Can Biomechanically Determined Stress be Perceived?

Back and overexertion injuries are a costly and debilitating problem in industry. It has been suggested that the best protective action in the prevention of back injuries is to rely on a person's perception of the risks, and allow them to operate within them. However, this assumes that a person is aware of the sensory information from the body concerning unsafe levels of stress, particularly in the back. Unfortunately, there is some question as to whether this assumption is valid. The purpose of this study was to determine how well physical stress resulting from performing occasional lifting exertions could be perceived. This required an evaluation to determine how perception (psychophysical approach) relates to physical tolerances (biomechanical approach). The results showed that back stress resulting from occasional lifting exertions is not well perceived in general. The fact that the stress was not well perceived by some may indicate why low back injuries are so pervasive in the population, and why engineering and ergonomic changes are needed to reduce the exposure to conditions that would overstress the back.