Any body position can cause discomfort and fatigue if it is maintained for long periods of time. Standing, for example, is a natural body posture, and by itself poses no particular health hazards. However, working for long periods in a standing position can cause sore feet, general muscular fatigue, and low back pain. In addition, improper layout of work areas, and certain tasks can make workers use unnatural standing positions.
Two aspects of body position can contribute to injuries. The first relates to body position. When parts of the body are near the extremes of their range of movements, stretching and compression of tendons and nerves occur. The longer a fixed or awkward body position is used, the more likely we are to develop WMSDs. For example, working with the torso bent forward (Figure 1), backward or twisted can place too much stress on the low back. Other examples of stressful body positions include reaching above shoulder level (Figure 2), reaching behind the body (Figure 3), rotating the arms (Figure 4), bending the wrist forward, backward, or side to side (Figure 5), and reaching forward too far out in front of the body (Figure 6).
The second aspect that contributes to WMSDs is holding the neck and the shoulders in a fixed position. To perform any controlled movement with the arm, muscles in the shoulder and the neck contract and stay contracted for as long as the task requires.
The contracted muscles squeeze the blood vessels, which restricts the flow of blood all the way down to the working muscles of the hand.
However, this is where the blood is needed the most because of the intense muscular effort. Two things happen as a result. The neck/shoulder muscles become overtired even though there is little or no movement. At the same time, the reduced blood supply to the rest of the arm accelerates fatigue in the muscles that are moving, making them more prone to injury.
Any body position can cause discomfort and fatigue if it is maintained for long periods of time. Standing, for example, is a natural body posture, and by itself poses no particular health hazards. However, working for long periods in a standing position can cause sore feet, general muscular fatigue, and low back pain. In addition, improper layout of work areas, and certain tasks can make workers use unnatural standing positions.Two aspects of body position can contribute to injuries. The first relates to body position. When parts of the body are near the extremes of their range of movements, stretching and compression of tendons and nerves occur. The longer a fixed or awkward body position is used, the more likely we are to develop WMSDs. For example, working with the torso bent forward (Figure 1), backward or twisted can place too much stress on the low back. Other examples of stressful body positions include reaching above shoulder level (Figure 2), reaching behind the body (Figure 3), rotating the arms (Figure 4), bending the wrist forward, backward, or side to side (Figure 5), and reaching forward too far out in front of the body (Figure 6).The second aspect that contributes to WMSDs is holding the neck and the shoulders in a fixed position. To perform any controlled movement with the arm, muscles in the shoulder and the neck contract and stay contracted for as long as the task requires.The contracted muscles squeeze the blood vessels, which restricts the flow of blood all the way down to the working muscles of the hand.However, this is where the blood is needed the most because of the intense muscular effort. Two things happen as a result. The neck/shoulder muscles become overtired even though there is little or no movement. At the same time, the reduced blood supply to the rest of the arm accelerates fatigue in the muscles that are moving, making them more prone to injury.
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