Introduction Webster's New World Dictionary (College Edition) defines ergonomics as "The Study of the problems of people in adjusting to their environment; especially the science that seeks to adapt work or working conditions to suit the individual worker. Ergonomics may also be thought of as the science of fitting the job to the individual worker. When there is a mismatch between the physical requirements of the job and the physical capacity of the worker, musculoskeletal disorders (MSDs) can result.

Who is at risk?

Workers who must repeat the same motion throughout their workday, who must do their work in an awkward position, who must use a great deal of force to perform their jobs, who must repeatedly lift heavy objects or who face a combination of these risk factors are most likely to develop MSDs. The level of risk depends on how long a worker is exposed to these conditions, how often they are exposed, and the level of exposure.

What are MSDs?

MSDs include a group of conditions that involve the nerves, tendons, muscles, and supporting structures such as intervertebral discs. They represent a wide range of disorders, which can differ in severity from mild periodic symptoms to severe chronic and debilitating conditions. Examples include:

• carpal tunnel syndrome
• tenosynovitis
• tension neck syndrome
• and low back pain

Contributing factors are aspects of work tasks that can lead to fatigue, MSD symptoms and injuries, or other types of problems. These factors may be present in one or more of the tasks employees must perform to accomplish their jobs. The contributing factors you and your employees should be aware of include:

• Awkward postures
• Repetitive motions
• Forceful exertions
• Pressure points (e.g., local contact stress)
• Vibration

Extreme high temperatures can increase the rate at which the body will fatigue. Exposure of the hands and feet to cold temperatures can decrease blood flow, muscle strength, and manual dexterity. These conditions can also cause excessive grip force to be applied to tool handles or objects. Another problem may be caused by tools or equipment that exhaust cold or hot air directly onto the operator.

In addition, the lighting in a workplace may be too dark or too bright for the work task. This may result in employees assuming awkward postures to accomplish work tasks and a loss of product quality. We will cover these factors in more detail in upcoming modules.

What are work-related MSDs (WMSD)?

Occasionally, in reading safety literature, you will come across this term. WMSDs are nothing more than MSDs caused or made worse by the work environment. WMSDs can cause severe and debilitating symptoms such as:

• pain, numbness, and tingling; reduced worker productivity
• lost time from work
• temporary or permanent disability
• inability to perform job tasks
• an increase in workers compensation costs.

Ergonomics studies the various risk factors brought to a job. There are three areas within which ergonomics risk factors exist: Risk factors inherent in the worker Risk factors inherent in the task Risk factors inherent in the environment Workers come in all shapes and sizes, each with unique attributes that present certain ergonomic risk factors to a given job. The task(s) of the job, itself, can present risk factors that increase the likelihood of an injury. Finally, the workplace environment, within which the worker and job exist, may also contain exposures to risk factors. We will cover each of these three risk factor categories in the course.

The impact of ergonomics

Musculoskeletal disorders are among the most prevalent medical problems in the U.S., affecting 7% of the population. They account for 14% of physician visits and 19% of hospital stays. 62% of persons with MSD report some degree of limitation on activity compared with 14% in the population at large.

Four out of ten days away from work cases were sprains or strains. Approximately one in five of these were suffered by laborers and freight, stock, and material movers; heavy and tractor-trailer truck drivers; and nursing aides, orderlies, and attendants. Musculoskeletal disorders (MSDs) accounted for 30 percent of the injuries and illnesses with days away from work, the same percentage as in 2005. Sprains and strains was the leading nature of injury and illness in every major industry sector. These injuries decreased by 6 percent for total private industry in 2006 and for both goods-producing and service-providing industries. Trade, transportation, and utilities reported 157,380 sprains and strains, 33 percent of the total. The overall number of cases of carpal tunnel syndrome decreased by 21 percent. Workers on the job 5 years or more had a decrease of 27 percent for these kinds of illnesses.

Last Words

Medical costs and workers’ compensation claims for serious MSDs may total $15,000 to $85,000 or more. It makes sense to give serious consideration to the risk factors in your workplace and the information in this course will help you do that. Before moving on to the next module, take the time now to answer the quiz questions below. Later, you'll enter these answers in the Final Exam and Quiz page online.