Elsevier

Applied Ergonomics

Volume 43, Issue 3, May 2012, Pages 554-563
Applied Ergonomics

Understanding the link between psychosocial work stressors and work-related musculoskeletal complaints

https://doi.org/10.1016/j.apergo.2011.08.009Get rights and content

Abstract

It is well established that psychosocial work stressors relate to employees’ work-related musculoskeletal disorder (WRMSD) symptoms. Using a model investigating psychological strain as a mediator between work stressors and WRMSD complaints, this study demonstrated that high levels role conflict, low job control, and low safety-specific leadership are associated with increased employee strain. Strain, in turn, was related to higher levels of WRMSD symptoms of the wrist/hand, shoulders, and lower back. Partial mediation of some relationships was also found, suggesting that additional meditational mechanisms for the relationships between stressors and musculoskeletal symptoms are plausible. This work supports the notion that psychosocial stressors in the work environment have important links to employee health, especially WRMSDs.

Highlights

► We test a model investigating psychological strain as a mediator between work stressors and WRMSDs. ► Role conflict, low job control, and low safety-specific leadership are related to employee strain. ► Strain is related to higher levels of WRMSD symptoms of the wrist/hand, shoulders, and lower back. ► Psychosocial stressors in the workplace have important links to WRMSDs.

Introduction

Work-related musculoskeletal disorders (WRMSDs) affect tendons, tendons sheaths, muscles, nerves, bursae, and blood vessels in the body. Every year, more than 70 million physician office visits can be attributed to WRMSD-related complaints (Sobeih et al., 2006). Moreover, a conservative estimate puts the economic burden resulting from symptoms related to WRMSDs (including costs associated with workers’ compensation, lost wages, and productivity) at $50 billion annually (Research Council and Institute of Medicine, 2001). Work-related musculoskeletal problems therefore represent a significant threat to employees’ health and well-being across a wide range of industries and occupations.

One line of work in this area has focused on the physical demands of work that employees must perform. For example, in the healthcare sector, patient lifting, positioning, and transferring are physical tasks that are particularly demanding, and have been associated with nurses’ WRMSDs and disability (e.g., Engels et al., 1996, Simon et al., 2008, Yassi et al., 1995). Similarly, for construction workers, physical job demands such as manual handling of heavy materials, awkward positions, and use of vibrating tools have been associated with high risk of WRMSDs (e.g., Latza et al., 2000, Sobeih et al., 2006). Retail and transportation workers often suffer from back injuries due to lifting and moving merchandise (Wassell et al., 2000). Taken together, biomechanical strain generated from physically strenuous tasks, awkward positions, and repetitive motions contribute to WRMSD complaints.

Lower back, hands, wrist, and shoulder WRMSDs are dominant in magnitude. Trunk and upper extremities have the highest prevalence of all WRMSDs (Bureau of Labor Statistics, BLS, 2007). Lower back injuries in particular comprise the most prevalent cause of absence from work out of the array of back/trunk problems (BLS, 2007). Furthermore, upper-extremity WRMSDs such as hand, wrist, and shoulder problems have become more prevalent over the past two decades, possibly due to increases in the widespread use of computer-based technology (Gerr et al., 1991). Thus, lower back, hands, wrist, and shoulder WRMSDs are of particular importance.

More recently, the psychosocial work stressors at work have been recognized as additional risk factors for WRMSDs (e.g., Lacey et al., 2007, Simon et al., 2008, Sobeih et al., 2006). For example, factors such as job dissatisfaction, lack of autonomy and social support, and high workload have been related to increased risk for WRMSDs (National Institute for Occupational Safety and Health, 1997, Sobeih et al., 2006). Similarly, high mental demands or pressure increased the risk for WRMSDs (Smith et al., 2004, Elovainio and Sinervo, 1997), especially when paired with low rewards (Simon et al., 2008). Additionally, lack of social support has also been shown to have negative impacts on risk for WRMSDs (Smith et al., 2004, Kaergaard and Andersen, 2000), as well as safety climate perceptions (Hofmann and Mark, 2006, Stone et al., 2007). Interestingly, Hollmann et al. (2001) found a three-way interaction between physical workload, mental job demand, and control in predicting nursing home staff members’ musculoskeletal symptoms. In particular, while control attenuated the association between job demand and symptoms when physical workload was low, it had little effect on the relationship between job demand and WRMSD symptoms when physical workload was high. Thus, psychosocial work stressors may have complex effects on WRMSDs beyond the simple bivariate relationships.

Unfortunately, although multiple theoretical models (e.g., Bonger et al., 1993, Faucett, 2005, Sauter and Swanson, 1996) exist in speculating the mechanisms underlying the associations between psychological factors and WRMSDs, research remains inconsistent in supporting hypotheses generated by different models (e.g., Swanson and Sauter, 2006, Wademan and Kjellberg, 2007). These conflicting research findings may be partly due to the lack of precision in the definition and measurement of the psychosocial aspects of jobs. Although most of the studies were couched on a job stress framework (e.g., Simon et al., 2008, Hollmann et al., 2001), very few directly tested the hypothesized pathway implied by the framework. Instead, effects of psychosocial work stressors (e.g., job demands, role conflict, lack of control, low levels of safety leadership) and strain (e.g., job dissatisfaction, negative mood, physical stress symptoms) were often lumped together (e.g., Smith et al., 2004, Yip, 2002), making it difficult to evaluate their relative impact on musculoskeletal symptoms. Additionally, few studies used established measures to assess psychosocial work stressors or strain, and instead opted for using single-item measures written specifically for the study (e.g., Smith et al., 2004, Swanson and Sauter, 2006). While these single-item measures may fit the purpose of a particular study, they can suffer from low reliability, imprecision, and narrowness of scope (Spector, 1992). Moreover, these studies typically examined only the bivariate relationships between psychosocial work stressors and musculoskeletal symptoms, rather than considering these variables within a more complex, stress process-based framework. Taken together, a direct test of a stress-based model that integrates established measures of psychosocial stressors, strain, and WRMSD symptoms can contribute to the literature by providing better understanding of the mechanisms linking psychosocial work stressors with musculoskeletal complaints.

The goal of the current study is to test a stress-based model that links psychosocial work stressors, strain, and WRMSD symptoms. We will first introduce the occupational stress model and explain how psychosocial work stressors are related to musculoskeletal complaints through psychological strain. Specific hypotheses based on the model will be presented. Results from structural equation modeling will be used test the proposed hypotheses.

This study contributes to the existing literature by approaching specific stressors and specific components of strain to better to evaluate their relative impact on particular musculoskeletal symptoms. Furthermore, this study examines relationships in a process-based framework, a fairly novel approach in this body of literature.

Occupational stress refers to the process through which employees perceive, appraise, and respond to adverse or challenging job demands at work (Frese and Zapf, 1988). The transactional approach suggests that the work environment and its stressors are assumed to cause strain responses by or in the person, and these strain responses have implications for workers’ subsequent attitudes and behaviors (Lazarus, 1991). Two specific elements of the stress process are distinguished. The first element is the stressors, which are situational stimuli that evoke responses from employees. Responses may be adaptive (i.e., increased motivation; LePine et al., 2004) or maladaptive (i.e., psychological strain, Jex, 1998). Strain refers to individuals’ maladaptive responses to environmental demands or stressors and may have emotional components (Beehr et al., 2000, Jex, 1998). When encountered with work stressors, employees may experience anxiety, tension, and feel overwhelmed by the amount of demands that they must fulfill. In other words, these emotional responses are representations of psychological strain. It should be noted that strain can also include physiological components such as hormonal or cardiovascular responses. However, the framework of the current study is focused on the psychological or emotional aspects of strain, from hence fourth referenced as “strain”.

There are a variety of occupational stressors that have been reported to have associations with strain. These range from job characteristics, social relationships at work, job insecurity, and even acute events at work such as homicides. Based on a recent taxonomy of occupational stressors (Rosen et al., 2010) three main categories of psychosocial work stressors will be discussed and a selection of stressors incorporated into our model: work role stressors, job control, and social characteristics. These categories are selected as they represent relatively stable characteristics in the work environment. As a result, employees may have prolonged exposure to these psychosocial work stressors. Chronic exposure to stressors can make the development of WRMSDs more likely as they are often developed via repetitive motion or over exertion across a period of time.

Work roles refer to the set of responsibilities and authorities associated with a particular position (Jackson and Schuler, 1985). Role conflict is one stressor which falls into this category and refers to employees receiving incompatible role expectations from different members of the organization (e.g., supervisor, coworker; Rosen et al., 2010). Job control, or autonomy, refers to employees’ ability to decide how and when to perform tasks and involvement in decision-making processes. Lack of control may elicit strain (Jex, 1998). Social characteristics are a set of stressors derived from interpersonal interactions, such as interpersonal conflicts, organizational politics, leadership styles, and abusive supervision.

One social characteristic stressor that may have direct ties to WRMSDs in particular is safety-specific leadership. Safety-specific leadership involves leaders’ emphasizing the value of safe performance, setting goals for injury prevention, and rewarding safety-related compliance (Kelloway et al., 2006). Lack of safety-specific leadership can be conceptualized as a psychosocial work stressor for several reasons. First, poor safety-specific leadership may signal to employees a general environmental context that is unconcerned with employee safety and well-being. Furthermore, poor safety leadership is likely associated with scarce support for employees to help them cope with safety hazards and injuries. Poor safety policies and procedures can affect WRMSD risk through the design of jobs, work pace (i.e., work pressure), and the level of employee safety training. Employees who perceive poor safety leadership may also feel that they are under pressure to disregard formal policies and procedures designed to protect their safety and well-being. In fact, safety-specific leadership may have ties to both strain and WRMSDs as it have been previously shown to relate to severe muscle and back pain (Barling et al., 2002, Kelloway et al., 2006).

Existing literature supports that these psychosocial work stressors have significant relationships to employee strain responses (e.g., Jackson and Schuler, 1985, Spector and Jex, 1998). For example, empirical studies have demonstrated that role conflict, job control and leadership are associated with strain (e.g., Jex and Beehr, 1991, Siu et al., 2004, Spector, 1986, Spector and Jex, 1998). Role conflict has been shown to relate to employee strain responses (e.g., Jackson and Schuler, 1985, Spector and Jex, 1998). Similarly, control has been shown to relate to strain (Spector and Jex, 1998). Effective leadership has been found to contribute to employees’ well-being (Nielsen et al., 2008) and has been reported to have a relationship to emotional exhaustion and burnout (Cole and Bedeian, 2007, Hetland et al., 2007). However, safety-specific leadership in particular has not been widely studied in relation to strain, although is expected to have a negative relationship to strain. Furthermore, this type of leadership may be of particular relevance to WRMSDs. Recent studies have found that safety-specific leadership behaviors, such as emphasizing the value of safe performance, setting goals for injury prevention, and rewarding safety-related compliance, contributed positively to the reduction of accidents and various occupational injuries, including severe muscle and back pain, for workers in heterogeneous industries (Barling et al., 2002, Kelloway et al., 2006).

As described earlier, psychosocial work stressors relate to employees’ WRMSD symptoms (National Institute for Occupational Safety and Health, 1997, Sobeih et al., 2006). One proposed model by Sauter and Swanson (1996), an ecological model of musculoskeletal disorders, is based on the notion that both physical and psychological factors in the work environment contribute to the experience of WRMSDs. Many parallels between this model and those in the psychosocial work stress literature exist. First, Sauter and Swanson suggest that work organization is directly associated with psychological strain which, in turn, influences musculoskeletal outcomes. Factors in the environment will elicit strain and this strain may have a direct impact on physical health. This idea is similar to the transactional stress model (Lazarus, 1991) as strain is one of the primary pathways by which the environment plays a role in health. Additionally, Sauter and Swanson discuss the experience of strain as an interpretive process which may be influenced by a variety of contextual and experiential factors. The transactional stress model also emphasizes the individual’s appraisal in leading to the experience of strain. Furthermore, the ecological model suggests that the outcome of strain (WRMSDs) may interact with the environment to increase environmental stressors. WRMSDs can also then feed back to influence the amount of stress felt at work. Similar to this theoretical proposition, the transactional stress model (Lazarus, 1991) emphasizes the importance person-environment transactions. Thus, both the ecological model and the transactional model provide a similar foundation from which to empirically explore the role of strain as a mediator between psychosocial work stressors and WRMSDs.

One way by which Sauter and Swanson (1996) posit the mediation to occur is through physiological consequences of experiencing strain. There are several physiological explanations for why strain may play a mediating role between psychosocial work stressors and WRMSDs. First, strain may mediate the effect of stressors on WRMSDs due to increases in muscular tension when employees experience strain. The muscle tension and other autonomic effects in the body may then compound the biomechanical strain employees are under when performing task-related physical efforts. In fact, previous research has suggested that strain may have a direct effect on muscular tension. For example, in experiments where participants were subject to stress-inducing tasks, psychological strain responses such as anxiety have been linked with muscular tension (e.g., Krantz et al., 2004, Lundberg et al., 1994). Researchers have suggested that prolonged experiences of muscular tension may explain why psychosocial work stressors and strain are linked to WRMSDs (Krantz et al., 2004, Lundberg et al., 1999). In addition, strain may lead to an increased physiological susceptibility to WRMSDs by affecting hormonal, circulatory, and respiratory responses that exacerbate the impact of physical risk factors (Blair, 1996, Landsbergis et al., 1994, Schleifer and Ley, 1994). It is possible that strain mediates the relationship between psychosocial work stressors and WRMSDs because the biophysiological reactions associated with strain can add to the effects of physical demands by limiting the ability of the body to repair tissue after microtrauma (Carayon et al., 1999). Strain could also result in reduced blood flow to the extremities and to the muscles, increased blood pressure, increased corticosteroids, such as cortisol, fluid retention in body tissues, increases in peripheral neurotransmitters, such as norepinephrine, and reduced effectiveness of immune system responses which all contribute to risk for WRMSDs (Carayon et al., 1999). A final possibility is that strain reactions such as frustration and anger could lead to risky behavior (i.e., over exertion) that increases WRMSD risk (Smith and Carayon, 1996). Thus, strain may theoretically be a mediator between psychosocial work stressors and WRMSDs.

While there are many possible mediating mechanisms between strain and WRMSDs as described above, we did not test them directly in the current study. Rather, the current study will test a theoretical model that links stressors to work-based musculoskeletal complaints via psychological strain. The stress-based model is presented in Fig. 1, which is consistent with the transactional stress model (Lazarus, 1991) and the ecological model of musculoskeletal disorders (Sauter and Swanson, 1996) described earlier. Based on the theoretical mechanisms by which stressors relate to WRMSD symptoms, role conflict, control, and safety-specific leadership were selected for the model. Indicators of frustration, anger, anxiety, and depression were used to create a latent variable of strain similar to prior work using a latent variable of psychological strain (Korunka and Vitouch, 1999). These strain responses, in turn, are expected to lead to increased WRMSD complaints. As mentioned earlier, biomechanical demands such as physically strenuous tasks, awkward positions, and repetitive motions contribute to WRMSD complaints. In order to best isolate how psychological strain may mediate the relationship between psychological work stressors and WRMSDs, biomechanical demands must be accounted for. Because physical demands placed on employees are expected to impact reports of WRMSD symptoms, it is included as a control variable in our model.

Hypothesis 1

  • (a) There will be a positive relationship between role conflict and work-related musculoskeletal complaints and (b) this relationship will be mediated by psychological strain.

Hypothesis 2

  • (a) There will be a negative relationship between job control and work-related musculoskeletal complaints and (b) this relationship will be mediated by psychological strain.

Hypothesis 3

  • (a) There will be a negative relationship between safety-specific leadership and work-related musculoskeletal complaints and (b) this relationship will be mediated by psychological strain.

Section snippets

Participants and procedure

Data were obtained from 277 full-time employees. The majority of the participants were females (79%) and Caucasian (69%), or African American (10%). The average age of the participants was 24 years old (SD = 6.6). Participants had an average tenure of 3 years (SD = 3.5) in their present job and worked a minimum of 20 h per week. The majority of participants worked in retail/service (41%; e.g., customer service representative) and professional (14%; e.g., nurse) industries. A small percentage of

Results

Table 1 reports the means, standard deviations, internal consistencies, and correlations among the focal variables. Each psychosocial work stressor was significantly related to at least one of the WRMSD symptoms. Consistent with our hypotheses, safety leadership was significantly related to wrist/hand (r = −.14) and lower back symptoms (r = −.13), and role conflict was significantly related to lower back symptoms (r = .16), thus providing partial support for Hypotheses 1a and 3a. Interestingly,

Discussion

The purpose of the current study was to understand the link between psychosocial work stressors, strain, and the musculoskeletal symptoms in a stress processed-based model. By cleanly separating stressors from strains, relying on improved measures, and using sophisticated methodology to test the theoretical model, the current work provides a significant added value to the current literature in this area. Our methodology included mediation analyses using structural equation modeling while

Acknowledgments

This work was partially funded by the National Institute for Occupational Safety and Health (NIOSH Training Grant No. T42 OH 008438) and conducted as a part of the Sunshine Education and Research Center at the University of South Florida. An earlier version of the paper has been presented at the 2010 Annual Meeting of the Academy of Management, Montreal, Canada. We would like to kindly thank Danesh Jaiprashad and Tom Bernard for their contributions to this project.

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