Physical Risk Factors
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.
Temperature Extremes
Extreme hot and cold temperatures can have a significant impact on musculoskeletal injuries.
When the body is exposed to extreme cold, blood vessels constrict, reducing blood flow to the affected area. This can result in increased pain and stiffness, as well as decreased mobility. Muscles, tendons, and ligaments can become more susceptible to injury in cold conditions due to decreased elasticity and increased brittleness. This can lead to strains, sprains, and tears.
One of the primary effects of heat on the musculoskeletal system is increased inflammation. When the body is exposed to high temperatures, blood vessels in the affected area dilate, which can lead to increased blood flow and fluid accumulation.
Knowledge Check Choose the best answer for the question.
3-3. In general, the longer the period of continuous work (e.g., tasks requiring sustained muscle contraction), the _____.
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