Influence of psychosocial stress and personality type on the biomechanical loading of neck and shoulder muscles

Abstract

The purpose of this study was to explore the influence of individual personality on the biomechanical response of neck and shoulder muscles to physical and psychosocial demands. Eighteen healthy male participants performed isometric pulling exertions in a semi-standing posture in the presence and absence of mentally demanding tasks. Surface electromyography (EMG) was used to quantify biomechanical response of neck and shoulder muscles, and the NASA Task Load Index (TLX) was used for subjective workload assessment. The effect of individual personality as a potential modifier was evaluated by classifying participants into thinking and feeling personality types. Mentally demanding tasks performed prior to the physical exertions significantly affected the muscle loading during the physical exertion. Activation of the shoulder as well as neck muscles increased with the addition of mental stress. Higher workload scores for mental and temporal demands, and frustration were reported by the participants during combined physical and mental tasks. In general, participants with feeling personality showed higher increase in the muscle activation level than participants with thinking personality corresponding to identical mental and physical demands, which indicate that response to mental stress during physically demanding tasks seems to be mediated by the individual personality. Relevance to industryWork environments in modern work places, with strong emphasis on efficiency, competitiveness, and downsizing, are characterized by a combination of physical and psychosocial demands. Individual factors such as personality traits are known to interact with these work-related factors to reconcile or aggravate the body's biomechanical response, yet the interacting effect of these factors on muscular loading is not clearly understood. The results of this study indicate that certain personalities are more vulnerable than others to increased muscle loading in response to mental stress during physically demanding tasks.