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

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.

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Trunk Posture Influences Neck Angle When Reading A Tablet Computer

Proceedings of the Human Factors and Ergonomics Society Annual Meeting ◽

10.1177/1541931213601216 ◽

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.

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

Ergonomics ◽

10.1080/00140139.2021.1873423 ◽

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

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How Do Drivers Hold Their Phone? Age, Prevalence, & Handedness

Proceedings of the Human Factors and Ergonomics Society Annual Meeting ◽

10.1177/1071181320641298 ◽

2020 ◽

Vol 64 (1) ◽

pp. 1254-1257

Author(s):

Trey Roady ◽

Kyle Wilson ◽

Jonny Kuo ◽

Michael G. Lenné

Keyword(s):

Law Enforcement ◽

Mobile Phone ◽

Eye Movement ◽

Older Drivers ◽

Neck Flexion ◽

Insufficient Evidence ◽

Mobile Phone Use

Objective Research shows frequent mobile phone use in vehicles but says little regarding how drivers hold their phone. This knowledge would inform countermeasures and benefit law enforcement in detecting phone use. Methods 934 participants were surveyed over phone-use prevalence, handedness, traffic-direction, and where they held their device. Results The majority (66%) reported using their phone while driving. Younger drivers were more likely to use their device. Of device-users, 67% preferred their passenger-side hand, 25% driver-side, and 8% both. Height- wise: 22% held in-lap, 52% even with the wheel, and 22% at wheel-top. Older drivers were more likely to hold the phone in the highest position The three most popular combinations were passenger-middle (35%), passenger-low (19%), and passenger-high (13.9%). There was insufficient evidence of differences based on handedness, prevalence, or traffic-direction. Conclusion Driver-preferred attention regions often require substantial neck flexion and eye-movement, which facilitates distraction detection. However, behavior may change in response to future interventions.

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Analysis of Muscle Activity on Sedentary Group Spinal Muscle in Different Sitting Postures

Journal of Medical Imaging and Health Informatics ◽

10.1166/jmihi.2020.2993 ◽

2020 ◽

Vol 10 (5) ◽

pp. 1178-1183

Author(s):

Yong Feng ◽

XianJian Chen

Keyword(s):

Sedentary Behavior ◽

Muscle Activity ◽

Repeated Measures ◽

Sitting Position ◽

Sitting Posture ◽

Time Points ◽

Sedentary Group ◽

Significant Difference ◽

Splenius Capitis ◽

The Relationship

The prevention of sedentary behavior and discussing the relationship between sedentary behavior and health are very significant. In this study, sEMG was used to detect the changes of spinal muscle activity in three positions: sitting, and standing. It was aimed to find out the sEMG characteristics of splenius capitis (SCA), trapezius (TR), erector spine muscle (ESM) and spinalis (SP) under the sedentary, sitting-moving and sittingstanding posture. Through the two-factor repeated measures analyses of variance, the results revealed that there were a significant difference in MPF and MF between SCA, ESM, TR and SP at different time points. The results showed that the MFslope and MPFslope of ESM, SP, TR, and SCA were smaller in the sitting position than in the sitting position. The MFslope and MPFslope of both SP and SCA were larger than that in the sedentary posture. These results confirm that sitting posture can alleviate spinal muscle fatigue compared to sedentary posture, while sitting posture can alleviate ESM and TR fatigue. The sitting-moving posture can’t improve the fatigue of SCA and SP which caused by sedentary posture.

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An investigation of an ergonomics intervention to affect neck biomechanics and pain associated with smartphone use

Work ◽

10.3233/wor-213463 ◽

2021 ◽

pp. 1-13

Author(s):

Minghao Tang ◽

Carolyn M. Sommerich ◽

Steven A. Lavender

Keyword(s):

Muscle Activity ◽

Head Tilt ◽

Trapezius Muscle ◽

Erector Spinae ◽

Neck Flexion ◽

Head Posture ◽

Subjective Perceptions ◽

Upper Trapezius ◽

Direct View ◽

Smartphone Use

BACKGROUND: Neck discomfort and pronounced neck flexion have been associated with smartphone use. OBJECTIVE: Eye glasses with a 90 deg prism in each lens were investigated as a potential intervention to reduce awkward head and neck postures during activities involving viewing the device. METHODS: Sixteen smartphone users with neck pain and 9 asymptomatic users performed a texting task on a smartphone with and without the prism glasses, in sitting and standing postures in a laboratory setting. RESULTS: Cervical erector spinae and upper trapezius muscle activity, head posture and motion, performance, discomfort and other subjective perceptions were assessed. Prism glasses reduced neck extensor muscle activity, neck flexion, and head tilt compared to the direct view. In the symptomatic group, the intervention produced less neck and shoulder discomfort compared to the direct view. CONCLUSIONS: This intervention could offer an alternative way of interacting with a smartphone while texting in stationary postures, by reducing exposure to pronounced flexed neck and head posture commonly seen in users, and thereby could reduce neck discomfort associated with smartphone use.

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The Combination of Different Ergonomic Supports during Dental Procedures Reduces the Muscle Activity of the Neck and Shoulder

Journal of Clinical Medicine ◽

10.3390/jcm8081230 ◽

2019 ◽

Vol 8 (8) ◽

pp. 1230

Author(s):

García-Vidal ◽

López-Nicolás ◽

Sánchez-Sobrado ◽

Escolar-Reina ◽

Medina-Mirapeix ◽

...

Keyword(s):

Muscle Activity ◽

Repeated Measures ◽

Repeated Measures Design ◽

Upper Trapezius ◽

Shoulder Muscles ◽

Dental Procedures ◽

Repeated Measures Analysis ◽

Anterior Deltoid ◽

Phantom Head ◽

Composite Restoration

Ergonomic supports have become popular for the prevention of musculoskeletal disorders. This study sought to evaluate the efficacy of different ergonomic supports and their combination to reduce muscle activity of the neck and shoulder muscles. A one-way repeated measures design was used to evaluate 36 practicing dentists while they performed three posterior composite restoration procedures on a phantom head. Portable surface electromyography (sEMG) recordings were used to measure the muscle activity of three muscles (Upper Trapezius, Lateral Deltoid and Anterior Deltoid) in the dominant upper extremity, with and without the use of different ergonomic supports (ergonomic stool, magnification lenses and both) during the performance of these tasks. A repeated measures analysis of variance was used. The muscle activity of all muscles differed significantly across the four ergonomic conditions during the three tasks. The use of ergonomic supports such as magnification lenses, the ergonomic stool, or the combination of both, is effective for decreasing the muscle activity of the three muscles during the three tasks, when compared to standard practice. In addition, the decrease of muscle activity was higher using magnification lenses when compared to the ergonomic stool. Furthermore, the greatest decrease was found with the combination of both supports.

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Myoelectric Activity Differences in Three Learning Sessions

Journal of Psychophysiology ◽

10.1027//0269-8803.16.2.92 ◽

2002 ◽

Vol 16 (2) ◽

pp. 92-96

Author(s):

Tiina Ritvanen ◽

Reijo Koskelo ◽

Osmo H„nninen

Keyword(s):

High School Students ◽

Muscle Activity ◽

Muscle Tension ◽

Emg Activity ◽

Traditional Learning ◽

Myoelectric Activity ◽

School Students ◽

Language Laboratory ◽

Upper Trapezius ◽

Muscle Groups

Abstract This study follows muscle activity in three different learning sessions (computer, language laboratory, and normal classroom) while students were studying foreign languages. Myoelectric activity was measured in 21 high school students (10 girls, 11 boys, age range 17-20 years) by surface electromyography (sEMG) from the upper trapezius and frontalis muscles during three 45-min sessions. Root mean square (RMS) average from both investigated muscles was calculated. The EMG activity was highest in both muscle groups in the computer-aided session and lowest in the language laboratory. The girls had higher EMG activity in both investigated muscle groups in all three learning situations. The measured blood pressure was highest at the beginning of the sessions, decreased within 10 min, but increased again toward the end of the sessions. Our results indicate that the use of a computer as a teaching-aid evokes more constant muscle activity than the traditional learning situations. Since muscle tension can have adverse health consequences, more research is needed to determine optimal classroom conditions, especially when technical aids are used in teaching.

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