 15 minutes,’ says Tim.”

[insight
Design a mouse that insights/works in tandem with correct back and neck position]

“‘Your spine naturally wants to be in an extended position with your shoulders back and your bottom slightly sticking out, but a chair with no lumbar support can allow your spine to move into a “c-shape”, which puts strain through the supporting muscles,’ says Tim”

References

Atkinson, L. (2020, Jul 21). Has working from home given us all back ache? [scot region]. Daily Mail Retrieved from https://ezproxy.kpu.ca:2443/login?url=https://www-proquest-com.ezproxy.kpu.ca:2443/docview/2425527275?accountid=35875

Tilted Mouse & Mouse pads

September 24, 2020 / Xavier Drysdale / 0 Comments

A study was conducted to test wether different mice, and mouse set ups could decrease carpal tunnel pressure and/or improve comfort. they used a traditional Dell mouse a base line (1) and the proceed with the following setups: Dell mouse with a gel mouse pad (2), Dell mouse with a sliding wrist guide (3), a vertical mouse.

They found that “[b]ecause the vertical mouse and wrist pads did not limit the increase in carpal tunnel pressure, the findings of this study do not endorse a strong recommendation for or against any of the ergonomic devices commonly recommended for patients with CTS. There may however be other mechanisms apart from changing carpal tunnel pressure by which ergonomic devices may exert potential beneficial effects. For instance, they may reduce pressure over the palmar branch of the median nerve which travels outside the carpal tunnel but can cause symptoms mimicking CTS”

References

Annina B. Schmid, Paul A. Kubler, Venerina Johnston, Michel W. Coppieters,
“A vertical mouse and ergonomic mouse pads alter wrist position but do not reduce carpal tunnel pressure in patients with carpal tunnel syndrome”,
Applied Ergonomics, Volume 47, 2015, Pages 151-156, ISSN 0003-6870, https://doi.org/10.1016/j.apergo.2014.08.020., http://www.sciencedirect.com/science/article/pii/S0003687014001598