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Loh PY, Choi J, Lin Y. Impact of task variation and microbreaks on muscle fatigue at seated and standing postures. Work 2023; 76:1039-1045. [PMID: 37182852 DOI: 10.3233/wor-220528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023] Open
Abstract
BACKGROUND Prolonged and sustained work posture among computer users is one of the main factors that contributes to musculoskeletal discomfort. Rest-break interventions such as task variation and microbreaks may help prevent muscle fatigue and work-related musculoskeletal disorder. OBJECTIVE We aimed to investigate the effects of task variation and microbreaks at seated and standing workstations on forearm muscle activity, namely extensor digitorum communis, extensor carpi ulnaris, flexor digitorum superficialis, and flexor carpi ulnaris; mouse operation force (vertical compression force); mouse operation parameters; and perceived body discomfort during mouse operation. METHODS Twelve healthy right-handed young adults were recruited (male: n = 7, 21.6±1.4 years; female: n = 5, 21.4±1.7 years). Participants performed three blocks of computer tasks (computer mouse operation and typing) in both seated and standing postures with each block lasting for 30 min. Surface electromyography (EMG) of the forearm muscles and operation force were monitored during computer mouse operation. Body discomfort rating was recorded at the end of each block. RESULTS With simulated task variation and microbreaks, work posture and work time showed no significant difference with EMG amplitude and mouse operation force. CONCLUSION Task variation and microbreaks could be of benefit to computer users by reducing muscle fatigue during long hours of computer work at both seated and standing workstations.
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Affiliation(s)
- Ping Yeap Loh
- Department of Life Design and Science, Faculty of Design, Kyushu University, Fukuoka, Japan
| | - Jeewon Choi
- Department of Industrial and Management Systems Engineering, Dong-A University, Busan, Korea
| | - Yu Lin
- Graduate School of Design, Kyushu University, Fukuoka, Japan
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Choi J, Lin Y, Loh PY. The Effects of Standing Working Posture on Operation Force and Upper Limb Muscle Activation When Using Different Pointing Devices. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:10217. [PMID: 36011848 PMCID: PMC9408334 DOI: 10.3390/ijerph191610217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 08/13/2022] [Accepted: 08/16/2022] [Indexed: 06/15/2023]
Abstract
This study investigated how sitting and standing working postures affected operation force, upper limb muscle activation, and task performance using different pointing devices. Fifteen male participants completed cursor aiming and dragging tasks using a conventional mouse, a vertical mouse, and a trackball at sitting and standing workstations. A custom-made force plate was used to measure operation forces applied to the pointing devices. Surface electromyography (EMG) was used to capture the activation of the biceps brachii, triceps brachii, deltoid, and trapezius. Task performance was measured by task success rates, and subjective ratings were obtained for the force required for operation, smoothness of operation, accuracy, and local fatigue in the upper limb. We quantified the following significant outcomes: (1) greater operation forces were found when standing; (2) standing reduced EMG amplitudes of the triceps and trapezius muscles for all tasks; (3) during the aiming task, the vertical mouse had greater operation forces; (4) during the dragging task, both the vertical mouse and trackball had greater operation forces; and (5) task success rates differed for pointing devices only when sitting. This study revealed the distinct biomechanical properties of standing working posture and suggested limited beneficial effects of alternative pointing devices in terms of task performance and subjective ratings.
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Affiliation(s)
- Jeewon Choi
- Department of Industrial and Management Systems Engineering, Dong-A University, 840, Hadan 2-dong, Saha-gu, Busan 604-714, Korea
| | - Yu Lin
- Graduate School of Design, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka 815-8540, Japan
| | - Ping Yeap Loh
- Department of Life Design and Science, Faculty of Design, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka 815-8540, Japan
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Muthuraj TS, Raja J, James JR, Raj JPM, Subramnian D, Varatharajan A. Standardized photometric assessment method: A novel approach for the analysis of dental ergonomic posture. J Indian Soc Periodontol 2020; 24:227-232. [PMID: 32773972 PMCID: PMC7307479 DOI: 10.4103/jisp.jisp_405_19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 02/18/2020] [Accepted: 02/26/2020] [Indexed: 12/04/2022] Open
Abstract
Background: Identification and documentation of the proper and improper dental ergonomic postures have gained its importance in the recent years due to the increased prevalence of work-related musculoskeletal disorders (WMSDs) among dentists and dental students who do not practice proper ergonomic procedure. Aim: The aim of the present study is to analysis ergonomic posture among dental students while performing supragingival scaling (SGS) procedure, using the standardized photometric assessment method (SPAM). Materials and Methods: A total number of 90 students from the third year (III year) to final year (IV year) and internship (Intern) (30 each) were included in the study. All the 90 students were asked to perform SGS procedure and were photographed and analyzed using the current technique. Eight dental ergonomic postures were analyzed in this study and grouped according to the classification system developed for scoring dental ergonomic postures by Garbin et al., in 2011. Analysis of variance test with Bonferroni correction was used to statistically analyze the collected data. Results: The mean index value for III year, IV year and Intern were 2.00, 2.03, and 2.13, respectively, which was not statistically significant (P = 0.709). Conclusions: Analysis of the dental students using the current method showed that most of them come under inadequate and regular category which puts them in a high risk for developing WMSDs. The SPAM to analyze the dental ergonomic posture was simple and effective and should be further explored in the future studies for its pros and cons.
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Affiliation(s)
- Thamil Selvan Muthuraj
- Department of Periodontics, CSI College of Dental Sciences and Research, Madurai, Tamil Nadu, India
| | - Jacob Raja
- Department of Periodontics and Implantology, Rajas Dental College and Hospital, Tirunelveli, Tamil Nadu, India
| | - Johnson Raja James
- Department of Periodontics and Implantology, Rajas Dental College and Hospital, Tirunelveli, Tamil Nadu, India
| | - Jeyaraj Prince Mohan Raj
- Department of Periodontics and Implantology, Rajas Dental College and Hospital, Tirunelveli, Tamil Nadu, India
| | - Divya Subramnian
- Department of Periodontics and Implantology, Rajas Dental College and Hospital, Tirunelveli, Tamil Nadu, India
| | - Abinaya Varatharajan
- Department of Public Health Dentistry, Karpaga Vinayaga Institute of Dental Sciences, Madhuranthagam, Tamil Nadu, India
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Huysmans MA, Eijckelhof BHW, Garza JLB, Coenen P, Blatter BM, Johnson PW, van Dieën JH, van der Beek AJ, Dennerlein JT. Predicting Forearm Physical Exposures During Computer Work Using Self-Reports, Software-Recorded Computer Usage Patterns, and Anthropometric and Workstation Measurements. Ann Work Expo Health 2018; 62:124-137. [PMID: 29186308 DOI: 10.1093/annweh/wxx092] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 10/31/2017] [Indexed: 11/14/2022] Open
Abstract
Objectives Alternative techniques to assess physical exposures, such as prediction models, could facilitate more efficient epidemiological assessments in future large cohort studies examining physical exposures in relation to work-related musculoskeletal symptoms. The aim of this study was to evaluate two types of models that predict arm-wrist-hand physical exposures (i.e. muscle activity, wrist postures and kinematics, and keyboard and mouse forces) during computer use, which only differed with respect to the candidate predicting variables; (i) a full set of predicting variables, including self-reported factors, software-recorded computer usage patterns, and worksite measurements of anthropometrics and workstation set-up (full models); and (ii) a practical set of predicting variables, only including the self-reported factors and software-recorded computer usage patterns, that are relatively easy to assess (practical models). Methods Prediction models were build using data from a field study among 117 office workers who were symptom-free at the time of measurement. Arm-wrist-hand physical exposures were measured for approximately two hours while workers performed their own computer work. Each worker's anthropometry and workstation set-up were measured by an experimenter, computer usage patterns were recorded using software and self-reported factors (including individual factors, job characteristics, computer work behaviours, psychosocial factors, workstation set-up characteristics, and leisure-time activities) were collected by an online questionnaire. We determined the predictive quality of the models in terms of R2 and root mean squared (RMS) values and exposure classification agreement to low-, medium-, and high-exposure categories (in the practical model only). Results The full models had R2 values that ranged from 0.16 to 0.80, whereas for the practical models values ranged from 0.05 to 0.43. Interquartile ranges were not that different for the two models, indicating that only for some physical exposures the full models performed better. Relative RMS errors ranged between 5% and 19% for the full models, and between 10% and 19% for the practical model. When the predicted physical exposures were classified into low, medium, and high, classification agreement ranged from 26% to 71%. Conclusion The full prediction models, based on self-reported factors, software-recorded computer usage patterns, and additional measurements of anthropometrics and workstation set-up, show a better predictive quality as compared to the practical models based on self-reported factors and recorded computer usage patterns only. However, predictive quality varied largely across different arm-wrist-hand exposure parameters. Future exploration of the relation between predicted physical exposure and symptoms is therefore only recommended for physical exposures that can be reasonably well predicted.
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Affiliation(s)
- Maaike A Huysmans
- Department of Public and Occupational Health and Amsterdam Public Health research institute, VU University Medical Center, The Netherlands.,Body@Work Research Center on Physical Activity, Work and Health, TNO-VU/VUmc, The Netherlands
| | - Belinda H W Eijckelhof
- Department of Public and Occupational Health and Amsterdam Public Health research institute, VU University Medical Center, The Netherlands.,Body@Work Research Center on Physical Activity, Work and Health, TNO-VU/VUmc, The Netherlands
| | | | - Pieter Coenen
- Department of Public and Occupational Health and Amsterdam Public Health research institute, VU University Medical Center, The Netherlands.,School of Physiotherapy and Exercise Science, Curtin University, Australia
| | - Birgitte M Blatter
- Body@Work Research Center on Physical Activity, Work and Health, TNO-VU/VUmc, The Netherlands.,Netherlands Organisation for Applied Scientific Research, TNO, The Netherlands
| | - Peter W Johnson
- Department of Environmental and Occupational Health Sciences, University of Washington, USA
| | - Jaap H van Dieën
- Body@Work Research Center on Physical Activity, Work and Health, TNO-VU/VUmc, The Netherlands.,Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, 'Vrije Universiteit' Amsterdam, Amsterdam Movement Sciences, The Netherlands
| | - Allard J van der Beek
- Department of Public and Occupational Health and Amsterdam Public Health research institute, VU University Medical Center, The Netherlands.,Body@Work Research Center on Physical Activity, Work and Health, TNO-VU/VUmc, The Netherlands
| | - Jack T Dennerlein
- Department of Public and Occupational Health and Amsterdam Public Health research institute, VU University Medical Center, The Netherlands.,Department of Environmental Health, Harvard T. H. Chan School of Public Health, USA.,Department of Physical Therapy, Movement, and Rehabilitation Sciences, Bouvé College of Health Sciences, Northeastern University, USA
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Kamil NSM, Dawal SZM. Effect of postural angle on back muscle activities in aging female workers performing computer tasks. J Phys Ther Sci 2015; 27:1967-70. [PMID: 26180359 PMCID: PMC4500022 DOI: 10.1589/jpts.27.1967] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 03/14/2015] [Indexed: 11/29/2022] Open
Abstract
[Purpose] This study investigated the effects of postural angle on back muscle activity
during a computer task in aging women. [Subjects] Seventeen women ≥50 years old
participated. [Methods] The participants were instructed to perform computer-related tasks
for 20 minutes on a workstation that simulated typical office working conditions. Back
posture was measured from the measured trunk and pelvic angles. Electromyography
activities were recorded simultaneously from the cervical erector spinae, longissimus, and
multifidus muscles. [Results] The lowest mean percentages of maximum voluntary contraction
for the cervical erector spinae and longissimus muscles were obtained when the upper trunk
and pelvic angles were between 0° to −5° from the sagittal plane. The back muscle
activities increased as the upper trunk and pelvic angles exceeded 0°. Statistical
analysis showed significant correlations between upper trunk angle and cervical erector
spinae and longissimus muscle activities. Similarly, pelvic angle was significantly
correlated with cervical erector spinae and multifidus muscle activities. [Conclusion] A
neutral back posture minimizes muscle activities in aging women performing computer
tasks.
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Affiliation(s)
| | - Siti Zawiah Md Dawal
- Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, Malaysia
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6
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Bruno Garza JL, Eijckelhof BHW, Huysmans MA, Johnson PW, van Dieen JH, Catalano PJ, Katz JN, van der Beek AJ, Dennerlein JT. Prediction of trapezius muscle activity and shoulder, head, neck, and torso postures during computer use: results of a field study. BMC Musculoskelet Disord 2014; 15:292. [PMID: 25186007 PMCID: PMC4161866 DOI: 10.1186/1471-2474-15-292] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Accepted: 08/27/2014] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Due to difficulties in performing direct measurements as an exposure assessment technique, evidence supporting an association between physical exposures such as neck and shoulder muscle activities and postures and musculoskeletal disorders during computer use is limited. Alternative exposure assessment techniques are needed. METHODS We predicted the median and range of amplitude (90th-10th percentiles) of trapezius muscle activity and the median and range of motion (90th-10th percentiles) of shoulder, head, neck, and torso postures based on two sets of parameters: the distribution of keyboard/mouse/idle activities only ("task-based" predictions), and a comprehensive set of task, questionnaire, workstation, and anthropometric parameters ("expanded model" predictions). We compared the task-based and expanded model predictions based on R2 values, root mean squared (RMS) errors, and relative RMS errors calculated compared to direct measurements. RESULTS The expanded model predictions of the median and range of amplitude of trapezius muscle activity had consistently better R2 values (range 0.40-0.55 compared to 0.00-0.06), RMS errors (range 2-3%MVC compared to 3-4%MVC), and relative RMS errors (range 10-14%MVC compared to 16-19%MVC) than the task-based predictions. The expanded model predictions of the median and range of amplitude of postures also had consistently better R2 values (range 0.22-0.58 compared to 0.00-0.35), RMS errors (range 2-14 degrees compared to 3-22 degrees), and relative RMS errors (range 9-21 degrees compared to 13-42 degrees) than the task-based predictions. CONCLUSIONS The variation in physical exposures across users performing the same task is large, especially in comparison to the variation across tasks. Thus, expanded model predictions of physical exposures during computer use should be used rather than task-based predictions to improve exposure assessment for future epidemiological studies. Clinically, this finding also indicates that computer users will have differences in their physical exposures even when performing the same tasks.
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Affiliation(s)
- Jennifer L Bruno Garza
- />Department of Environmental Health, Harvard University, Boston, USA
- />Division of Occupational and Environmental Medicine, UConn Health, Farmington, USA
| | - Belinda HW Eijckelhof
- />Department of Public and Occupational Health VU University Medical Center, Amsterdam, The Netherlands
- />EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands
- />Body@Work Research Center on Physical Activity, Work and Health, TNO-VU/VUmc, Amsterdam, The Netherlands
| | - Maaike A Huysmans
- />Department of Public and Occupational Health VU University Medical Center, Amsterdam, The Netherlands
- />EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands
- />Body@Work Research Center on Physical Activity, Work and Health, TNO-VU/VUmc, Amsterdam, The Netherlands
| | - Peter W Johnson
- />Department of Environmental Health, University of Washington Seattle, Seattle, USA
| | - Jaap H van Dieen
- />Faculty of Human Movement Sciences, VU University, Amsterdam, The Netherlands
| | - Paul J Catalano
- />Department of Biostatistics, Harvard School of Public Health Boston, Boston, USA
- />Dana Farber Cancer Institute Boston, Boston, USA
| | - Jeffrey N Katz
- />Department of Environmental Health, Harvard University, Boston, USA
- />Department of Epidemiology, Harvard School of Public Health, Boston, USA
- />Division of Rheumatology, Immunology and Allergy, Brigham and Women’s Hospital, Boston, USA
- />Department of Orthopaedic Surgery, Brigham and Women’s Hospital, Boston, USA
| | - Allard J van der Beek
- />Department of Public and Occupational Health VU University Medical Center, Amsterdam, The Netherlands
- />EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands
- />Body@Work Research Center on Physical Activity, Work and Health, TNO-VU/VUmc, Amsterdam, The Netherlands
| | - Jack T Dennerlein
- />Department of Environmental Health, Harvard University, Boston, USA
- />EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands
- />Department of Physical Therapy, Bouvé College of Health Sciences, Northeastern University, Boston, USA
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7
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Bruno Garza JL, Eijckelhof BH, Huysmans MA, Catalano PJ, Katz JN, Johnson PW, van Dieen JH, van der Beek AJ, Dennerlein JT. The effect of over-commitment and reward on trapezius muscle activity and shoulder, head, neck, and torso postures during computer use in the field. Am J Ind Med 2013; 56:1190-200. [PMID: 23818000 PMCID: PMC4522287 DOI: 10.1002/ajim.22192] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/07/2013] [Indexed: 11/09/2022]
Abstract
BACKGROUND Because of reported associations of psychosocial factors and computer related musculoskeletal symptoms, we investigated the effects of a workplace psychosocial factor, reward, in the presence of over-commitment, on trapezius muscle activity and shoulder, head, neck, and torso postures during computer use. METHODS We measured 120 office workers across four groups (lowest/highest reward/over-commitment), performing their own computer work at their own workstations over a 2-hr period. RESULTS Median trapezius muscle activity (P = 0.04) and median neck flexion (P = 0.03) were largest for participants reporting simultaneously low reward and high over-commitment. No differences were observed for other muscle activities or postures. CONCLUSIONS These data suggest that the interaction of reward and over-commitment can affect upper extremity muscle activity and postures during computer use in the real work environment. This finding aligns with the hypothesized biomechanical pathway connecting workplace psychosocial factors and musculoskeletal symptoms of the neck and shoulder.
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Affiliation(s)
| | - Belinda H.W. Eijckelhof
- Department of Public and Occupational Health, VU University Medical Center, Amsterdam, The Netherlands
- EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands
- Body@Work Research Center on Physical Activity, Work and Health, TNO-VU/VUmc, Amsterdam, The Netherlands
| | - Maaike A. Huysmans
- Department of Public and Occupational Health, VU University Medical Center, Amsterdam, The Netherlands
- EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands
- Body@Work Research Center on Physical Activity, Work and Health, TNO-VU/VUmc, Amsterdam, The Netherlands
| | - Paul J. Catalano
- Department of Biostatistics, Harvard School of Public Health, Boston, U.S.A
- Dana Farber Cancer Institute, Boston, U.S.A
| | - Jeffrey N. Katz
- Department of Environmental Health, Harvard University, Boston, U.S.A
- Department of Epidemiology, Harvard School of Public Health, Boston, U.S.A
- Division of Rheumatology, Immunology and Allergy, Brigham and Women’s Hospital, Boston, U.S.A
- Department of Orthopaedic Surgery, Brigham and Women’s Hospital, Boston, U.S.A
| | - Peter W. Johnson
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, U.S.A
| | - Jaap H. van Dieen
- EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands
- Research institute MOVE, Faculty of Human Movement Sciences, VU University Amsterdam, Amsterdam, the Netherlands
| | - Allard J. van der Beek
- Department of Public and Occupational Health, VU University Medical Center, Amsterdam, The Netherlands
- EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands
- Body@Work Research Center on Physical Activity, Work and Health, TNO-VU/VUmc, Amsterdam, The Netherlands
| | - Jack T. Dennerlein
- Department of Environmental Health, Harvard University, Boston, U.S.A
- EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands
- Department of Physical Therapy, Northeastern University, Boston, U.S.A
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Asundi K, Johnson PW, Dennerlein JT. Variance in direct exposure measures of typing force and wrist kinematics across hours and days among office computer workers. ERGONOMICS 2012; 55:874-884. [PMID: 22676481 DOI: 10.1080/00140139.2012.681807] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
UNLABELLED To determine the number of direct measurements needed to obtain a representative estimate of typing force and wrist kinematics, continuous measures of keyboard reaction force and wrist joint angle were collected at the workstation of 22 office workers while they completed their own work over three days, six hours per day. Typing force and wrist kinematics during keyboard, mouse and idle activities were calculated for each hour of measurement along with variance in measurements between subjects and between day and hour within subjects. Variance in measurements between subjects was significantly greater than variance in measurements between days and hours within subjects. Therefore, we concluded a single, one-hour period of continuous measures is sufficient to identify differences in typing force and wrist kinematics between subjects. Within subjects, day and hour of measurement had a significant effect on some measures and thus should be accounted for when comparing measures within a subject. PRACTITIONER SUMMARY The dose response relationship between exposure to computer related biomechanical risk factors and musculoskeletal disorders is poorly understood due to the difficulty and cost of direct measures. This study demonstrates a single hour of direct continuous measures is sufficient to identify differences in wrist kinematics and typing force between individuals.
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Affiliation(s)
- Krishna Asundi
- Department of Environmental Health, Harvard School of Public Health, Boston, MA, USA
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9
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Bruno Garza JL, Eijckelhof BHW, Johnson PW, Raina SM, Rynell PW, Huysmans MA, van Dieën JH, van der Beek AJ, Blatter BM, Dennerlein JT. Observed differences in upper extremity forces, muscle efforts, postures, velocities and accelerations across computer activities in a field study of office workers. ERGONOMICS 2012; 55:670-681. [PMID: 22455518 DOI: 10.1080/00140139.2012.657692] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
This study, a part of the PRedicting Occupational biomechanics in OFfice workers (PROOF) study, investigated whether there are differences in field-measured forces, muscle efforts, postures, velocities and accelerations across computer activities. These parameters were measured continuously for 120 office workers performing their own work for two hours each. There were differences in nearly all forces, muscle efforts, postures, velocities and accelerations across keyboard, mouse and idle activities. Keyboard activities showed a 50% increase in the median right trapezius muscle effort when compared to mouse activities. Median shoulder rotation changed from 25 degrees internal rotation during keyboard use to 15 degrees external rotation during mouse use. Only keyboard use was associated with median ulnar deviations greater than 5 degrees. Idle activities led to the greatest variability observed in all muscle efforts and postures measured. In future studies, measurements of computer activities could be used to provide information on the physical exposures experienced during computer use. Practitioner Summary: Computer users may develop musculoskeletal disorders due to their force, muscle effort, posture and wrist velocity and acceleration exposures during computer use. We report that many physical exposures are different across computer activities. This information may be used to estimate physical exposures based on patterns of computer activities over time.
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Affiliation(s)
- J L Bruno Garza
- Department of Environmental Health, Harvard University, Boston, MA, USA
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Straker L, Maslen B, Burgess-Limerick R, Johnson P, Dennerlein J. Evidence-based guidelines for the wise use of computers by children: physical development guidelines. ERGONOMICS 2010; 53:458-477. [PMID: 20309743 DOI: 10.1080/00140130903556344] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Computer use by children is common and there is concern over the potential impact of this exposure on child physical development. Recently principles for child-specific evidence-based guidelines for wise use of computers have been published and these included one concerning the facilitation of appropriate physical development. This paper reviews the evidence and presents detailed guidelines for this principle. The guidelines include encouraging a mix of sedentary and whole body movement tasks, encouraging reasonable postures during computing tasks through workstation, chair, desk, display and input device selection and adjustment and special issues regarding notebook computer use and carriage, computing skills and responding to discomfort. The evidence limitations highlight opportunities for future research. The guidelines themselves can inform parents and teachers, equipment designers and suppliers and form the basis of content for teaching children the wise use of computers. STATEMENT OF RELEVANCE: Many children use computers and computer-use habits formed in childhood may track into adulthood. Therefore child-computer interaction needs to be carefully managed. These guidelines inform those responsible for children to assist in the wise use of computers.
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Affiliation(s)
- L Straker
- School of Physiotherapy, Curtin University of Technology, Perth, WA, Australia.
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11
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Won EJ, Johnson PW, Punnett L, Dennerlein JT. Upper extremity biomechanics in computer tasks differ by gender. J Electromyogr Kinesiol 2009; 19:428-36. [DOI: 10.1016/j.jelekin.2007.11.012] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2007] [Revised: 11/20/2007] [Accepted: 11/20/2007] [Indexed: 11/28/2022] Open
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Thomsen JF, Gerr F, Atroshi I. Carpal tunnel syndrome and the use of computer mouse and keyboard: a systematic review. BMC Musculoskelet Disord 2008; 9:134. [PMID: 18838001 PMCID: PMC2569035 DOI: 10.1186/1471-2474-9-134] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2007] [Accepted: 10/06/2008] [Indexed: 12/05/2022] Open
Abstract
Background This review examines evidence for an association between computer work and carpal tunnel syndrome (CTS). Methods A systematic review of studies of computer work and CTS was performed. Supplementary, longitudinal studies of low force, repetitive work and CTS, and studies of possible pathophysiological mechanisms were evaluated. Results Eight epidemiological studies of the association between computer work and CTS were identified. All eight studies had one or more limitation including imprecise exposure and outcome assessment, low statistical power or potentially serious biases. In three of the studies an exposure-response association was observed but because of possible misclassification no firm conclusions could be drawn. Three of the studies found risks below 1. Also longitudinal studies of repetitive low-force non-computer work (n = 3) were reviewed but these studies did not add evidence to an association. Measurements of carpal tunnel pressure (CTP) under conditions typically observed among computer users showed pressure values below levels considered harmful. However, during actual mouse use one study showed an increase of CTP to potentially harmful levels. The long term effects of prolonged or repeatedly increased pressures at these levels are not known, however. Conclusion There is insufficient epidemiological evidence that computer work causes CTS.
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Affiliation(s)
- Jane F Thomsen
- Department of Occupational Medicine, Copenhagen University Hospital in Glostrup, Nordre Ringvej, DK-2600 Glostrup, Denmark.
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13
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Mochizuki G, Sibley KM, Esposito JG, Camilleri JM, McIlroy WE. Cortical responses associated with the preparation and reaction to full-body perturbations to upright stability. Clin Neurophysiol 2008; 119:1626-37. [PMID: 18479966 DOI: 10.1016/j.clinph.2008.03.020] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2007] [Revised: 03/10/2008] [Accepted: 03/20/2008] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To examine the cortical activity associated with 'central set' preparations for induced whole-body instability. METHODS Self-initiated and temporally unpredictable perturbations to standing balance were caused by the release of a load coupled to a cable affixed to a harness while participants stood on a force plate. Electroencephalographic and electromyographic signals were recorded. RESULTS Peak activity was located at the Cz electrode. The predictable condition elicited a DC shift 950 ms prior to perturbation onset and was 18.0+/-10.5 micro V in magnitude. Pre-perturbation activity was not associated with the motor act of perturbation initiation and was dissociable from cortical activity related to anticipatory postural muscle activation. Following perturbation onset, N1 potentials were observed with a peak amplitude of 17.6+/-7.2 micro V and peak latency of 140.1+/-25.9 ms. In unpredictable trials, pre-perturbation activity was absent. The peak amplitude (32.0+/-14.8 micro V) and latency (156.5+/-11.8 ms) of the post-perturbation N1 potential were significantly larger (p=0.002) and later (p<0.001) than for predictable trials. CONCLUSIONS Self-initiated postural instability evokes cortical activity prior to and following perturbation onset. Pre-perturbation cortical activity is associated with changing central set to modulate appropriate perturbation-evoked balance responses. SIGNIFICANCE These findings establish a link between reactive balance control and cortical activity that precedes and follows perturbations to stability.
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Affiliation(s)
- G Mochizuki
- Toronto Rehabilitation Institute, University Centre, Toronto, Canada.
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Lee DL, McLoone H, Dennerlein JT. Observed finger behaviour during computer mouse use. APPLIED ERGONOMICS 2008; 39:107-13. [PMID: 17400173 DOI: 10.1016/j.apergo.2006.12.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2005] [Revised: 05/22/2006] [Accepted: 12/29/2006] [Indexed: 05/14/2023]
Abstract
Two-button computer mouse users may exhibit sustained, static finger lifting behaviours to prevent inadvertent activations by avoiding finger pressure on the buttons, which leads to prolonged, static finger extensor muscle loading. One hundred graduate students were observed during normal computer work in a university computer facility to qualify and quantify the prevalence of lifted finger behaviours and extended finger postures, as well as wrist/forearm and grip behaviour, during specific mouse activities. The highest prevalences observed were 48% of the students lifted their middle finger during mouse drag activities, and 23% extended their middle finger while moving the mouse. In addition, 98% of the students rested their wrist and forearm (77%) or wrist only (21%) on the workstation surface, and 97% had an extended wrist posture (15 degrees -30 degrees ) when using the mouse. Potential applications of these findings include future computer input device designs to reduce finger lifting behaviour and exposures to risk factors of hand/forearm musculoskeletal pain.
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Affiliation(s)
- David L Lee
- Department of Environmental Health, Harvard School of Public Health, Boston, MA 02115, USA
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Muscle fatigue in relation to forearm pain and tenderness among professional computer users. J Occup Med Toxicol 2007; 2:17. [PMID: 18067676 PMCID: PMC2245952 DOI: 10.1186/1745-6673-2-17] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2007] [Accepted: 12/08/2007] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND To examine the hypothesis that forearm pain with palpation tenderness in computer users is associated with increased extensor muscle fatigue. METHODS Eighteen persons with pain and moderate to severe palpation tenderness in the extensor muscle group of the right forearm and twenty gender and age matched referents without such complaints were enrolled from the Danish NUDATA study of neck and upper extremity disorders among technical assistants and machine technicians. Fatigue of the right forearm extensor muscles was assessed by muscle twitch forces in response to low frequency (2 Hz) percutaneous electrical stimulation. Twitch forces were measured before, immediately after and 15 minutes into recovery of an extensor isometric wrist extension for ten minutes at 15 % Maximal Voluntary Contraction (MVC). RESULTS The average MVC wrist extension force and baseline stimulated twitch forces were equal in the case and the referent group. After the fatiguing contraction, a decrease in muscle average twitch force was seen in both groups, but the decrease was largest in the referent group: 27% (95% CI 17-37) versus 9% (95% CI -2 to 20). This difference in twitch force response was not explained by differences in the MVC or body mass index. CONCLUSION Computer users with forearm pain and moderate to severe palpation tenderness had diminished forearm extensor muscle fatigue response. Additional studies are necessary to determine whether this result reflects an adaptive response to exposure without any pathophysiological significance, or represents a part of a causal pathway leading to pain.
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Griffiths KL, Mackey MG, Adamson BJ. The impact of a computerized work environment on professional occupational groups and behavioural and physiological risk factors for musculoskeletal symptoms: a literature review. JOURNAL OF OCCUPATIONAL REHABILITATION 2007; 17:743-765. [PMID: 17987369 DOI: 10.1007/s10926-007-9108-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
INTRODUCTION Computers have become an essential tool for many office based professional occupations, but their use is also accompanied by change to work demands and psychosocial work environment. Whilst considerable research exists relating to the potential health risks associated with computer work amongst semi-skilled occupations, there is a paucity of knowledge regarding the impact of an increasingly computerized workplace on the physical and psychological wellbeing of professional occupations. METHODS A literature search was conducted using OVID Medline, PsycINFO and Cinahl databases. Papers published between 1980 and 2007 were selected for review. These included epidemiological and experimental studies that explored the relationships among occupational demands and stressors, work behaviours and musculoskeletal health in workers operating in a computerized work environment. RESULTS In response to workload, deadline and performance monitoring pressures, many professional workers are often encouraged to perform long hours of computer work with high mental demands; work at a hectic workpace resulting in heightened muscle tension and forces, and with inadequate work breaks. These factors were identified in this review as risk factors for work related musculoskeletal symptoms. CONCLUSION As new technology continues to computerise the way professionals do their work, it is important for organizations to identify and measure the risks to health and wellbeing associated with these changes. Further research with professional groups is needed to support effective risk management decisions.
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Dennerlein JT, Johnson PW. Changes in upper extremity biomechanics across different mouse positions in a computer workstation. ERGONOMICS 2006; 49:1456-69. [PMID: 17028089 DOI: 10.1080/00140130600811620] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
In order to determine differences in biomechanical risk factors across different mouse positions within computer workstations a repeated measures laboratory study was completed with 30 adults (15 females 15 males). The subjects performed mouse-intensive tasks during two experiments. One experiment examined three mouse positions: a standard mouse (SM) position with the mouse directly to the right of the keyboard; a central mouse (CM) position with the mouse between the keyboard and the body, positioned in the body's mid-sagittal plane; a high mouse (HM) position, which simulated using a keyboard drawer with the mouse on the primary work surface. The second experiment compared two mouse positions: the SM position and a more central position using a keyboard without a number keypad (NM). Electrogoniometers and inclinometers measured wrist and upper arm postures and surface electromyography measured muscle activity of four forearm muscles and three shoulder muscles. The CM mouse position was found to produce the most neutral upper extremity posture across all measures. The HM position produced the least neutral posture and resulted in the highest level of muscle activity. Compared to the SM position, the NM position reduced wrist extension slightly and promoted a more neutral shoulder posture. Little difference in muscle activity was observed between the SM and NM positions. In conclusion, of these alternative mouse positions, the HM position was the least desirable, whereas the CM position reduced overall awkward postures associated with mouse-intensive computer tasks.
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Affiliation(s)
- Jack T Dennerlein
- Department of Environmental Health, Harvard School of Public Health, Boston, MA, USA.
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18
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Delisle A, Larivière C, Plamondon A, Imbeau D. Comparison of three computer office workstations offering forearm support: impact on upper limb posture and muscle activation. ERGONOMICS 2006; 49:139-60. [PMID: 16484142 DOI: 10.1080/10610270500450739] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The aims of the study were: 1) to determine whether resting the forearms on the work surface, as compared to chair armrests, reduces muscular activation; 2) to compare the sensitivity of different electromyographic (EMG) summary parameters. Eighteen healthy subjects performed computer work (with keyboard and mouse alternately) for 20 min while resting their forearms on a work surface adjustable in height (Workstation A), on the chair's armrests with an adjustable workstation (Workstation B) or on their chair's armrests with a non-adjustable workstation (Workstation C). The EMG amplitude of the trapezius and deltoid muscles was little influenced by the workstations, whereas their EMG variability increased with Workstation A, which was interpreted as a positive effect. However, the EMG amplitude of the mouse-side extensor digitorum muscle was higher with Workstation A. Alternating between resting the forearms on the work surface and on the chairs' armrests could solicit different muscles during computer work, and could be considered as a strategy for preventing musculoskeletal disorders. The new exposure variation analysis summary parameters used were sensitive to small workstation changes, thus supporting their use in future studies.
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Affiliation(s)
- Alain Delisle
- Robert-Sauvé Occupational Health and Safety Research Institute (IRSST) Canada, Montreal, Quebec H3A 3C2, Canada.
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19
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Dennerlein JT, Johnson PW. Different computer tasks affect the exposure of the upper extremity to biomechanical risk factors. ERGONOMICS 2006; 49:45-61. [PMID: 16393803 DOI: 10.1080/00140130500321845] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
In order to determine differences in biomechanical risk factors across computer tasks, a repeated measures laboratory experiment was completed with 30 touch-typing adults (15 females and 15 males). The participants completed five different computer tasks: typing text, completing an html-based form with text fields, editing text within a document, sorting and resizing objects in a graphics task and browsing and navigating a series of intranet web pages. Electrogoniometers and inclinometers measured wrist and upper arm postures, surface electromyography measured muscle activity of four forearm muscles and three shoulder muscles and a force platform under the keyboard and force-sensing computer mouse measured applied forces. Keyboard-intensive tasks were associated with less neutral wrist postures, larger wrist velocities and accelerations and larger dynamic forearm muscle activity. Mouse-intensive tasks (graphics and intranet web page browsing) were associated with less neutral shoulder postures and less variability in forearm muscle activity. Tasks containing a mixture of mouse and keyboard use (form completion and text editing) were associated with higher shoulder muscle activity, larger range of motion and larger velocities and accelerations of the upper arm. Comparing different types of computer work demonstrates that mouse use is prevalent in most computer tasks and is associated with more constrained and non-neutral postures of the wrist and shoulder compared to keyboarding.
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Affiliation(s)
- Jack T Dennerlein
- Department of Environmental Health, Harvard School of Public Health, Boston, MA, USA.
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van Doorn RRA, Unema PJA, Hendriks EJ. The locus of adaptation to altered gain in aimed movements. Hum Mov Sci 2005; 24:31-53. [PMID: 15896863 DOI: 10.1016/j.humov.2005.03.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2004] [Revised: 12/15/2004] [Accepted: 03/16/2005] [Indexed: 11/26/2022]
Abstract
Altered gain settings cause a mismatch between the actual movement amplitude across the surface and the distance covered on a real time visual display. The present study pursued three objectives of how adaptation to altered gain affects aimed motor behavior. First, we replicated findings of an earlier study reporting a negative linear relation between gain and both target acquisition time and end-point variability. This means that our data do not agree with the classic U-shaped relation between gain and acquisition time. Second, our results proved to be robust when we manipulated movement difficulty by varying target distance. And third, dividing a movement into four successive sections on the basis of key kinematic events revealed the locus of the adaptation to altered gain within movement execution. Time differences between gain conditions proved to start at a very early part of the movement, but appeared to be absent in the final movement section. In contrast, differences between gain conditions regarding the use of online feedback were also present in the last part of the movement during which the final target approach takes place.
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Affiliation(s)
- Robert R A van Doorn
- Department of Experimental Psychology, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands.
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Thorn S, Forsman M, Hallbeck S. A comparison of muscular activity during single and double mouse clicks. Eur J Appl Physiol 2005; 94:158-67. [PMID: 15714288 DOI: 10.1007/s00421-004-1312-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2004] [Accepted: 12/10/2004] [Indexed: 10/25/2022]
Abstract
Work-related musculoskeletal disorders (WMSDs) in the neck/shoulder region and the upper extremities are a common problem among computer workers. Occurrences of motor unit (MU) double discharges with very short inter-firing intervals (doublets) have been hypothesised as a potential additional risk for overuse of already exhausted fibres during long-term stereotyped activity. Doublets are reported to be present during double-click mouse work tasks. A few comparative studies have been carried out on overall muscle activities for short-term tasks with single types of actions, but none on occurrences of doublets during double versus single clicks. The main purpose of this study was to compare muscle activity levels of single and double mouse clicks during a long-term combined mouse/keyboard work task. Four muscles were studied: left and right upper trapezius, right extensor digitorum communis (EDC) and right flexor carpi ulnaris. Additionally, MU activity was analysed through intramuscular electromyography in the EDC muscle for a selection of subjects. The results indicate that double clicking produces neither higher median or 90th percentile levels in the trapezius and EDC muscles, nor a higher disposition for MU doublets, than does single clicking. Especially for the 90th percentile levels, the indications are rather the opposite (in the EDC significantly higher during single clicks in 8 of 11 subjects, P < 0.05). Although it cannot be concluded from the present study that double clicks are harmless, there were no signs that double clicks during computer work generally constitute a larger risk factor for WMSDs than do single clicks.
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Affiliation(s)
- Stefan Thorn
- National Institute for Working Life, Goteborg, Sweden.
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Lindegård A, Wahlström J, Hagberg M, Hansson GA, Jonsson P, Wigaeus Tornqvist E. The impact of working technique on physical loads - an exposure profile among newspaper editors. ERGONOMICS 2003; 46:598-615. [PMID: 12745690 DOI: 10.1080/0014013031000071360] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The aim of this study was to investigate the possible associations between working technique, sex, symptoms and level of physical load in VDU-work. A study group of 32 employees in the editing department of a daily newspaper answered a questionnaire, about physical working conditions and symptoms from the neck and the upper extremities. Muscular load, wrist positions and computer mouse forces were measured. Working technique was assessed from an observation protocol for computer work. In addition ratings of perceived exertion and overall comfort were collected. The results showed that subjects classified as having a good working technique worked with less muscular load in the forearm (extensor carpi ulnaris p=0.03) and in the trapezius muscle on the mouse operating side (p=0.02) compared to subjects classified as having a poor working technique. Moreover there were no differences in gap frequency (number of episodes when muscle activity is below 2.5% of a reference contraction) or muscular rest (total duration of gaps) between the two working technique groups. Women in this study used more force (mean force p=0.006, peak force p=0.02) expressed as % MVC than the men when operating the computer mouse. No major differences were shown in muscular load, wrist postures, perceived exertion or perceived comfort between men and women or between cases and symptom free subjects. In conclusion a good working technique was associated with reduced muscular load in the forearm muscles and in the trapezius muscle on the mouse operating side. Moreover women used more force (mean force and peak force) than men when operating the click button (left button) of the computer mouse.
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Affiliation(s)
- A Lindegård
- Department of Occupational and Environmental Medicine, University Hospital, Lund, Sweden.
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