Influence of neck flexion angle on gravitational moment and neck muscle activity when using a smartphone while standing

Ergonomics ◽  
2021 ◽  
pp. 1-12
Author(s):  
Weerasak Tapanya ◽  
Rungthip Puntumetakul ◽  
Manida Swangnetr Neubert ◽  
Rose Boucaut
Keyword(s):  
Muscle Activity ◽  
Flexion Angle ◽  
Neck Muscle ◽  
Neck Flexion ◽  
Gravitational Moment

Trunk Posture Influences Neck Angle When Reading A Tablet Computer

2016 ◽  
Vol 60 (1) ◽  
pp. 942-942
Author(s):  
Kaitlin M. Gallagher ◽  
Ethan C. Douglas
Keyword(s):  
Muscle Activity ◽  
Erector Spinae ◽  
Flexion Angle ◽  
Neck Flexion ◽  
Handheld Computer ◽  
Extensor Muscles ◽  
Head Flexion ◽  
The Moment ◽  
Trunk Position ◽  
Gravitational Moment

In 2013, 64% of American households owned a handheld computer device (e-reader, tablet, smartphones, etc.). The presence of these devices has grown more quickly than our understanding of their effects on musculoskeletal disorders. Their use on a tabletop or a person’s lap causes increased head and neck flexion, as well as an inreased gravitational moment produced by the weight of the head (Straker et al., 2009, Young et al., 2012, Vasavada et al., 2015). A limitation to these studies is that they keep a standard trunk position throughout all tasks; however, people can also assume a semi-reclined position when reading a tablet. The purpose of this study was to determine the influence of a semi-reclined trunk position on neck and head flexion angle, and cervical erector spinae muscle activity. Nineteen participants (10 male, 9 female) read off of a tablet in four postures: with the tablet in their lap, on a tabletop, off of a standard computer monitor, and semi-reclined to an angle of 30 degrees from the vertical. Having the tablet on the lap ( M=16%MVC, SD=8%MVC) significantly increased muscle activity of the cervical erector spinae ( p=.0023) compared to reading off of a monitor or in the semi-reclined position (approximately 10%MVC). Neck and head flexion angles significantly increased ( p<.001) when reading the tablet off the lap (neck M=56.8o, SD=17.3o; head M=53.4o, SD=12.9o) versus the computer (neck M=6.4o, SD=6.4o; head M=8.2o, SD=7.4o), however, the head angle during semi-reclined reading stayed more vertical despite having the highest increase in neck flexion angle (neck M=71.6o, SD=14.0o; head M=19.7o, SD=9.2o). In the semi-reclined position, the gravitational moment of the head is second smallest for the four reading positions. In theory, this is desired as the moment that must be produced by the musculature and surround tissues would be less. The downside to this posture is that many of the neck extensor muscles may still not be in optimal force and moment production position. Many of the neck muscles that assist with extension originate from C5 to T5 and insert on C5 and above (Vasavada et al., 1998). At 30 degrees of neck flexion, the moment generating capability of the spenius and semispinalis muscles are decreased compared to when at a neutral position and fascicle length of splenius cervicis, capitis, and semispinalis capitis muscles experience changes of more than 70% of optimal length (Vasavada et al., 1998). While many of the extensor muscles only show moment arms that vary by 1 cm or less, for some there can be about a 2-3 cm changes as one goes from a flexed to extended neck posture (Vasavada et al., 1998). These combined changes mean that the force producing capabilities of the neck extensor muscles may be compromised a semi-reclined position. Future studies should report torso angle to properly analyze biomechanical risk factors during handheld computer use and compare results between studies.

Effects of Chair Support on Biomechanical Exposures on the Neck During Mobile Phone Use

2018 ◽  
Vol 62 (1) ◽  
pp. 948-951 ◽  
Author(s):  
Jaejin Hwang ◽  
Kartheek Reddy Syamala ◽  
Ravi Charan Ailneni ◽  
Jeong Ho Kim
Keyword(s):  
Mobile Phone ◽  
Muscle Activity ◽  
Repeated Measures ◽  
Flexion Angle ◽  
Neck Flexion ◽  
Mobile Phone Use ◽  
Upper Trapezius ◽  
Splenius Capitis ◽  
Gravitational Moment ◽  
Head Neck

The goal of this study was to evaluate how chair support (armrest and back support) affect the head/neck kinematics and muscle activity as compared to no chair support among four different phone positions (eye, chest, lap, and self-selected level). In a repeated-measures laboratory experiment with 20 subjects (10 males and 10 females), we measured head/neck flexion angle, gravitational moment and muscle activity in upper trapezius (TRAP) and splenius capitis (SPL). The results showed that chair support significantly reduced the head/neck flexion (p’s < 0.001), gravitational moment (p < 0.001), and muscle activity in TRAP and SPL (p’s < 0.001). With chair support, holding a phone at self-selected levels resulted in the largest reduction in head/neck flexion angle and gravitational moment while the eye-level location showed the lowest neck/shoulder muscle activity. The study findings indicate that the mobile phone use with adequate chair support may significantly reduce the physical stress in the neck and shoulder regions as compared to no chair support.

Effect of neck flexion angles on neck muscle activity among smartphone users with and without neck pain

Ergonomics ◽  
2019 ◽  
Vol 62 (12) ◽  
pp. 1524-1533 ◽  
Author(s):  
Suwalee Namwongsa ◽  
Rungthip Puntumetakul ◽  
Manida Swangnetr Neubert ◽  
Rose Boucaut
Keyword(s):  
Neck Pain ◽  
Muscle Activity ◽  
Neck Muscle ◽  
Neck Flexion

Head Rotation and Muscle Activity When Conducting Document Editing Tasks with a Head-Mounted Display

2018 ◽  
Vol 62 (1) ◽  
pp. 952-955
Author(s):  
Eunjee Kim ◽  
Gwanseob Shin
Keyword(s):  
Muscle Activity ◽  
Head Rotation ◽  
Myoelectric Activity ◽  
Neck Muscle ◽  
Neck Flexion ◽  
Head Mounted Display ◽  
Shoulder Muscles ◽  
Flexion Moment ◽  
Subjective Discomfort ◽  
Healthy Participants

Potential ergonomic issues associated with the use of a head mounted display (HMD) for office productivity applications have not yet been quantitatively evaluated. A laboratory experiment was conducted to quantitatively evaluate physical stresses and the productivity of the use of HMD. Twenty healthy participants conducted a document editing task for 60 minutes once with an external display and once with a HMD. Head rotation in sagittal and transverse planes, myoelectric activity of neck and shoulder muscles, subjective discomfort ratings and productivity were collected periodically during the task. Results found significantly (p<0.05) greater head rotation movements on both planes, neck muscle activities, and discomfort ratings and decreased productivity when conducting the task with the HMD as compared when using the external display. Difficulty in reading texts due to insufficient resolution of the HMD screen, additional load and neck flexion moment from the weight of the device were responsible for the greater physical stresses associated with the use of HMD.

A Novel Neck Support Design to Alleviate Worker Neck Pain

2015 ◽  
Author(s):  
Christina A. Yee ◽  
Homayoon Kazerooni
Keyword(s):  
Neck Pain ◽  
Muscle Activity ◽  
Dental Students ◽  
Upper Body ◽  
Neck Muscle ◽  
Office Work ◽  
Neck Flexion ◽  
Muscle Loading ◽  
Varying Environments ◽  
Force Generator

Neck pain is common among occupations like dentistry and office work because workers in these professions tend to hold their necks in static flexion for extended periods of time. But there are few products available to help alleviate workers’ neck pain while still allowing them to carry out their daily tasks in varying environments. For example, office workers can use products like ergonomic chairs and desks to help promote proper posture, but these arrangements restrict workers to workspaces equipped with their necessary equipment and proper setup. Meanwhile, in the medical field, products like loupes, lights, and ergonomic workbenches are available to enhance visibility and reduce workers’ neck flexion angles. But these products have yet to fully eliminate the problem of neck pain especially in occupations like dentistry where static neck flexion is common. Therefore, the goal of this project is to develop a new neck support technology which alleviates neck pain caused by static neck flexion while still allowing workers full mobility and functionality in their workplace. Our design decreases muscle loading on the neck during neck flexion by reducing the moment on the neck using a device which acts as a “headrest” to support the head. In turn, the device redistributes forces to the upper body while still allowing full range of motion to the user. More specifically, our design applies an opposing force to the user’s forehead during neck flexion via a force generator attached to a headband which is attached to the head. The force generator is anchored to the upper body to permit use in varying environments without the need for special equipment or setups. We confirmed our design decreases muscle loading by building a prototype then performing surface electromyography (EMG) testing which showed not just a statistically significant reduction in neck muscle activity using one-way analysis of variance, but more distinctly a unanimous decrease in neck muscle activity during neck flexion for all seven test subjects with an overall average decrease of 60% among all subjects and 80% for certain subjects. Once we confirmed our design’s effectiveness in reducing neck muscle activity during static neck flexion which implied the ability to reduce neck strain, we improved our prototype’s functionality and aesthetics based on test subject feedback, our own observations, and dentists’ comments. Then, we performed workplace testing on two dentists with one dentist’s work focused mainly on hygiene while the other dentist’s work focused mostly on dental procedures. Overall, both dentists offered helpful feedback from different dental field perspectives for future prototype improvements with regards to comfort and functionality. They also provided promising comments regarding their visions for future device use which included training dental students on proper posture and applications in other occupations like office work and surgery.

Changes in the range of head flexion rotation and neck muscle activity after prolonged use of a smartphone

2020 ◽  
Vol 64 (1) ◽  
pp. 930-933
Author(s):  
Donghyun Song ◽  
Eunjee Kim ◽  
Yujin Kwon ◽  
Hyorim Kim ◽  
Gwanseob Shin
Keyword(s):  
Muscle Activity ◽  
Activity Level ◽  
Flexion Angle ◽  
Health Concern ◽  
Neck Muscle ◽  
Study Results ◽  
Smartphone Use ◽  
Head Flexion ◽  
Full Head ◽  
Over Time

Text-neck has been the main health concern among smartphone users. The current study explored a potential association between the duration of static head flexion posture during smartphone use and the viscoelastic changes of the cervical spine passive tissues. Ten participants conducted a smartphone task for 30 minutes, and their full head flexion angle and the neck muscle activity during a head extension motion were quantified before, in the middle, and after the 30-min task. Participants reported higher neck discomfort ratings after smartphone use, and the neck muscle activity showed an increasing trend over time. However, no significant difference was found in the muscle activity level between the three time levels. Full head flexion angle also did not vary significantly over time (p > 0.05). Study results imply the reduction of tissue stiffness during smartphone use, but warrant further research with a more sensitive evaluation method.

scholarly journals On-track Measurements in Motocross: The Correlation of Neck Muscle Activity and Contact Incidents of Helmet and Neck Brace

2016 ◽  
Vol 147 ◽  
pp. 613-617
Author(s):  
Gerrit Thiele ◽  
Patricia Kafka ◽  
Stefan Litzenberger ◽  
Anton Sabo
Keyword(s):  
Muscle Activity ◽  
Neck Muscle

Attenuation of human neck muscle activity following repeated imposed trunk-forward linear acceleration

2003 ◽  
Vol 150 (4) ◽  
pp. 458-464 ◽  
Author(s):  
Jean-Sébastien Blouin ◽  
Martin Descarreaux ◽  
Ariane Bélanger-Gravel ◽  
Martin Simoneau ◽  
Normand Teasdale
Keyword(s):  
Muscle Activity ◽  
Linear Acceleration ◽  
Neck Muscle

scholarly journals The Effect of Posture and Duration of Smartphone Usage on Neck Flexion Angle

2019 ◽  
Vol 63 (1) ◽  
pp. 962-966
Author(s):  
Sundus Alfaitouri ◽  
Ahamed Altaboli
Keyword(s):  
Young Adults ◽  
Flexion Angle ◽  
Neck Flexion ◽  
Web Browsing ◽  
Standing Posture ◽  
Photographic Analysis ◽  
Over Time

The main objective of this study was to measure and examine changes in the neck flexion angle while using a Smartphone according to posture and duration of usage. Photographic analysis procedures were carried out to measure the neck flexion angle. The participants in this study were twenty young adults (half males); they stood against a scaled board and used the same Smartphone for web-browsing for twenty minutes. Photos were taken at zero, five, ten, fifteen and twenty minutes. This procedure was repeated for each participant at three postures (standing, sitting without arms rest, sitting with arms rested on a table). The results revealed statistically significant effects of both posture and duration of usage; neck flexion angle increased significantly over time in all postures and was significantly smaller in the standing posture than in the sitting postures. A significant effect of gender was also identified; males displayed larger neck flexion angles than females.

Head Movements and Neck Muscle Activity During Air Combat Maneuvering

2020 ◽  
Vol 91 (1) ◽  
pp. 26-31 ◽  
Author(s):  
Roope Sovelius ◽  
Maunu Mäntylä ◽  
Heini Huhtala ◽  
Juha Oksa ◽  
Rasmus Valtonen ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Muscular Activity ◽  
Head Movements ◽  
Neck Muscle ◽  
Activity Levels ◽  
Sitting Posture ◽  
Field Of Vision ◽  
Air Combat ◽  
The Difference ◽  
Neutral Posture

BACKGROUND: The aim of the study was to determine the characteristics of cervical muscle activity in different head movements when using helmet mounted display in air combat maneuvering.METHODS: Cervical EMG was measured with eight F/A-18 pilots using the Joint Helmet Mounted Cueing System (JHMCS) during air combat maneuvering. In-flight Gz acceleration and continuous head position were recorded. Muscular activity was compared between head movements in isolation and combined with torso movement. In addition, the effect of the direction of head movements and the use of head support of the ejection seat on muscle activity was determined.RESULTS: Muscular loading increased in the cervical flexors and extensors when using the torso during targeting beyond the field of vision in the neutral sitting posture; the difference was significant in the flexors, but activity levels were higher in the extensors. Cervical muscles are loaded to a lesser extent if the head is kept in a stable position during Gz loading. Muscular activity in the neck muscles was higher when the pilot was moving the head out of neutral posture rather than toward neutral posture. The use of the headrest as a support decreased muscle activity in the extensors, but resulted in higher activity in the flexor muscles.DISCUSSION: All analyzed conditions were significantly affected by an increase in Gz. An increase of muscle activity with torso movements is considered as a positive factor as it reflects maintained muscular support for the cervical spine. Presented results may be helpful when specific conditioning programs and cockpit ergonomics are developed for fighter pilots.Sovelius R, Mäntylä M, Huhtala H, Oksa J, Valtonen R, Tiitola L, Leino T. Head movements and neck muscle activity during air combat maneuvering. Aerosp Med Hum Perform. 2020; 91(1):26–31.

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