Work Stress and Musculoskeletal Disorders Symptoms: The Effect of Psychosocial and Psychological Risk Factors

Abstract

The use of computer is a common activity for most people regardless of their occupation, gender and age. Mobile computing products such as laptops, computer tablets and smart phones encourage computer usage anytime and anywhere. In a certain way, computer products help people to improve their quality of life. The usage of computers is not always in a good and comfortable condition. Sometimes, computer users need to use their computers in a stressful psychological and psychosocial condition. It is feared that computer usage under this stressful psychological and psychosocial conditions will contribute to musculoskeletal disorder symptoms. The influence of psychological and psychosocial factors on musculoskeletal disorders has been debated for years. Many researches including cross sectional studies, experimental studies in laboratories or data collection in field areas have been conducted in order to determine the influence of psychological and psychosocial factors on musculoskeletal disorders. Yet, none of the psychological and psychosocial factors has been consistently and significantly associated with this disorder. Inconsistent roles of psychological and psychosocial factors on musculoskeletal disorders have been found in cross sectional studies among several occupations including dentists and construction workers. Even for experimental studies in a laboratory setting, there were various results obtained. These results indicate the inadequate knowledge regarding this issue. Psychological and psychosocial factors on musculoskeletal disorders are a broad field. There are many elements that can be included. In previous cross sectional studies, most of the time, the psychological and psychosocial factors investigated were different between each other. Even though there were studies examining the same factor (i.e mental demand), the assessment/questionnaires used were different, which might significantly affect the results. The same mechanism happened in previous experimental studies. Most of the time, the methodology used to induce the psychological and psychosocial stress were different between each other, which consequently might produce different results. Based on this motivation, the main objective of this dissertation is to find out and determine the relationship and the effect of psychological and psychosocial factors on musculoskeletal disorder symptoms especially during mobile computing product usage. Nevertheless, the role of physical factors on musculoskeletal disorders is well known and has been recognized for decades. Therefore, this dissertation also includes physical factors as part of this study. There are two phases of study in this dissertation. In the first phase, three cross sectional studies were done between three different occupations. These occupations include dentists, internship doctors and construction workers. These three occupations have different levels of physical demand as well as psychological and psychosocial stress. The main aim of these studies is to find out the relationship between psychological and psychosocial factors and the prevalence of musculoskeletal disorders in the field area. Six psychological and psychosocial factors have been assessed based on the same criteria (i.e job satisfaction, mental demand) using the same questionnaires which is Job Stress Questionnaire from NIOSH. From these studies, different degree of association between psychological and psychosocial factors and prevalence of musculoskeletal disorders has been found. In the second phase, three experimental studies were used to determine the effect of psychological and psychosocial factors on three independent variables during mobile computing product usage. These independent variables are muscle activity, visual discomfort and head posture. All these variables are connected to musculoskeletal disorder symptoms even though the exact mechanism is still unknown and debatable. Several stressors were used in the first experiment during four computer devices usage. Several hypotheses were developed in order to find out the role of psychological and psychosocial factors on muscle activity during different computer device usage. Inconsistent results regarding the influence of psychological and psychosocial on muscle activity in previous studies were taken into consideration and included into the hypothesis. The role of different device usage on muscle activity was also analyzed. There are different types of activities that can be elicited using computers such as typing, gaming, programming and many others. Reading is one of the most common activity during computer usage. Therefore, in the second experiment, the roles of psychological and psychosocial factors on visual discomfort as well as other body parts that shows signs of discomfort were analyzed during reading activities using laptops and computer tablets. The results obtained from this experiment were assumed to be related to head posture. Mobile computing products mobility allows the user to use them in various ways and places. Thus, in the final experiment, computer position were also included as part of the experiment. The effect of time pressure during laptop and computer tablet usage on different positions were analyzed in terms of visual discomfort and head posture. Musculoskeletal disorders are multifactorial disorders. Different risk factors may act on the different mechanisms and consequently cause the same symptoms. It is expected that this study would provide some insight and contribute some knowledge to other researchers regarding the role of psychological and psychosocial factors on musculoskeletal disorders especially during mobile computing product usage.