Factors Inherent in the Worker
Physical Fitness
The relationship of physical activity and MSDs is more complicated than just "cause and effect." Physical activity may cause injury.
Fitness, for most physical activities, is a measure of a combination of strength, endurance, flexibility, musculoskeletal timing, and coordination. In a study of male fire fighters, physical fitness and conditioning appeared to have significant preventive effects on back injuries.
When physical fitness is examined as a risk factor for WMSDs, results are mixed. One study reported that only 7% of absenteeism could be explained by age, sex, and physical fitness. On the other hand, another study found that physical capacity was related to musculoskeletal fitness.
Although physical fitness and activity are generally accepted as ways of reducing work-related MSDs. There is clear evidence that stretching exercises do have a positive effect on the reduction of WMSDs.
The lack of physical activity may increase susceptibility to injury. A lack of physical activity after injury may increase the risk of further injury. The probability of injury increases as muscles weaken. Consequently, demanding repetitive or static muscular work requires energy, not necessarily strength. You may be strong, but not have sufficient energy to do the task.
- Isometric (Static) work occurs when the muscles remain contracted for an extended period of time with no movement, as in holding an object. Muscles do not get the chance to relax and can fatigue quickly.
- Isotonic (Dynamic) work involves repetitive contraction and relaxation of the muscles and is less tiring and more efficient than static work. The motion of the muscles also help pump blood supplying oxygen and eliminating carbon dioxide.
Knowledge Check Choose the best answer for the question.
2-6. Based on epidemiologic evidence, it is clear that a positive effect on the reduction of MSDs occurs when workers _____.
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