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The effects of an office ergonomics training and chair intervention on worker knowledge

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Applied Ergonomics 40 (2009) 124–135 www.elsevier.com/locate/apergo

The effects of an ofce ergonomics training and chair intervention on worker knowledge, behavior and musculoskeletal risk
Michelle Robertsona,, Benjamin C. Amick IIIb, Kelly DeRangoc, Ted Rooneyd, Lianna Bazzanid, Ron Harriste, Anne Mooref
a

Liberty Mutual Research Institute for Safety, 71 Frankland Road, Hopkinton, MA 01748, USA b Institute for Work and Health, Toronto, Canada c Kalamazoo, MI, USA d Health and Work Outcomes, Brunswick, ME, USA e The University of Texas School of Public Health, Houston, TX, USA f York University, Toronto, Canada Received 21 July 2007; accepted 21 December 2007

Abstract A large-scale eld intervention study was undertaken to examine the effects of ofce ergonomics training coupled with a highly adjustable chair on ofce workers' knowledge and musculoskeletal risks. Ofce workers were assigned to one of three study groups: a group receiving the training and adjustable chair (n 96), a training-only group (n 63), and a control group (n 57). The ofce ergonomics training program was created using an instructional systems design model. A pre/post-training knowledge test was administered to all those who attended the training. Body postures and workstation set-ups were observed before and after the intervention. Perceived control over the physical work environment was higher for both intervention groups as compared to workers in the control group. A signicant increase in overall ergonomic knowledge was observed for the intervention groups. Both intervention groups exhibited higher level behavioral translation and had lower musculoskeletal risk than the control group. r 2008 Elsevier Ltd. All rights reserved.
Keywords: Ofce ergonomics intervention; Training; Musculoskeletal risk

1. Introduction Work-related musculoskeletal disorders (WMSDs) among ofce workers are receiving growing attention. With over 45,000,000 computers in US workplaces, concerns exist about an escalation in the incidence of computer-related WMSDs (Tittiranonda et al., 1999). Studies have revealed a variety of contributing factors to musculoskeletal discomfort including: increased job demands and more hours working at a computer (e.g., Bernard et al., 1994; Faucett and Rempel, 1994), increased levels of psychological stress (e.g., Bongers et al., 1993; Carayon and Smith, 2000; Marcus and Gerr, 1996; Faucett and Rempel, 1994), and a lack of specic
Corresponding author.

E-mail address: michelle.robertson@libertymutual.com (M. Robertson). 0003-6870/$ - see front matter r 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.apergo.2007.12.009

ergonomic features in the workstations and ofce buildings (e.g., Nelson and Silverstein, 1998; Sauter et al., 1990). Typically these studies are cross-sectional in design (Demure et al., 2000). Although there is a growing interest among employers to improve ofce workplaces, few longitudinal eld studies have examined the effects of ofce ergonomics interventions on worker's health and performance (Brewer et al., 2006; Buckle, 1997; National Research Council Institute of Medicine, 2001; Karsh et al., 2001). There is some evidence, however that ergonomics training (Brisson et al., 1999) in workstation and building design (e.g., Aaras et al., 2001; Hagberg et al., 1995; Lewis et al., 2002; Nelson and Silverstein, 1998; Rudakewych et al., 2001; Sauter et al., 1990) can prevent or reduce musculoskeletal and visual discomforts and symptoms in ofce environments. One method for reducing the prevalence of musculoskeletal and visual symptoms is to provide specialized

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ergonomics training and workstation changes. Ofce ergonomics training helps employees to understand proper workstation set-up and postures (e.g., Brisson et al., 1999; Bohr, 2000; Ketola et al., 2002; Lewis et al., 2002; Verbeek, 1991). Green and Briggs (1989) showed that merely providing adjustable furniture alone may not prevent the onset of overuse injury. However, a signicant decrease in WMSDs has been observed when workers were given an adjustable/exible work environment, coupled with ergonomics training (Robertson and O'Neill, 1999). Further, the provision of control over the work environment through adjustability and knowledge may enhance worker effectiveness as well as health (McLaney and Hurrell, 1988; O'Neill, 1994; Robertson and Huang, 2006). A large-scale longitudinal eld intervention study was implemented to examine the effects of ofce ergonomics training coupled with a highly adjustable chair on ofce worker's ergonomics knowledge, computing behaviors and postures, and health and performance compared to training-only and control groups. Using the instructional system design (ISD) (Knirk and Gustafson, 1986) as a guide, we developed an ofce ergonomics training workshop with the goal of motivating workers to conduct selfevaluations and to reorganize and adjust their workspace. Fig. 1 shows a theory of change guiding our research model and questions (Amick et al., 2003). Participants were assigned to one of three study groups: a group receiving the adjustable chair and ergonomics training (C+T), an ergonomics training-only group (T-only), and a control group. We proposed the following hypotheses: Hypothesis 1. Ofce ergonomics knowledge and intent to change ofce workstation set-ups will increase for the C+T and T-only intervention groups on pre- vs. postintervention tests. Hypothesis 2. Perceived control over the work environment will increase for the T-only group compared to a

control group, with a greater increase for the C+T group as compared to the T-only and control groups. Hypothesis 3. There will be a reduction in musculoskeletal risk for the T-only group as compared to the control group, with a greater reduction for the C+T groups compared to the T-only and control groups. Hypothesis 4. There will be an increase in workstation rearrangement and trained computing behaviors and postures for the T-only group as compared to a control group with a greater increase for the C+T group as compared to the T-only and control groups. 2. Methods 2.1. Study participants All participants were employees from one public sector department of revenue services whose jobs involved collecting tax revenues. Participants had access to the internet and worked in sedentary, computer-intensive jobs requiring at least 4 h per day working at an ofce computer and at least 6 h per day sitting in an ofce chair. Individuals who led a Workers' Compensation claim in the past 6 months were excluded. Informed consent documentation was transferred over the internet on a secure website. The Liberty Mutual Research Institute Institutional Review Board for the protection of human subjects approved the study. 2.2. Workplace settings The study took place at 11 remote ofce locations, some being 200–300 miles away from the corporate ofce. Overall the architectural design of the workplaces varied but, in general, consisted of long hallways with private ofces in the center of the oor and system panel individual workstations located around the perimeter. Natural lighting

Training

Knowledge Productivity Health

Highly Adjustable Chair

Postures & Behaviors Functional Health

Satisfaction
Fig. 1. Theory of change. This model depicts the expectation that when an ofce ergonomics training program is implemented, an increase in ergonomics knowledge will motivate workers to modify working postures and behaviors (e.g., break patterns, workstation set-up). The training, coupled with the chair, is expected to improve postures and behaviors that reduce musculoskeletal loads, thereby decreasing musculoskeletal symptoms and improving health. A decrease in symptoms inuences job functioning and ultimately contributes to performance.

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was limited for those situated closer to the center of oor and better for those near the windows. Direct glare from the windows could be controlled by window shades. The individual workstations were ''L''-shaped work surfaces, with non-adjustable storage, xed work surface heights and monitors, and minimally adjustable chairs. Some workstations had adjustable keyboard trays, mouse surfaces, and document holders. 2.3. Study design A quasi-experimental, longitudinal eld study design was employed consisting of two pre-intervention and three post-intervention measures (Campbell and Stanley, 1966). Pre-intervention measures of both outcomes and covariates of theoretical importance were assessed to control for any between-groups differences at baseline. Attempts were made to balance workload requirements and job descriptions as much as possible across the three groups. Workers were not randomly assigned to the study groups; our intent was to minimize the potential for the control group to obtain ergonomic knowledge from the other two study groups. Participants were therefore assigned to groups based on geographic separation by different supervisory units, oors, and buildings. Over a 16-month period, participants were asked to complete ve online surveys: 2 months and 1 month prior to intervention and 2, 6, and 12 months following intervention. Individual workstation assessments and body postures were observed (1 pre- and 1 post-intervention) along with two training knowledge tests (pre- and immediate post-training). Fig. 2 details the specic outcome measures that will be reported and when they were taken.

2.4. Ofce ergonomics training intervention: instructional system design The ISDs approach includes six phases: analysis, design, develop, implement, evaluate, and feedback. Each of these steps are discussed below and their applicability to the design of the ergonomic training intervention for the specied study sites. 2.4.1. Analysis Needs assessment included two steps. First, interviews were conducted by one of the authors (MMR) with the company's corporate ergonomist, nurse practitioner, and facility manager to identify existing related ofce health, safety and ergonomics training programs, and to review who had been trained in the study workforce. The semistructured interviews lasted approximately 1 h and were guided by open-ended questions that focused on identifying the training and ergonomic organizational practices, policies and procedures, the existing ergonomic and safety training programs (content, design, delivery), and the perception of employee's knowledge level regarding ofce ergonomics. Second, the corporate facility manager provided a facility walk-through for one researcher (MMR) to view the company's ofce spaces, workstation congurations, layout, and furniture. 2.4.2. Design Based on the needs assessment and previous work in ofce ergonomics training (Robertson and O'Neill, 1999), the training goals, objectives, and procedures were dened. The training goals were to: (1) understand ofce ergonomic principles, (2) perform ergonomic self-evaluation of
Study timeline and measurements

Pre-Intervention -2 -1

Intervention# 0

Post-Intervention +2 +6 +12

Measures Employee surveys (WEH)*; Perceived control

Observations: OEA** and RULA*** Ergonomics knowledge Pre-post training tests

*Work Environment and Health (WEH) survey ** Office Ergonomics Assessment (OEA) *** Rapid Upper Limb Assessment (RULA) #Office ergonomics intervention consisting of ergonomics training and highly adjustable chair; 3 Groups: Group 1 = Chair + Training, Group 2 = Training-Only, Group 3 = control

Fig. 2. Study timeline and measurement periods.

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workspaces, and (3) adjust and rearrange one's own workspace. Nine instructional objectives were specied:



recognizing WMSDs and risk factors, understanding the importance of varying work postures, knowing how to rearrange the workstation to maximize the ''comfort zone'', recognizing and understanding visual issues in the ofce environment, reducing visual discomfort, understanding computing habits (rest breaks), knowing how to change work–rest patterns, being aware of the company's existing health and ergonomic programs, knowing how to obtain ergonomic accessories through the company's programs.

the training at each of the 11 participating company sites using the same training materials. Facilitators were trained ergonomists and health experts. Training lasted for 1.5 h and was introduced by a supervisor. All supervisors attended the training. Each participant was either provided with the newly adjustable chair at the workshop (group 1; Chair+Training) or came to the training with his or her existing chair (group 2: Training-only). Group 3, the control group, was trained after the study was completed as an obligation and benet to the participating worksite. 2.4.5. Evaluate Training's effectiveness was evaluated based on a ve level training evaluation framework (Knirk and Gustafson, 1986; Kirkpatrick, 1979): (1) baseline assessment, prior to training, (2) trainee reaction, (3) learning, (4) performance, and (5) organizational results. In Level 4, behavioral and symptom measures may be included as they are relevant to measures of effectiveness regarding ergonomic training interventions. Evaluation results for Levels 1–3, and part of Level 4 are presented. Symptom reporting and productivity results of this ergonomic intervention study are reported in Amick et al. (2003) and DeRango et al. (2003), respectively. The training effectiveness measures included: Level 1: pretraining ofce ergonomics knowledge tests; Level 2: trainees' reaction to the ergonomics workshop (usefulness, value, and relevance); Level 3: pre–post ofce ergonomics knowledge tests; and Level 4: observed behavioral changes. All of these measures and instruments are described below. 2.4.6. Feedback E-mail messages provided feedback to the trainees on the results of the knowledge tests and served as reminders of the ofce ergonomics principles. Messages were sent at 1 and 3 months post-training. These communications were coordinated by the company's facilities manager, who spearheaded the research project. The 1-month posttraining e-mail notied the trainees of the results of the course evaluation and knowledge tests highlighting the item(s) with the greatest improvements and the item(s) with the least improvement. The 3-month post-training e-mail included selected results from the post-training observed behaviors and contained reminders about working postures and tips on healthy computing habits and exercises. Also, reminders about corporate resources concerning ergonomics were given at 1 and 3 months following the training. 2.5. Ofce ergonomic chair The ergonomic chair chosen for the intervention has highly adjustable design features including width telescoping armrests, dynamic back support, gliding seat depth, plus the standard ANSI VDT(1998) ergonomic chair requirements (e.g., lumbar support, seat height adjustment, waterfall seat pan front, and ve-coaster base). The intent of these adjustable features is to support the ergonomic

For each objective, appropriate presentation strategies and media were determined. Active adult learning models, which allow for a high level of interaction among the trainers and trainees (Gordon, 1994), were specied for use in the training. 2.4.3. Develop Multi-media presentation provided for various learning modalities for the trainees. The primary media presentation included power point slides, an ''Ofce Ergonomics Today'' video, demonstrations, and pictures of various trainees' computer workspaces. Practice sessions, performance feedback, group discussion, and problem solving activities were all used to facilitate the learning process. Each trainee used their own ofce chair and learned appropriate adjustments. Group exercises and breakouts were designed and consisted of having the trainees conduct ergonomic assessments of several computer workspaces and provide recommendations. Debrieng and feedback were provided by the co-facilitators. Participants were provided with an opportunity to share real-life examples and experiences related to their computer workspaces. These active learning exercises were designed to instill desired attitudes toward healthy computing, skills of how to use their workspaces, as well as transference of these skills to behaviors when the trainee returned to their workspace. We developed several training materials including: a facilitators handbook, and a computer ergonomic guidelines (''Ergo-Guidelines'') handout with recommendations and solutions. These ergonomic handouts were intended for the trainees to use for future reference. 2.4.4. Implement The training and evaluation materials, including the pre/ post-knowledge tests, were piloted with 25 ofce workers at another worksite. The training materials and the instructional sequence were modied to meet the training time limit of 90 min. For consistency, the same two cofacilitators, using the same training materials, delivered

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goal of improving the worker t to his or her ofce workspace (Bush and Hubbard, 1999). For a detailed description of the chair design features and functions see Amick et al. (2003). 2.6. Instrument and outcome measures Several instruments were used in the study including: (1) Work Environment and Health (WEH) survey (Amick et al., 2003), which asks workers to report comfort, satisfaction, health, computer use, performance, and basic demographic information, (2) two observational tools; Ofce Environment Assessment (OEA), and Rapid Upper Limb Assessment (RULA), (3) ofce ergonomics knowledge tests, and (4) ofce ergonomics workshop evaluation. 2.6.1. Work Environment and Health (WEH) survey Perceived control over their work environment and knowledge was measured by an objective, 18-item checklist to determine: (a) the number of adjustable features within the workspace and chair (availability of control), (b) the number of features that employees knew how to adjust (knowledge of control) within a workstation and chair, and (c) whether they had adjusted the items (exercise of control) for both the workstation and chair. Response categories were ''yes'', ''no'', or ''don't know''. The knowledge of adjustability score was determined by the number of features the worker knew how to adjust divided by the number of adjustable features in the workspace. The exercise adjustability score was determined by the number of features the workers had adjusted divided by the number of adjustable features in the workspace. The result was four indices representing the degree of the workers' perception of control over their physical environment: (1) chair knowledge of adjustability, (2) chair exercise of adjustability, (3) workstation knowledge of adjustability, and (4) workstation exercise of adjustability. The total score is the summative average where a higher score indicates more knowledge and exercise of adjustability. 2.6.2. Rapid Upper Limb Assessment (RULA) observational tool RULA was used to assess working postures and the associated muscular effort and exerting forces of computer users (McAtamney and Corlett, 1993; Lueder and Corlett, 1996). A computerized version of RULA was developed based on the RULA illustrations and scoring tables reported in Lueder and Corlett (1996) (McGorry and Chang, 2002). Four scores were generated for both the left and the right sides of the body: Score A: upper arm/wrist/ wrist twist, Score B: neck, trunk, legs, Score C: Score A+muscle and force scores, Score D: Score B+muscle and force scores, Grand score: combination of Score C and Score D+weighted combination of the four subscores. The grand score is based upon the estimated risk of injury due to musculoskeletal loading. The scales range from 0 to 5

where a higher score represents more of postural load, muscular effort, and musculoskeletal risk. 2.6.3. Ofce Environment Assessment observational tool The OEA is a new observational tool intended to evaluate the ergonomic conguration of the overall workspace and items within the worker's control to change. This 39-item instrument allows for observing the impact of the ergonomic training program on the behaviors of ofce workers. There are 7 categorical areas: (1) work surface conguration (2 items), comfort zone and accessories (10 items), keyboard and mouse (13 items), monitor (7 items), lighting and glare (6 items), and chair features (9 items). The OEA generates two scores. First, the overall Appropriate Ergonomic Conguration (AEC) score is calculated as the percent of all items correctly congured, regardless of their adjustability. This score reects how many items within the workspace were appropriately positioned or adjusted relative to the worker's needs— irrespective of whether the items could be manipulated in any way by the worker. Second, the Training Outcome (TO) score is calculated as the percent of all items that could be changed and were correctly congured within the worker's workspace. The total score is the mean percent, ranging from 0 to 1, where higher AEC and TO scores represent more appropriately adjusted/or moved items. Trained raters decided whether or not something was adjustable, moveable, or properly congured. Each participant was unobtrusively observed while they were performing representative computing postures such as keying and mousing. 2.7. Inter-rater reliability procedure Four observers, all with backgrounds in ergonomics, were trained on the OEA and RULA observational instruments. Observers were trained by one of the authors (MMR). Training consisted of a 3.5 h workshop, including a review of the purpose, the instruments, the operational denition of terms, the basic observational techniques, and the procedural use of the instruments. First, observers individually practiced rating on a series of selected pictures of ofce workers in class, followed by interactive practice sessions with paired trainees in the eld. Immediate performance feedback was given by the instructor. Each observer then conducted a series of assessments on the same individuals until there was 90% agreement across items and the gold standard (the instructor). This process required 5 practice assessments with the whole group of observers before the 90% agreement was reached. After the training was completed, each observer participated in an inter-rater reliability study. Sixteen participants were randomly selected and simultaneously evaluated. Intraclass Correlation Coefcients (ICC), with observers treated as a random factor, were determined for the RULA subscores and grand scores and the OEA scores (AEC and TO). A second study was conducted

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post-intervention. An ICC score of 0.70 was considered appropriate for an adequate reliability among observers. 2.8. Ofce ergonomics knowledge pre–post-tests Pre- and post-training ofce ergonomics knowledge tests were distributed to the training intervention groups while they were assembled in the training room. These tests consisted of 17 questions assessing seven knowledge areas of ofce ergonomics: (1) work-related risk factors (2 items), (2) physical ergonomic features (2 items), (3) body posture (6 items), (4) workstation layout and conguration (4 items), (6) rest breaks (1 item), and (7) ergonomic practices and resources (2 items). The total number of correct items was summed for each participant, ranging from 0 to 17, with 17 being a perfect score. The post-training knowledge test had one additional open-ended question: ''What immediate changes are you going to make to your computer workstation as a result of this ofce ergonomics training?'' Responses were content coded by two raters who rst reviewed all of the comments together, identied specic themes, and then coded the responses until 100% agreement was met between them. 2.9. Ofce ergonomics training workshop evaluation Workshop ratings provided by participants consisted of 17 items assessing satisfaction with the training format and objectives (6 items), the facilitators (4 items), and course materials (7 items). Responses were provided on a 4-point Likert scale from ''1'' (strongly agree) to ''4'' (strongly disagree) for 14 items and ''1'' (very useful) to ''4'' (not useful) for 3 items. 2.10. Statistical analyses To test the pre–post-differences in mean scores for the four perceived control indices, a simple multivariate model

in STATA was conducted. Multilevel analyses were completed using MLwiN 1.1 (2001) and all other analyses using STATA 7 (2000). Differences in correct responses pre-test vs. post-test overall, and between knowledge areas were tested using paired t-tests (i.e., design layout vs. body posture). 3. Results 3.1. Participation rates For the overall study, 316 workers were invited to participate and 219 provided informed consent for a participation rate of 69.3%. Study participant demographic and workplace characteristics have been described previously: the mean age was 47; 60% of the participants were female; and nearly all participants were white or Caucasian (Amick et al., 2003). Average time spent in an ofce chair and computing was 5–6 h per day. Table 1 presents the breakdown by group for those who participated, completed the WEH surveys, attended the training, and were observed. The sample size for the control group was n 57, chair+training (C+T) n 96 and trainingonly (T-only) n 63. There was no signicant difference regarding the drop out rates among the groups, and there was a high level of retention (88%) (see Amick et al., 2003). 3.2. Inter-rater reliability for RULA and OEA Tables 2 and 3 presents the calculated ICCs for each RULA subscores and grand scores, and the two OEA subscores, AEC and TO scores, respectively. The differences in the ICCs between Time 1 and Time 2 were due to the additional practice time and feedback given to the evaluators on understanding the instrument and operational denitions of items in the observational measures.

Table 1 Number of participants by group and measurement period, who completed work environment and health surveys, training knowledge tests, and observations Study groups Study time measurement period Time 1 Pre-intervention WEHa Trained experimental groups Observed OEAb Time 2 Post-intervention Observed RULAc WEH Observed OEA Observed RULA

Training and chair n 96 Training-only n 63 Control n 57
a b

85 51 53

86 59

62 45 45

51 37 44

79 48 43

57 29 24

69 38 44

WEH: Work Environment and Health Questionnaire (perceived control over environment questions). OEA: Ofce Ergonomics Assessment. c RULA: Rapid Upper Limb Assessment.

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130 Table 2 RULA intraclass correlation coefcients ICC—right side of body score Time 1a Score A (upper arm/wrist/wrist twist) Score B (Neck, trunk, legs) Score C (Score A+muscle and force) Score D (Score B+muscle and force) Grand score (Score C and Score D)
a

M. Robertson et al. / Applied Ergonomics 40 (2009) 124–135

ICC—left side of body score Time 1 0.40 0.40 0.32 0.37 0.44 Time 2 0.85 0.99 0.90 0.99 0.86

Time 2 0.93 0.99 0.93 0.99 0.65

0.66 0.37 0.58 0.40 0.42

Time 1 is pre-intervention with 16 observations and 4 observers. Time 2 is post-intervention with 27 observations and 4 observers.

Table 3 OEA intraclass correlation coefcients ICC Time 1a AEC score (Appropriate Ergonomic Conguration) TO score (Training Outcome)
a

the control group after the intervention. Fig. 4 presents trainees' self-report of immediate workstation changes following training.
Time 2 0.91 0.92

3.5. Perceived control over the work environment Responses to the knowledge and exercise of chair adjustability questions showed a positive change for the groups receiving the training as compared to the control group, though not statistically signicant (p40.05). An observed positive change was noted in the responses to the knowledge of workstation adjustability questions for the chair+training (pre-intervention M 0.70; post-intervention M 0.76) and training-only groups (pre-intervention M 0.81; post-intervention M 0.90) as compared to the control group (pre-intervention M 0.85; post-intervention M 0.82). However, no signicant change was found for the knowledge and exercise workstation adjustability questions. 3.6. Observed postural and behavioral changes Selection of confounders followed a statistical analysis protocol described in Amick et al. (2003). Of the 30 covariates measured through the WEH, 10 were identied as potentially relevant to the OEA and RULA observational outcomes. These 10 were: hours spent working at ofce computer, repetitive hand and wrist activity, decision latitude, social support, body mass index categorization, general health, wearing of eyeglasses, age, and gender. A separate confounder selection process was conducted for each outcome modeled. Through the covariate selection process, only repetitiveness of hand/wrist activity (0 no repetitiveness and 6 highly repetitive) remained in the models predicting the OEA outcomes, and no covariates remained in the models predicting the RULA grand scores. 3.6.1. Postural changes: RULA Table 4 presents the multilevel model results. The models show that both trained intervention groups signicantly improved their observed computing body postures (lower RULA scores) compared to the control group, for both the

0.60 0.61

Time 1 is pre-intervention with 16 observations and 4 observers. Time 2 is post-intervention with 27 observations and 4 observers.

3.3. Ofce ergonomic knowledge 3.3.1. Trainee's reaction Participants in the two intervention groups found the training to be benecial as reported on the post-training evaluation questionnaire by either strongly agreeing (64%) or agreeing (36%). Trainees' responses to the question, ''Will they be able to apply this information to their job'' yielded 63% strongly agreeing and 37% agreeing. 3.3.2. Trainee's learning Results of the pre/post-knowledge test revealed signicant increases in knowledge about: overall ofce ergonomics (t(143)=13.7, po0.001), the use of ergonomic workstation and chair features (t(143)=7.8, po0.001), improvement of body postures (t(143)=8.9, po0.001), company ergonomic practices and company resources (t(143)=12.4, po0.001) (see Fig. 3). 3.4. Self-reported intended behavior changes: post-training test Pertaining to self-reported intended behaviors, over 93% of the trainees responded to the open-ended question: ''yWhat immediate changes are you going to make to your computer workstation as a result of this ofce ergonomics training?'' Of those that responded (n 124), 45% indicated at least two or more changes with changes to the chair, appropriate workstation adjustments, and monitor placement the most frequently provided responses. Similarly, these responses were observed for

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100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Overall* WMSD risk Physical Body Factors ergonomic posture* features* Workstation Layout

131

Pre Post

Percent Correct

Rest Breaks Ergonomic practices, resources*

Fig. 3. Percentage of correct responses on the pre–post ofce ergonomic knowledge questions (n 145; experimental groups; chair+training and training-only), *po0.001.

45 40 35 30 Percent 25 20 15 10 5 0 Types of Changes

Monitor Keyboard/keyboard tray Glare Review whole set-up Furniture

Chair Documents/document holder Footrest Posture

Comfort zone Mouse Laptop Take "micro" breaks

Fig. 4. Percentage of intended types of workstation changes as reported by the trainees (n 124 responses).

right and left side of the body. The C+T intervention group experienced a signicant improvement in computing postures post-intervention compared to the control group for the left side of the body (b 2.25; z 7.77; po0.05) and for the right side of the body (b 1.94; z 6.23; po0.05). The T-only group experienced a statistically signicant improvement in computing posture post-intervention compared to the control group for the left side of the body (b 1.88; z 5.77; p 0.00) and for the right side of the body (b 1.98; z 5.73; p 0.00). The difference between C+T and the T-only groups for both the left and right side of the body were not statistically signicant. Changes in the RULA scores for the left and right side of the body are depicted in Fig. 5.

3.6.2. Behavioral changes: Ofce Ergonomics Assessment (OEA) The results of the multilevel model for the OEA show that the chair with training group did not experience postintervention improvements in workstation changes for either TO (b 0.034; z 1.35; p 0.176) or AEC (b 0.045; z 1.9; p 0.057) as compared to the control group (see Table 4). The training-only group experienced a statistically signicant improvement post-intervention in workstation changes (TO) (b 0.71; z 2.49; p 0.01) and AEC (b 0.079; z 2.97; p 0.003) as compared to the control group. Post hoc analysis revealed that with the removal of the covariate hand/wrist repetitiveness, the chair with training group model for TO approaches signicance p 0.075 compared to the control group.

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132 M. Robertson et al. / Applied Ergonomics 40 (2009) 124–135 Table 4 Multi-level models for Rapid Upper Limb Assessment (RULA) and Ofce Environment Assessment (OEA) Variable name RULA models: Grand score, left side Coefcient (Std. error) Chair with training Training-only Intervention phase Chair+trainingintervention (interaction term) Training-onlyintervention (interaction term) Intercept term Level 1 variance Level 2 variance Variable name 0.15 0.21 0.53 2.25 (0.24) (0.26) (0.22) (0.29) Grand score, right side Coefcient (Std. error) 0.43 0.21 0.54 1.94 (0.24) (0.26) (0.23) (0.31)

1.88 (0.33) 4.31 (0.17) 0.98 (0.07) 0.59 (0.11) OEA models: Training Outcome (TO) model Coefcient (Std. error)

1.98 (0.35) 4.63 (0.18) 1.07 (0.07) 0.50 (0.13)

Appropriate Ergonomic Conguration (AEC) model Coefcient (Std. error) 0.051 0.042 0.091 0.045 (0.017) (0.019) (0.019) (0.024)

Chair with training Training-only Intervention phase Chair+trainingintervention (interaction term) Training-onlyintervention (interaction term) Repetitive hand/wrist activity Intercept term Level 1 variance Level 2 variance
po0.05.

0.041 0.039 0.088 0.034

(0.018) (0.020) (0.021) (0.025)

0.071 (0.028) 0.016 0.580 0.068 0.058 (0.004) (0.022) (0.006) (0.008)

0.079 (0.027) 0.013 0.600 0.064 0.056 (0.004) (0.021) (0.005) (0.007)

Change in RULA Grand Score

1
Left Side Right Side

0.5 0 -0.5 -1 -1.5
Chair With Training Training Only Control

-2

Fig. 5. Changes in RULA grand score for postural changes on the left and right side of body for each study group after intervention. Changes in RULA scores (postural changes) are calculated from the predicated model values pre- and post-intervention.

The difference between chair with training group and the training-only groups for the TO and AEC scores were not statistically signicant (p40.05). The percent improvements for the OEA regarding observed behavioral changes are depicted in Fig. 6. 4. Discussion This study examined the effects of an ofce ergonomics intervention, consisting of ofce ergonomics training and a

highly adjustable chair, on workers knowledge, computing behaviors, postures, and risk of musculoskeletal and visual discomfort. Due to the knowledge gained following an ofce ergonomics intervention improved postures and computing behaviors may be observed. The trainees reported that the ofce ergonomics training was benecial and that they could apply the information to their work environment. Additionally, there was an increase in ofce ergonomics knowledge and skills of the participants from pre- to post-intervention. Participants exhibited a large,

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0.18 Change in Mean Scores 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Training Outcome Chair With Training Appropriate Ergonomic Configuration Training Only Control

Fig. 6. Mean changes in Ofce Ergonomics Assessment (OEA) scores (Training Outcome) and Appropriate Ergonomic Conguration (AEC) for each study group pre- and post-intervention.

signicant increase in knowledge about body postures, ergonomic design features, and corporate resources. Through training, these employees were encouraged to use corporate resources to achieve an ergonomic t with their new chair as well as setting up and arranging their workstations components. Participants gained a high level of knowledge and awareness of where to go and who to contact concerning the use of corporate ergonomic resources and facility adjustments and changes. At the end of the study, the control group was trained and it is noted that the three groups did not differ signicantly from one another in their average level of knowledge pre- and post-intervention (p's40.05). The lack of signicant results on the environmental control and adjustability control questions was surprising. However, positive changes were observed for both trained groups for all four perceived control indices. There may have been an issue of statistical power due to the varying number of adjustable items in the workstation. In some instances, participants only needed to adjust one thing in their workstation or chair. Observational results indicate that the two trained groups exhibited a higher level of behavioral translation leading to less awkward postures and musculoskeletal loading. Trained participants were more likely to make appropriate behavioral changes to their workstation than the control group. With the participant's increased knowledge and skills of ofce ergonomics, workers were more likely to ergonomically adjust their workstation, chair setup and other ergonomic accessories, thereby reducing nonneutral postures and muscular effort, as was indicated by lower RULA grand scores and improved OEA scores. The marginal non-signicant ndings for the OEA for the chair with training group may be due to several issues. One is it may be due to the fact that the hand/wrist repetitiveness covariate is acting as an outcome as it showed improvement post-intervention. Second, it appears that the chair with training group started at higher OEA scores than the other two groups, thus minimizing the amount of potential change. However, the chair and

training group had positive changes in the workstation arrangement and reduction in hand/wrist activity postintervention. Moreover, this group appears to be applying the training and making appropriate changes, which may have possibly inuenced the movement patterns of the hand and wrist, thus reducing the repetitive motions. These results are consistent with those of Ketola et al. (2002) showing that trained groups in ofce ergonomics demonstrated less musculoskeletal discomfort than the reference group. Bohr (2000) found that those who received ofce ergonomics education reported less pain/discomfort and psychosocial work stress following the intervention than those who did not receive education, however it was unclear whether the differences in reported pain/discomfort or psychosocial work stress were related to better work area conguration or improved worker postures. The study results suggest that with the increased knowledge in ergonomics, positive changes in workstation conguration are associated with behavioral changes. However, this was only in the training-only intervention group, whereas the C+T group only showed signicant improvements in computing work postures. These changes were translated into improved working postures, thus potentially reducing musculoskeletal risks. Furthermore, as reported elsewhere, we have observed a reduction in musculoskeletal symptom growth over the workday and visual symptoms (Menendez et al., 2006) for the C+T group, and a reduction in average pain levels over the workday (Amick et al., 2003) for both C+T and T-only intervention groups. Given these changed computer working postures, there is the potential to reduce musculoskeletal loading which may lead to improved performance and positive return on investment (shown in our earlier work; DeRango et al., 2003). 4.1. Study limitations and strengths Limitations of the study are: the degree to which threats to internal and external validity can be addressed given the study eld design, the lack of randomization (however, a

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134 M. Robertson et al. / Applied Ergonomics 40 (2009) 124–135 Mattila, M. (Eds.), Proceedings of the 13th Triennial Congress of the International Ergonomics Association, vol. 4. Finnish Institute of Occupational Health, Helsinki, pp. 141–143. Bush, T., Hubbard, R., 1999. An evaluation of postural motions, chair motions, and contact in four ofce seats. In: Proceedings of the Human Factors and Ergonomics Society 43rd Annual Meeting. Houston, TX. Campbell, D.R., Stanley, J.C., 1966. Experimental and Quasi-experimental Designs for Research. Rand McNally, New York. Carayon, P., Smith, M.J., 2000. Work organization and ergonomics. Appl. Ergon. 31 (6), 649–662. Demure, B., Luippold, R., Bigelow, C., Ali, D., Mundt, K., Liese, B., 2000. Video display terminal workstation improvement program: I. Baseline associations between musculoskeletal discomfort and ergonomic features of workstations. J. Occup. Environ. Med. 42 (8), 783–791. DeRango, K., Amick, B.C., Robertson, M.M., Rooney, T., Bazanni, L., 2003. The productivity consequences of two ergonomic interventions. Institute for Work and Health Working Paper 286, Toronto, Canada. Faucett, J., Rempel, D., 1994. VDT-related musculoskeletal symptoms: interactions between work posture and psychosocial work factors. Am. J. Ind. Med. 26, 597–612. Gordon, S.E., 1994. Systematic Training Program Design: Maximizing Effectiveness and Minimizing Liability. Prentice-Hall, Englewood Cliffs, NJ. Green, R.A., Briggs, C.A., 1989. Effect of overuse injury and the importance of training on the use of adjustable workstations by keyboard operators. J. Occup. Med. 31 (6), 557–562. Hagberg, M., Silverstein, B.A., Wells, R., Smith, M.J., Hendrick, H.W., Carayon, P., Perusse, M., 1995. Work-Related Musculoskeletal Disorders (WMSDs): A Reference Book for Prevention. Taylor & Francis, London. Karsh, B., Moro, F.B.P., Smith, M.J., 2001. The efcacy of workplace ergonomic interventions to control musculoskeletal disorders: a critical examination of the peer-reviewed literature. Theor. Issues Ergon. Sci. 2 (1), 23–96. Ketola, R., Toivonen, R., Hakkanen, M., Luukkonen, R., Takala, E., Viikari-Juntura, E., Expert Group in Ergonomics, 2002. Effects of ergonomic intervention in work with video display units. Scand. J. Work Environ. Health 28 (1), 18–24. Kirkpatrick, D., 1979. Techniques for evaluating training programs. Train. Dev. J. 31 (11), 9–12. Knirk, F., Gustafson, K.L., 1986. Instructional Technology: A Systematic Approach to Education. Holt, Rinehart & Winston, New York, USA. Lewis, R.J., Fogleman, M., Deeb, J., Crandall, E., Agopsowicz, D., 2002. Effectiveness of a VDT ergonomics training program. Int. J. Ind. Ergon. 27 (2), 119–131. Lueder, R., Corlett, N., 1996. A proposed RULA for computer users. In: Proceedings of the Ergonomics Summer Workshop, UC Berkeley Center for Occupational & Environmental Health Continuing Education Program. Marcus, M., Gerr, F., 1996. Upper extremity musculoskeletal symptoms among female ofce workers: associations with video display terminal use and occupational psychosocial stressors. Am. J. Ind. Med. 29, 161–170. Menendez, C.C., Robertson, M.M., Amick, B.C., DeRango, K. Harrist, R., Rooney, T., Bazzani, L., 2006. Evaluating visual symptoms changes after two ofce ergonomics interventions. In: Proceedings of the Human Factors and Ergonomics Society 50th Annual meeting, Santa Monica, CA. McAtamney, L., Corlett, E.N., 1993. RULA: a survey method for the investigation of work-related upper limb disorders. Appl. Ergon. 24, 45–57. McGorry, R.W., Change, C.C., Teare, P., Dempsey, P.G., 2002. A exible hand-held ergonomics evaluation tool. Ergon. Des. 10, 117–121. McLaney, M.A., Hurrell, J.J., 1988. Control, stress, and job satisfaction in Canadian nurses. Work Stress 2, 217–224. MLwiN (Software), 2001. Version 1.10. Multilevel Models Project Institute of Education, London.

range of covariates was measured and the risk of contamination was reduced), and the limited postural information collected due to cost, time, and intrusiveness. Also, the pre-intervention ICC's for the observational measures were marginal. Strengths of this study are: its systematic process for training program development, ''presence of a control group, high participation rate, limited loss to follow-up'' the full participation of the managers and supervisors, including strong support of senior management, and its study design being longitudinal in nature with individual level measures. 5. Conclusion Overall, our study ndings suggest that due to the knowledge gained from ofce ergonomics training and an adjustable chair, workers were able to appropriately change and adjust their workstation and chair set-up more ergonomically and effectively. Further eld intervention research is needed to support these ndings and to replicate them with different ofce workplace designs and training programs. These ndings would contribute to a knowledge base on how to optimally design workplace interventions to help create injury-free environments for ofce workers. Acknowledgments The authors would like to acknowledge and thank the following Liberty Mutual colleagues who served as reviewers for this paper: Drs. William Horrey and Mary Lesch, as well as Steelcase, Inc. and Noe Palacios and Paul Allie who contributed to data collection. References
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