Which of the following is an ergonomic risk factor associated with musculoskeletal disorders?

• A. Heavy lifting
• B. Temperature extremes
• C. Visual strain
• D. Repetitive motions

Answer: (D)

Repetitive motions create repetitive stress on the same muscles, tendons, and nerves. When a task is performed again and again with little variation and not enough time for tissues to recover, tiny injuries accumulate, leading over time to overuse disorders such as tendinopathies or nerve compression. This pattern is a classic ergonomic risk because the tissue is repeatedly loaded in the same way, often with modest force but many cycles per hour or day, which drives cumulative strain.

In contrast, heavy lifting involves higher force per lift, which can cause acute strain or compromise joints and the spine, but the hallmark ergonomic risk factor for many musculoskeletal disorders is the repetition and sustained loading. Temperature extremes and visual strain affect comfort or the nervous system in different ways and are less about the direct repetitive mechanical load on musculoskeletal tissues. To reduce risk, modify tasks to vary motions, insert microbreaks, design tools and workstations for neutral postures, and distribute workload to lessen repetitive exposure.