1
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De Carvalho DE, Callaghan JP. Effect of office chair design features on lumbar spine posture, muscle activity and perceived pain during prolonged sitting. ERGONOMICS 2023; 66:1465-1476. [PMID: 36437777 DOI: 10.1080/00140139.2022.2152113] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 11/18/2022] [Indexed: 06/16/2023]
Abstract
Chair design features are typically compared using multiple seats, which can lead to confounding effects. Using a single chair, configurable to four designs (control, lumbar support, seat pan tilt and scapular relief), we investigated the effect of chair design on spine posture and movement, muscle activity and perceived pain in a sample of 31 asymptomatic adults. A total of 39% of the population were classified as pain developers, having significantly higher peak pain levels across most body regions. The lumbar support and seat pan tilt condition resulted in more neutral spine and pelvic postures. Greater muscle activity was found in the seat pan condition and non-pain developers displayed lower spine muscle activation levels overall. Despite some improvements in spine posture, sitting-induced pain was present in the study sample at similar proportions to those reported previously. Future studies may consider investigating interventions targeted to sitting-induced pain developers as opposed to the general population. Practitioner summary: Four office chair configurations were tested. The lumbar support and seat pan tilt conditions resulted in the most neutral back posture but did not mitigate the clinically significant levels of sitting-induced pain experienced by a large portion of the tested sample. Future work should target interventions to these individuals.
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Affiliation(s)
- D E De Carvalho
- Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada
| | - J P Callaghan
- Department of Kinesiology & Health Sciences, Faculty of Health, University of Waterloo, Waterloo, ON, Canada
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2
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Wang Q, Huo Y, Xu Z, Zhang W, Shang Y, Xu H. Effects of backrest and seat-pan inclination of tractor seat on biomechanical characteristics of lumbar, abdomen, leg and spine. Comput Methods Biomech Biomed Engin 2023; 26:291-304. [PMID: 35403500 DOI: 10.1080/10255842.2022.2062229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Seat is a direct human-machine interaction component between the tractor and driver, and thus its reasonable parameter design is of great significance for preventing occupational diseases and improving driving comfort, safety and operation efficiency. In this study, a biomechanical model of seat-driver system was established with the AnyBody biomechanical software. The activities of the lumbar, abdominal and leg muscles and the load of the spine of the driver were used as indicators for quantitative simulation analysis of the inclination of backrest and seat-pan. The results reveal that the optimal range of backrest inclination angle is 3-15°, which contributes to the lowest muscle activity and spinal load of the driver. As for the seat-pan inclination, the activities of lumbar and abdominal muscles and the spinal load generally show slight fluctuations with increasing inclination angle, but there are complex changes in the activities of leg muscles, and the seat-pan inclination angle of 5-16° was determined as the optimal range for better overall driving comfort.
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Affiliation(s)
- Qichao Wang
- College of Engineering, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Agricultural Equipment in Mid-lower Reaches of the Yangtze River, Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
| | - Yihuan Huo
- College of Engineering, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Agricultural Equipment in Mid-lower Reaches of the Yangtze River, Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
| | - Zheng Xu
- College of Engineering, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Agricultural Equipment in Mid-lower Reaches of the Yangtze River, Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
| | - Wenjie Zhang
- College of Engineering, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Agricultural Equipment in Mid-lower Reaches of the Yangtze River, Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
| | - Yujun Shang
- College of Engineering, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Agricultural Equipment in Mid-lower Reaches of the Yangtze River, Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
| | - Hongmei Xu
- College of Engineering, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Agricultural Equipment in Mid-lower Reaches of the Yangtze River, Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan, China
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3
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Zhang X, Cheng Z, Zhang M, Zhu X, Zhang X. Comfort Prediction of Office Chair Surface Material Based on the ISSA-LSSVM. SENSORS (BASEL, SWITZERLAND) 2022; 22:9822. [PMID: 36560192 PMCID: PMC9784787 DOI: 10.3390/s22249822] [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: 10/12/2022] [Revised: 12/05/2022] [Accepted: 12/11/2022] [Indexed: 06/17/2023]
Abstract
This study serves the purpose of assisting users in selecting a comfortable seat surface material for office chairs and enhancing users' comfort while using office chairs. To address the issue that the selection of traditional seat surface material is too subjective and that the prediction effect is poor, an improved sparrow search algorithm (ISSA) optimized least squares support vector machine (LSSVM) method for office chair seat surface material comfort prediction has been proposed. Sparrow Search Algorithm (SSA) was optimized with Sobol sequences, nonlinear inertial weights, and a crisscross optimization algorithm to produce the Improved Sparrow Search Algorithm (ISSA), and then the relevant parameters of the LSSVM algorithm were optimized with the modified algorithm to improve its prediction performance. The prediction accuracy of the ISSA-LSSVM model is as high as 95.75% by combining the body pressure distribution experiments; the root mean square error (RMSE) is 0.29; the goodness of fit (R2) is 0.92; the mean absolute error (MAE) is 0.24; the standard deviation (RSD) is 5.99%. The ISSA-LSSVM model predicts seat surface material comfort more accurately and reliably. This strategy can assist consumers to narrow down their seat surface material choices and even suggest an optimal selection. In this way, it can boost users' pleasure with office chairs, which has great potential for wide application.
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Affiliation(s)
- Xuyinglong Zhang
- Material Science and Engineering College, Northeast Forestry University, Harbin 15000, China
| | - Zilian Cheng
- Department of Performing Arts and Culture, The Catholic University, Bucheon 14662, Republic of Korea
| | - Mengyang Zhang
- Engineering and Technology College, Northeast Forestry University, Harbin 15000, China
| | - Xiaodong Zhu
- Material Science and Engineering College, Northeast Forestry University, Harbin 15000, China
| | - Xianquan Zhang
- Material Science and Engineering College, Northeast Forestry University, Harbin 15000, China
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4
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A Development of the Self Shape Adjustment Cushion Mechanism for Improving Sitting Comfort. SENSORS 2021; 21:s21237959. [PMID: 34883963 PMCID: PMC8659628 DOI: 10.3390/s21237959] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 11/14/2021] [Accepted: 11/26/2021] [Indexed: 11/16/2022]
Abstract
The seat comfort of automobiles is one of the significant factors for determining the driver’s fatigue, emotional experience, and individual space (which captures their individuality, rather than just a means of transportation in modern society). Conventional automobile seats could not provide seating comfort suitable for all drivers, in the form of seats that fit each driver’s body type and the difficulty of meeting individual needs. This study proposes self-shape adjustable (the SSA seats) seats that improve the sitting comfort, safety, and secure the stability, by adjusting shape fit to the driver’s body type. The SSA seats transforms the seat itself, in a way that improves the distribution of contact pressure and reduces sitting fatigue, with the pneumatic system. The transformed seats provide better sitting comfort and safety than the conventional automobile seat, by providing a seat shape suitable for the body shape of all users. It was verified that the SSA seats, proposed in this paper, have a uniform and improved pressure distribution, compared to the conventional seat, in various sitting postures; the contact area between the seat and user is enlarged, and the pressure concentrated on the ischial bone is lowered. In addition, it was proven (through user evaluation) that quantitative evaluation verification was the same as qualitative evaluation results.
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5
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Lantoine P, Lecocq M, Bougard C, Dousset E, Marqueste T, Bourdin C, Allègre JM, Bauvineau L, Mesure S. Car seat impact on driver's sitting behavior and perceived discomfort during prolonged real driving on varied road types. PLoS One 2021; 16:e0259934. [PMID: 34784401 PMCID: PMC8594853 DOI: 10.1371/journal.pone.0259934] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 11/01/2021] [Indexed: 12/02/2022] Open
Abstract
Prolonged driving under real conditions can entail discomfort linked to driving posture, seat design features, and road properties like whole-body vibrations (WBV). This study evaluated the effect of three different seats (S1 = soft; S2 = firm; S3 = soft with suspension system) on driver's sitting behavior and perceived discomfort on different road types in real driving conditions. Twenty-one participants drove the same 195 km itinerary alternating highway, city, country, and mountain segments. Throughout the driving sessions, Contact Pressure (CP), Contact Surface (CS), Seat Pressure Distribution Percentage (SPD%) and Repositioning Movements (RM) were recorded via two pressure mats installed on seat cushion and backrest. Moreover every 20 minutes, participants rated their whole-body and local discomfort. While the same increase in whole-body discomfort with driving time was observed for all three seats, S3 limited local perceived discomfort, especially in buttocks, thighs, neck, and upper back. The pressure profiles of the three seats were similar for CP, CS and RM on the backrest but differed on the seat cushion. The soft seats (S1 & S3) showed better pressure distribution, with lower SPD% than the firm seat (S2). All three showed highest CP and CS under the thighs. Road type also affected both CP and CS of all three seats, with significant differences appearing between early city, highway and country segments. In the light of these results, automotive manufacturers could enhance seat design for reduced driver discomfort by combining a soft seat cushion to reduce pressure peaks, a firm backrest to support the trunk, and a suspension system to minimize vibrations.
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Affiliation(s)
- Pascaline Lantoine
- Aix-Marseille Univ, CNRS, ISM, Marseille, France
- Stellantis, Centre Technique de Vélizy, Vélizy-Villacoublay, France
| | | | - Clément Bougard
- Stellantis, Centre Technique de Vélizy, Vélizy-Villacoublay, France
| | | | | | | | | | | | - Serge Mesure
- Aix-Marseille Univ, CNRS, ISM, Marseille, France
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Mohammad Yusof NAD, Karupiah K, Mohd Tamrin SB, Rasdi I, How V, Sambasivam S, Mohamad Jamil PAS, K. C. Mani K, Sadeghi Naeini H, Mohd Suadi Nata DH. Effectiveness of lumbar support with built-in massager system on spinal angle profiles among high-powered traffic police motorcycle riders: A randomised controlled trial. PLoS One 2021; 16:e0258796. [PMID: 34665845 PMCID: PMC8525748 DOI: 10.1371/journal.pone.0258796] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 10/06/2021] [Indexed: 11/21/2022] Open
Abstract
Traffic police riders are exposed to prolonged static postures causing significant angular deviation of the musculoskeletal, including the lumbar angle (L1-L5). This postural alteration contributes to awkward posture, musculoskeletal disorders and spinal injury, especially in the lower back area, as it is one of the most severe modern diseases nowadays. Thus, the study aimed to evaluate the effect of lumbar support with a built-in massager system on spinal angle profiles among traffic police riders. A randomised controlled trial (pre-testpost-test control design) was used to assess spinal angle pattern while riding the high-powered motorcycle for 20 minutes. Twenty-four traffic police riders were randomly selected to participate and 12 riders were assigned to the control group and 12 riders to the experimental group. The pre-test and post-test were conducted at a one-week interval. Each participant was required to wear a TruPosture Smart Shirt (to monitor spinal posture). The TruPosture Apps recorded the spinal angle pattern. The data indicated that the police riders using motorcycle seat with lumbar support and built-in massager system showed a huge improvement in maintaining posture which only involves slight spinal angle deviation changes from the spinal reference angle throughout the 20 minutes ride. The data collected then were analysed using the Mann-Whitney test and Wilcoxon signed-ranked test to verify a statistically significant difference between and within the control and experimental groups. There were significant differences in all sensors between the control group and experimental groups (p<0.05) and within the experimental group. According to the findings, it can be said that the ergonomic intervention prototype (lumbar support with built-in massager system) successfully helps to maintain and improve the natural curve of the spinal posture. This indirectly would reduce the risk of developing musculoskeletal disorders and spinal injury among traffic police riders.
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Affiliation(s)
- Nur Athirah Diyana Mohammad Yusof
- Faculty of Medicine and Health Sciences, Department of Environmental and Occupational Health, Universiti Putra Malaysia, UPM Serdang, Selangor, Malaysia
| | - Karmegam Karupiah
- Faculty of Medicine and Health Sciences, Department of Environmental and Occupational Health, Universiti Putra Malaysia, UPM Serdang, Selangor, Malaysia
| | - Shamsul Bahri Mohd Tamrin
- Faculty of Medicine and Health Sciences, Department of Environmental and Occupational Health, Universiti Putra Malaysia, UPM Serdang, Selangor, Malaysia
| | - Irniza Rasdi
- Faculty of Medicine and Health Sciences, Department of Environmental and Occupational Health, Universiti Putra Malaysia, UPM Serdang, Selangor, Malaysia
| | - Vivien How
- Faculty of Medicine and Health Sciences, Department of Environmental and Occupational Health, Universiti Putra Malaysia, UPM Serdang, Selangor, Malaysia
| | - Sivasankar Sambasivam
- Faculty of Medicine and Health Sciences, Department of Environmental and Occupational Health, Universiti Putra Malaysia, UPM Serdang, Selangor, Malaysia
| | - Putri Anis Syahira Mohamad Jamil
- Faculty of Medicine and Health Sciences, Department of Environmental and Occupational Health, Universiti Putra Malaysia, UPM Serdang, Selangor, Malaysia
| | - Kulanthayan K. C. Mani
- Faculty of Medicine and Health Sciences, Department of Community Health, Universiti Putra Malaysia, UPM Serdang, Selangor, Malaysia
| | - Hassan Sadeghi Naeini
- Industrial Design Department, School of Architecture & Environmental Design, Iran University of Science & Technology, Tehran, Iran
| | - Dayana Hazwani Mohd Suadi Nata
- Faculty of Health Sciences, Center for Toxicology and Health Risk Studies, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
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7
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Clapp SR, McCauley PR, Karwowski W, Hancock PA. The seat of happiness? The effect of seat comfort on the achievement of psychological flow during transactional work. APPLIED ERGONOMICS 2021; 96:103508. [PMID: 34157479 DOI: 10.1016/j.apergo.2021.103508] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 06/13/2021] [Accepted: 06/14/2021] [Indexed: 06/13/2023]
Abstract
Psychological flow is highly pleasurable, time-limited form of engagement in a task which has been shown to produce benefits in the workplace. Flow has historically been studied in the context of the interaction between the task and the performer. However, in work settings such as an office, many other factors may contribute to or hinder the achievement of flow. This present study broadens the research on flow to test the extent to which seating comfort while executing a challenging task influences an individual's ability to achieve flow. Fifty-four participants in this study were randomly assigned to one of two seat types and given a set of tasks to perform via a computer simulation. Seat comfort, coupled with participants' perceptions of their ability to concentrate on the simulation's set of tasks, was found to predict participants' flow experiences. Implications and future directions are discussed.
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Affiliation(s)
- Steven R Clapp
- Department of Industrial Engineering and Management Systems, University of Central Florida, Florida, USA.
| | | | - Waldemar Karwowski
- Department of Industrial Engineering and Management Systems, University of Central Florida, Florida, USA
| | - P A Hancock
- Department of Psychology, University of Central Florida, Florida, USA
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8
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Guo LX, Dong RC, Yuan S, Feng QZ, Fan W. Influence of seat lumbar support adjustment on muscle fatigue under whole body vibration: An in vivo experimental study. Technol Health Care 2021; 30:455-467. [PMID: 34275916 DOI: 10.3233/thc-212840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND In order to alleviate muscle fatigue and improve ride comfort, many published studies aimed to improve the seat environment or optimize seating posture. However, the effect of lumbar support on the lumbar muscle of seated subjects under whole body vibration is still unclear. OBJECTIVE This study aimed to investigate the effect of lumbar support magnitude of the seat on lumbar muscle fatigue relief under whole body vibration. METHODS Twenty healthy volunteers without low back pain participated in the experiment. By measuring surface electromyographic signals of erector spinae muscles under vibration or non-vibration for 30 minutes, the effect of different lumbar support conditions on muscle fatigue was analyzed. The magnitude of lumbar support d is assigned as d1= 0 mm, d2= 20 mm and d3= 40 mm for no support, small support and large support, respectively. RESULTS The results showed that lumbar muscle activation levels vary under different support conditions. For the small support case (d2= 20 mm), the muscle activation level under vibration and no-vibration was the minimum, 42.3% and 77.7% of that under no support (d1= 0 mm). For all support conditions, the muscle activation level under vibration is higher than that under no-vibration. CONCLUSIONS The results indicate that the small support yields the minimum muscle contraction (low muscle contraction intensity) under vibration, which is more helpful for relieving lumbar muscle fatigue than no support or large support cases. Therefore, an appropriate lumbar support of seats is necessary for alleviating lumbar muscle fatigue.
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Affiliation(s)
- Li-Xin Guo
- School of Mechanical Engineering and Automation, Northeastern University, Shenyang, Liaoning, China
| | - Rui-Chun Dong
- School of Mechanical Engineering and Automation, Northeastern University, Shenyang, Liaoning, China
| | | | - Qing-Zhi Feng
- Department of Audio and Video Material Examination Technology, Criminal Investigation Police University of China, Shenyang, Liaoning, China
| | - Wei Fan
- School of Mechanical Engineering and Automation, Northeastern University, Shenyang, Liaoning, China
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Channak S, Klinsophon T, Janwantanakul P. The effects of chair intervention on lower back pain, discomfort and trunk muscle activation in office workers: a systematic review. INTERNATIONAL JOURNAL OF OCCUPATIONAL SAFETY AND ERGONOMICS 2021; 28:1722-1731. [PMID: 33970803 DOI: 10.1080/10803548.2021.1928379] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Objectives. The chair is a standard piece of workstation equipment in an office. Previous studies showed that a suitable chair may reduce musculoskeletal symptoms. This review investigated the effect of chair intervention on lower back pain (LBP), discomfort and trunk muscle activation among office workers. Methods. Five electronic databases from 1980 to May 2020 were searched for relevant randomized and non-randomized controlled trials. The methodological quality of the included studies was assessed using the 13-item Cochrane risk of bias tool. Quality of evidence was assessed and rated according to Grading of Recommendations, Assessment, Development and Evaluations (GRADE) guidelines. Results. Two randomized controlled trials, 10 repeated-measures studies and two prospective cohort studies were included in this review. Nine studies were rated as high quality. The results indicated very low-quality to low-quality evidence for the conflicting effect of chair intervention on pain and discomfort reduction as well as trunk muscle activation among office workers. When stratified by chair type, the level of evidence for health benefits derived from any type of chair was still of very low to low quality. Conclusion. Unless supplementary high-quality studies provide different evidence, chair interventions are not recommended to reduce LBP or discomfort and activate trunk muscles.
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Affiliation(s)
- Sirinant Channak
- Faculty of Allied Health Sciences, Chulalongkorn University, Thailand
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10
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Tanoue H, Mitsuhashi T, Sako S, Inaba R. An exploratory study on the impact of static and dynamic sitting postures on lumbar and pelvic mobility during visual display terminal work. J Phys Ther Sci 2021; 33:406-412. [PMID: 34083879 PMCID: PMC8165355 DOI: 10.1589/jpts.33.406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2020] [Accepted: 02/06/2021] [Indexed: 11/24/2022] Open
Abstract
[Purpose] Limited studies exist on the impact of sustained work at a visual display
terminal (VDT) on the position and motion of the pelvis and lumbar spine. We evaluated the
changes in movement of the lumbar column and pelvis during VDT work. [Participants and
Methods] We evaluated the sitting posture of 20 healthy adults while they performed VDT
work. The effects of the sitting posture on lumbo-pelvic position and motion were captured
using a three-dimensional accelerometer. Between-posture effects of VDT work were
evaluated using an analysis of variance (ANOVA). A two-way ANOVA was used to assess the
root mean square (RMS) values of the 80-min VDT work period for each posture. A one-way
ANOVA was used to evaluate pre- and post-work changes in RMS values during the finger
floor distance test (FFD). [Results] People in the dynamic sitting balance chair
(DSBC)-based posture demonstrated significantly higher pelvic RMS values than those in
reclining and upright sitting postures. The DSBC-based posture was also associated with
significantly higher pre- and post-work lumbar and pelvic RMS values during the FFD than
in the reclining and upright sitting postures. [Conclusion] The dynamic balance chair may
be an effective method of establishing a pattern of spinal exercise during prolonged
sitting.
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Affiliation(s)
- Hironori Tanoue
- Department of Rehabilitation, Aichi Koseiren Asuke Hospital: 20 Nakata, Yagami-cho, Toyota-shi, Aichi-ken 444-2351, Japan
| | | | - Shunji Sako
- Department of Physical Therapy, Nagoya Isen School Corporation Vocational College, Japan
| | - Ryoichi Inaba
- Department of Occupational Health, Graduate School of Medicine, Gifu University, Japan
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11
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Jalilian H, Gorjizadeh O, Najafi K, Falahati M. Effects of whole body vibration and backrest angle on perceived mental workload and performance. EXCLI JOURNAL 2021; 20:400-411. [PMID: 33746669 PMCID: PMC7975586 DOI: 10.17179/excli2020-2699] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 02/11/2021] [Indexed: 01/10/2023]
Abstract
Mental Workload (MWL) and human performance are widely contributing concepts in human factors. The objective of the current study is to investigate the perceived MWL and human performance during whole-body vibration (WBV) exposure while seated at different backrest angles. Nineteen healthy male participants completed both the NASA-TLX and rating scale mental effort (RSME) after performing two difficulty levels of computerized dual tasks. The participants' performance was measured in these conditions while seated with a backrest angle of 100 and 120 degrees and exposed to WBV (intensity: 0.5 m/s2; frequency 3-20 Hz) for 5 minutes. No significant effect on performance or perceived MWL (p<0.05) was found when changes were made to the backrest angles. Exposure to WBV under two backrest angles increased mental demand (p=0.04), effort (p=0.03) and frustration (p=0.03) and negatively affected human performance (p<0.05). The present study showed that exposure to WBV could be an important variable for designing work environments that require a high level of performance and mental demand while seated. However, the findings exhibited no association between inclining backrest angle and human performance or perceived MWL.
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Affiliation(s)
- Hamed Jalilian
- Department of Occupational Health Engineering, Research Center for Environmental Pollutants, Faculty of Health, Qom University of Medical Sciences, Qom, Iran.,Student Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Omid Gorjizadeh
- Student Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Kamran Najafi
- Student Research Committee, Hamedan University of Medical Sciences, Hamedan, Iran
| | - Mohsen Falahati
- Department of Occupational Health Engineering, Faculty of Health, Saveh University of Medical Sciences, Saveh, Iran
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12
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Wang J, Zhi JY, Du Y, Xiang ZR, Feng S, Chen JP. A method identifying key optimisation points for aircraft seat comfort. ERGONOMICS 2021; 64:287-304. [PMID: 33026947 DOI: 10.1080/00140139.2020.1834150] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 10/04/2020] [Indexed: 06/11/2023]
Abstract
Seating is the overriding factor influencing aircraft cabin comfort. To efficiently enhance seat comfort, this paper proposes a method to identify key optimisation points for seat comfort. Seat discomfort indicators are recognised based on a comparison of perceived performance with expectation. Confirmatory factor analysis is used to explore the latent variables of discomfort indicators, and a structural model was used to analyse correlations between latent variables. Finally, the most important latent variable influencing seat comfort was clarified. Analysis results of survey data from narrow-body aircraft show that seat discomfort indicators centre on the physical performance of the seat and include four latent variables: support performance, personal space, contact surface features, and safety and stability. Support performance determines body posture while travelling and is the overriding latent variable influencing seat comfort. This research establishes aircraft seat discomfort indicators, latent variables formed through the mutual linkage of discomfort indicators, and the structural relations between latent variables. The results can assist in the formulation of comfort optimisation procedures for aircraft seats. Practitioner summary: A method identifying the key points of aircraft seat comfort optimisation was proposed, which includes three steps: recognising discomfort indicators, exploring the relationship between discomfort indicators, and confirming the most important variable influencing seat comfort. Results provide guidance for aircraft seat optimisation. Abbreviations: SEM: structural equation modelling; EFA: exploratory factor analysis; CFA: confirmatory factor analysis; PA-OV: path analysis with observed variables; CR: construct reliability; AVE: average variance extracted; CMIN: likelihood-ratio chi-square; DF: degrees of freedom; GFI: goodness-of -fit index; AGFI: adjusted goodness-of -fit index; RMSEA: root mean square error of approximation; NNFI: non-normed fit index; RFI: relative fit index; CFI: comparative fit index; CN: critical N.
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Affiliation(s)
- Jin Wang
- Department of Industrial Design, School of Architecture and Design, Southwest Jiaotong University, Chengdu, China
| | - Jin-Yi Zhi
- Department of Industrial Design, School of Architecture and Design, Southwest Jiaotong University, Chengdu, China
- Institute of Design and Research for Man-Machine-Environment Engineering System, Southwest Jiaotong University, Chengdu, China
| | - Yang Du
- Department of Industrial Design, School of Architecture and Design, Southwest Jiaotong University, Chengdu, China
| | - Ze-Rui Xiang
- Department of Industrial Design, School of Architecture and Design, Southwest Jiaotong University, Chengdu, China
- Institute of Design and Research for Man-Machine-Environment Engineering System, Southwest Jiaotong University, Chengdu, China
| | - Shu Feng
- Department of Industrial Design, School of Architecture and Design, Southwest Jiaotong University, Chengdu, China
| | - Jian-Ping Chen
- The Second Research Institute of Civil Aviation Administration of China, Chengdu, China
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13
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Liu Z, Cascioli V, McCarthy PW. Review of Measuring Microenvironmental Changes at the Body-Seat Interface and the Relationship between Object Measurement and Subjective Evaluation. SENSORS 2020; 20:s20236715. [PMID: 33255342 PMCID: PMC7727653 DOI: 10.3390/s20236715] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 11/13/2020] [Accepted: 11/20/2020] [Indexed: 12/11/2022]
Abstract
Being seated has increasingly pervaded both working and leisure lifestyles, with development of more comfortable seating surfaces dependent on feedback from subjective questionnaires and design aesthetics. As a consequence, research has become focused on how to objectively resolve factors that might underpin comfort and discomfort. This review summarizes objective methods of measuring the microenvironmental changes at the body–seat interface and examines the relationship between objective measurement and subjective sensation. From the perspective of physical parameters, pressure detection accounted for nearly two thirds (37/54) of the publications, followed by microclimatic information (temperature and relative humidity: 18/54): it is to be noted that one article included both microclimate and pressure measurements and was placed into both categories. In fact, accumulated temperature and relative humidity at the body–seat interface have similarly negative effects on prolonged sitting to that of unrelieved pressure. Another interesting finding was the correlation between objective measurement and subjective evaluation; however, the validity of this may be called into question because of the differences in experiment design between studies.
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Affiliation(s)
- Zhuofu Liu
- The Higher Educational Key Laboratory for Measuring and Control Technology and Instrumentations of Heilongjiang Province, Harbin University of Science and Technology, Harbin 150080, China
- Correspondence: ; Tel.: +86-139-0451-2205
| | - Vincenzo Cascioli
- Murdoch University Chiropractic Clinic, Murdoch University, Murdoch 6150, Australia;
| | - Peter W. McCarthy
- Faculty of Life Science and Education, University of South Wales, Treforest, Pontypridd CF37 1DL, UK;
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Stanglmeier MJ, Paternoster FK, Paternoster S, Bichler RJ, Wagner PO, Schwirtz A. Automated driving: A biomechanical approach for sleeping positions. APPLIED ERGONOMICS 2020; 86:103103. [PMID: 32342893 DOI: 10.1016/j.apergo.2020.103103] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 01/31/2020] [Accepted: 03/23/2020] [Indexed: 06/11/2023]
Abstract
Occupants of autonomous vehicle have frequently indicated the desire to sleep or rest while driving, yet little has been known regarding the suitable design criteria for a biomechanically reasoned in-vehicle sleeping position. This study was aimed at evaluating the biomechanical quality of different backrest and seat pan angle combinations, and at predicting the most favourable sleeping positions based on vehicle restriction. More specifically, the interface pressure distribution and subjective suitability rating of 23 subjects was assessed in a total of nine (3 × 3) combinations of seat pan (20°, 30°, 40°) and backrest (145°, 155°, 165°) angles. Biomechanical quality was evaluated with an interface pressure score (IPS) based on sensitivity weighted pressures and the total contact area. Two-way repeated measures ANOVA revealed that IPS significantly improves with increasing seat pan angle whereas backrest angles of 155° or 165° lead to significant better IPS compared to flatter ones (145°). The overall highest IPS was observed for a 40°-seat pan angle in combination with a 155°-backrest angle. Subjective suitability rating revealed that people prefer a combination of 165° backrest angle with a seat pan of 20°; however, eight of nine combinations can be considered as suitable for sleeping. Therefore, the combination of a 40°-seat pan angle and 155° backrest is recommended by the present study for an in-vehicle sleeping position due to the increased biomechanical quality.
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Affiliation(s)
- Maximilian J Stanglmeier
- BMW Group, Knorrstraße 147, 80788, München, Germany; Department of Biomechanics in Sports, Technical University of Munich, Uptown München-Campus D, Georg-Brauchle-Ring 60/62, 80992, München, Germany.
| | - Florian K Paternoster
- Department of Biomechanics in Sports, Technical University of Munich, Uptown München-Campus D, Georg-Brauchle-Ring 60/62, 80992, München, Germany
| | | | | | | | - Ansgar Schwirtz
- Department of Biomechanics in Sports, Technical University of Munich, Uptown München-Campus D, Georg-Brauchle-Ring 60/62, 80992, München, Germany
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15
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Eggleston ST. Mouse with your arm™: Facilitating forearm support using the chair armrest to prevent and mitigate musculoskeletal disorders. Work 2020; 65:483-495. [PMID: 32083609 DOI: 10.3233/wor-203103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Musculoskeletal disorders (MSDs) can be prevented by avoiding trauma caused by poor posture, compression, force, and repetition. Neutral postures are recommended to avoid MSDs. OBJECTIVE This study introduces Mouse With Your Arm™ (MWYA) methodology which promotes sitting back in a chair, using the chair's armrest for forearm support at relaxed elbow height, matching surface and armrest height, and keeping the mouse on the surface edge. This position allows optimal task chair use, facilitates movement and neutral postures, avoids compression and contact stress, and is effective in mitigating MSDs. METHOD MWYA was applied and measured in the field for more 23 years providing over 3,500 individualized assessments to integrate a participant's unique characteristics, reported health concerns, tasks, tools, and environment to achieve and sustain whole-body neutral and comfortable working postures. RESULTS Previous research has consistently recommended use of forearm support by a desk, apparatus, or wrist rest, and resulted in non-neutral, static postures and measured health consequences. By using armrests for support, MWYA avoids the potential of MSDs as can be caused by these previously endorsed postures. CONCLUSION By applying the five MWYA principles, computer users comprehend neutral posture and put forth the effort essential to creating healthy human computer relationships.
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Affiliation(s)
- Sara Taylor Eggleston
- Founder of Structured Health Resources, Inc. and Mouse With Your Arm Methodology, Ann Arbor, MI, USA. Tel.: +1 734-224-2425; E-mail:
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16
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Moriguchi CS, Sato TO, Coury HJCG. An Instrumented Workstation to Evaluate Weight-Bearing Distribution in the Sitting Posture. Saf Health Work 2019; 10:314-320. [PMID: 31497327 PMCID: PMC6718046 DOI: 10.1016/j.shaw.2019.01.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 10/22/2018] [Accepted: 01/21/2019] [Indexed: 10/27/2022] Open
Abstract
Background Sitting posture may be related to risk factors, including inadequate weight-bearing support, particularly when maintained for long periods. Considering that body weight is loaded in a closed support system composed of the seat, backrest, floor and working surface, the aims of the present study were to describe the development of an ergonomic sitting workstation to continuously record weight-bearing at the seat, chair, backrest, work surface, and floor and to test its measurement properties: reproducibility, criterion-related validity, and sensitivity. Methods Rigid bodies (1 to 30 kg) and participant weights were recorded to evaluate the workstation measurement properties. Results Rigid body tests showed variation values less than 0.050 kg on reproducibility test and errors below 5% of measured value on criterion validity tests. Participant tests showed no statistically significant differences between repeated measures (p ≥ 0.40), errors were less than 2% of participant weights and sensitivity presented statistically significant changes (p = 0.007). Conclusion The sitting workstation proposed showed to be reliable, valid and sensitive for use in future ergonomic studies to evaluate the sitting posture.
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Affiliation(s)
| | - Tatiana O Sato
- Federal University of São Carlos, Physical Therapy Department, São Carlos, Brazil
| | - Helenice J C G Coury
- Federal University of São Carlos, Physical Therapy Department, São Carlos, Brazil
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Campbell MJ, Toth AJ, Moran AP, Kowal M, Exton C. eSports: A new window on neurocognitive expertise? PROGRESS IN BRAIN RESEARCH 2018; 240:161-174. [PMID: 30390829 DOI: 10.1016/bs.pbr.2018.09.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Understanding the neurological changes that take place as expertise develops is a central topic in both cognitive psychology and cognitive neuroscience. Here, we argue that video games, despite previous misconceptions, are an excellent model environment from which one can examine the development of neurocognitive expertise. Of particular relevance we argue is the area of esports, which encompass video/computer games played within the medium of cyberspace competitively and increasingly professionally. The massive scale of participation, controlled environments, structured skill ratings, pervasive social nature, and large repositories of data, together make esports potentially a very fruitful area for scientific research to increase our understanding of a new era of cognitive athletes. This chapter reviews the progress and prospects for esports research with a particular focus on the effects of gaming on neurocognition. We also outline some exciting new avenues and techniques from which we hope to further elucidate the benefits of esports on the brain.
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Affiliation(s)
- Mark J Campbell
- Department of Physical Education and Sport Sciences, University of Limerick, Limerick, Ireland; Lero Irish Software Research Centre, University of Limerick, Limerick, Ireland.
| | - Adam J Toth
- Department of Physical Education and Sport Sciences, University of Limerick, Limerick, Ireland; Lero Irish Software Research Centre, University of Limerick, Limerick, Ireland
| | - Aidan P Moran
- School of Psychology, University College Dublin, Dublin, Ireland
| | - Magdalena Kowal
- Department of Physical Education and Sport Sciences, University of Limerick, Limerick, Ireland; Lero Irish Software Research Centre, University of Limerick, Limerick, Ireland
| | - Chris Exton
- Lero Irish Software Research Centre, University of Limerick, Limerick, Ireland; Department of Computer Science, University of Limerick, Limerick, Ireland
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Liu S, Qu Y, Hou S, Li K, Li X, Zhai Y, Ji Y. Comfort evaluation of a subject-specific seating interface formed by vibrating grains. APPLIED ERGONOMICS 2018; 71:65-72. [PMID: 29764615 DOI: 10.1016/j.apergo.2018.03.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 03/21/2018] [Accepted: 03/22/2018] [Indexed: 06/08/2023]
Abstract
Sitting is the most common posture for work in offices, and spinal cord injury (SCI) patients who are wheelchair dependent spend 10.6 h per day seated in wheelchairs. Thus, the comfort of subject-specific interfaces is increasingly important for the well-being of patients and office workers. This paper introduces a new method of forming a subject-specific interface, based on vibrating grains. Twenty subjects (10 females and 10 males) participated in the sitting test. Interface comfort was evaluated using the pressure distribution and subjective rating methods. Five seating interface types were compared. The results showed that compared with a flat interface, the interfaces formed by vibrating grains had a significantly reduced peak contact pressure (PeakCP) (by more than 58.03%), and that PeakCP was highly correlated with the comfort rating (R = -0.533) and discomfort rating(R = -0.603). This new method shows promise for guiding the future development of customized seating interfaces.
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Affiliation(s)
- Shenghui Liu
- School of Mechanical Engineering, Hebei University of Technology, Dingzigu Road No.8, Hongqiao District, Tianjin, 300130, PR China(1)
| | - Yunxia Qu
- School of Mechanical Engineering, Hebei University of Technology, Dingzigu Road No.8, Hongqiao District, Tianjin, 300130, PR China(1)
| | - Shujun Hou
- School of Mechanical Engineering, Hebei University of Technology, Dingzigu Road No.8, Hongqiao District, Tianjin, 300130, PR China(1).
| | - Kai Li
- School of Mechanical Engineering, Hebei University of Technology, Dingzigu Road No.8, Hongqiao District, Tianjin, 300130, PR China(1)
| | - Xinye Li
- School of Mechanical Engineering, Hebei University of Technology, Dingzigu Road No.8, Hongqiao District, Tianjin, 300130, PR China(1)
| | - Yang Zhai
- School of Mechanical Engineering, Hebei University of Technology, Dingzigu Road No.8, Hongqiao District, Tianjin, 300130, PR China(1)
| | - Yunxiao Ji
- School of Mechanical Engineering, Hebei University of Technology, Dingzigu Road No.8, Hongqiao District, Tianjin, 300130, PR China(1)
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Cattarello P, Vinelli S, D'Emanuele S, Gazzoni M, Merletti R. Comparison of chairs based on HDsEMG of back muscles, biomechanical and comfort indices, for violin and viola players: A short-term study. J Electromyogr Kinesiol 2018; 42:92-103. [PMID: 30015135 DOI: 10.1016/j.jelekin.2018.06.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 06/01/2018] [Accepted: 06/20/2018] [Indexed: 11/17/2022] Open
Abstract
This work investigates the effect of different seats on violin and viola players sitting postures using High-Density-surface-Electromyography techniques (HDsEMG), biomechanical and comfort indices. Five types of chairs were assessed on 18 violin and three viola players by comparing: (a) pelvic tilt and kyphosis and lordosis angles, (b) subjective comfort indices, and (c) EMG amplitude of erector spinae and trapezius. Sitting "as you like" on a standard orchestra chair is the condition with the highest subjective comfort (but not significantly different from other chairs). A saddle chair with low back support is associated to the lowest EMG of the erector spinae (p < 0.05) and a saddle stool is associated to the spinal angles closest to those of the standing posture. In 12 out of 21 (57%) musicians, the erector spinae was activated in an intermittent manner, regardless of the chair used. These findings justify further research on the selected chairs, on muscle fatigue and on the intermittent postural control strategy.
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Affiliation(s)
- Paolo Cattarello
- LISiN, Department of Electronics and Telecommunications, Politecnico di Torino, Torino, Italy
| | - Silvia Vinelli
- School of Medicine, Department of Surgical Science, Degree Course in Physiotherapy, University of Torino, Torino, Italy
| | - Samuel D'Emanuele
- School of Exercise and Sport Sciences, University of Torino, Torino, Italy
| | - Marco Gazzoni
- LISiN, Department of Electronics and Telecommunications, Politecnico di Torino, Torino, Italy.
| | - Roberto Merletti
- LISiN, Department of Electronics and Telecommunications, Politecnico di Torino, Torino, Italy.
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20
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Liu Z, Yuan Y, Liu M, Cascioli V, McCarthy PW. Investigating thermal performance of different chairs at the user-seat interface by a temperature sensor array system while participants perform office work. J Tissue Viability 2018; 27:83-89. [DOI: 10.1016/j.jtv.2018.03.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 03/19/2018] [Accepted: 03/25/2018] [Indexed: 12/13/2022]
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21
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Kim MH, Yoo WG. Comparison of temporal changes in trunk flexion angle and gluteal pressure during continuous sitting. J Phys Ther Sci 2017; 29:1186-1187. [PMID: 28744043 PMCID: PMC5509587 DOI: 10.1589/jpts.29.1186] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Accepted: 04/17/2017] [Indexed: 11/24/2022] Open
Abstract
[Purpose] This study investigated temporal changes in trunk flexion angle and gluteal pressure during computer work with continuous sitting. [Subjects and Methods] This study involved 10 males subjects aged 21-29 years. During 30 min of data collection with a Tekscan system and a video camera, peak gluteal pressure and changes in trunk flexion angle were analyzed with the COMFOM at research 6.20 and Pro-Trainer 10.1 programs, respectively, at 10, 20, and 30 min. [Results] The result showed no significant change in gluteal pressure after 10, 20, or 30 min. However, changes in trunk flexion angle increased significantly after 10 min <20 min <30 min. [Conclusion] Trunk flexion is necessary for repositioning, unless one can maintain a posture for a long time without movement. Future research should analyze repositioning methods according to individual characteristics.
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Affiliation(s)
- Min-Hee Kim
- Department of Physical Therapy, College of Biomedical Science and Engineering, Inje University, Republic of Korea
| | - Won-Gyu Yoo
- Department of Physical Therapy, College of Biomedical Science and Engineering, Inje University, Republic of Korea
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Sales RBC, Pereira RR, Aguilar MTP, Cardoso AV. Thermal comfort of seats as visualized by infrared thermography. APPLIED ERGONOMICS 2017; 62:142-149. [PMID: 28411724 DOI: 10.1016/j.apergo.2017.03.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 02/21/2017] [Accepted: 03/03/2017] [Indexed: 06/07/2023]
Abstract
Published studies that deal with the question of how the temperature of chair seats influences human activities are few, but the studies considering such a factor, a function of the type of material, could contribute to improvements in the design of chairs. This study evaluates seat temperatures of 8 types of chairs made of different materials. The parts of the furniture that people come into contact with, and the thermal response of the material to heating and cooling have been evaluated. Infrared thermography was used for this, as it is a non-contact technique that does not present any type of risk in the measurement of temperatures. Seats made of synthetic leather (leatherette), wood and polyester fabric were found to have the highest temperatures, and the plywood seat showed the lowest. The study has also revealed that thermography can contribute to studies of thermal comfort of chair seats in addition to determining the most suitable material.
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Affiliation(s)
- Rosemary Bom Conselho Sales
- Universidade do Estado de Minas Gerais, Av. Presidente Antônio Carlos, 7545, Bairro São Luiz, 31270-010 Belo Horizonte, Minas Gerais, Brazil.
| | - Romeu Rodrigues Pereira
- Universidade do Estado de Minas Gerais, Av. Presidente Antônio Carlos, 7545, Bairro São Luiz, 31270-010 Belo Horizonte, Minas Gerais, Brazil.
| | - Maria Teresa Paulino Aguilar
- Universidade Federal de Minas Gerais, Av. Presidente Antônio Carlos, 6627, Pampulha, 31270-901 Belo Horizonte, Minas Gerais, Brazil.
| | - Antônio Valadão Cardoso
- Universidade do Estado de Minas Gerais, Av. Presidente Antônio Carlos, 7545, Bairro São Luiz, 31270-010 Belo Horizonte, Minas Gerais, Brazil.
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Hiemstra-van Mastrigt S, Groenesteijn L, Vink P, Kuijt-Evers LFM. Predicting passenger seat comfort and discomfort on the basis of human, context and seat characteristics: a literature review. ERGONOMICS 2017; 60:889-911. [PMID: 27633349 DOI: 10.1080/00140139.2016.1233356] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
This literature review focused on passenger seat comfort and discomfort in a human-product-context interaction. The relationships between anthropometric variables (human level), activities (context level), seat characteristics (product level) and the perception of comfort and discomfort were studied through mediating variables, such as body posture, movement and interface pressure. It is concluded that there are correlations between anthropometric variables and interface pressure variables, and that this relationship is affected by body posture. The results of studies on the correlation between pressure variables and passenger comfort and discomfort are not in line with each other. Only associations were found between the other variables (e.g. activities and seat characteristics). A conceptual model illustrates the results of the review, but relationships could not be quantified due to a lack of statistical evidence and large differences in research set-ups between the reviewed papers. Practitioner Summary: This literature review set out to quantify the relationships between human, context and seat characteristics, and comfort and discomfort experience of passenger seats, in order to build a predictive model that can support seat designers and purchasers to make informed decisions. However, statistical evidence is lacking from existing literature.
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Affiliation(s)
- Suzanne Hiemstra-van Mastrigt
- a TNO , Leiden , The Netherlands
- b Faculty of Industrial Design Engineering , Delft University of Technology , Delft , The Netherlands
| | - Liesbeth Groenesteijn
- a TNO , Leiden , The Netherlands
- b Faculty of Industrial Design Engineering , Delft University of Technology , Delft , The Netherlands
| | - Peter Vink
- b Faculty of Industrial Design Engineering , Delft University of Technology , Delft , The Netherlands
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Galindo-Estupiñan ZT, Maradei-García MF, Espinel-Correal F. [Low back pain perception from the prolonged use of a dynamic seat in sitting posture]. Rev Salud Publica (Bogota) 2017; 18:412-424. [PMID: 28453104 DOI: 10.15446/rsap.v18n3.42897] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 02/22/2016] [Indexed: 11/09/2022] Open
Abstract
Objective To determine whether a tilting system located in the seat of a chair allows for performing voluntary macro-repositioning movements of the pelvis in order to reduce the perception of pain after a prolonged period in the sitting posture. Methods Eight women participated in the experiment. They were asked to sit on the chair with the tilting system and the chair without the tilting system for sixty minutes on two different days but carried out at the same time of day. Discomfort was assessed with the visual analogic scale. Results people used the tilting system to do postural changes of macro-repositioning. However, these movements were less than the movements done with the body, not using the system. Moreover, discomfort perception was the same for each chair. This might be due to the fact that total of macro-repositioning movements did not change. Conclusion Future research should evaluate the effect of tilting systems that provide macro-repositioning in a controlled form, not like in this study. Also, it is necessary to study if these types of automatic systems contribute to the reduction of the discomfort due to a prolonged period in the sitting posture.
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Cardoso M, Girouard M, Callaghan JP, Albert WJ. An ergonomic evaluation of city police officers: an analysis of perceived discomfort within patrol duties. INTERNATIONAL JOURNAL OF OCCUPATIONAL SAFETY AND ERGONOMICS 2016; 23:175-184. [DOI: 10.1080/10803548.2016.1249728] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
| | | | - Jack P. Callaghan
- School of Kinesiology and Health Studies, University of Waterloo, Canada
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Singh R, Carranza Leon DA, Morrow MM, Vos-Draper TL, Mc Gree ME, Weaver AL, Woolley SM, Hallbeck S, Gebhart JB. Effect of chair types on work-related musculoskeletal discomfort during vaginal surgery. Am J Obstet Gynecol 2016; 215:648.e1-648.e9. [PMID: 27319363 DOI: 10.1016/j.ajog.2016.06.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 05/27/2016] [Accepted: 06/07/2016] [Indexed: 02/06/2023]
Abstract
BACKGROUND Evidence supports that surgeons are at high risk for work-related musculoskeletal disorders. OBJECTIVE The objective of the study was to compare the effect of different chairs on work-related musculoskeletal discomfort for surgeons during vaginal operations. STUDY DESIGN This crossover study randomly assigned 4 surgeons to 4 chair types using a 4 × 4 Latin square model: a conventional round stool, a round stool with a backrest, a saddle chair with a backrest, and a Capisco chair. Subjective assessments of surgeon discomfort were performed with a validated body discomfort survey, and workload was assessed with the surgical task load index. The objective postural load was quantified with inertial measurement units of the modified rapid upper limb assessment limits. Subjective and objective assessments of chair comfort were performed with an 11 point scale and seat interface pressure-mapped distributions, respectively. The primary outcome was the difference in body discomfort scores between pre- and postsurgery measurements. Secondary outcomes were the differences in chair comfort scores, postural load, and seating interface pressure-mapped distribution. For each outcome, comparisons among the chair types were based on fitting a linear mixed model that handled the surgeon as a random effect and the chair type as a fixed effect. RESULTS Data were collected for 48 vaginal procedures performed for pelvic organ prolapse. Mean (SD) duration of surgery was 122.3 (25.1) minutes. Surgeons reported body discomfort during 31 procedures (67.4%). Subjective increase in discomfort from the preoperative state was noted most commonly in the lower back (n = 14, 30.4%), followed by right shoulder (n = 12, 26.1%), upper back (n = 8, 17.4%), hips and buttocks (n = 7, 15.2%), left shoulder (n = 6, 13.0%), right or left thigh (n = 6, 13.0%), and neck (n = 6, 13.0%). Pre- and postsurgery body discomfort scores did not differ with respect to chair type. Chair discomfort scores for the round stool and the saddle chair were significantly higher than the round stool with backrest and the Capisco chair (P < .001). Although the average modified rapid upper limb assessment postural scores showed moderate to high musculoskeletal risk of neck and shoulder discomfort across the 4 surgeons; chair type did not affect postural scores. The saddle chair had significantly reduced dispersion of seated pressure vs the round stool with backrest (P ≤ .001), depicted by the number of cells with pressure values >5 mm Hg. An increased dispersion of pressure across the chair surface was associated with increased comfort (Spearman correlation, 0.40, P = .006). CONCLUSION Musculoskeletal strain and associated discomfort for surgeons are very high during vaginal operations. Chair type can affect comfort, and chairs with more uniform distribution and fewer pressure points are more comfortable. However, the chair type used in surgery did not influence the musculoskeletal postural load findings.
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Crytzer TM, Hong EK, Dicianno BE, Pearlman J, Schmeler M, Cooper RA. Identifying characteristic back shapes from anatomical scans of wheelchair users to improve seating design. Med Eng Phys 2016; 38:999-1007. [DOI: 10.1016/j.medengphy.2016.06.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 05/09/2016] [Accepted: 06/09/2016] [Indexed: 11/16/2022]
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Nijholt N, Tuinhof T, Bouwens J, Schultheis U, Vink P. An estimation of the human head, neck and back contour in an aircraft seat. Work 2016; 54:913-23. [DOI: 10.3233/wor-162355] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- N. Nijholt
- Faculty of Industrial Design Engineering, Delft University of Technology, Delft, The Netherlands
| | - T. Tuinhof
- Faculty of Industrial Design Engineering, Delft University of Technology, Delft, The Netherlands
| | - J.M.A. Bouwens
- ZODIAC Seats US Division, Human Factors and Ergonomics, Gainesville, TX, USA
| | - U. Schultheis
- ZODIAC Seats US Division, Human Factors and Ergonomics, Gainesville, TX, USA
| | - P. Vink
- Faculty of Industrial Design Engineering, Delft University of Technology, Delft, The Netherlands
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Cascioli V, Liu Z, Heusch A, McCarthy PW. A methodology using in-chair movements as an objective measure of discomfort for the purpose of statistically distinguishing between similar seat surfaces. APPLIED ERGONOMICS 2016; 54:100-9. [PMID: 26851469 DOI: 10.1016/j.apergo.2015.11.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 11/30/2015] [Accepted: 11/30/2015] [Indexed: 05/23/2023]
Abstract
This study presents a method for objectively measuring in-chair movement (ICM) that shows correlation with subjective ratings of comfort and discomfort. Employing a cross-over controlled, single blind design, healthy young subjects (n = 21) sat for 18 min on each of the following surfaces: contoured foam, straight foam and wood. Force sensitive resistors attached to the sitting interface measured the relative movements of the subjects during sitting. The purpose of this study was to determine whether ICM could statistically distinguish between each seat material, including two with subtle design differences. In addition, this study investigated methodological considerations, in particular appropriate threshold selection and sitting duration, when analysing objective movement data. ICM appears to be able to statistically distinguish between similar foam surfaces, as long as appropriate ICM thresholds and sufficient sitting durations are present. A relationship between greater ICM and increased discomfort, and lesser ICM and increased comfort was also found.
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Affiliation(s)
- Vincenzo Cascioli
- Murdoch University, School of Health Professions, Murdoch University Chiropractic Clinic, Perth, Western Australia, 6150, Australia.
| | - Zhuofu Liu
- Harbin University of Science and Technology, China.
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Zemp R, Taylor WR, Lorenzetti S. Seat pan and backrest pressure distribution while sitting in office chairs. APPLIED ERGONOMICS 2016; 53 Pt A:1-9. [PMID: 26674398 DOI: 10.1016/j.apergo.2015.08.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 08/05/2015] [Accepted: 08/12/2015] [Indexed: 06/05/2023]
Abstract
Nowadays, an increasing amount of time is spent seated, especially in office environments, where sitting comfort and support are increasingly important due to the prevalence of musculoskeletal disorders. The aim of this study was to develop a methodology for chair-specific sensor mat calibration, to evaluate the interconnections between specific pressure parameters and to establish those that are most meaningful and significant in order to differentiate pressure distribution measures between office chairs. The shape of the exponential calibration function was highly influenced by the material properties and geometry of the office chairs, and therefore a chair-specific calibration proved to be essential. High correlations were observed between the eight analysed pressure parameters, whereby the pressure parameters could be reduced to a set of four and three parameters for the seat pan and the backrest respectively. In order to find significant differences between office chairs, gradient parameters should be analysed for the seat pan, whereas for the backrest almost all parameters are suitable.
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Affiliation(s)
- Roland Zemp
- Institute for Biomechanics, ETH Zürich, Vladimir-Prelog-Weg 3, 8093 Zürich, Switzerland.
| | - William R Taylor
- Institute for Biomechanics, ETH Zürich, Vladimir-Prelog-Weg 3, 8093 Zürich, Switzerland
| | - Silvio Lorenzetti
- Institute for Biomechanics, ETH Zürich, Vladimir-Prelog-Weg 3, 8093 Zürich, Switzerland
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Curran M, O'Sullivan L, O'Sullivan P, Dankaerts W, O'Sullivan K. Does Using a Chair Backrest or Reducing Seated Hip Flexion Influence Trunk Muscle Activity and Discomfort? A Systematic Review. HUMAN FACTORS 2015; 57:1115-1148. [PMID: 26175544 DOI: 10.1177/0018720815591905] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2014] [Accepted: 05/15/2015] [Indexed: 06/04/2023]
Abstract
OBJECTIVE This paper systematically reviews the effect of chair backrests and reducing seated hip flexion on low back discomfort (LBD) and trunk muscle activation. BACKGROUND Prolonged sitting commonly exacerbates low back pain (LBP). Several modifications to seated posture and chair design have been recommended, including using chairs with backrests and chairs that reduce hip flexion. METHOD Electronic databases were searched by two independent assessors. Part 1 of this review includes 26 studies comparing the effect of sitting with at least two different hip angles. In Part 2, seven studies that compared the effect of sitting with and without a backrest were eligible. Study quality was assessed using the PEDro scale. RESULTS Significant confounding variables and a relatively small number of randomized controlled trials (RCTs) involving people with LBP complicates analysis of the results. There was moderate evidence that chair backrests reduce paraspinal muscle activation, and limited evidence that chair backrests reduce LBD. There was no evidence that chairs involving less hip flexion reduce LBP or LBD, or consistently alter trunk muscle activation. However, participants in several studies subjectively preferred the modified chairs involving less hip flexion. CONCLUSION The limited evidence to support the use of chairs involving less seated hip flexion, or the effect of a backrest, is consistent with the limited evidence that other isolated chair design features can reduce LBP. APPLICATION LBP management is likely to require consideration of several factors in addition to sitting position. Larger RCTs involving people with LBP are required.
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Affiliation(s)
- Máire Curran
- University of Limerick, Limerick, IrelandCurtin University, Perth, AustraliaUniversity of Leuven, Leuven, BelgiumUniversity of Limerick, Limerick, Ireland
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Kamp I, Van Veen S, Vink P. Comfortable mobile offices: A literature review of the ergonomic aspects of mobile device use in transportation settings. Work 2015; 52:279-87. [DOI: 10.3233/wor-152165] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- I. Kamp
- University of Technology Delft, Delft, The Netherlands
| | - S.A.T. Van Veen
- University of Technology Delft, Delft, The Netherlands
- BMW AG Forschungs-und Innovationszentrum, Munich, Germany
| | - P. Vink
- University of Technology Delft, Delft, The Netherlands
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Yoo I. The effects of backrest thickness on the shoulder muscle load during wheelchair propulsion. J Phys Ther Sci 2015; 27:1767-9. [PMID: 26180316 PMCID: PMC4499979 DOI: 10.1589/jpts.27.1767] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 02/14/2015] [Indexed: 12/01/2022] Open
Abstract
[Purpose] This study investigated the optimal thickness of the wheelchair backrest for
lumbar load and increased comfort. [Subjects] Fifteen healthy people participated.
[Methods] The study examined three randomized backrest conditions: no pad; a 3-cm-thick
lumbar pad; and a 6-cm-thick lumbar pad. The location of the lumbar pad was standardized
at the mid-lumbar level (L3). Participants were instructed to propel the wheelchair using
only the handrims. [Results] Activation of the anterior deltoid, upper trapezius, and
biceps brachii muscles was significantly reduced when the participants used the 3-cm pad
compared to no pad, while it was significantly increased in the anterior deltoid, upper
trapezius, posterior deltoid, and biceps brachii when the participants used the 6-cm pad
compared to the 3-cm pad. Muscle activation did not differ significantly between the no
pad and the 6-cm lumbar pad conditions. [Conclusion] A lumbar pad decreased the activation
of the upper extremity muscles. We believe that padding of the appropriate thickness will
lead to effective muscle activation while propelling a wheelchair and decrease the risk of
musculoskeletal disease.
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Affiliation(s)
- Ingyu Yoo
- Department of Occupational Therapy, College of Medical Sciences, Jeonju University, Republic of Korea
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The effect of a newly developed wheelchair with thoracic and pelvic support on cervical movement and muscle activity in healthy elderly women. Eur Geriatr Med 2015. [DOI: 10.1016/j.eurger.2014.11.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Zemp R, Taylor WR, Lorenzetti S. Are pressure measurements effective in the assessment of office chair comfort/discomfort? A review. APPLIED ERGONOMICS 2015; 48:273-282. [PMID: 25683554 DOI: 10.1016/j.apergo.2014.12.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 09/01/2014] [Accepted: 12/29/2014] [Indexed: 05/29/2023]
Abstract
Nowadays, the majority of jobs in the western world involves sitting in an office chair. As a result, a comfortable and supported sitting position is essential for employees. In the literature, various objective methods (e.g. pressure measurements, measurements of posture, EMG etc.) have been used to assess sitting comfort/discomfort, but their validity remains unknown. This review therefore examines the relationship between subjective comfort/discomfort and pressure measurements while sitting in office chairs. The literature search resulted in eight papers that met all our requirements. Four studies identified a relationship between subjective comfort/discomfort and pressure distribution parameters (including correlations of up to r = 0.7 ± 0.13). However, the technique for evaluating subjective comfort/discomfort seems to play an important role on the results achieved, therefore placing their validity into question. The peak pressure on the seat pan, the pressure distribution on the backrest and the pressure pattern changes (seat pan and backrest) all appear to be reliable measures for quantifying comfort or discomfort.
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Affiliation(s)
- Roland Zemp
- Institute for Biomechanics ETH Zurich, Wolfgang-Pauli Strasse 10, 8093 Zurich, Switzerland.
| | - William R Taylor
- Institute for Biomechanics ETH Zurich, Wolfgang-Pauli Strasse 10, 8093 Zurich, Switzerland
| | - Silvio Lorenzetti
- Institute for Biomechanics ETH Zurich, Wolfgang-Pauli Strasse 10, 8093 Zurich, Switzerland
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Purepong N, Channak S, Boonyong S, Thaveeratitham P, Janwantanakul P. The effect of an acupressure backrest on pain and disability in office workers with chronic low back pain: A randomized, controlled study and patients' preferences. Complement Ther Med 2015; 23:347-55. [PMID: 26051569 DOI: 10.1016/j.ctim.2015.03.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Revised: 03/08/2015] [Accepted: 03/10/2015] [Indexed: 12/31/2022] Open
Abstract
OBJECTIVE This study investigated the effects of an acupoint-stimulating lumbar backrest on pain and disability in office workers who suffering from low back pain (LBP) as well as the preference influence on pain and disability. METHODS Sixty-four participants were randomly assigned to two groups: one with no intervention (n=32) and another with 1 month of backrest use (n=32). An additional group (n=37) who wished to try 1 month of acupressure backrest were recruited to indicate the preference effect. Pain and disability were two key outcomes. RESULTS Significant differences between control and randomized acupressure backrest groups were found at 2 week period for disability and at 4 weeks for pain after the backrest use. Also, significant differences were found in both groups for 3 month period with an increase of the treatment effect on pain and disability. Both control and randomized acupressure backrest groups showed greater improvement in pain and disability scores which were more than the minimal clinically important change (30% improvement for both outcomes). No significant difference was found for pain and disability between the randomized and preferred backrest groups. CONCLUSION These findings suggested 1-month of acupressure backrest use could improve LBP conditions. Preference was not a powerful moderator to the significant treatment effect.
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Affiliation(s)
- Nithima Purepong
- Department of Physical Therapy, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand.
| | - Sirinant Channak
- Department of Physical Therapy, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand.
| | - Sujitra Boonyong
- Department of Physical Therapy, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand.
| | - Premtip Thaveeratitham
- Department of Physical Therapy, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand.
| | - Prawit Janwantanakul
- Department of Physical Therapy, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand.
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Curran M, Dankaerts W, O'Sullivan P, O'Sullivan L, O'Sullivan K. The effect of a backrest and seatpan inclination on sitting discomfort and trunk muscle activation in subjects with extension-related low back pain. ERGONOMICS 2014; 57:733-43. [PMID: 24670078 DOI: 10.1080/00140139.2014.897378] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Few studies have demonstrated that seating modifications reduce low back pain (LBP). One recent study found that a forward-inclined seatpan reduced low back discomfort (LBD), however this was only examined in people with flexion-related LBP. No study has yet investigated its effectiveness among people with extension-related LBP. This crossover study examined 12 subjects with extension-related LBP. Sitting discomfort and surface electromyography of three trunk muscles were recorded during a 10-minute typing task while sitting with two different seatpan inclinations, both with and without a backrest. LBD (p < 0.001) and overall body discomfort (OBD) (p = 0.016) were significantly greater on the forward-inclined seatpan. The backrest did not alter trunk muscle activation or sitting discomfort. The results demonstrate that in a specific subgroup of people with extension-related LBP, increasing forward seatpan inclination significantly increased LBD and OBD. Future research should consider matching ergonomics prescriptions according to the individual presentation of people with LBP.
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Affiliation(s)
- Máire Curran
- a Department of Clinical Therapies, University of Limerick , Limerick , Ireland
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Grondin DE, Triano JJ, Tran S, Soave D. The effect of a lumbar support pillow on lumbar posture and comfort during a prolonged seated task. Chiropr Man Therap 2013; 21:21. [PMID: 23826832 PMCID: PMC3766244 DOI: 10.1186/2045-709x-21-21] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Accepted: 06/05/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Several risk factors exist for the development of low back pain, including prolonged sitting and flexed spinal curvature. Several investigators have studied lumbar support devices and spinal curvatures in sitting, however few have investigated a pain population and reported a quantitative measure of comfort. The purpose of the current project was to determine whether a lumbar support pillow, outfitted with a cut-out to accommodate the bulk of posterior pelvic soft tissue volume, is more effective than a standard chair in promoting a neutral spinal posture and improving subjective and objective measures of comfort in healthy individuals and patients with low back pain. METHODS Twenty eight male participants with and without a history of low back pain sat in a standard office chair and in a chair with the lumbar support pillow for 30 minutes. Lumbar and thoracolumbar postures were measured through electromagnetic markers. Comfort was determined based on the least squares radius of centre of pressure shifting, measured at the buttock-chair interface as well as reported discomfort through visual analog scales. Chair support effects were assessed through ANOVA methods. The study was approved by the Canadian Memorial Chiropractic College research ethics board. RESULTS There was a main effect of condition on lumbar posture (p = 0.006) and thoracolumbar posture (p = 0.014). In the lumbar region, the support and standard chair differed by 2.88° (95% CI; 1.01-4.75), with the lumbar support being closer to neutral than the standard chair. In the thoracolumbar region, the support and standard chair differed by -2.42° (95% CI; -4.22 to -0.62), with the standard chair being closer to neutral than the support device. The centre of pressure measure was significantly improved with the pillow (p = 0.017), however there were no subjective changes in comfort. CONCLUSIONS A lumbar support pillow with a cut-out for the posterior pelvic tissues improved an objective measure of comfort in healthy individuals and patients with low back pain. Lumbar flattening was decreased and thoracolumbar curvature was increased. However, angular changes were small and future work is required to determine clinical relevance over the long term. TRIAL REGISTRATION ClinicalTrials.gov, NCT00754585.
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Affiliation(s)
- Diane E Grondin
- Canadian Memorial Chiropractic College, 6100 Leslie Street, Toronto, ON M2H 3J1, Canada
| | - John J Triano
- Canadian Memorial Chiropractic College, 6100 Leslie Street, Toronto, ON M2H 3J1, Canada
| | - Steve Tran
- Canadian Memorial Chiropractic College, 6100 Leslie Street, Toronto, ON M2H 3J1, Canada
| | - David Soave
- Canadian Memorial Chiropractic College, 6100 Leslie Street, Toronto, ON M2H 3J1, Canada
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Beard GF, Griffin MJ. Discomfort during lateral acceleration: influence of seat cushion and backrest. APPLIED ERGONOMICS 2013; 44:588-594. [PMID: 23312371 DOI: 10.1016/j.apergo.2012.11.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2012] [Revised: 09/27/2012] [Accepted: 11/27/2012] [Indexed: 06/01/2023]
Abstract
Lateral acceleration causes discomfort but how the discomfort depends on the frequency of acceleration or characteristics of seating is poorly understood. Using magnitude estimation, twelve male subjects rated the discomfort caused by lateral oscillation at eight frequencies (0.2-1.0 Hz) across four seating conditions (a rigid seat and a train seat, both with and without backrests). Discomfort increased with increasing frequency of lateral acceleration in a similar manner for all four seating conditions. However, at all frequencies and with both seats there was less discomfort when sitting with backrest support than without. Least discomfort occurred on the train seat with backrest and greatest discomfort on the rigid seat without backrest. Current standards predict an additive effect of backrest on vibration discomfort, but the findings show that low frequency lateral acceleration can cause less discomfort when sitting with a backrest than when sitting on the same seat without a backrest.
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Affiliation(s)
- George F Beard
- Human Factors Research Unit, Institute of Sound and Vibration Research, University of Southampton, Highfield, Southampton, United Kingdom.
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40
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Park S, Yoo W. Effect of EMG‐based Feedback on Posture Correction during Computer Operation. J Occup Health 2013; 54:271-7. [PMID: 22673646 DOI: 10.1539/joh.12-0052-oa] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- Se‐yeon Park
- Department of Physical TherapyThe Graduate School, Inje UniversityRepublic of Korea
| | - Won‐gyu Yoo
- Department of Physical TherapyCollege of Biomedical Science and Engineering and Elderly Life Redesign Institute, Inje UniversityRepublic of Korea
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Karuppiah K, Salit MS, Ismail MY, Ismail N, Tamrin SBM. Evaluation of motorcyclist's discomfort during prolonged riding process with and without lumbar support. AN ACAD BRAS CIENC 2012. [PMID: 23207711 DOI: 10.1590/s0001-37652012000400031] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
OBJECTIVE The primary aim of this study is to examine the effects of a backrest: using a prototype of a lumbar support presented in author's earlier study on the discomfort rating of the body parts of motorcyclist. METHODS One hundred motorcyclists participated in this study, all in good physical condition and with no immediate complaint of musculoskeletal disorders. Each participant was asked to sit for 2 hours on a motorcycle in two different sessions (with and without the lumbar support) in a controlled room environment. At every 15 minutes interval the participants were required to rate their discomfort level on the Borg's CR-10 questionnaire. RESULTS The rate of discomfort level (in all body parts) decreased over time during the testing period with the prototype. In terms of the discomfort 'break point', participants identified low back and upper back as the most affected body parts prior to comfort changes during the testing period with the use of the prototype. CONCLUSIONS The use of this prototype provides a protective mechanism for the motorcyclist's musculoskeletal system, particularly the spinal column. Therefore, this prototype is capable of providing ideal posture while simultaneously enhancing the comfortability of the motorcyclist during the riding process (by reducing discomfort).
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Affiliation(s)
- Karmegam Karuppiah
- Department of Environmental and Occupational Health, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Selangor, Malaysia.
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HOWARD BRADLEY, YANG JINGZHOU. A NEW STABILITY CRITERION FOR HUMAN SEATED TASKS WITH GIVEN POSTURES. INT J HUM ROBOT 2012. [DOI: 10.1142/s0219843612500156] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In digital human modeling (DHM), the analysis of postural stability has five main goals: to determine if a posture is stable or unstable through an explicit criterion; to quantify the level of stability or provide a margin of stability that accounts for the height of the center of mass (COM) above the support plane(s); to be valid in the presence of externally applied forces and moments; be able to assess stability when multiple noncoplanar support planes exist, as is the case with seated postures; and to give insight into the support reaction force (SRF) distribution. To date, there is not a method for analyzing stability that can effectively meet each goal. This paper presents a new stability criterion and stability analysis that accomplishes each intended goal. The stability analysis is derived from the calculation of joint torque using the recursive Lagrangian dynamic formulation. A 56-degree-of-freedom (DOF) articulated digital human model is used to model seated postures to demonstrate the proposed stability criterion. Different given postures with different external load cases are presented.
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Affiliation(s)
- BRADLEY HOWARD
- Department of Mechanical Engineering, Texas Tech University, Lubbock, TX 79409, USA
| | - JINGZHOU YANG
- Department of Mechanical Engineering, Texas Tech University, Lubbock, TX 79409, USA
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Howard B, Cloutier A, Yang J(J. Physics-Based Seated Posture Prediction for Pregnant Women and Validation Considering Ground and Seat Pan Contacts. J Biomech Eng 2012; 134:1475437. [DOI: 10.1115/1.4007006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Indexed: 11/08/2022]
Abstract
An understanding of human seated posture is important across many fields of scientific research. Certain demographics, such as pregnant women, have special postural limitations that need to be considered. Physics-based posture prediction is a tool in which seated postures can be quickly and thoroughly analyzed, as long the predicted postures are realistic. This paper proposes and validates an optimization formulation to predict seated posture for pregnant women considering ground and seat pan contacts. For the optimization formulation, the design variables are joint angles (posture); the cost function is dependent on joint torques. Constraints include joint limits, joint torque limits, the distances from the end-effectors to target points, and self-collision avoidance constraints. Three different joint torque cost functions have been investigated to account for the special postural characteristics of pregnant women and consider the support reaction forces (SRFs) associated with seated posture. Postures are predicted for three different reaching tasks in common reaching directions using each of the objective function formulations. The predicted postures are validated against experimental postures obtained using motion capture. A linear regression analysis was used to evaluate the validity of the predicted postures and was the criteria for comparison between the different objective functions. A 56 degree of freedom model was used for the posture prediction. Use of the objective function minimizing the maximum normalized joint torque provided an R2 value of 0.828, proving superior to either of two alternative functions.
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Affiliation(s)
- Bradley Howard
- Human-Centric Design Research Laboratory, Department of Mechanical Engineering, Texas Tech University, Lubbock, TX, 79409
| | - Aimee Cloutier
- Human-Centric Design Research Laboratory, Department of Mechanical Engineering, Texas Tech University, Lubbock, TX, 79409
| | - Jingzhou (James) Yang
- Human-Centric Design Research Laboratory, Department of Mechanical Engineering, Texas Tech University, Lubbock, TX, 79409
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Dynamics of Seated Computer Work Before and After Prolonged Constrained Sitting. J Appl Biomech 2012; 28:297-303. [DOI: 10.1123/jab.28.3.297] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
This laboratory study investigated seated computer work before and after prolonged constrained sitting. Discomfort ratings and kinetic and kinematics data were recorded in nine healthy males performing computer work for 5 min before and after 96 min of sitting. The displacement of the center of pressure (CoP) in anterior-posterior and medial-lateral directions and lumbar curvature (LC) were calculated. The root mean square, standard deviation, and sample entropy values were computed from the CoPs and LC signals to assess the magnitude, amount of variability, and regularity of sitting dynamics, respectively. The discomfort increased for the buttocks (p= .02).The standard deviation and sample entropy values of the CoPs and LC signals, respectively, increased (p< .04) and decreased (p< .004) whereas the root mean square remained unchanged (p> .15) after prolonged constrained sitting compared with before. This present study showed that during seated computer work, prolonged constrained sitting affected the amount of variability and the regularity of sitting postural control, whereas the magnitude was not affected. The importance of the dynamics of sitting control may challenge the idea of a static and ideal seated posture at work.
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Groenesteijn L, Ellegast RP, Keller K, Krause F, Berger H, de Looze MP. Office task effects on comfort and body dynamics in five dynamic office chairs. APPLIED ERGONOMICS 2012; 43:320-8. [PMID: 21718963 DOI: 10.1016/j.apergo.2011.06.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Accepted: 05/31/2011] [Indexed: 05/23/2023]
Abstract
In the present study, we investigated the effect of office tasks on posture and movements in field settings, and the comfort rating for chair characteristics and correlation with type of task. The tasks studied were: computer work, telephoning, desk work and conversation. Postures, movements, chair part inclinations and comfort rating data were collected from 12 subjects. Computer work showed the lowest physical activity, together with upright trunk and head position and low backrest inclination. Conversation shows the highest activity of head legs and low back together with the highest cervical spine extension. In contrast, desk work provoked the most cervical spine flexion and showed the second lowest activity. The telephoning tasks showed medium activity and the highest kyphosis. Conversation showed the highest backrest inclination. Positive comfort relations were found for computer work and a "swing system" chair, for telephoning and an active longitudinal seat rotation, and for desk work and a chair with a three-dimensionally moveable seat.
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Affiliation(s)
- Liesbeth Groenesteijn
- Business Unit Work and Employment, TNO Quality of Life, P.O. Box 718, 2130 AS Hoofddorp, The Netherlands.
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Settling down time following initial sitting and its relationship with comfort and discomfort. J Tissue Viability 2011; 20:121-9. [PMID: 21684748 DOI: 10.1016/j.jtv.2011.05.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Accepted: 05/19/2011] [Indexed: 11/23/2022]
Abstract
This study examined the subjective rating of wheelchair comfort and discomfort (numerical rating scale questionnaire) and the duration of objective in-chair movement reduction "settling down time" following initial contact with the seating surface. Healthy young subjects (n = 22) sat for 5 min on contoured foam or wood cushion surfaces fitted to otherwise identical wheelchairs. Force sensing resistors attached to each quadrant of the sitting interface measured the relative movements of the subjects over time. A significant correlation was found between settling down time (SDT) and reported leg/feet discomfort (p = 0.003; correlation co-efficient = 0.44); and a significant negative correlation was found between SDT and overall comfort (p = 0.015; correlation co-efficient = -0.36). When comparing cushion surfaces: SDT was significantly longer (p < 0.0001) for subjects sitting on wood (5.8 s) compared to contoured foam (3.9 s); Leg/feet discomfort was significant higher (p = 0.007) for subjects sitting on wood (1.1 out of 10) compared to contoured foam (0.3 out of 10); Overall discomfort was significant higher (p = 0.009) for subjects sitting on wood (1.3 out of 10) compared to contoured foam (0.5 out of 10); Comfort was significantly lower (p = 0.001) for subjects sitting on wood (6.5 out of 10) compared to contoured foam (8.3 out of 10); Support was significantly lower (p = 0.001) for subjects sitting on wood (6.4 out of 10) compared to contoured foam (8 out of 10). The results of this study suggest that the shape and firmness of the surface at the buttock-wheelchair interface can affect a subject's SDT following initial contact with the seat as well as their perception of comfort and discomfort. In addition, there appears to be a relationship between longer SDT's and increased discomfort ratings, and shorter SDT's and increased comfort ratings. Therefore, testing for SDT's may be useful in the indirect objective assessment of wheelchair cushions and possibly other types of seating surfaces with design differences that aim to improve comfort and minimize discomfort.
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Park SY, Yoo WG. Effects of a Posture-Sensing Air Seat Device (PSASD) on Kinematics and Trunk Muscle Activity during Continuous Computer Work. J Physiol Anthropol 2011; 30:147-51. [DOI: 10.2114/jpa2.30.147] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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Marques NR, Hallal CZ, Gonçalves M. Características biomecânicas, ergonômicas e clínicas da postura sentada: uma revisão. FISIOTERAPIA E PESQUISA 2010. [DOI: 10.1590/s1809-29502010000300015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A posição sentada é a mais adotada nos ambientes de trabalho, na escola e nas atividades de lazer. Porém, a manutenção prolongada dessa posição ocasiona a adoção de posturas inadequadas e sobrecarrega as estruturas do sistema musculoesquelético, o que pode acarretar dor e lesão na coluna lombar. A presente revisão teve como objetivo identificar os fatores biomecânicos, ergonômicos e clínicos envolvidos na sustentação da postura sentada. Para isso, foram consultadas as bases de dados ISI Web of Knowledge, Medline, Pubmed e EBSCO Host, sendo selecionados 72 artigos publicados entre 1965 e 2010. Foi possível identificar que na posição sentada não existe uma postura ideal a ser sustentada, mas algumas posturas são mais recomendadas do que outras, tal como a postura sentada ereta e a postura lordótica. As cadeiras influenciam o padrão da posição sentada: conforme seu design, pode permitir maior variedade de posturas. Modificações na cadeira e a utilização de exercícios para o aumento da resistência muscular e da propriocepção, bem como a reeducação postural, são intervenções úteis para reduzir o impacto causado pela posição sentada prolongada no sistema musculoesquelético.
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Rahmatalla S, Smith R, Meusch J, Xia T, Marler T, Contratto M. A quasi-static discomfort measure in whole-body vibration. INDUSTRIAL HEALTH 2010; 48:645-653. [PMID: 20953081 DOI: 10.2486/indhealth.mswbvi-28] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A new methodology for objective evaluation of discomfort in whole-body vibration (WBV) is introduced in this work. The proposed objective discomfort characterizes discomfort based on the relative motion between adjacent segments of the human body from neutral positions. It peaks when the joints reach their limits. The objective discomfort has been tested on five subjects in the fore-aft direction using discrete sinusoidal frequencies of 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 7, 8, 9, 10, 12, 14, and 16 Hz. Each frequency file runs for 15 s with a 3 s resting period as a reference for discomfort comparison. All files run at a constant acceleration of 0.7 m/s(2). The subjects were tested with back support and without back support, and their subjective discomfort was reported based on the Borg CR-10 scale. The proposed objective discomfort has shown significant correlation with the subjective discomfort. The objective discomfort has also been tested on five subjects under multiple-axis random WBV with three common industrial seating configurations (seat-mounted control, floor-mounted control, and steering wheel), and has shown promising results.
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Affiliation(s)
- Salam Rahmatalla
- Department of Civil and Environmental Engineering, 4121 Seamans Center for Engineering, The University of Iowa, Iowa City, Iowa 52242, USA.
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Telfer S, Spence WD, Solomonidis SE. The potential for actigraphy to be used as an indicator of sitting discomfort. HUMAN FACTORS 2009; 51:694-704. [PMID: 20196294 DOI: 10.1177/0018720809352789] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
OBJECTIVE A novel technique that uses actigraphy, the study of activity involving the use of body-mounted accelerometers, to detect the discomfort-related movements of a sitting individual has been proposed as a potential indicator of sitting discomfort, and the purpose of this study was to test its validity. BACKGROUND Objective measurement of sitting discomfort has always been challenging for researchers. Electromyographic measurements, pressure mapping, and a wide range of other techniques have all been investigated with limited success. METHOD The activity monitor's ability to detect and measure seated movement was assessed, and 12 participants were tested on four different chairs (100-min sessions for each). RESULTS The activity monitor was able to detect participants' sitting movements (Pearson coefficients > 0.9). The chairs were shown to have significantly different subjective discomfort ratings, all of which increased over time. The movements detected by the activity monitor also increased significantly with time, and the amount measured was greater in the chairs rated as most uncomfortable. Regression analysis indicated that the actigraphy data were able to account for 29.6% of the variation in perceived discomfort ratings. CONCLUSION Actigraphy can reliably detect sitting movements and may be of use in measuring sitting discomfort. APPLICATION Potential applications of this technique exist for seating research in the automotive industry, health care, and office and leisure chairs.
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Affiliation(s)
- Scott Telfer
- Bioengineering Unit, University of Strathclyde, Glasgow, United Kingdom.
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