Interaction of Physical and Mental Workplace Stressors: Their Impact on Spinal Loads

For the first time, this study investigated how individuals react to both physical and mental workplace factors and how these reactions impact the loads on the spine. Thirty males and thirty females performed asymmetric lifting tasks at two different lift rates (2 and 8 lifts/min) and accompanied by two levels of mental concentration demands (none and keyboard entry task). Three-dimensional spinal loads were found to be greater for the faster lift rate and highest when mental concentration accompanied the fastest lift rate. Individuals responded to increases in lifting rates and mental demands by altering their trunk and hip motions as well as produced greater muscle coactivity. Thus, how an individual performs a particular lifting tasks is dependent upon both the physical requirements of the job but also the mental aspects. Workplace stressors that have the ability to influence the time pressures on the individuals have the potential to significantly influence the biomechanical responses and ultimately the loads on the spine.