Ergonomics In The News: Fitting Job To (The) Worker

Using the Google News search link that I created on the left sidebar, I found an excellent write-up on our profession (even if it uses the cliche "carpal tunnel syndrome" reference) in the Baltimore Sun, published on February 22nd. Hurray for mainstream media exposure!

Article link

Sunday Spotlight: Anti-Fatigue Matting

(picture courtesy http://www.osha.gov)

For people that work at stationary workstations for the majority of their day, anti-fatigue matting is an indispensible material that saves many from sore feet, legs, and backs. It does this by replacing the hard floor beneath with a mat comprised of a softer, more compressible material, such as rubber. This allows the tremendous forces expressed by the operator's body to be absorbed by the matting, rather than it being reflected back at the operator's feet. The mat deforms under pressure from the body, greatly reducing fatigue caused by prolonged exposure to a hard floor.

The mat also encourages blood flow in the legs, as the softness of the mat causes minute muscular contractions resulting from slight movements that would not otherwise happen on a harder surface. This allows improved transport of nutrients and waste to and from the legs, thereby reducing the buildup of lactic acid, a compound that is partly repsonsible for pain in the legs after a long shift of static standing.

When selecting an anti-fatigue mat, be sure that:

1. The mat is soft enough to be comfortable, but hard enough to allow the operator to maintain a stable footing.
2. Has beveled edges so that separate mats can lock together, reducing a potential tripping hazard.
3. The environment where the mat is being used is considered. In a wet environment, the mat material should be non-slip to reduce slipping hazards. In a hospital, mats should be easy to clean to avoid infection hazards.

Also, be sure to inspect any anti-fatigue matting that you may have on a regular basis. Matting that has gone hard from prolonged use will be less effective than a newer mat, and older mats may curl at the edges, creating a tripping hazard.

While jobs should be designed to incorporate as much movement as possible, the hazards of static standing are often unavoidable. The anti-fatigue mat does much to migtigate those risks; henceforth, no standing workstation should be deprived of its benefits.

Ergonomics: Not Just For Humans Anymore

Though the aim of this blog is to focus on issues within the field of ergonomics, I could not resist posting a link to this entry on a personal weblog that I stumbled across this evening.

Ergonomics: making life better for humans, and their best friends!

Sunday Spotlight: The Computer Mouse

After the chair, one of the most often used implements in today's office is the computer mouse. Pictured above is a typical mouse with no-frills or amenities. It is because of its design and increased use however, that it can contribute to the development of Carpal Tunnel Syndrome (Source: Ergonomics, Volume 42, Number 10, pg 1350 - 1360), among other aggravations.

The rise of the body of the mouse relative to the work surface causes the user to put their wrist into sustained extension, narrowing the carpal tunnel within the wrist. With the use of the fine muscles in the forearm to perform mousing tasks, the tendons from those muscles rub against the ligaments and the median nerve, causing inflammation in the tendons, subsequently causing compression of the median nerve, and thus, the symptoms that characterize Carpal Tunnel Syndrome.

Additionally, a standard mouse with a trackball bottom tends to get dirty on a regular basis, resulting in increased effort to move the mouse, and wasted time spent cleaning the insides of the mouse to restore responsiveness. Ironically, the latest advances in mousing technology have created new problems in spite of "solving" the old issues. Wireless mice drain the batteries that they run on fairly quickly, thus not solving the wasted time issue; it is plausible that they may have made it even worse, especially if a fresh supply of batteries is not readily at hand!

In light of the issues addressed above, here is some general infomation and advice to keep in mind when obtaining a mouse:

• Ideally, a vertical mouse or a pistol-grip mouse should be acquired. These mice require the user to keep their wrists in a neutral orientation (i.e. the "handshake" position) in order to be operated.
• The mouse that you use should be an optical mouse, and those of the wired variety. This ties the mouse to a constant power source, eliminating the maintenance issues of the old trackball mice and wireless mice. Any issues with the wire can be minimized by keeping the hard drive close enough to the user so that there is enough slack, avoiding a "tug of war" between the user and the hard drive.
• The mouse should be positioned so that the user does NOT have to reach for it. The mouse should be right in the palm of the user's hand without having to move the forearm off the armrest of their chair.
• All mouse users should take a 3-5 minute microbreak per hour from their computer to help break up cumulative stress from continuous usage of the mouse.
• The user should cradle the mouse in the palm of their hand, and should avoid gripping it. Doing so will reduce muscular stress in the tendons of the forearm muscles.

Human Factors vs. Ergonomics: Are They The Same? Are They Different?

From somebody who has recently become interested in our field, to some of our most seasoned professionals, it has been the subject of confusion and debate. In research articles, business circles, and in the mainstream media, the terms "human factors" and "ergonomics" have been used interchangably, implying that they are essentially one and the same.

However, those who use the term "human factors" primarily to describe their work often deal in more specific subject matter than those who use "ergonomics" to describe themselves. This distinction is so pronounced that the BCPE has two separate designations at the top of their professional accreditation structure, CPE (Certified Professional Ergonomist), and CHFP (Certified Human Factors Professional).

Indeed, those who engage in human factors work tend to concentrate on the cognitive side of the field, and are often involved in the design of controls and complex systems. Alternatively, those who identify themselves as ergonomics professionals often concern themselves with human performance issues (e.g. manual material handling, anthropometric compatibility, awkward posture reduction, etc).

However, to muddy the waters further, there are instances on both sides of the profession where they cross over to the other's specialty, and use that information to flesh out the completion of their respective tasks. For example, a human factors professional will position important controls within 12" of the operator to avoid extended reaching, a design guideline often utilized in physical ergonomic interventions. When consulting operators in the workplace, a ergonomist may recommend the colouring of controls and the moving parts that they control in the same colour. This recommendation, often made by human factors professionals, improves the neurological perception of the operator in relation to the controls that they are supposed to trigger, reducing the learning curve for new employees and overall operator error.

Overall, human factors and ergonomics are the same in definition: the science of studying workplaces in order to improve safety, efficiency, and human performance. The difference in the two terms occurs where definition of work in the field is concerned: the first instances of human factors being implemented in the U.S. occured with the military, where the bulk of work performed concerned the design of complex systems, such as fighter jets. The term stuck wherever work on controls, systems, and human cognition was being conducted, hence its association to this day. Ergonomics came in as a defining term as the profession evolved, as the focus shifted towards human performance, hence its association with physical issues.

In conclusion, this blog will use "ergonomics" to refer to all issues addressed by this blog, as the science of fitting the work to the person should be linked to one term.

We are in the business of making things easier for people, so clearing up confusion ought to be one of our specialities!

How-To: Reducing Non-Neutral Shoulder Postures

Today, I will be continuing an ongoing series of primers to help our readers identify non-neutral body postures. Today's area of focus is the shoulder. The shoulder is a loosely-bound confluence of body structures, being the meeting place of the humerus (upper arm) and the clavicle (collarbone). As such, unnecessary work-related stress can put the joint at risk for injury.

There are 3 major situations where the shoulder can be found outside of its neutral orientation:


SHOULDER FLEXION

Problem: The work system/object in question is outside of the operator's optimal envelope of reach (12"), forcing them to reach forward, putting their shoulder into a position known as flexion.

Solution: Bring the work system/object closer to the operator so that they are within 12" optimally, and no further than 18". Eliminate/reduce any physical barriers that prevent the operator from getting sufficiently close to their work, provided that eliminating that physical barrier does not compromise safety.


SHOULDER EXTENSION

Problem: The operator interacts with work systems/objects behind them out of neccesity/habit, or pulls a cart instead of pushing it.

Solution: Situate the work systems/objects in front or the side of the operator, placing the controls/objects within 12" of the operator optimally, and no more than 18" overall. Have the worker use a push cart rather than one that is pulled, as it uses larger muscle groups than pulling does, thus reducing the damaging effects of chronic muscle fatigue (Source: OSHA)


SHRUGGED SHOULDERS

Problem: The work surface is too high for the work being performed on it, causing the operator to shrug their shoulders. Work systems/objects accessed above shoulder level also causes shrugging of the shoulders.

Solution: Adjust the working height so that fall within the parameters of the work that is being performed. The work surface should be between 37.5" - 47" for precision tasks, 33.5" - 43" for light work, and 26" - 37" for heavy work (Source: CCOHS). All work surfaces should be fully adjustable to allow for appropriate micro adjustments. All work systems/objects should be accessible below shoulder level as much as humanly possible.

Sunday Spotlight: The Office Chair

The office chair. The primary focal point of stereotypes when it comes to the public's perception of ergonomics...


... and tonight, the focus of this week's Sunday Spotlight!


For the office worker, it is the most important of equipment that they come into contact during the course of their day. The vast majority of their productive time is spent while seated in these devices. The ability, or lack thereof, of the chair to accomodate the worker's needs can prevent or actively encourage muscloskeletal disorders.

The negative issues surrounding ergonomically-incorrect chairs are numerous, a few examples being:

• A chair lacking vertical adjustment may result in a worker being too low to type properly at their workstation, causing soft tissue compression in the wrists. Coversely, the worker may be situated too high, forcing them to hunch over, which can lead to back problems. Furthermore, a chair that is too high for the user can cause soft tissue compression in the lower thighs, impeding blood circulation in the lower legs.

• A lack of a proper lumbar back support causes the lower back muscles to engage in static contractions, which can lead to lower back pain over time.

• A lack of armrests forces the user to support the weight of their arms themselves, which can lead to fatigue and pain.

And so on and so forth...


As I eluded to in the introduction to this post, chairs are an ergonomically-complex subject. However, a few general rules apply when selecting an office chair for your business...

1. Adjustability is everything. From the chair height, to the armrests and the back support, the ability to change the layout of the chair to suit the person who will be working in it is crucial. Ergonomic interventions become a lot less complicated when you have the relativity of many different settings, rather than the absolutes of only a few.
2. Back supports are a must. Sitting for hours on end without a proper back support will expose the lower back muscles to punishing static forces that will mess them up in the long run. A back support that allows the lumbar curve of the lower vertabrae to be retained will greatly reduce these forces.
3. Train office workers on how to properly adjust their chairs, and what they are designed to do. The latest, most ergonomically-compliant chair on the market will yield you no returns if the person sitting in it does not know how to use it. They will continue utilizing old postures out of habit unless they are instructed and convinced otherwise.

How To: Reducing Non-Neutral Neck Postures

Today, I will begin a series that will serve as a primer on how to reduce or eliminate non-neutral body postures. Non-neutral body postures are one of the two key drivers of ergonomic issues in the workplace (the other being excessive force). This first post will focus on the neck.

There are 4 different postures that the neck can assume outside of the neutral position. They are: flexion (bending down), extension (looking up, neck bent back), side-bending, and rotation (looking over your shoulder).

If the operator's neck is in any of these positions more than twice in an average minute, non-neutral neck postures are an ergonomic issue in your workplace.

The following suggestions may be overly general, and may not be feasible depending on the workplace in question, but they are meant to serve as a general guide, and they should be utilized if it is at all possible to do so.


Neck Flexion (looking down):



PROBLEM: The object/work surface/fixture is too low.

SOLUTION: Raise the work surface so that the operator can engage the object/work surface/fixture without bending the neck more than 20 degrees downward.


Neck Extension (looking up):



PROBLEM: The object/work surface/fixture is too high.

SOLUTION: Lower the work surface so that the operator can engage the object/work surface/fixture without bending the neck upwards.


Neck Side-Bending:



PROBLEM: The object/work surface/fixture is off-centre from the operator, or a physical barrier between the work area and the operator forces them to assume this posture.

SOLUTION: Re-align the work area or the operator so that they are directly in front of the area in question. Remove or reduce the physical barrier, or move work to area of the facility where physical barriers do not pose a problem. Use mirrors to allow the operator to see the work area while keeping their neck in a non-neutral posture.


Neck Rotation (looking over the shoulder):



PROBLEM: There are work objects that require the operator to look to the side in order to complete their tasks.

SOLUTION: Bring controls closer and/or in front of the operator so that they do not require the operator to look constantly to the side. Have all important objects within a 12" reach, and all other objects within 18". For drivers, where checking over the shoulder is a necessity of operation, share driving with another operator, or if alone, take a break from driving once every 2 hours for 10 minutes.