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ISSN : 1598-7248 (Print)
ISSN : 2234-6473 (Online)
Industrial Engineering & Management Systems Vol.20 No.2 pp.109-118
DOI : https://doi.org/10.7232/iems.2021.20.2.109

Effectiveness of Ergonomic Intervention in Work-related Postures and Musculoskeletal Disorders of Call Center Workers: A Case-control Study

Lito M. Amit*, Young-Woong Song
Department of Safety and Occupational Health Applied Sciences, Keene State College, Keene, NH 03435, USA
Department of Occupational Health, Daegu Catholic University, Republic of Korea
*Corresponding Author, E-mail: lito.amit@keene.edu
August 31, 2020 April 8, 2021

ABSTRACT


Improper posture, inadequate workstation, and prolonged computer use are established risk-factors of musculoskeletal disorders (MSDs). It has been found that following ergonomic intervention increases workers’ office ergonomics knowledge and awareness and can lead to a significant decrease in self-reported MSDs. The objectives of this study were to measure the level of self-reported MSDs of call center workers in the Philippines and determine the effectiveness of an ergonomic intervention on their posture and MSDs symptoms. We conducted a case-control study among 32 call center workers for four weeks. Ergonomic intervention on posture and workstation was provided to the experimental group. We utilized rapid upper limb assessment (RULA) and rapid entire body assessment (REBA) as primary outcome measures and body part discomfort (BPD) questionnaire as a secondary outcome measure. Wilcoxon signed-rank tests were performed within groups to determine significant differences in scores of RULA, REBA, and BPD (P ≤ 0.05). Significant improvement in the posture of the workers was observed after 4 weeks of following the ergonomic intervention manifested in their RULA and REBA scores. However, the workers’ MSDs symptoms were unable to significantly improve. This was attributed to the limited time of the intervention and inadequate workstation.



초록


    1. INTRODUCTION

    The reported relationship between computer-use and musculoskeletal disorders (MSDs) among office workers is well-established. For example, a study found that prolonged use of computers causes pain or discomfort on the head, neck, low back, upper back, wrists or hands, shoulders, ankles or feet, knees, hips, and elbows (Janwantanakul et al., 2008). The World Health Organization (WHO) identified various risk factors to MSDs such as repeated manipulations of objects, continuous sitting in a fixed posture disadvantageous to the musculature, static work with holding the hands overhead, deconditioning due to low muscular demand and long-lasting physical inactivity, monotonous repetitive manipulations, continuous keyboard, and mouse-use during data entry and lighting and temperature among others (Luttmann et al., 2003).

    Recently, there is a growing interest among investigators to alleviate conditions among office workers about prolonged use of computers. Research has now been shifted from investigating the prevalence to preventing MSDs through intervention programs. For instance, researchers found that a sit-stand desk was effective in reducing workplace sedentary behavior in an at-risk population of office workers (MacEwen et al., 2017). It was also shown that after following an ergonomic intervention, there was a significant increase in workers’ office ergonomics knowledge and awareness which led to the significant decrease of self-reported MSDs (Robertson and O’Neill, 2003). In a longitudinal study among Italian office workers, Pillastrini and his team (2010) provided ergonomic intervention in work posture and workstation to workers for 3 years. Their result showed a reduced point-prevalence of low back pain.

    In 2008, the Department of Labor and Employment (DOLE) in the Philippines through the Occupational Safety and Health Center (OSHC) issued a document that contained practical information for call center workers’ health and safety (DOLE-OSHC, 2008). Information includes managing health and safety hazards, computerrelated health disorders (e.g., visual fatigue and workrelated musculoskeletal disorders), health problems linked to telephone use, psychosocial stressors at work, prolonged night-work, health, and safety tips for computer use, etc. While it is readily available online, most (if not all) call center workers seem unaware of its existence, not to mention its practical use. In 2015, a walk-through survey in one of the capital’s call center companies was conducted by a group of Filipino researchers with the aim to describe and assess the occupational health and safety of call center workers in the country (Campo et al., 2015). They proposed a project called “CALL” which stands for Compliance with OSHC Standards for ALL. The result highlighted various forms of stress and ergonomic issues (e.g., sustained static position, repetitive movements, and shift work) as one of the physical hazards identified with rest periods as the only existing control measure available at hand.

    Like other office workers, Filipino call center employees often report MSDs pains such as in the neck, shoulder, wrists, and back areas (Amit et al., 2020). These issues were associated with poor workstation design such as computer monitors placed above eye level, work surfaces that were too high, or non-adjustable chairs. Consequently, the development of muscle and joint pains was attributable to long uninterrupted hours of work with computers, invariable and sedentary work, and low job satisfaction among the Filipino call center workers. This further supports the identified causes of MSDs mentioned above.

    As of this writing, there is an insufficient body of published literature documenting, measuring, and preventing MSDs in the Philippines. This gap poses a challenge to local researchers to determine the gravity of MSDs and introduce programs that would help promote awareness of the interventions necessary to foster prevention in this population. In this study, we hypothesized that after four weeks of ergonomic intervention, the postures of the workers in the experimental group will improve and body discomfort due to MSDs symptoms will decrease. The objectives of this study were to measure the level of self-reported MSDs complaints of call center workers in the Philippines and determine the effectiveness of an ergonomic intervention on their posture and MSDs symptoms.

    2. MATERIALS AND METHODS

    2.1 Design and Participants of the Study

    This study was conducted for four weeks between January and February 2019 in the Philippines. It utilized a case-control study design that involved 32 call center workers from Cebu and Manila who worked for the same company. Their participation in this study was voluntary. We used a non-probability convenience sampling method because the company is small and employed less than a hundred employees both in Cebu and Manila sites including those with administrative tasks. Thirty-six call center workers were first selected but only 32 respondents completed their participation following 4 dropouts (11%). Sixteen of the respondents were grouped as controlled and the other 16 were grouped as experimental (case).

    2.2 Procedures

    This study implemented a 4-week ergonomic intervention program to call center workers. During this period, we made multiple visits to the experimental sites in the cities of Cebu and Manila. An orientation was conducted for all participating call center workers during the first day. The participants were selected based on sound health and no history of serious illness or chronic form of MSDs. Their claim of having sound health was confirmed by the company’s human resource officer keeping their medical records. Then, the participants were given copies of the body part discomfort (BPD) questionnaire for the pre-intervention assessment of their MSDs. The first page contained a letter of consent and a section where they wrote their demographic profile and work-related information, such as age, sex, height and weight, smoking tendency, number and duration of daily breaks, work experience, and computer use per day. Afterward, they were grouped as either experimental or controlled by drawing lots. On the same day, photographs of each participant were taken for a pre-evaluation of their rapid upper limb assessment (RULA) and rapid entire body assessment (REBA) analyses.

    On the second day, we met the case-group participants. Each one was provided with a copy of an informational brochure containing all the necessary information as to the major problems related to video display terminal (VDT) use, ergonomic criteria for an adequate workstation, correct posture at VDT workstations, benefits of micro-breaks during work, recommended frequency and duration of micro-breaks, proposed exercises, and recommended lifestyle and physical activity. The contents were adapted from a European Council directive and were used in a previous study (Pillastrini et al., 2010). We discussed each section thoroughly with the case group.

    Subsequently, call center workers in the experimental group were instructed to return to their workstations where modifications of their workstations and corrections of postures were provided. It took at least 15 minutes to complete the modifications of each case-group participant’s workstation. During the last week of the study, which was the researchers’ third visit, another set of photographs was taken while call center workers from both groups were taking calls for a post-postural analysis. Also, we made three unannounced site visits in between the follow-up periods. These surprise visits were made to observe whether participants from the case group religiously followed or not the suggested work postures and alterations of the workstations when unaware of the researchers’ presence. In each visit, we spent at least an hour observing the variations of postures and actual mechanics of the workers whilst performing their tasks. These observations were noted for later analyses. The same set of procedures were followed in both study sites; Manila and Cebu.

    2.3 Intervention

    An informational brochure containing ergonomic intervention information on VDT workstation design and posture was introduced to the case group participants. This was adapted from a previous study (Pillastrini et al., 2010). The contents of the brochure included: major problems related to VDT use, ergonomic criteria for an adequate workstation, correct posture at VDT workstations, benefits of micro-breaks during work, recommended frequency and duration of micro-breaks, proposed exercises, and recommended lifestyle and physical activity. A few modifications and updates were made on the informational brochure containing the ergonomic standards about designs and postures for VDT workers to accommodate recent changes in (for instance) the type of computer monitor used in workplaces these days (from analog to flat screen). These pieces of information were used as a guiding principle to evaluate the posture of the participants while taking calls.

    We also adjusted and altered the existing workplace design on screen inclination, orientation, and height, backrest inclination, chair height, keyboard inclination and location, and mouse location. The adjustment for each participant differed depending on their anthropometric characteristics. There was a limited opportunity to maximize adjustment of the chairs’ height due to its limited height capacity and the inability to adjust the desk height and inclination due to its fixed installation. Also, we were unable to provide an adjustable chair, desk, lumbar support, footrest, and lamp for adequate lighting. The introduction of ergonomic intervention we made took half of the day for each company site taking 10-15 minutes for each call center worker. During the 4-week duration of the study, we paid three follow-up visits to each site to provide consultation and supervision to the study participants.

    2.4 Outcome measures

    2.4.1 RULA Score

    We used rapid upper limb assessment (RULA) and rapid entire body assessment (REBA) as primary outcome measures in the evaluation of work-related postures of each participating call center worker before and after the introduction of an ergonomic intervention. These two methods were used to evaluate the movements and postures effects of the said intervention. Rapid upper limb assessment was developed to evaluate the exposure of individual workers to ergonomic risk factors associated with upper extremity MSDs (McAtamney and Corlett, 2004). The RULA ergonomic assessment tool considers biomechanical and postural load requirements of job tasks/demands on the neck, trunk, and upper extremities. This worksheet evaluates required body posture, force, and repetition. Based on the evaluations, scores were entered for each body region in section A for the arm and wrist and section B for the neck and trunk. The same with REBA, after the data for each region, were collected and scored, they were then used to compile the risk factor variables, generating a single score that represents the level of MSD (Musculoskeletal Disorders) risk with 7 as the highest score and 1 as the lowest.

    2.4.2 REBA Score

    The rapid entire body assessment (REBA) method analyzes posture by measuring the articular angles and by observing the load or force and repetitiveness of movements and the frequency of position changes (McAttamney and Hignett, 2004). The postures of the neck, trunk, upper and lower arms, legs, and wrists are grouped into ranges. Each posture range, relative to the anatomical regions evaluated is scored progressively as the distance from the segment’s neutral position increases.

    The REBA score is calculated from three summary measurements. Score A is the sum of the posture scores for the trunk, neck, and legs and the load/force score, whereas score B is the sum of the posture scores for the upper arms, lower arms, wrists, and the coupling score for each hand. The REBA score is calculated by adding score A and score B to the Activity score, which is a measure based on the static postures, the frequency of small range movements, and the frequency of the substantial change in dynamic postures. Data for each body region were used to compile the risk factor variables, generating a single score that represents the level of MSDs risk at 11+ point category scale from 1 (negligible risk, no action required) to 11+ (very high risk, implement change). Both REBA and RULA analyses were conducted using each participants’ photographs taken before and after the ergonomic intervention program was introduced.

    2.4.3 BPD Questionnaire

    A secondary outcome measure was also utilized in this study by using a body part discomfort (BPD) questionnaire (Corlett and Bishop, 1976). This tool asked each call center worker to score any pain or discomfort in a specific body region in the last 7 days with severity ranging from 0 (no symptom) to 5 (intolerable) as previously used and described. In this method, body part discomfort frequency (BPDF) was determined as the number of body parts rated greater than zero, body part discomfort severity (BPDS) as the average of the nonzero ratings, and body part discomfort frequency severity (BPDFS) as the product of BPDF and BPDS. This outcome measure determined whether the individual and perceived pain or discomfort of each worker in the case group had improved after following the ergonomic intervention for four weeks, therefore validating the effectiveness of the said intervention material.

    2.5 Data Analyses

    Descriptive and continuous data were expressed as frequencies, arithmetic means, and standard deviations (mean ± SD). Mann-Whitney U tests and McNemar’s Exact Tests were performed to determine homogeneity of the control and case groups in terms of age, body mass index (BMI), smoking, and work experience. Also, Wilcoxon signed-rank tests were performed within groups for the pre-and post-intervention periods for RULA, REBA, BPDF (Body Part Discomfort Frequency), BPDS (Body Part Discomfort Severity), and BPDFS (Body Part Discomfort Frequency Severity) scores for both Cebu and Manila participants. All statistical analyses were performed with Statistical Package for Social Sciences (SPSS) version 23. The level of significance in this study was set at P ≤ 0.05.

    3. RESULTS

    A total of 32 call center workers participated in this study (Table 1). The average age of the workers from the case group was 28.8 years and 32.1 years for the control group. There were 4 male and 12 female workers for both groups. The average BMI of the case group was 23.6 kg/m2 and 24.1 kg/m2 for the control group. Five of the case group workers smoked and 11 were non-smokers. The average work experience of the case group was 39.2 months (about 3 and a half years) and 54.5 months (about 4 and a half years) for the control group. There were 8 workers from Manila and 8 workers from Cebu selected as part of the case group.

    Table 2 presents the summary of the RULA mean scores during the pre-and post-intervention periods. The RULA score of the experimental group for Manila decreased from 4.3 to 1.4 from the baseline. For Cebu, it decreased from 3.0 to 1.6 mean score. Scores A and B for the experimental group from Manila also declined from 3.9 to 1.5 and 4.1 to 1.5, respectively. Scores A and B for Cebu (case group) also showed a decrease from 3.3 to 1.6 and 4.1 to 1.1. The total RULA score of the workers in the experimental group was 3.6 during the pre-intervention and 1.8 after four weeks of intervention. Table 2 also shows observed significant differences between the RULA scores of the experimental group after following the intervention. No observable difference can be seen in the RULA scores of the control group during the pre-and post-intervention periods.

    The summary of the REBA scores for Manila, Cebu, and combined groups is presented below (Table 3). The REBA score of the experimental group from Manila had a decrease of 5.9 after the intervention period. Scores A and B also decreased from 6.8 to 2.3 and 4.6 to1.8, respectively. The experimental group from Cebu showed a similar trend with a REBA score of 9.1 to 2.9 after the intervention period. Scores A and B had decreased scores of 3.7 and 4.7, respectively. The total REBA score of all the case group workers decreased from 9.1 to 6.1. Changes in the REBA scores of the experimental group after the intervention period were significant with P values of less than 0.05. On the other hand, the REBA scores of participants in the control group were consistently high before and after the intervention periods.

    The changes in postures of case group workers are shown in Figure 1. Before the intervention, the study participants’ postures showed high risks for MSDs. For example, workers A and B showed slumped back and raised legs. Their feet were not fully resting on the floor. Also, their shoulders were raised and arms extended while typing. On the other hand, photographs C and D indicated corrected postures of the workers after ergonomic interventions were introduced. The feet of the workers were fully rested on the floor and trunk in an upright position with a slight backward tilting of 10 degrees and the low back touching the backrest. Also, workers showed relaxed shoulders and arms after the intervention.

    Table 4 shows the BPDF, BPDS, and BPDFS mean scores of the participants during the pre- and postintervention periods. The BPDF score of the case group (Manila) changed from 6.6 to 3.9 after the intervention. The BPDS and BPDFS scores decreased to 1.4 and 5.8 from 1.8 and 12.5 after the intervention. For the Cebu case group, the BPDF score decreased from 4.9 to 3.9, 1.5 to 1 and 7.3 to 4.1 for BPDS and BPDFS, respectively. The combined case group also had a decreased score after the intervention period. Additionally, there was no significant difference between the pre and post BPDF, BPDS, and BPDFS scores of the experimental groups except for the total BPDF (P 0.028) and BPDFS (P 0.017) difference scores of the case and control groups. The trend of the scores increased among the workers in the control group.

    4. DISCUSSION

    This study was conducted to measure the selfreported rate of MSDs among Filipino call center workers and determine the effectiveness of an ergonomic intervention in reducing their symptoms. Rapid upper limb assessment assesses strained postures while REBA evaluates the occurrences of repetitive movements of workers. According to the findings of the current study, both REBA and RULA scores of study participants under the case group (Cebu and Manila) significantly changed from baseline to the 4th week of assessment. A 9.1 REBA score of the case group from Cebu decreased to 2.9 after four weeks of following the ergonomic intervention program. Participants from Manila (case group) had a decreased REBA score of 5.9. These results support the effectiveness of the ergonomic interventions to workers’ postures. Also, the RULA scores of the case group participants (Cebu and Manila) significantly decreased after four weeks of following postural and workstation interventions. Research confirms a relationship between musculoskeletal load expressed as a function of parameters that describe posture, force and time sequences, and the incidence of MSDs (Van Niewenhuyse et al., 2006). Results from the present study are supported by this interaction. Within four weeks, the case group participants had decreased biomechanical loading following postural interventions. Biomechanical factors—posture and exerted force (so-called external force) are the most important documented factors related to a workstation.

    In this study, both company sites (Cebu and Manila) had similar poor workstation designs. At the onset of this study, we found that workstations were out of the recommended measurements. Modifications and adjustments were needed in all five areas of the workstation such as chair and desk height, backrest inclination, screen height, inclination and orientation, mouse location, and keyboard inclination and location. Changes in the workstation design such as mouse and keyboard location, screen orientation, and posture of the workers were made.

    However, there were some inadequacies concerning the corrections of workstation design such as chairs and desks height due to their limiting adjustment abilities. The association of non-adjustable workstation and MSDs symptoms and efficiency of human performance were reported in several studies (Tew et al., 2015;Shikdar and Al-Kindi, 2007;Eason, 1991;Lu and Aghazadeh, 1996). For instance, the adjustment of the height of the chair was limited to a maximum of 50 cm. This length is unfavorable and low to reach the desk for workers with a height lower than 160 cm without raising their shoulders and abducting both arms while typing. In this limited seat height, the feet of shorter workers were not entirely resting on the floor, forearms unable to comfortably rest on the desk resulting in unrelaxed shoulders. This awkward posture is a known risk factor for developing chronic shoulder pain in an accumulated time of exposure. Although the desk height is within the standard measurement of 80 cm, it is fixed and does not allow an 8-degree inclination recommendation.

    Also, computers’ central processing units (CPUs) were placed on either side of the monitor or side of the leg space creating a limited amount of legroom for workers to move freely and comfortably, thus, resulting in an awkward sitting position. The recommended desk surface area is 120 cm; both company sites had a uniform measure of 90 cm. These factors were seen to be important risk factors for the consistently high REBA and RULA scores of study participants in the control groups.

    In comparison to the REBA and RULA scores of the case groups to their BPD scores, the results disagreed. After four weeks of intervention, the collective scores of BPD frequency, severity, and frequency-severity results were unable to show significant improvement (P > 0.05). For instance, the BPDF score of case group workers from Cebu decreased by 1 point after four weeks with a P-value of 0.482 and a decline of 2.2 points for the Manila case group from the BPDF score of 6.6 (P = 0.344). For body parts mean scores (data not shown), lower arms score for the combined case groups (Manila and Cebu) (P = 0.047), Manila case group workers (P = 0.041) showed significant differences, while shoulders for the Cebu case group (P = 0.053). Interestingly, a few of the body regions (lower back and mid-back, (P = < 0.05) of the workers in the control group during the pre-and postintervention periods showed significant differences although this may be attributed purely to chance.

    While postures can be corrected at once after training and education were given to the workers, this may not necessarily provide an immediate effect to the internal pain caused by prolonged exposure to risk factors such as improper posture and poor ergonomic design in the workplace (Van Niewenhuyse et al., 2006). An 8-hour, 5 days a week exposure to risk factors for call center workers may result in musculoskeletal discomfort ranging from mild to severe.

    Personal ergonomic interventions were more often described as ongoing, an emphasis that sees reducing risks and injuries as part of continual improvement processes, and to work more safely and productively (Van Eerd et al., 2010). Since there is no one best way to implement an ergonomic intervention program, it is imperative to design one that caters to potential differences. To achieve this goal and maximize the potential and effectiveness of an ergonomic intervention program, suggestions are provided for a participatory approach. This includes the following: (a) create teams with appropriate members, (b) involve the right people in the participatory ergonomic process, (c) define participants’ responsibilities, (d) make decisions using group consultation, (d) provide ergonomic training, and (e) address key facilitators/barriers.

    In a way, the present study followed a form of participatory approach; however, a few items of the abovementioned suggestions critical to an effective intervention were not met due to time and resource constraints. For example, a consultation of participants before designing the intervention program could have been made considering participants’ input and clearly defining responsibilities. We believed that the abovementioned suggestions are vaguely relevant and that may have affected the perceived body discomfort of the participants and the optimum effectiveness of the ergonomic intervention. Further, the use of an ergonomic standard adapted from a previous study provides a substantial comparison of effectiveness between workers with a job of similar nature. As mentioned above, an ongoing, longitudinal ergonomic program proves to be effective in reducing pain as in the case of a 3-year cross-over trial. The partial ineffectiveness of the intervention in the current study as per workers’ perception of pain (BPD results) may have been affected by the short duration of the intervention.

    Another probable reason for this ineffectiveness with regards to the body pain discomfort frequency, severity, and frequency-severity was the inconsistencies of the standards and guidelines. For example, it was found that several types of ergonomics standards and guidelines are in existence worldwide, including national legislation, international and national standards, national guidelines issued by government agencies or voluntary standard organizations, and technology agreements between companies and trade unions (Woo et al., 2016). All these standards and guidelines disagree on proper sitting posture, viewing angle of the monitor, viewing distance of the monitor, seat and backrest requirements, etc. A few of the reasons given were the workers’ individual preference on sitting posture, anthropometric variables (e.g., height and weight), demographics (e.g., age and race). Thus, although the adopted ergonomic guidelines used in the current study were effective among Italian office workers, they may not necessarily be effective when used with office workers of different demographic backgrounds. Most ergonomic evaluations related to office furniture focusing how well it conforms to the dimensional criteria of a particular standard but conforming to the standards falling far short of meeting the broad range of postures. Also, Springer (2010) believes that it is better to consider a wide variety of activities in which people engage, not just one primary activity.

    5.1 Study Limitations

    The duration of the ergonomic intervention given to the workers was a crucial factor in the success of the study. Four weeks is short to create substantial changes in the self-reported symptoms and rate of MSDs among participants in the case group. Most studies of this nature were conducted following a longitudinal period of 6 months to 3 years. This may have influenced the effect of the ergonomic intervention on the occurrence of MSDs symptoms as shown in their BPD results.

    Next is the small number of study participants. Previous ergonomic intervention studies had a varying number of participants from less than ten to a thousand. Although we initially planned to involve a bigger number of participants, the strict policy of offshore call center companies in the Philippines to accommodate researchers (Campo et al., 2015) prevented the investigators from involving a larger number of study participants. It is therefore suggested that the same study with a larger sample be conducted in the future. Also, the unavailability of ergonomically designed equipment as part of the intervention could have been an essential aid in pain reduction.

    Finally, there was no tracking made by the researcher whether workers continuously followed the intervention following termination of observation. Therefore, it is recommended that if an adaptation of ergonomic interventions concerning proper postures and workplace design be made by call center companies, there should be authorized personnel functioning as a health and safety officer responsible for constantly facilitating, monitoring, and evaluating the adherence of workers to ergonomic intervention program for better and positive results.

    5. CONCLUSION

    This research aimed to measure MSDs symptoms and the effectiveness of an ergonomic intervention given to call center workers in the Philippines. Significant improvement in the posture of the workers in the case group was observed after 4 weeks of following the ergonomic intervention. This was manifested in the decreased RULA and REBA scores. However, a contradicting result was found on the perceived body discomfort of the workers. Their MSDs symptoms were unable to significantly improve. This result was attributed to the limited time of the intervention and an inadequate workstation (i.e., fixed working desk, the limited height of the chair, and poor lighting). It is suggested that further research be conducted by integrating these factors.

    Figure

    IEMS-20-2-109_F1.gif

    Call center workers’ postures before intervention (A and B); Workers with slumped back, feet not resting on the floor, with raised shoulders and extended arms. Call center workers’ postures after the intervention (C and D); Workers in upright sitting postures, back slightly resting backward at 10 degrees and feet fully resting on the floor. Workers in relaxed shoulders and an acceptable angle of arms while typing.

    Table

    Characteristics of study participants

    Rapid upper limb assessment (RULA) mean scores in pre and post intervention periods

    Rapid entire body assessment (REBA) mean scores in pre and post intervention periods

    BPDF, BPDS and BPDFS mean scores in pre and post intervention periods

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