Ergonomics Awareness Training
This is an awareness session to assist in ensuring that personnel are provided training describing various risk factors associated with their jobs, tools, tasks, processes, and equipment as prescribed by OPNAVINST 5100.23(series).
|The following training is for Naval Postgraduate School personnel. If you are from another command and you require ergonomics training, please seek guidance from your command safety office.|
Ergonomics is the study of how to fit the workplace to the worker. While the use of the term ergonomics has become more common lately, ergonomics is not a new science. The term was actually coined in 1857 by a Polish scholar. The key points to remember are that ergonomics should:
Where does the word Ergonomics come from? Ergonomics is derived from two Greek words Ergon meaning work, and Nomos meaning principles or laws, therefore, ergonomics is the study of work.
Fitting the Worker to the Workplace
A worker should not have to adjust themselves to accommodate their workplace set up. If a worker must adjust to fit the workplace they become at risk to sustain a work-related musculoskeletal disorder or WMSD.
Example: A worker that is trying to fit into their workplace by adjusting their posture. This worker wears bifocals and must view a monitor through the bottom portion of her glasses which forces her to extend her neck back to view the screen. Prolonged periods in this posture could cause neck and eye strain.
To reduce the risk of WMSDs, the workplace should be designed to fit the worker. The worker no longer has to extend their neck back to view the monitor because the monitor has been positioned at the proper sight level, directly in front of the user. This is an example of a workplace that is fit to the worker.
Importance of Ergonomics
The application of ergonomics can:
|Work-Related Musculoskeletal Injuries|
Injuries affect not only the worker but the people they interact with as well.
For example, a serviceman lifting and carrying a piece of a bridge incurs back strain. Co-workers may have to work harder to compensate for their injured colleague, which may increase their risk of injury. Safety and health personnel must document and investigate the incident, which involves supervisors, administrative assistance, and management. Medical personnel are involved in the diagnosis and treatment of the injury.
The effects can carry over into the serviceman’s career and personal life. Family and friends may have the task of caring for him during his recovery and taking on some of his responsibilities around the home, such as maintaining the yard, fixing the cars, or even coaching little league. The impacts of an injury extend well beyond the worker who experiences the problem.
Injuries – Musculoskeletal Disorders (MSD)
WMSDs are a category of injuries and disorders that deal with the musculoskeletal system. These disorders are not usually caused by acute trauma but instead occur slowly over time due to wear and tear on soft tissues such as:
MSDs are preventable but everyone is at risk.
Work-related Musculoskeletal Disorders (WMSDs)
WMSDs are MSDs that are caused or aggravated by work practices and/or environments. WMSDs do not generally result from a single event or accident, but rather are disorders that have developed gradually from chronic workplace and occupational conditions causing repeated trauma.
Common WMSDs include:
WMSDs go by other names, including:
Some people who have been diagnosed with a disorder such as carpal tunnel syndrome may not know that it is a part of the category of injuries known as WMSDs.
Signs and Symptoms of WMSD
Early detection is key to preventing WMSDs, therefore, seek medical attention if you are experiencing any of the signs or symptoms listed here. Signs and symptoms of WMSDs include:
There are two types of risk factors for developing WMSDs:
Physical Risk Factors
Physical work place risk factors can cause WMSDs to develop. The risk factors must occur in combination to present a risk of WMSDs and they typically magnify each other as a result. There are six common physical risk factors:
Contributing Risk Factors
In addition to the six physical risk factors, there are three important contributing risk factors. Contributing factors can contribute to, but do not cause, WMSDs. For example, temperature and humidity affect the worker performing repetitive work. When it is too hot and too humid, workers fatigue more quickly and become more susceptible to injury. Contributing risk factors are generally harder to control than physical risk factors. Contributing risk factors include:
|Physical Risk Factors|
Compression or Contact Stress
Compression occurs when an object presses on soft tissue. This concentration of force on small areas reduces blood flow and nerve transmission and can damage the soft tissue. Compression occurs from:
Ergo Tip - As a rule of thumb, jewelry should be loose fitting and not cause an impression on the skin. This will reduce exposure to contact stress.
Neutral Posture vs. Non-neutral Posture
Posture or position dictates how hard the body works.
Neutral posture - a posture that maximizes strength, speed, endurance, and comfort while decreasing the risk of WMSDs.
Non-neutral posture - an awkward or unsupported position that stretches the physical limits and which can cause muscle fatigue, micro-trauma to tendons or ligaments, and compress or elongate soft tissues such as nerves.
Working Neutral Standing Posture
Neutral posture is the position where the least tension or pressure on nerves, tendons, muscles and bones occurs. It is also the position where muscles are at their resting length, neither contracted nor stretched. Neutral standing posture can be recognized by the following body landmarks:
Even in bulky clothing and PPE you should still be able to see these body landmarks.
Working Neutral Sitting Posture
You can recognize neutral posture at a computer workstation by looking for key body landmarks.
Holding a posture for extended periods of time is known as a static posture. Static postures prevent the flow of blood which brings nutrients to the muscles and carries away waste products. Holding a muscle in contraction causes waste products to build up and can lead to fatigue and discomfort.
Vibration is another type of physical risk factor. A simple definition of vibration is rapid movement back and forth; however, vibration involves the exposure to movement against the body from all directions. Vibration occurs in two forms:
Whole Body Vibration
Whole body vibration is caused by standing or sitting on vibrating surfaces, which in turn causes muscle contractions and fatigue. The vibration works its way through the body and results in muscle fatigue and contractions. High or prolonged exposure to whole body vibration can affect the skeletal muscles and digestive system and cause lower back disorders. An example of workers who experience this type of vibration are heavy vehicle operators who are exposed to whole body vibration when they drive.
Hand-arm vibration is usually caused when a worker holds a vibrating hand tool for a long period of time. This action causes reduced blood flow to the fingers and can lead to blanching of the fingers or Raynaud’s Syndrome. Cold weather is a contributing factor to vibration-related WMSDs. Some of the WMSDs associated with hand-arm vibration are:
What are some examples of tools that contribute to hand-arm vibration? A chain saw, jack hammer, impact wrench, saws-all, needle gun, riveter, chipping hammers, soil compactor, pavement breaker, floor buffer are all considered percussion types of tools which typically produce high levels of vibration. A jig saw, grinder, and sander usually cause moderate vibration.
Force is the use of power or exertion to move, direct, or operate equipment. The less force required to operate equipment the less traumatic it is to the body. Excessive force exertion may cause the muscles to meet or exceed their maximum capability, resulting in possible fatigue or injury. Repeated muscle trauma can result in damage or injury.
High Force Examples
High force risk factors can occur while lifting, carrying, pushing, pinching and gripping. Posture and position are important in considering high force risks. The power zone for lifting with the greatest strength and lowest risk of injury is close to the body between thigh and shoulder height. And, it is important to note that lifting even a 20 lb weight one hundred times a day in a non-neutral posture may pose a high force risk. The following guidelines are from the MIL Standard 1472F.
The physical risk factor repetition is defined as performing the same motion or group of motions excessively, for example:
Repetition usually occurs in conjunction with other risk factors. It is important to note that if you change the job but still use same muscle group you are not doing anything different. Repetition is often seen in tasks such as assembly, typing, operating machinery, or loading and unloading a vehicle. What is an example of using the same muscle groups for different tasks? Typing and using a calculator are different task yet they use the same muscle groups and create the same stress.
How long a task is performed or how frequently the same muscle groups are used in a day contributes to the risk factor known as duration. Duration is defined as the time period that an action continues or lasts. Continuous use does not allow muscles time to recover and in turn magnifies other risk factors. The key point to remember is that the longer the duration the greater the exposure and the greater the risk. Taking breaks, reducing the amount of time spent on similar tasks, and alternating between jobs that use different actions can help reduce duration exposure.
|Contributing Risk Factors|
Inadequate muscle recovery is a contributing risk factor as working without rest can cause fatigue and contribute to injury. Working the same muscles without rest may result in injury. Muscles need blood flow to supply nutrients and oxygen, and to carry away the waste products of muscle metabolism. Without sufficient muscle recovery, lactic acid can build up in the muscle. Inadequate muscle recovery can lead to fatigue and discomfort as well as possible injury. Stretching, using alternative muscle groups, and taking short breaks can aid in recovery and help prevent fatigue.
Temperature is a known contributing risk factor. Working in cold environments places a greater aerobic demand on the worker which means they fatigue faster. Cold Cold temperatures impair blood flow in the extremities reducing tactile sensation, muscle strength and dexterity. Cold makes gripping harder, therefore more muscle force must be applied increasing the likelihood of injury. Cold temperatures can increase the risk of injury from vibration exposure. Heat Prolonged work in hot environments can result in fatigue and a variety of heat related illnesses. Wearing PPE may increase the risk of suffering heat related illnesses.
Personal Risk Factors
Personal factors also contribute to WMSDs, which is one of the reasons why it cannot be predicted who will suffer a WMSD, because factors other than those in the workplace contribute to risk. Personal risk factors do not cause WMSDs but are contributing risk factors. Some examples include:
MSDs are often easy to prevent and there are many ways to reduce ergonomic risk factors and help fit the workplace to the worker. Solutions can be grouped into three main categories: 1) Engineering controls 2) Administrative Controls 3) Personal Protective Equipment. Often the best solution involves a combination of approaches.
1. Engineering Controls – This is the most effective and preferred method of reducing ergonomic risk factors. Examples include:
2. Administrative Controls to Improve Work Policies and Procedures. Examples include:
3. Personal Protective Equipment (PPE). Examples include:
Note regarding backbelts: Back belts have been studied extensively, and experts have concluded that they are not effective in preventing back injuries. Some believe that, in fact, they may cause injury by encouraging workers to lift heavier objects or by making muscles weaker. Most importantly, they do not make workers stronger or more able to perform a lift that is awkward or too heavy; however, wearers often BELIEVE they can handle more than they are able. This is often refered to as the "Superman Effect." In 1997 the office of the Under Secretary of Defense sent forth a Memorandum to all DOD agencies regarding Ergonomics and Back Injury Prevention Programs. The official policy is: "DOD does not recognize back support belts or wrist splints as personal protective equipment, or support the use of these devices in the prevention of back or wrist injuries. These devices are considered medical appliances, and may be prescribed by a credentialed health care provider who will assume responsibility for medical clearance, proper fit of the device, and treatment monitoring and supervision." NPS is does not provide back supports to employees. If an employee feels they are in need of such a support they should consult their private health care provider.
The key points to remember about ergonomics are that:
|Local Information and Additional Resources|
Please see the following helpful Ergonomics guides: