Ergonomics

As with any hazard, prevention is the best practice. Poor ergonomics (meaning poor design of equipment and methods to optimize human well-being) can cause or contribute to acute and chronic injuries. Something as simple as repetitive strain injuries (doing a task over and over again ignoring sound ergonomic guidelines) can lead to long-term disability.

If you do any of the following, ergonomics plays a role: work, sit, stand, control machinery, drive vehicles, play computer games, participate in sporting activities, watch sporting activities, type on keyboards to access the internet, etc. We all qualify.

Ergonomics is literally the applied science of equipment design intended to maximize productivity by reducing operator fatigue and discomfort.  The term is also used to describe design factors.

Costs from injuries associated with ergonomics are significant and impact all types of work environments.

The Liberty Mutual Research Institute for Safety began an initiative to develop a reliable ranking of the 10 leading injuries and their direct costs to industry. Indirect costs (efficiency loses, morale, impact on other employees, families, etc.), which are often greater than direct costs, are not included in the number. Of the 51 billion in direct workers’ compensation costs, the bar graph indicates the 5 categories associated with ergonomics.

Physical Risk Factors

Awkward postures. Body postures determine which joints and muscles are used in an activity and the amount of force or stresses that are generated or tolerated. For example, more stress is placed on the spinal discs when lifting, lowering, or handling objects with the back bent or twisted, compared with when the back is straight.

Manipulative or other tasks requiring repeated or sustained bending or twisting of the wrists, knees, hips, or shoulders also impose increased stresses on these joints. Activities requiring frequent or prolonged work over shoulder height can be particularly stressful.

Forceful exertions (including lifting, pushing, and pulling). Tasks that require forceful exertions place higher loads on the muscles, tendons, ligaments, and joints. Increasing force means increasing body demands such as greater muscle exertion along with other physiological changes necessary to sustain an increased effort. Prolonged or recurrent experiences of this type can give rise to not only feelings of fatigue but may also lead to musculoskeletal problems when there is inadequate time for rest or recovery. Force requirements may increase with:

• increased weight of a load handled or lifted,
• increased bulkiness of the load handled or lifted,
• use of an awkward posture,
• the speeding up of movements,
• increased slipperiness of the objects handled (requiring increased grip force),
• the presence of vibration (e.g., localized vibration from power handtools leads to use of an increased grip force),
• forceful pinch grip compared with gripping the object with your whole hand), and
• use of small or narrow tool handles that lessen grip capacity.

Repetitive motions. If motions are repeated frequently (e.g., every few seconds) and for prolonged periods such as an 8-hour shift, fatigue and muscle-tendon strain can accumulate. Tendons and muscles can often recover from the effects of stretching or forceful exertions if sufficient time is allotted between exertions. Effects of repetitive motions from performing the same work activities are increased when awkward postures and forceful exertions are involved. Repetitive actions as a risk factor can also depend on the body area and specific act being performed.

Duration. Duration refers to the amount of time a person is continually exposed to a risk factor. Job tasks that require use of the same muscles or motions for long durations increase the likelihood of both localized and general fatigue. In general, the longer the period of continuous work (e.g., tasks requiring sustained muscle contraction), the longer the recovery or rest time required.

Frequency. Frequency refers to how many times a person repeats a given exertion within a given period of time. Of course, the more often the exertion is repeated, the greater the speed of movement of the body part being exerted. Also, recovery time decreases the more frequently an exertion is completed. And, as with duration, this increases the likelihood of both localized and general fatigue.

Contact stresses. Repeated or continuous contact with hard or sharp objects such as non-rounded desk edges or unpadded, narrow tool handles may create pressure over one area of the body (e.g., the forearm or sides of the fingers) that can inhibit nerve function and blood flow.

Vibration. Exposure to local vibration occurs when a specific part of the body comes in contact with a vibrating object, such as a power hand tool. Exposure to whole-body vibration can occur while standing or sitting in vibrating environments or objects, such as when operating heavy-duty vehicles or large machinery.

Other conditions. Workplace conditions that can influence the presence and magnitude of the risk factors for Musculoskeletal Disorders can include:

• cold temperatures,
• insufficient pauses and rest breaks for recovery,
• machine paced work, and
• unfamiliar or unaccustomed work

In addition to the above conditions, other aspects of work may not only contribute to physical stress but psychological stress as well. As long as we believe we have adequate control over all aspects of our job, we may experience normal (positive) stress. However, if we believe we have little control over job demands, we may suffer from abnormal (negative) distress with accompanying ill health and possible irrational behaviors. Under distress, the probability of an injury or illness increases.

Risk Management Department offers ergonomic assessments to any department on campus for existing or future work/educational environments. If you have any questions regarding ergonomics, please contact the Risk Management Department at 801-422-4468.