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Astrologo AN, Nano S, Klemm EM, Shefelbine SJ, Dennerlein JT. Determining the effects of AR/VR HMD design parameters (mass and inertia) on cervical spine joint torques. APPLIED ERGONOMICS 2024; 116:104183. [PMID: 38071785 DOI: 10.1016/j.apergo.2023.104183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 10/01/2023] [Accepted: 11/19/2023] [Indexed: 01/16/2024]
Abstract
This study aimed to determine gravitational and dynamic torques and muscle activity of the neck across a series of design parameters of head mounted displays (mass, center of mass, and counterweights) associated with virtual and augmented reality (VR/AR). Twenty young adult participants completed five movement types (Slow and Fast Flexion/Extension and Rotation, and Search) while wearing a custom-designed prototype headset that varied the three design parameters: display mass (0, 200, 500, and 750 g), distance of the display's center of mass in front of the eyes (approximately 1, 3, and 5 cm anteriorly), and counterweights of 0, 166, 332, and 500 g to balance the display mass of 500 g at 7 cm. Inverse dynamics of a link segment model of the head and headset provided estimates of the torques about the joint between the skull and the occiput-first cervical vertebrae (OC1) and joint between the C7 and T1 vertebrae (C7). Surface electromyography (EMG) measured bilateral muscle activity of the splenius and upper trapezius muscles. Adding 750 g of display mass nearly doubled root mean square joint torques across all movement types. Increasing the distance of the display mass in front of the eyes by 4 cm increased torques about OC1 for the Slow and Fast Rotation and Search movements by approximately 20%. Adding a counterweight decreased torques about OC1 during the rotation and search tasks but did not decrease the torques experienced in the lower cervical spine (C7). For the flexion/extension axis, the magnitude of the dynamic torque component was 20% or less of the total torque experienced whereas for the rotation axis the magnitude of the dynamic torque component was greater than 50% of the total torque. Surface EMG root mean square values significantly varied across movement types with the fast rotation having the largest values; however, they did not vary significantly across the headset configurations.
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Affiliation(s)
| | - Sarah Nano
- Department of Bioengineering, Northeastern University, Boston, MA, USA
| | - Elizabeth M Klemm
- Department of Bioengineering, Northeastern University, Boston, MA, USA
| | - Sandra J Shefelbine
- Department of Bioengineering, Northeastern University, Boston, MA, USA; Department of Mechanical & Industrial Engineering, Northeastern University, Boston, MA, USA
| | - Jack T Dennerlein
- Sargent College of Health and Rehabilitation Sciences, Boston University, Boston, MA, USA.
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2
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Hadagali P, Fischer SL, Callaghan JP, Cronin DS. Quantifying the Importance of Active Muscle Repositioning a Finite Element Neck Model in Flexion Using Kinematic, Kinetic, and Tissue-Level Responses. Ann Biomed Eng 2024; 52:510-525. [PMID: 37923814 DOI: 10.1007/s10439-023-03396-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Accepted: 10/24/2023] [Indexed: 11/06/2023]
Abstract
PURPOSE Non-neutral neck positions are important initial conditions in impact scenarios, associated with a higher incidence of injury. Repositioning in finite element (FE) neck models is often achieved by applying external boundary conditions (BCs) to the head while constraining the first thoracic vertebra (T1). However, in vivo, neck muscles contract to achieve a desired head and neck position generating initial loads and deformations in the tissues. In the present study, a new muscle-based repositioning method was compared to traditional applied BCs using a contemporary FE neck model for forward head flexion of 30°. METHODS For the BC method, an external moment (2.6 Nm) was applied to the head with T1 fixed, while for the muscle-based method, the flexors and extensors were co-contracted under gravity loading to achieve the target flexion. RESULTS The kinematic response from muscle contraction was within 10% of the in vivo experimental data, while the BC method differed by 18%. The intervertebral disc forces from muscle contraction were agreeable with the literature (167 N compression, 12 N shear), while the BC methodology underpredicted the disc forces owing to the lack of spine compression. Correspondingly, the strains in the annulus fibrosus increased by an average of 60% across all levels due to muscle contraction compared to BC method. CONCLUSION The muscle repositioning method enhanced the kinetic response and subsequently led to differences in tissue-level responses compared to the conventional BC method. The improved kinematics and kinetics quantify the importance of repositioning FE neck models using active muscles to achieve non-neutral neck positions.
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Affiliation(s)
- Prasannaah Hadagali
- Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada
| | - Steven L Fischer
- Kinesiology and Health Sciences, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada
| | - Jack P Callaghan
- Kinesiology and Health Sciences, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada
| | - Duane S Cronin
- Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada.
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3
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Kim E, Song D, Park D, Kim H, Shin G. Effect of smartphone use on cervical spine stability. J Biomech 2024; 166:112053. [PMID: 38513400 DOI: 10.1016/j.jbiomech.2024.112053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 03/13/2024] [Accepted: 03/17/2024] [Indexed: 03/23/2024]
Abstract
Using a smartphone often involves a sustained head-forward tilt posture, which may deteriorate the mechanism of muscle reaction efficiency or reduce the stiffness of connective tissues of the cervical spine. These changes in muscular and connective tissues can impair cervical spine stability and contribute to developing neck pain symptoms. In this experiment, change in the cervical spine stability associated with a sustained smartphone use posture was evaluated by quantifying the effective stiffness and the reflexive responses of the head to sudden perturbations. Seventeen young smartphone users maintained their heads tilted forward approximately 30° for 30 min while watching videos on their smartphones in sitting. Data show that the measures of cervical spine stability did not change significantly after the smartphone use task despite developing mild to moderate neck and upper body discomfort symptoms. Study findings imply that keeping the head tilt posture for 30 min for smartphone use did not significantly alter spinal stability, rejecting its association with neck discomfort.
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Affiliation(s)
- Eunjee Kim
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea.
| | - Donghyun Song
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Dasom Park
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Hyorim Kim
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Gwanseob Shin
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
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4
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Wang L, Yu S, Chen D, Li W, Chu J, Fan H. Effects of aircraft tray table height and neck posture on passenger comfort: A study of the economy class cabin. Work 2022; 75:287-302. [PMID: 36591679 DOI: 10.3233/wor-220043] [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: 12/29/2022] Open
Abstract
BACKGROUND The tray table in economy class air travel may cause excessive neck flexion and discomfort in passengers. OBJECTIVE The purpose of this study is to examine the influence of different tray table heights on the neck posture and discomfort perception of passengers. METHODS A passenger experience survey was used to determine the passengers' view that the tray table was not high enough, and that most passengers were dissatisfied with the overall comfort evaluation of the tray table, especially passengers with obesity. Three head-neck angles and discomfort perceptions of six body parts in 58 participants were recorded by neck posture 3D scanning and perceived level of discomfort assessment, respectively. RESULTS Tray tables at the original height (68 cm) caused unnatural neck posture and discomfort in participants. Raising the tray table can improve the neck posture of participants and reduce discomfort. However, raising the tray table too high will cause more shoulder discomfort in participants. Based on the results, 78 (±2) cm is suggested as the suitable thresholds range of tray tables for economy class air travel. CONCLUSION The results and findings of this study could provide a theoretical base for the optimization of tray table design.
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Affiliation(s)
- Long Wang
- Key Laboratory of Industrial Design and Ergonomics, Ministry of Industry and Information Technology, Xi'an, Shaanxi, China.,Shaanxi Engineering Laboratory for Industrial Design, Northwestern Polytechnical University, Xi'an, Shaanxi, China
| | - Suihuai Yu
- Key Laboratory of Industrial Design and Ergonomics, Ministry of Industry and Information Technology, Xi'an, Shaanxi, China.,Shaanxi Engineering Laboratory for Industrial Design, Northwestern Polytechnical University, Xi'an, Shaanxi, China
| | - Dengkai Chen
- Key Laboratory of Industrial Design and Ergonomics, Ministry of Industry and Information Technology, Xi'an, Shaanxi, China.,Shaanxi Engineering Laboratory for Industrial Design, Northwestern Polytechnical University, Xi'an, Shaanxi, China
| | - Wenhua Li
- Key Laboratory of Industrial Design and Ergonomics, Ministry of Industry and Information Technology, Xi'an, Shaanxi, China.,Shaanxi Engineering Laboratory for Industrial Design, Northwestern Polytechnical University, Xi'an, Shaanxi, China
| | - Jianjie Chu
- Key Laboratory of Industrial Design and Ergonomics, Ministry of Industry and Information Technology, Xi'an, Shaanxi, China.,Shaanxi Engineering Laboratory for Industrial Design, Northwestern Polytechnical University, Xi'an, Shaanxi, China
| | - Hao Fan
- Key Laboratory of Industrial Design and Ergonomics, Ministry of Industry and Information Technology, Xi'an, Shaanxi, China.,Shaanxi Engineering Laboratory for Industrial Design, Northwestern Polytechnical University, Xi'an, Shaanxi, China
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5
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Lee R, James C, Edwards S, Skinner G, Young JL, Snodgrass SJ. Evidence for the Effectiveness of Feedback from Wearable Inertial Sensors during Work-Related Activities: A Scoping Review. SENSORS (BASEL, SWITZERLAND) 2021; 21:6377. [PMID: 34640695 PMCID: PMC8512480 DOI: 10.3390/s21196377] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 09/16/2021] [Accepted: 09/18/2021] [Indexed: 01/03/2023]
Abstract
Background: Wearable inertial sensor technology (WIST) systems provide feedback, aiming to modify aberrant postures and movements. The literature on the effects of feedback from WIST during work or work-related activities has not been previously summarised. This review examines the effectiveness of feedback on upper body kinematics during work or work-related activities, along with the wearability and a quantification of the kinematics of the related device. Methods: The Cinahl, Cochrane, Embase, Medline, Scopus, Sportdiscus and Google Scholar databases were searched, including reports from January 2005 to July 2021. The included studies were summarised descriptively and the evidence was assessed. Results: Fourteen included studies demonstrated a 'limited' level of evidence supporting posture and/or movement behaviour improvements using WIST feedback, with no improvements in pain. One study assessed wearability and another two investigated comfort. Studies used tri-axial accelerometers or IMU integration (n = 5 studies). Visual and/or vibrotactile feedback was mostly used. Most studies had a risk of bias, lacked detail for methodological reproducibility and displayed inconsistent reporting of sensor technology, with validation provided only in one study. Thus, we have proposed a minimum 'Technology and Design Checklist' for reporting. Conclusions: Our findings suggest that WIST may improve posture, though not pain; however, the quality of the studies limits the strength of this conclusion. Wearability evaluations are needed for the translation of WIST outcomes. Minimum reporting standards for WIST should be followed to ensure methodological reproducibility.
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Affiliation(s)
- Roger Lee
- School of Health Sciences, The University of Newcastle, Newcastle 2308, Australia; (C.J.); (S.J.S.)
- Centre for Brain and Mental Health Research, The University of Newcastle, Newcastle 2308, Australia
| | - Carole James
- School of Health Sciences, The University of Newcastle, Newcastle 2308, Australia; (C.J.); (S.J.S.)
- Centre for Resources Health and Safety, The University of Newcastle, Newcastle 2308, Australia
| | - Suzi Edwards
- School of Health Sciences, The University of Sydney, Sydney 2006, Australia;
| | - Geoff Skinner
- School of Information and Physical Sciences, The University of Newcastle, Newcastle 2308, Australia;
| | - Jodi L. Young
- Department of Physical Therapy, Bellin College, Green Bay, WI 54311, USA;
| | - Suzanne J. Snodgrass
- School of Health Sciences, The University of Newcastle, Newcastle 2308, Australia; (C.J.); (S.J.S.)
- Centre for Brain and Mental Health Research, The University of Newcastle, Newcastle 2308, Australia
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Tapanya W, Puntumetakul R, Neubert MS, Hunsawong T, Boucaut R. Ergonomic arm support prototype device for smartphone users reduces neck and shoulder musculoskeletal loading and fatigue. APPLIED ERGONOMICS 2021; 95:103458. [PMID: 33991854 DOI: 10.1016/j.apergo.2021.103458] [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: 11/05/2020] [Revised: 04/15/2021] [Accepted: 04/29/2021] [Indexed: 06/12/2023]
Abstract
Smartphone use is a risk factor for both neck and shoulder musculoskeletal disorders. The objective of this study was to evaluate an ergonomic arm support prototype device, which may help improve posture while using a smartphone, by determining its effect on muscle activity, muscle fatigue, and neck and shoulder discomfort. Twenty-four healthy young adult smartphone users performed 20 min of smartphone game playing under two different conditions, smartphone use with support prototype device (i.e. intervention condition) and without (i.e. control condition), while neck and shoulder posture were controlled at 0° neck flexion and 30° shoulder flexion. Activity and fatigue of four muscles were measured using surface electromyography (sEMG), these were: anterior deltoid (AD), cervical erector spinae (CES), upper trapezius (UT) and lower trapezius (LT). The intervention condition showed significantly decreased activity of all muscles. Fatigue of all muscles, except LT, significantly increased over time compared to the start point in the control condition. There was no significant difference in muscle fatigue between each time point in the intervention condition. In conclusion, the ergonomic arm support prototype device can be used as ergonomic intervention to reduce neck and shoulder muscle loading and fatigue.
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Affiliation(s)
- Weerasak Tapanya
- Research Center in Back, Neck, Other Joint Pain and Human Performance, Khon Kaen University, Khon Kaen, Thailand; School of Physical Therapy, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand
| | - Rungthip Puntumetakul
- Research Center in Back, Neck, Other Joint Pain and Human Performance, Khon Kaen University, Khon Kaen, Thailand; School of Physical Therapy, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand.
| | - Manida Swangnetr Neubert
- Research Center in Back, Neck, Other Joint Pain and Human Performance, Khon Kaen University, Khon Kaen, Thailand; Program of Production Technology, Faculty of Technology, Khon Kaen University, Khon Kaen, Thailand
| | - Torkamol Hunsawong
- Research Center in Back, Neck, Other Joint Pain and Human Performance, Khon Kaen University, Khon Kaen, Thailand; School of Physical Therapy, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand
| | - Rose Boucaut
- University of South Australia: Allied Health and Human Performance, iCAHE (International Centre for Allied Health Evidence), Adelaide, Australia
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7
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Tapanya W, Puntumetakul R, Swangnetr Neubert M, Boucaut R. Influence of neck flexion angle on gravitational moment and neck muscle activity when using a smartphone while standing. ERGONOMICS 2021; 64:900-911. [PMID: 33428546 DOI: 10.1080/00140139.2021.1873423] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 12/15/2020] [Indexed: 06/12/2023]
Abstract
This study compares the effects of different neck flexion angles on neck gravitational moment and muscle activity of users that stand and operate a smartphone. Thirty-two healthy young adult smartphone users performed texting tasks for three minutes at four different neck flexion angles (0°, 15°, 30°, and 45°) while standing. Neck gravitational moment and cervical erector spinae (CES) and upper trapezius (UT) activity were investigated. When the neck flexion angle increased, the gravitational moment of the neck increased significantly. The muscle activity of CES significantly increased when the neck flexion angle increased, whereas that of UT decreased. The lowest gravitational moment of the neck at 0° flexion was consistent with the lowest CES muscle activity and the lowest neck discomfort score. In conclusion, for texting while standing, adults should maintain their neck posture at 0° flexion to reduce the gravitational force acting on the cervical spine and alleviate neck discomfort. Practitioner Summary: During smartphone use when standing, excessive neck flexion (30° and 45° flexion) should be avoided. The suggested neck posture when operating a smartphone while standing is 0° flexion. Abbreviations: CES: cervical erector spinae; UT: upper trapezius; COG: centre of gravity; MSDs: musculoskeletal disorders; CROM: cervical range of motion; sEMG: surface electromyography; VAS: visual analogue scale; MVCs: maximum voluntary contractions.
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Affiliation(s)
- Weerasak Tapanya
- School of Physical Therapy, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand
- Research Center in Back, Neck, Other Joint Pain and Human Performance (BNOJPH), Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand
| | - Rungthip Puntumetakul
- School of Physical Therapy, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand
- Research Center in Back, Neck, Other Joint Pain and Human Performance (BNOJPH), Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand
| | - Manida Swangnetr Neubert
- Research Center in Back, Neck, Other Joint Pain and Human Performance (BNOJPH), Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand
- Department of Production Technology, Faculty of Technology, Khon Kaen University, Khon Kaen, Thailand
| | - Rose Boucaut
- University of South Australia: Allied Health and Human Performance, iCAHE (International Centre for Allied Health Evidence), Adelaide, Australia
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8
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Jun D, Johnston V, McPhail SM, O'Leary S. A Longitudinal Evaluation of Risk Factors and Interactions for the Development of Nonspecific Neck Pain in Office Workers in Two Cultures. HUMAN FACTORS 2021; 63:663-683. [PMID: 32119582 DOI: 10.1177/0018720820904231] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
OBJECTIVE To identify risk factors for the development of interfering neck pain in office workers including an examination of the interaction effects between potential risk factors. BACKGROUND The 1-year incidence of neck pain in office workers is reported as the highest of all occupations. Identifying risk factors for the development of neck pain in office workers is therefore a priority to direct prevention strategies. METHODS Participants included 214 office workers without neck pain from two cultures. A battery of measures evaluating potential individual and workplace risk factors were administered at baseline, and the incidence of interfering neck pain assessed monthly for 12 months. Survival analysis was used to identify relationships between risk factors and the development of interfering neck pain. RESULTS One-year incidence was 1.93 (95% CI [1.41, 2.64]) per 100 person months. Factors increasing the risk of developing interfering neck pain were older age, female gender, increased sitting hours, higher job strain, and stress. A neutral thorax sitting posture, greater cervical range of motion and muscle endurance, and higher physical activity were associated with a decreased risk of neck pain. The effects of some risk factors on the development of neck pain were moderated by the workers' coping resources. CONCLUSION Multiple risk factors and interactions may explain the development of neck pain in office workers. Therefore, plans for preventing the development of interfering neck pain in office workers should consider multiple individual and work-related factors with some factors being potentially more modifiable than others.
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Affiliation(s)
- Deokhoon Jun
- 1974 The University of Queensland, Brisbane, Australia
| | | | - Steven M McPhail
- 1969 Queensland University of Technology, Brisbane, Australia
- Metro South Health, Brisbane, Australia
| | - Shaun O'Leary
- 1974 The University of Queensland, Brisbane, Australia
- Royal Brisbane and Women's Hospital, Australia
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9
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König M, Haensel C, Jaschinski W. How to place the computer monitor: measurements of vertical zones of clear vision with presbyopic corrections. Clin Exp Optom 2021; 98:244-53. [DOI: 10.1111/cxo.12274] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 10/23/2014] [Accepted: 11/25/2014] [Indexed: 11/28/2022] Open
Affiliation(s)
- Mirjam König
- Leibniz Research Centre for Working Environment and Human Factors, Dortmund, Germany
| | - Claudia Haensel
- Leibniz Research Centre for Working Environment and Human Factors, Dortmund, Germany
| | - Wolfgang Jaschinski
- Leibniz Research Centre for Working Environment and Human Factors, Dortmund, Germany
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10
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Mingels S, Dankaerts W, van Etten L, Bruckers L, Granitzer M. Lower spinal postural variability during laptop-work in subjects with cervicogenic headache compared to healthy controls. Sci Rep 2021; 11:5159. [PMID: 33664350 PMCID: PMC7933416 DOI: 10.1038/s41598-021-84457-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 02/15/2021] [Indexed: 11/12/2022] Open
Abstract
Spinal postural variability (SPV) is a prerequisite to prevent musculoskeletal complaints during functional tasks. Our objective was to evaluate SPV in cervicogenic headache (CeH) since CeH is characterized by such complaints. A non-randomized repeated-measure design was applied to compare SPV between 18 participants with reporting CeH aged 29–51 years, and 18 matched controls aged 26–52 years during a 30-min-laptop-task. Habitual spinal postures (degrees) of the cervical, thoracic and lumbar spine were analysed using 3D-Vicon motion analysis. SPV, to express variation in mean habitual spinal posture, was deducted from the postural analysis. Mean SPV of each spinal segment was lower in the CeH-group compared to the control-group. Within the CeH-group, SPV of all except one spinal segment (lower-lumbar) was higher compared to the group’s mean SPV. Within the control-group, SPV was more comparable to the group’s mean SPV. SPV differed between groups. Averaging data resulted in decreased SPV in the CeH-group compared to the control-group during the laptop-task. However, the higher within-group-SPV in the CeH-group compared to the group’s mean SPV accentuated more postural heterogeneity. It should be further determined if addressing individual SPV is a relevant intervention.
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Affiliation(s)
- Sarah Mingels
- REVAL Rehabilitation Research Centre, Biomedical Research Institute, Faculty of Rehabilitation Sciences, Hasselt University, 3500, Hasselt, Belgium. .,Musculoskeletal Research Unit, Department of Rehabilitation Sciences, Faculty of Kinesiology and Rehabilitation Sciences, Leuven University, 3000, Leuven, Belgium.
| | - Wim Dankaerts
- Musculoskeletal Research Unit, Department of Rehabilitation Sciences, Faculty of Kinesiology and Rehabilitation Sciences, Leuven University, 3000, Leuven, Belgium
| | - Ludo van Etten
- Department of Biometrics, Zuyd Hogeschool, 6419, Heerlen, The Netherlands
| | - Liesbeth Bruckers
- Interuniversity Institute for Biostatistics and Statistical Bioinformatics, Hasselt University, 3500, Hasselt, Belgium
| | - Marita Granitzer
- REVAL Rehabilitation Research Centre, Biomedical Research Institute, Faculty of Rehabilitation Sciences, Hasselt University, 3500, Hasselt, Belgium
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11
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Adachi G, Oshikawa T, Akuzawa H, Kaneoka K. Differences in the activity of the shoulder girdle and lower back muscles owing to postural alteration while using a smartphone. THE JOURNAL OF MEDICAL INVESTIGATION 2020; 67:274-279. [PMID: 33148901 DOI: 10.2152/jmi.67.274] [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: 11/14/2022]
Abstract
The purpose of this study was to clarify the influence of different postures on the activity of the shoulder girdle and lower back muscles while using a smartphone. Sixteen healthy male participants maintained two postures while using a smartphone : a good posture in which the tragus and acromion were closer to the vertical line passing through the greater trochanter, and a poor posture in which the tragus and acromion were farther from the vertical line passing through the greater trochanter. The target muscles were the rhomboid major (Rhom), upper trapezius, middle trapezius, lower trapezius (LT), lumbar erector spinae (LES), and lumbar multifidus (LMF). The activities of the Rhom and LT were significantly lower with poor posture than those with good posture. The activities of LES and LMF were significantly higher with poor posture than those with good posture. The results of this study indicated that poor posture was associated with hypoactivity of the shoulder girdle muscles and hyperactivity of the lower back muscles when compared with good posture. Poor posture for prolonged periods while using a smartphone would lead to malfunction of the shoulder girdle muscles and musculofascial lower back pain. J. Med. Invest. 67 : 274-279, August, 2020.
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Affiliation(s)
- Gen Adachi
- Graduate School of Sport Sciences, Waseda University, Saitama, Japan.,Baseball & Sports Clinic, Kanagawa, Japan
| | - Tomoki Oshikawa
- Graduate School of Sport Sciences, Waseda University, Saitama, Japan
| | - Hiroshi Akuzawa
- Faculty of Sport Sciences, Waseda University, Saitama, Japan
| | - Koji Kaneoka
- Faculty of Sport Sciences, Waseda University, Saitama, Japan
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12
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Penumudi SA, Kuppam VA, Kim JH, Hwang J. The effects of target location on musculoskeletal load, task performance, and subjective discomfort during virtual reality interactions. APPLIED ERGONOMICS 2020; 84:103010. [PMID: 31785450 DOI: 10.1016/j.apergo.2019.103010] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 10/01/2019] [Accepted: 11/22/2019] [Indexed: 06/10/2023]
Abstract
The objective of this study was to evaluate the effect of different target locations on musculoskeletal loading and task performance during virtual reality (VR) interactions. A repeated-measures laboratory study with 20 participants (24.2 ± 1.5 years; 10 males) was conducted to compare biomechanical exposures (joint angle, moment, and muscle activity in the neck and shoulder), subjective discomfort, and task performance (speed and accuracy) during two VR tasks (omni-directional pointing and painting tasks) among different vertical target locations (ranged from 15° above to 30° below eye height). The results showed that neck flexion/extension angle and moment, shoulder flexion angle and moment, shoulder abduction angle, muscle activities of neck and shoulder muscles, and subjective discomfort in the neck and shoulder significantly varied by target locations (p's < 0.001). The target locations at 15° above and 30° below eye height demonstrated greater shoulder flexion (up to 52°), neck flexion moment (up to 2.7Nm), anterior deltoid muscle activity, and subjective discomfort in the neck and shoulder as compared to the other locations. This result indicates that excessive vertical target locations should be avoided to reduce musculoskeletal discomfort and injury risks during VR interactions. Based on relatively lower biomechanical exposures and trade-off between neck and shoulder postures, vertical target location between eye height and 15° below eye height could be recommended for VR use.
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Affiliation(s)
- Sai Akhil Penumudi
- Department of Industrial and Systems Engineering, Northern Illinois University, DeKalb, IL, USA
| | - Veera Aneesh Kuppam
- Department of Industrial and Systems Engineering, Northern Illinois University, DeKalb, IL, USA
| | - Jeong Ho Kim
- School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, USA
| | - Jaejin Hwang
- Department of Industrial and Systems Engineering, Northern Illinois University, DeKalb, IL, USA.
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13
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Jin S, Kim J, Kim D. The effect of tablet use on trunk posture while sitting. Work 2020; 65:581-589. [DOI: 10.3233/wor-203112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Sangeun Jin
- Department of Industrial Engineering, The Human and Safety Engineering Laboratory, Pusan National University, Busan, Republic of Korea
| | - Jaehyuk Kim
- Department of Industrial Engineering, The Human and Safety Engineering Laboratory, Pusan National University, Busan, Republic of Korea
| | - Daemin Kim
- The Human Mechatronics Engineering Laboratory, Division of Mechatronics Engineering, Dongseo University, Busan, Republic of Korea
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Barrett JM, McKinnon C, Callaghan JP. Cervical spine joint loading with neck flexion. ERGONOMICS 2020; 63:101-108. [PMID: 31594480 DOI: 10.1080/00140139.2019.1677944] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 08/26/2019] [Indexed: 06/10/2023]
Abstract
Cervical spine flexion is a common posture for those using computers, tablets, and smartphones; the latter being dubbed 'text-neck' in recent years. Coincidentally, flexion has been flagged as a significant mechanical risk factor for the development of chronic neck pain. Unfortunately, few modelling endeavours have attempted to quantify the intervertebral joint loads throughout the cervical spine in flexion, while still accounting for muscular activation. Eight healthy male subjects undertook five trials beginning in a neutral posture, flexed to 45 degrees, and returned to a neutral posture. 3 D head-trunk angles and surface electromyography from 10 neck muscles (5 bilaterally) were used as inputs into an inverse dynamic cervical spine model based on a 50th percentile male to compute the compression and anteroposterior (AP) shear forces for this flexion task. In general, compression increases cranially to caudally throughout the cervical spine, but levels off at the C5-C6 level. Conversely, in a neutral posture, there is a constant 18 N of anterior shear at each joint level. Compression increased twofold throughout the cervical spine with flexion, whereas anterior shear increased fourfold in the upper cervical spine and dramatically decreased caudally. The dramatic change in joint kinetics provides some mechanical evidence for the role of posture and interplay with muscle activity in the development of chronic neck pain. Results from this study can reinforce the need for appropriate workstation and monitor configurations and support the increased loading hypothesised to occur in 'text neck' postures. Practitioner summary: The purpose of this investigation was to quantify the compression and shear forces in the neck in 45 degrees of flexion compared to neutral. Flexion increased compression throughout the cervical spine 1.6-fold compared to a neutral posture. In the upper cervical spine, AP-shear increased four-fold compared to neutral. Abbreviation: AP: anteroposterior.
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Affiliation(s)
| | - Colin McKinnon
- Department of Kinesiology, University of Waterloo, Waterloo, Canada
| | - Jack P Callaghan
- Department of Kinesiology, University of Waterloo, Waterloo, Canada
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15
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Yu Z, He D, Xiong J, Pan Z, Feng L, Xu J, Han Z, Gragnaniello C, Koga H, Phan K, Azimi P, Lee JJ, Ha Y, Cao K. Extensor muscle-preserving laminectomy in treating multilevel cervical spondylotic myelopathy compared with laminoplasty. ANNALS OF TRANSLATIONAL MEDICINE 2019; 7:472. [PMID: 31700908 DOI: 10.21037/atm.2019.08.17] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Background Laminectomy and laminoplasty are popularly used in posterior cervical spine surgery but still have involved complications. We aimed to compare the clinical outcomes of microscope-assisted extensor muscle-preserving laminectomy (MA-EMPL) and open-door laminoplasty (ODLP) in treating multilevel cervical spondylotic myelopathy (MCSM). Methods A prospective study was designed to enroll twenty patients with MCSM underwent MA-EMPL, and recruit twenty-four patients with MCSM received ODLP (control). Radiographic measurements, outcome indicators including Japanese Orthopedic Association (JOA) score and visual analogue score (VAS) were used to evaluate technical effectiveness. Surgical complications were documented to assess technical safety. Results Postoperative cervical curvature index and range of neck motion (ROM) were not significantly changed except ROM in ODLP group. Postoperative JOA score and VAS in both groups showed improvements at final follow-up. There was no statistical difference in postoperative neurological recovery rates between two groups (67.6%±17.8% vs. 70.15%±19.6%, P=0.632). However, VAS was significantly lower at postoperative 1 month in MA-EMPL group compared with ODLP group (P<0.001). The incidences of C5 palsy were 0 vs. 16.7% between MA-EMPL group and ODLP group. There was no axial symptom occurred in MA-EMPL group while six patients in ODLP group (0 vs. 25%, P=0.049). In addition, the mean blood loss and hospital stay were lesser in MA-EMPL group compared with ODLP group (P<0.001, P=0.002, respectively). Conclusions MA-EMPL is an effective, safe and minimally invasive method in treatment of MCSM. Compared with ODLP, MA-EMPL has advantage to decrease intraoperative blood loss, hospital stay, postoperative VAS and axial symptom, as well as preserve postoperative ROM.
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Affiliation(s)
- Zhiming Yu
- Spine Center, the Second Affiliated Hospital of Nanchang University, Nanchang 330006, China
| | - Da He
- Department of Spine Surgery, Beijing Jishuitan Hospital, Fourth Clinical College of Peking University, Beijing 100035, China
| | - Jiachao Xiong
- Spine Center, the Second Affiliated Hospital of Nanchang University, Nanchang 330006, China
| | - Zhimin Pan
- Spine Center, the Second Affiliated Hospital of Nanchang University, Nanchang 330006, China.,Department of Neurosurgery, Spine and Spinal Cord Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Lingxuan Feng
- Spine Center, the Second Affiliated Hospital of Nanchang University, Nanchang 330006, China
| | - Jiang Xu
- Spine Center, the Second Affiliated Hospital of Nanchang University, Nanchang 330006, China
| | - Zhimin Han
- Department of Orthopaedics, the First Affiliated Hospital of Nanchang University, Nanchang 330006, China
| | | | - Hisashi Koga
- Department of Orthopaedics, Iwai Orthopaedic Medical Hospital, Tokyo, Japan
| | - Kevin Phan
- NeuroSpine Surgery Research Group (NSURG); Prince of Wales Clinical School, University of New South Wales, Sydney, Australia
| | - Parisa Azimi
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.,Functional Neurosurgery Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Jong-Joo Lee
- Department of Neurosurgery, Bundang Jesaeng Hospital, Seongnam, Korea
| | - Yoon Ha
- Department of Neurosurgery, Spine and Spinal Cord Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Kai Cao
- Spine Center, the Second Affiliated Hospital of Nanchang University, Nanchang 330006, China
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Oakman J, Stuckey R, Kinsman N. Using evidence to support the design of submarine control console workstations. APPLIED ERGONOMICS 2019; 79:54-65. [PMID: 31109462 DOI: 10.1016/j.apergo.2019.04.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 04/01/2019] [Accepted: 04/14/2019] [Indexed: 06/09/2023]
Abstract
PURPOSE This paper outlines an approach to develop practical guidelines to support the design of submarine control console workstations. METHOD Guideline development was undertaken for 13 physical design criteria, provided to the research team. Data was gathered from four sources: a systematic literature review, relevant standards, population specific anthropometric data, and user focus groups. The systematic review included risk of bias, quality assessment and evidence synthesis. RESULTS & CONCLUSION The systematic review retrieved 43 relevant articles in relation to seven of the 13 design criteria. Very few high-quality studies were identified. The combined evidence available from each of the four data sources was collated and used to provide a set of guidelines for each of the 13 criteria, highlighting the importance of the use of multiple data sources. This approach has applicability beyond this study where the need exists to collate evidence sources beyond the scientific literature.
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Affiliation(s)
- Jodi Oakman
- Centre for Ergonomics, and Human Factors, School of Psychology and Public Health, College of Science, Health and Engineering, La Trobe University, Bundoora, VIC, 3083, Australia.
| | - Rwth Stuckey
- Centre for Ergonomics, and Human Factors, School of Psychology and Public Health, College of Science, Health and Engineering, La Trobe University, Bundoora, VIC, 3083, Australia
| | - Natasha Kinsman
- Centre for Ergonomics, and Human Factors, School of Psychology and Public Health, College of Science, Health and Engineering, La Trobe University, Bundoora, VIC, 3083, Australia
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17
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Ailneni RC, Syamala KR, Kim IS, Hwang J. Influence of the wearable posture correction sensor on head and neck posture: Sitting and standing workstations. Work 2019; 62:27-35. [PMID: 30741711 DOI: 10.3233/wor-182839] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Flexed head and neck postures are associated with the development of neck pain in the office environment. There is little evidence regarding whether a wearable posture sensor would improve the head and neck postures of office workers. OBJECTIVE The aim of this study was to evaluate the effect of the wearable posture sensor on the posture and physical demands on the head and neck during office work. METHODS Nineteen participants performed a typing task with and without the wearable sensor in the sitting and standing positions. They were allowed to adjust their workstation during the experiment based on a psychophysical method. The flexion angles of the head and neck, the gravitational moment on the neck, and the positions of the workstation components were measured. RESULTS On average, participants with the wearable sensor had 8% lower neck flexion angles and 14% lower gravitational moments on the neck than those of participants without the wearable sensor. The effect of the wearable sensor on reducing postural stress of the neck was more significant when using the standing workstation compared to the sitting workstation. CONCLUSIONS The wearable posture sensor could be an effective tool to alleviate the postural stress of the neck in the office setting.
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Affiliation(s)
- Ravi Charan Ailneni
- Department of Industrial and Systems Engineering, Northern Illinois University, DeKalb IL, USA
| | - Kartheek Reddy Syamala
- Department of Industrial and Systems Engineering, Northern Illinois University, DeKalb IL, USA
| | - In-Sop Kim
- School of Allied Health and Communicative Disorders, Northern Illinois University, DeKalb, IL, USA
| | - Jaejin Hwang
- Department of Industrial and Systems Engineering, Northern Illinois University, DeKalb IL, USA
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18
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Jin S, Kim M, Park J, Jang M, Chang K, Kim D. A comparison of biomechanical workload between smartphone and smartwatch while sitting and standing. APPLIED ERGONOMICS 2019; 76:105-112. [PMID: 30642514 DOI: 10.1016/j.apergo.2018.11.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Revised: 11/26/2018] [Accepted: 11/29/2018] [Indexed: 06/09/2023]
Abstract
Increasing concerns about musculoskeletal disorders in the upper back arising from excessive daily use of the smartwatch have been widely validated by the rising prevalence of discomfort. This study explored the smartwatch as a potential ergonomic intervention over the smartphone. Fourteen healthy participants completed five tasks (application setting, calling, message typing, message checking and vocal message entry) with smartphone and smartwatch in both sitting and standing postures. The neck-shoulder kinematics and muscle activation levels were monitored to assess the effects of the tasks, devices, and postures. The results indicated greater head flexion, head rotation and shoulder abduction and greater muscle activities for smartwatch use compared to smartphone use, but the performance measure (i.e., elapsed time) was superior for smartwatch use in all tasks except message typing. Collectively, only short and simple tasks such as message checking and application setting should be conducted with the smartwatch.
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Affiliation(s)
- Sangeun Jin
- The Human and Safety Engineering Laboratory, Department of Industrial Engineering, Pusan National University, Busan, 46241, Republic of Korea.
| | - Minsung Kim
- The Human and Safety Engineering Laboratory, Department of Industrial Engineering, Pusan National University, Busan, 46241, Republic of Korea.
| | - Jihyeon Park
- The Human and Safety Engineering Laboratory, Department of Industrial Engineering, Pusan National University, Busan, 46241, Republic of Korea.
| | - Minsung Jang
- The Human and Safety Engineering Laboratory, Department of Industrial Engineering, Pusan National University, Busan, 46241, Republic of Korea.
| | - Kyuseok Chang
- The Human and Safety Engineering Laboratory, Department of Industrial Engineering, Pusan National University, Busan, 46241, Republic of Korea.
| | - Daemin Kim
- The Human and Safety Engineering Laboratory, Department of Industrial Engineering, Pusan National University, Busan, 46241, Republic of Korea.
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19
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Korakakis V, O'Sullivan K, O'Sullivan PB, Evagelinou V, Sotiralis Y, Sideris A, Sakellariou K, Karanasios S, Giakas G. Physiotherapist perceptions of optimal sitting and standing posture. Musculoskelet Sci Pract 2019; 39:24-31. [PMID: 30469124 DOI: 10.1016/j.msksp.2018.11.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Revised: 10/28/2018] [Accepted: 11/09/2018] [Indexed: 12/17/2022]
Abstract
BACKGROUND Assessment of, and advice about, spinal posture is common when people with spinal pain present to physiotherapists. Most descriptions regarding optimal spinal posture have been qualitative in nature. OBJECTIVES To determine the beliefs of physiotherapists regarding optimal sitting and standing posture. DESIGN Online survey. METHOD 544 Greek physiotherapists selected an optimal sitting (choice of seven) and standing (choice of five) posture, while providing justification for their choice. RESULTS Education regarding optimal sitting and standing posture was considered "considerably" or "very" important by 93.9% of participants. Three different sitting postures, and two different standing postures, were selected as the optimal posture by 97.5% and 98.2% of physiotherapists respectively. While this reflects a lack of complete consensus on optimal posture, the most commonly selected postures were all some variation of upright lordotic sitting, in contrast slouched spinal curves (sitting) or forward head posture (sitting and standing) almost never being selected as optimal. Interestingly, participants used similar arguments (e.g. natural curves, muscle activation) to justify their selection regardless of the spinal configuration of each selected posture. CONCLUSIONS These results reinforce previous data suggesting that upright lordotic sitting postures are considered optimal, despite a lack of strong evidence that any specific posture is linked to better health outcomes. While postural re-education may play a role in the management of spinal pain for some patients, awareness of such widespread and stereotypical beliefs regarding optimal posture may be useful in clinical assessment and management.
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Affiliation(s)
- Vasileios Korakakis
- Faculty of Physical Education and Sport Sciences, University of Thessaly, Trikala, Greece; Aspetar, Orthopaedic and Sports Medicine Hospital, Doha, Qatar; Hellenic Orthopaedic Manipulative Therapy Diploma (HOMTD), Athens, Greece.
| | - Kieran O'Sullivan
- Aspetar, Orthopaedic and Sports Medicine Hospital, Doha, Qatar; Faculty of Education and Health Sciences, University of Limerick, School of Allied Health, Limerick, Ireland
| | - Peter B O'Sullivan
- School of Physiotherapy, Curtin University, Perth, Western Australia, Australia; Bodylogic Physiotherapy, Private Practice, Perth, Western Australia, Australia
| | | | - Yiannis Sotiralis
- Hellenic Orthopaedic Manipulative Therapy Diploma (HOMTD), Athens, Greece
| | - Alexandros Sideris
- Hellenic Orthopaedic Manipulative Therapy Diploma (HOMTD), Athens, Greece
| | | | | | - Giannis Giakas
- Faculty of Physical Education and Sport Sciences, University of Thessaly, Trikala, Greece
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20
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Syamala KR, Ailneni RC, Kim JH, Hwang J. Armrests and back support reduced biomechanical loading in the neck and upper extremities during mobile phone use. APPLIED ERGONOMICS 2018; 73:48-54. [PMID: 30098642 DOI: 10.1016/j.apergo.2018.06.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 06/11/2018] [Accepted: 06/12/2018] [Indexed: 06/08/2023]
Abstract
Mobile phone use is known to be associated with musculoskeletal pain in the neck and upper extremities because of related physical risk factors, including awkward postures. A chair that provides adequate support (armrests and back support) may reduce biomechanical loading in the neck and shoulder regions. Therefore, we conducted a repeated-measures laboratory study with 20 participants (23 ± 1.9 years; 10 males) to determine whether armrests and back support during mobile phone use reduced head/neck flexion, gravitational moment, and muscle activity in the neck and shoulder regions. The results showed that the chair support (armrests and back support) reduced head/neck flexion (p < 0.001), gravitational moment (p < 0.001), and muscle activity (p < 0.01) in the neck and shoulder regions significantly compared to no chair support. These results indicate that a chair with adequate support can be an effective intervention to reduce the biomechanical exposures and associated muscular pain in the neck and shoulders during mobile phone use.
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Affiliation(s)
- Kartheek Reddy Syamala
- Department of Industrial and Systems Engineering, Northern Illinois University, DeKalb, IL, USA
| | - Ravi Charan Ailneni
- Department of Industrial and Systems Engineering, Northern Illinois University, DeKalb, IL, USA
| | - Jeong Ho Kim
- School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, USA
| | - Jaejin Hwang
- Department of Industrial and Systems Engineering, Northern Illinois University, DeKalb, IL, USA.
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21
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Vasavada AN, Hughes E, Nevins DD, Monda SM, Lin DC. Effect of Subject-Specific Vertebral Position and Head and Neck Size on Calculation of Spine Musculoskeletal Moments. Ann Biomed Eng 2018; 46:1844-1856. [PMID: 29987540 DOI: 10.1007/s10439-018-2084-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 06/25/2018] [Indexed: 12/23/2022]
Abstract
Spine musculoskeletal models used to estimate loads and displacements require many simplifying assumptions. We examined how assumptions about subject size and vertebral positions can affect the model outcomes. Head and neck models were developed to represent 30 subjects (15 males and 15 females) in neutral posture and in forward head postures adopted while using tablet computers. We examined the effects of (1) subject size-specific parameters for head mass and muscle strength; and (2) vertebral positions obtained either directly from X-ray or estimated from photographs. The outcome metrics were maximum neck extensor muscle moment, gravitational moment of the head, and gravitational demand, the ratio between gravitational moment and maximum muscle moment. The estimates of maximum muscle moment, gravitational moment and gravitational demand were significantly different when models included subject-specific vertebral positions. Outcome metrics of models that included subject-specific head and neck size were not significantly different from generic models on average, but they had significant sex differences. This work suggests that developing models from X-rays rather than photographs has a large effect on model predictions. Moreover, size-specific model parameters may be important to evaluate sex differences in neck musculoskeletal disorders.
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Affiliation(s)
- Anita N Vasavada
- Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, 99164-6515, USA. .,Department of Integrative Physiology and Neuroscience, Pullman, WA, USA. .,Washington Center for Muscle Biology, Pullman, WA, USA.
| | - Ellis Hughes
- Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, 99164-6515, USA
| | - Derek D Nevins
- Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, 99164-6515, USA.,School of Mechanical and Materials Engineering, Washington State University, Pullman, WA, USA
| | - Steven M Monda
- Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, 99164-6515, USA
| | - David C Lin
- Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, 99164-6515, USA.,Department of Integrative Physiology and Neuroscience, Pullman, WA, USA.,Washington Center for Muscle Biology, Pullman, WA, USA
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22
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Lee SP, Hsu YT, Bair B, Toberman M, Chien LC. Gender and posture are significant risk factors to musculoskeletal symptoms during touchscreen tablet computer use. J Phys Ther Sci 2018; 30:855-861. [PMID: 29950780 PMCID: PMC6016313 DOI: 10.1589/jpts.30.855] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 03/27/2018] [Indexed: 11/24/2022] Open
Abstract
[Purpose] To investigate the prevalence of neck and shoulder symptoms during the use of
tablet computer, and to identify the risk factors associated with these symptoms.
[Subjects and Methods] A cross-sectional survey was conducted to study tablet computer
usage, posture during use, and neck and shoulder symptoms in 412 participants in a school
setting. Significant risk factors for musculoskeletal symptoms during tablet computer use
were identified. [Results] Overall prevalence of musculoskeletal symptoms during tablet
computer use was 67.9% with greater prevalence of neck symptoms (neck: 84.6%;
shoulder/upper extremity: 65.4%). Significant risk factors associated with symptoms during
use were: current musculoskeletal symptoms, gender, roles, and postural factors including:
sitting without back support, sitting with device in lap, and lying on the side and on the
back during tablet computer use. A multivariate analysis further showed that the odds for
females to have symptoms were 2.059 times higher than males. [Conclusion] The findings
revealed that female gender and other postural factors were significantly associated with
musculoskeletal symptoms during the use of tablet computer. Among all postural factors,
sitting without back support was identified as the most important risk factor for having
musculoskeletal symptoms.
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Affiliation(s)
- Szu-Ping Lee
- Department of Physical Therapy, University of Nevada, Las Vegas: 4505 S. Maryland Parkway, Box 453029, Las Vegas, NV 89154-3029, USA
| | - Ya-Ting Hsu
- Department of Physical Therapy, University of Nevada, Las Vegas: 4505 S. Maryland Parkway, Box 453029, Las Vegas, NV 89154-3029, USA.,HealthSouth Rehabilitation Hospital of Henderson, USA
| | | | | | - Lung-Chang Chien
- Department of Environmental and Occupational Health, University of Nevada, Las Vegas, USA
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23
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Chiang HYA, Liu CH. Exploration of the associations of touch-screen tablet computer usage and musculoskeletal discomfort. Work 2017; 53:917-25. [PMID: 26967038 DOI: 10.3233/wor-162274] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Tablet users may be at high risk of developing physical discomfort because of their usage behaviors and tablet design. OBJECTIVE Investigate the usage of tablets, variations in head and neck posture associated with different tablet tilt angles, and the association of tablet use with users' musculoskeletal discomfort. METHODS A survey of users' subjective perceptions conducted by questionnaire and measurements of users' postures by a 3D Motion analysis system was used to explore the effects of tablet use. RESULTS The questionnaire results indicated that over half of the participants reported physical discomfort after using tablets, with the most prevalent discomfort in the neck and shoulders, and more intensity of discomfort for the back although only few participants experienced it. Chi-squared tests indicated that significantly more participants who tended to use tablet computers to play games reported having musculoskeletal discomfort after using a tablet. In addition, preferences for tablet tilt angles varied across tasks (reading and game playing). The results from the 3D motion analysis revealed that head and neck flexion angles were significantly reduced when the tablets were positioned at relatively steep tilt angles. Neck flexion angle was significantly higher in game playing. CONCLUSIONS These data add information regarding to the usage of tablet and its associations with physical discomfort (significantly more participants who tended to use tablet computers to play games reported having musculoskeletal discomfort after using a tablet). Steep tilt angles (such as 60°) may cause tablet users to decrease their head and neck flexion angles, which could lead to a more neutral, effortless, and ergonomically correct posture. Maintaining proper neck posture during active activities such as game playing is recommended to avoid neck discomfort.
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24
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Douglas EC, Gallagher KM. The influence of a semi-reclined seated posture on head and neck kinematics and muscle activity while reading a tablet computer. APPLIED ERGONOMICS 2017; 60:342-347. [PMID: 28166894 DOI: 10.1016/j.apergo.2016.12.013] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 12/19/2016] [Accepted: 12/20/2016] [Indexed: 06/06/2023]
Abstract
Increased tablet computer usage calls for a proper understanding of potential injury risks from these devices. The purpose of this study was to assess the influence of tablet computer reading postures on head and neck flexion and muscle activity. Nineteen participants completed read a tablet computer in four different postures (standard computer monitor, tablet on a desk, tablet in the lap, semi-reclined with tablet in the lap). Reading the tablet in a semi-reclined trunk posture with the tablet in one's lap increased (p < 0.001) neck flexion angle (71.6%ROM) relative to reading from the standard computer monitor (6.39%ROM). Head flexion in the semi-reclined posture (19.7%ROM) and muscle activity (8.88%MVC) were similar to when reading from a standard computer monitor. Despite potentially reducing the gravitational moment produced by the head, the semi-reclined position could still compromise the force capabilities of the neck extensor musculature and result in increased strain on the passive tissues of the spine. Future work should assess how the semi-reclined position influences cervical intervertebral angles and passive tissue properties of the cervical spine. Overall, more research needs to be conducted on thoracic spine kinematics while reading a tablet computer.
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Affiliation(s)
- Ethan C Douglas
- Department of Health, Human Performance, and Recreation, University of Arkansas, Fayetteville, AR 72701, United States
| | - Kaitlin M Gallagher
- Department of Health, Human Performance, and Recreation, University of Arkansas, Fayetteville, AR 72701, United States.
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25
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Guan X, Fan G, Chen Z, Zeng Y, Zhang H, Hu A, Gu G, Wu X, Gu X, He S. Gender difference in mobile phone use and the impact of digital device exposure on neck posture. ERGONOMICS 2016; 59:1453-1461. [PMID: 27046745 DOI: 10.1080/00140139.2016.1147614] [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] [Indexed: 06/05/2023]
Abstract
This cross-sectional study aimed to identify gender differences in the cervical postures when young adults were using mobile phones, as well as the correlations between the postures and the digital devices use (computer and mobile phone). Questionnaires regarding the habits of computer and mobile phone use were administrated to 429 subjects aged from 17 to 33 years old (19.75 ± 2.58 years old). Subjects were instructed to stand habitually and use a mobile phone as in daily life; the sagittal head and cervical postures were measured by head flexion, neck flexion angle and gaze angle. Male participants had a significantly larger head flexion angle (96.41° ± 12.23° vs. 93.57° ± 12.62°, p = 0.018) and neck flexion angle (51.92° ± 9.55° vs. 47.09° ± 9.45°, p < 0.001) than females. There were significant differences in head (F = 3.62, p = 0.014) and neck flexion (F = 3.99, p = 0.009) between different amounts of computer use. Practitioner Summary: We investigated possible gender differences in head and neck postures of young adults using mobile phones, as well as the potential correlations between these postures and digital device use. We found that males displayed larger head and neck flexion angles than females, which were associated with the amount of computer use.
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Affiliation(s)
- Xiaofei Guan
- a Department of Orthopedics , Shanghai Tenth People's Hospital, Tongji University School of Medicine , Shanghai , China
| | - Guoxin Fan
- a Department of Orthopedics , Shanghai Tenth People's Hospital, Tongji University School of Medicine , Shanghai , China
| | - Zhengqi Chen
- a Department of Orthopedics , Shanghai Tenth People's Hospital, Tongji University School of Medicine , Shanghai , China
| | - Ying Zeng
- b Department of Regenerative Medicine , Tongji University School of Medicine , Shanghai , China
| | - Hailong Zhang
- a Department of Orthopedics , Shanghai Tenth People's Hospital, Tongji University School of Medicine , Shanghai , China
| | - Annan Hu
- a Department of Orthopedics , Shanghai Tenth People's Hospital, Tongji University School of Medicine , Shanghai , China
| | - Guangfei Gu
- a Department of Orthopedics , Shanghai Tenth People's Hospital, Tongji University School of Medicine , Shanghai , China
| | - Xinbo Wu
- a Department of Orthopedics , Shanghai Tenth People's Hospital, Tongji University School of Medicine , Shanghai , China
| | - Xin Gu
- a Department of Orthopedics , Shanghai Tenth People's Hospital, Tongji University School of Medicine , Shanghai , China
| | - Shisheng He
- a Department of Orthopedics , Shanghai Tenth People's Hospital, Tongji University School of Medicine , Shanghai , China
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26
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Leung MY, Lo J, Leung YY. Accuracy of Different Modalities to Record Natural Head Position in 3 Dimensions: A Systematic Review. J Oral Maxillofac Surg 2016; 74:2261-2284. [PMID: 27235181 DOI: 10.1016/j.joms.2016.04.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 04/18/2016] [Accepted: 04/18/2016] [Indexed: 11/26/2022]
Abstract
PURPOSE Three-dimensional (3D) images are taken with positioning devices to ensure a patient's stability, which, however, place the patient's head into a random orientation. Reorientation of images to the natural head position (NHP) is necessary for appropriate assessment of dentofacial deformities before any surgical planning. The aim of this study was to review the literature systematically to identify and evaluate the various modalities available to record the NHP in 3 dimensions and to compare their accuracy. MATERIALS AND METHODS A systematic literature search of the PubMed, Cochrane Library and Embase databases, with no limitations on publication time or language, was performed in July 2015. The search and evaluations of articles were performed in 4 rounds. The methodologies, accuracies, advantages, and limitations of various modalities to record NHP were examined. RESULTS Eight articles were included in the final review. Six modalities to record NHP were identified, namely 1) stereophotogrammetry, 2) facial markings along laser lines, 3) clinical photographs and the pose from orthography and scaling with iterations (POSIT) algorithm, 4) digital orientation sensing, 5) handheld 3D camera measuring system, and 6) laser scanning. Digital orientation sensing had good accuracy, with mean angular differences from the reference within 1° (0.07 ± 0.49° and 0.12 ± 0.54°, respectively). Laser scanning was shown to be comparable to digital orientation sensing. The method involving clinical photographs and the POSIT algorithm was reported to have good accuracy, with mean angular differences for pitch, roll, and yaw within 1° (-0.17 ± 0.50°). Stereophotogrammetry was reported to have the highest reliability, with mean angular deviations in pitch, roll, and yaw for active and passive stereophotogrammetric devices within 0.1° (0.004771 ± 0.045645° and 0.007572 ± 0.079088°, respectively). CONCLUSIONS This systematic review showed that recording the NHP in 3 dimensions with a digital orientation sensor has good accuracy. Laser scanning was found to have comparable accuracy to digital orientation sensing, but routine clinical use was limited by its high cost and low portability. Stereophotogrammetry and the method using a single clinical photograph and the POSIT algorithm were potential alternatives. Nevertheless, clinical trials are needed to verify their applications in patients. Preferably, digital orientation sensor should be used as a reference for comparison with new proposed methods of recording the NHP in future research.
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Affiliation(s)
- Ming Yin Leung
- Resident, Discipline of Oral and Maxillofacial Surgery, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China
| | - John Lo
- Honorary Associate Professor, Discipline of Oral and Maxillofacial Surgery, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China
| | - Yiu Yan Leung
- Clinical Assistant Professor, Discipline of Oral and Maxillofacial Surgery, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China.
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Decker M, Gomas KA, Narvy SJ, Vangsness CT. The influence of a dynamic elastic garment on musculoskeletal and respiratory wellness in computer users. INTERNATIONAL JOURNAL OF OCCUPATIONAL SAFETY AND ERGONOMICS 2016; 22:550-556. [PMID: 27191925 DOI: 10.1080/10803548.2016.1182321] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
BACKGROUND Evidence is growing that computer users are at increased risk of developing musculoskeletal disorders, particularly those involving the upper extremity, with significant financial cost and lost productivity. OBJECTIVE The purpose of this study was to determine the short-term effects of wearing a dynamic elastic garment (Posture Shirt[Formula: see text]; AlignMed, USA) on musculoskeletal wellness and health in the computer workplace. METHODS Ninety-six computer users were evaluated. The Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire was completed. A functional assessment of posture, lung function, and grip strength was performed after wearing the Posture Shirt[Formula: see text] for 4 weeks. A training log was kept to track usage of the garment, as well as weekly sensations of fatigue, productivity, and energy level. RESULTS After 4 weeks, there was statistically significant improvement in forward shoulder and head posture, thoracic kyphosis, and grip strength. Improvements in spirometry measures did not meet statistical significance. Postural fatigue and muscular fatigue decreased by 21% and 29%, respectively, and energy level and productivity increased by 20% and 13%, respectively. CONCLUSION This prospective study demonstrated positive short-term impact of the Posture Shirt[Formula: see text] on both subjective and objective measures of posture, lung function, grip strength, fatigue, and productivity.
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Yu D, Green C, Kasten SJ, Sackllah ME, Armstrong TJ. Effect of alternative video displays on postures, perceived effort, and performance during microsurgery skill tasks. APPLIED ERGONOMICS 2016; 53 Pt A:281-289. [PMID: 26585502 PMCID: PMC5737936 DOI: 10.1016/j.apergo.2015.10.016] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 10/20/2015] [Accepted: 10/28/2015] [Indexed: 06/05/2023]
Abstract
Physical work demands and posture constraint from operating microscopes may adversely affect microsurgeon health and performance. Alternative video displays were developed to reduce posture constraints. Their effects on postures, perceived efforts, and performance were compared with the microscope. Sixteen participants performed microsurgery skill tasks using both stereo and non-stereoscopic microscopes and video displays. Results showed that neck angles were 9-13° more neutral and shoulder flexion were 9-10° more elevated on the video display than the microscope. Time observed in neck extension was higher (30% vs. 17%) and neck movements were 3x more frequent on the video display than microscopes. Ratings of perceived efforts did not differ among displays, but usability ratings were better on the microscope than the video display. Performance times on the video displays were 66-110% slower than microscopes. Although postures improved, further research is needed to improve task performance on video displays.
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Affiliation(s)
- Denny Yu
- Center for Ergonomics, University of Michigan, 1205 Beal Ave, Ann Arbor, MI 48109, USA.
| | - Cooper Green
- Center for Ergonomics, University of Michigan, 1205 Beal Ave, Ann Arbor, MI 48109, USA.
| | - Steven J Kasten
- Department of Surgery, University of Michigan, 1500 E. Medical Center Dr. SPC 5343, Ann Arbor, MI 48109-5343, USA.
| | - Michael E Sackllah
- Center for Ergonomics, University of Michigan, 1205 Beal Ave, Ann Arbor, MI 48109, USA.
| | - Thomas J Armstrong
- Center for Ergonomics, University of Michigan, 1205 Beal Ave, Ann Arbor, MI 48109, USA.
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Vasavada AN, Nevins DD, Monda SM, Hughes E, Lin DC. Gravitational demand on the neck musculature during tablet computer use. ERGONOMICS 2015; 58:990-1004. [PMID: 25643042 DOI: 10.1080/00140139.2015.1005166] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2013] [Accepted: 12/24/2014] [Indexed: 06/04/2023]
Abstract
Tablet computer use requires substantial head and neck flexion, which is a risk factor for neck pain. The goal of this study was to evaluate the biomechanics of the head-neck system during seated tablet computer use under a variety of conditions. A physiologically relevant variable, gravitational demand (the ratio of gravitational moment due to the weight of the head to maximal muscle moment capacity), was estimated using a musculoskeletal model incorporating subject-specific size and intervertebral postures from radiographs. Gravitational demand in postures adopted during tablet computer use was 3-5 times that of the neutral posture, with the lowest demand when the tablet was in a high propped position. Moreover, the estimated gravitational demand could be correlated to head and neck postural measures (0.48 < R(2) < 0.64, p < 0.001). These findings provide quantitative data about mechanical requirements on the neck musculature during tablet computer use and are important for developing ergonomics guidelines. Practitioner Summary: Flexed head and neck postures occur during tablet computer use and are implicated in neck pain. The mechanical demand on the neck muscles was estimated to increase 3-5 times during seated tablet computer use versus seated neutral posture, with the lowest demand in a high propped tablet position but few differences in other conditions.
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Affiliation(s)
- Anita N Vasavada
- a Voiland School of Chemical Engineering and Bioengineering, Washington State University , Pullman, WA , USA
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Weidling P, Jaschinski W. The vertical monitor position for presbyopic computer users with progressive lenses: how to reach clear vision and comfortable head posture. ERGONOMICS 2015; 58:1813-29. [PMID: 26010363 DOI: 10.1080/00140139.2015.1035764] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
UNLABELLED When presbyopic employees are wearing general-purpose progressive lenses, they have clear vision only with a lower gaze inclination to the computer monitor, given the head assumes a comfortable inclination. Therefore, in the present intervention field study the monitor position was lowered, also with the aim to reduce musculoskeletal symptoms. A comparison group comprised users of lenses that do not restrict the field of clear vision. The lower monitor positions led the participants to lower their head inclination, which was linearly associated with a significant reduction in musculoskeletal symptoms. However, for progressive lenses a lower head inclination means a lower zone of clear vision, so that clear vision of the complete monitor was not achieved, rather the monitor should have been placed even lower. The procedures of this study may be useful for optimising the individual monitor position depending on the comfortable head and gaze inclination and the vertical zone of clear vision of progressive lenses. PRACTITIONER SUMMARY For users of general-purpose progressive lenses, it is suggested that low monitor positions allow for clear vision at the monitor and for a physiologically favourable head inclination. Employees may improve their workplace using a flyer providing ergonomic-optometric information.
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Affiliation(s)
- Patrick Weidling
- a Leibniz Research Centre for Working Environment and Human Factors , Ardeystraße 67, D-44139 Dortmund , Germany
| | - Wolfgang Jaschinski
- a Leibniz Research Centre for Working Environment and Human Factors , Ardeystraße 67, D-44139 Dortmund , Germany
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Abstract
Repetitive or prolonged head flexion posture while using a smartphone is known as one of risk factors for pain symptoms in the neck. To quantitatively assess the amount and range of head flexion of smartphone users, head forward flexion angle was measured from 18 participants when they were conducing three common smartphone tasks (text messaging, web browsing, video watching) while sitting and standing in a laboratory setting. It was found that participants maintained head flexion of 33-45° (50th percentile angle) from vertical when using the smartphone. The head flexion angle was significantly larger (p < 0.05) for text messaging than for the other tasks, and significantly larger while sitting than while standing. Study results suggest that text messaging, which is one of the most frequently used app categories of smartphone, could be a main contributing factor to the occurrence of neck pain of heavy smartphone users. Practitioner Summary: In this laboratory study, the severity of head flexion of smartphone users was quantitatively evaluated when conducting text messaging, web browsing and video watching while sitting and standing. Study results indicate that text messaging while sitting caused the largest head flexion than that of other task conditions.
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Affiliation(s)
- Sojeong Lee
- a Department of Human and Systems Engineering , Ulsan National Institute of Science and Technology , Ulsan , Korea
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Nevins DD, Zheng L, Vasavada AN. Inter-individual variation in vertebral kinematics affects predictions of neck musculoskeletal models. J Biomech 2014; 47:3288-94. [PMID: 25234351 DOI: 10.1016/j.jbiomech.2014.08.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Revised: 08/12/2014] [Accepted: 08/18/2014] [Indexed: 02/08/2023]
Abstract
Experimental studies have found significant variation in cervical intervertebral kinematics (IVK) among healthy subjects, but the effect of this variation on biomechanical properties, such as neck strength, has not been explored. The goal of this study was to quantify variation in model predictions of extension strength, flexion strength and gravitational demand (the ratio of gravitational load from the weight of the head to neck muscle extension strength), due to inter-subject variation in IVK. IVK were measured from sagittal radiographs of 24 subjects (14F, 10M) in five postures: maximal extension, mid-extension, neutral, mid-flexion, and maximal flexion. IVK were defined by the position (anterior-posterior and superior-inferior) of each cervical vertebra with respect to T1 and its angle with respect to horizontal, and fit with a cubic polynomial over the range of motion. The IVK of each subject were scaled and incorporated into musculoskeletal models to create models that were identical in muscle force- and moment-generating properties but had subject-specific kinematics. The effect of inter-subject variation in IVK was quantified using the coefficient of variation (COV), the ratio of the standard deviation to the mean. COV of extension strength ranged from 8% to 15% over the range of motion, but COV of flexion strength was 20-80%. Moreover, the COV of gravitational demand was 80-90%, because the gravitational demand is affected by head position as well as neck strength. These results indicate that including inter-individual variation in models is important for evaluating neck musculoskeletal biomechanical properties.
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Shahidi B, Haight A, Maluf K. Differential effects of mental concentration and acute psychosocial stress on cervical muscle activity and posture. J Electromyogr Kinesiol 2013; 23:1082-9. [PMID: 23800438 DOI: 10.1016/j.jelekin.2013.05.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Revised: 05/28/2013] [Accepted: 05/29/2013] [Indexed: 10/26/2022] Open
Abstract
Physical and psychosocial stressors in the workplace have been independently associated with the development of neck pain, yet interactions among these risk factors remain unclear. The purpose of this study was to compare the effects of mentally challenging computer work performed with and without exposure to a psychosocial stressor on cervical muscle activity and posture. Changes in cervical posture and electromyography of upper trapezius, cervical extensor, and sternocleidomastoid muscles were compared between a resting seated posture at baseline, a low stress condition with mental concentration, and a high stress condition with mental concentration and psychosocial stress in sixty healthy office workers. Forward head posture significantly increased with mental concentration compared to baseline, but did not change with further introduction of the stressor. Muscle activity significantly increased from the low stress to high stress condition for both the dominant and non-dominant upper trapezius, with no corresponding change in activity of the cervical extensors or flexors between stress conditions. These findings suggest that upper trapezius muscles are selectively activated by psychosocial stress independent of changes in concentration or posture, which may have implications for the prevention of stress-related trapezius myalgia in the workplace.
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Affiliation(s)
- Bahar Shahidi
- Physical Therapy Program, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA.
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Edmondston SJ, Sharp M, Symes A, Alhabib N, Allison GT. Changes in mechanical load and extensor muscle activity in the cervico-thoracic spine induced by sitting posture modification. ERGONOMICS 2011; 54:179-186. [PMID: 21294015 DOI: 10.1080/00140139.2010.544765] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The influence of whole body sitting posture on cervico-thoracic posture, mechanical load and extensor muscle activity was examined in 23 asymptomatic adults. Cervical and upper thoracic extensor muscle activity measured in guided slouched and lumbo-pelvic neutral postures was normalised to that measured in a self-selected habitual posture. Head and neck posture and gravitational load moment measurements were obtained in each posture. Sagittal head translation, upper cervical extension and load moment were significantly greater in the slouched posture (p < 0.001). Contrasting patterns of cervical and thoracic extensor activity were observed in the slouched and neutral postures, with cervical extensor activity 40% higher in the slouched posture (p < 0.0001). Thoracic extensor activity was significantly higher in the lumbo-pelvic neutral posture than the habitual posture (p = 0.002). The significant changes in extensor muscle activity with postural modification appear to be induced by the associated change in mechanical load moment of the head. STATEMENT OF RELEVANCE: More neutral sitting postures reduce the demand on the cervical extensor muscles and modify the relative contribution of cervical and thoracic extensors to the control of head and neck posture. Postures that promote these patterns of muscular activity may reduce cervical spine loading and the development of posture-related neck pain.
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Affiliation(s)
- Stephen J Edmondston
- School of Physiotherapy and Curtin Health Innovation Research Institute, Curtin University of Technology, Perth, Western Australia. S.Edmondston@.curtin.edu.au
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Straker L, Maslen B, Burgess-Limerick R, Johnson P, Dennerlein J. Evidence-based guidelines for the wise use of computers by children: physical development guidelines. ERGONOMICS 2010; 53:458-477. [PMID: 20309743 DOI: 10.1080/00140130903556344] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Computer use by children is common and there is concern over the potential impact of this exposure on child physical development. Recently principles for child-specific evidence-based guidelines for wise use of computers have been published and these included one concerning the facilitation of appropriate physical development. This paper reviews the evidence and presents detailed guidelines for this principle. The guidelines include encouraging a mix of sedentary and whole body movement tasks, encouraging reasonable postures during computing tasks through workstation, chair, desk, display and input device selection and adjustment and special issues regarding notebook computer use and carriage, computing skills and responding to discomfort. The evidence limitations highlight opportunities for future research. The guidelines themselves can inform parents and teachers, equipment designers and suppliers and form the basis of content for teaching children the wise use of computers. STATEMENT OF RELEVANCE: Many children use computers and computer-use habits formed in childhood may track into adulthood. Therefore child-computer interaction needs to be carefully managed. These guidelines inform those responsible for children to assist in the wise use of computers.
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Affiliation(s)
- L Straker
- School of Physiotherapy, Curtin University of Technology, Perth, WA, Australia.
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Straker L, Pollock C, Maslen B. Principles for the wise use of computers by children. ERGONOMICS 2009; 52:1386-1401. [PMID: 19851906 DOI: 10.1080/00140130903067789] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Computer use by children at home and school is now common in many countries. Child computer exposure varies with the type of computer technology available and the child's age, gender and social group. This paper reviews the current exposure data and the evidence for positive and negative effects of computer use by children. Potential positive effects of computer use by children include enhanced cognitive development and school achievement, reduced barriers to social interaction, enhanced fine motor skills and visual processing and effective rehabilitation. Potential negative effects include threats to child safety, inappropriate content, exposure to violence, bullying, Internet 'addiction', displacement of moderate/vigorous physical activity, exposure to junk food advertising, sleep displacement, vision problems and musculoskeletal problems. The case for child specific evidence-based guidelines for wise use of computers is presented based on children using computers differently to adults, being physically, cognitively and socially different to adults, being in a state of change and development and the potential to impact on later adult risk. Progress towards child-specific guidelines is reported. Finally, a set of guideline principles is presented as the basis for more detailed guidelines on the physical, cognitive and social impact of computer use by children. The principles cover computer literacy, technology safety, child safety and privacy and appropriate social, cognitive and physical development. The majority of children in affluent communities now have substantial exposure to computers. This is likely to have significant effects on child physical, cognitive and social development. Ergonomics can provide and promote guidelines for wise use of computers by children and by doing so promote the positive effects and reduce the negative effects of computer-child, and subsequent computer-adult, interaction.
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Affiliation(s)
- L Straker
- Curtin University of Technology, Perth, WA, Australia.
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