Which of the following is considered a primary ergonomic risk factor for musculoskeletal disorders?

Repetitions are considered a primary ergonomic risk factor for musculoskeletal disorders because they can lead to fatigue and strain on the muscles and joints involved in repetitive tasks. When an individual performs a task repeatedly without adequate breaks, it increases the likelihood of overuse injuries. This is particularly pertinent in occupational settings where workers may engage in repetitive movements such as typing, assembly line work, or manual handling. The accumulation of strain from high repetitions, often combined with other factors like force or awkward postures, can significantly contribute to the development of conditions such as tendonitis or carpal tunnel syndrome.

In contrast, while age, gender, and body composition can influence an individual's susceptibility to musculoskeletal disorders, they are not considered primary ergonomic risk factors in the same way that repetition is. Age may affect healing and overall physical health, gender might influence certain physical capacities or injuries, and body composition could impact overall body mechanics. However, these factors are more about individual characteristics and predispositions rather than direct ergonomic risks linked to specific tasks.