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.

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

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.

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

Work ◽  
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.

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.

Comparison among low intensity bridge exercises using suspension devices based on muscle activity and subjective difficulty

2021 ◽  
pp. 1-6
Author(s):  
Sang-Yeol Lee ◽  
Se-Yeon Park
Keyword(s):  
Inclination Angle ◽  
Muscle Activity ◽  
Erector Spinae ◽  
Trunk Muscles ◽  
Oblique Muscle ◽  
Abdominal Muscles ◽  
Internal Oblique Muscle ◽  
Low Intensity ◽  
Erector Spinae Muscle ◽  
Internal Oblique

BACKGROUND: Recent clinical studies have revealed the advantages of using suspension devices. Although the supine, lateral, and forward leaning bridge exercises are low-intensity exercises with suspension devices, there is a lack of studies directly comparing exercise progression by measuring muscular activity and subjective difficulty. OBJECTIVE: To identify how the variations in the bridge exercise affects trunk muscle activity, the present study investigated changes in neuromuscular activation during low-intensity bridge exercises. We furthermore explored whether the height of the suspension point affects muscle activation and subjective difficulty. METHODS: Nineteen asymptomatic male participants were included. Three bridge exercise positions, supine bridge (SB), lateral bridge (LB), forward leaning (FL), and two exercise angles (15 and 30 degrees) were administered, thereby comparing six bridge exercise conditions with suspension devices. Surface electromyography and subjective difficulty data were collected. RESULTS: The rectus abdominis activity was significantly higher with the LB and FL exercises compared with the SB exercise (p< 0.05). The erector spinae muscle activity was significantly higher with the SB and LB exercises, compared with the FL exercise (p< 0.05). The LB exercise significantly increased the internal oblique muscle activity, compared with other exercise variations (p< 0.05). The inclination angle of the exercise only affected the internal oblique muscle and subjective difficulty, which were significantly higher at 30 degrees compared with 15 degrees (p< 0.05). CONCLUSIONS: Relatively higher inclination angle was not effective in overall activation of the trunk muscles; however, different bridge-type exercises could selectively activate the trunk muscles. The LB and SB exercises could be good options for stimulating the internal oblique abdominis, and the erector spinae muscle, while the FL exercise could minimize the erector spinae activity and activate the abdominal muscles.

scholarly journals Using a Back Exoskeleton During Industrial and Functional Tasks—Effects on Muscle Activity, Posture, Performance, Usability, and Wearer Discomfort in a Laboratory Trial

2021 ◽  
pp. 001872082110072
Author(s):  
Tessy Luger ◽  
Mona Bär ◽  
Robert Seibt ◽  
Monika A. Rieger ◽  
Benjamin Steinhilber
Keyword(s):  
Heart Rate ◽  
Muscle Activity ◽  
Vastus Lateralis ◽  
Erector Spinae ◽  
Stair Climbing ◽  
Trunk Flexion ◽  
User Friendliness ◽  
Timed Up And Go ◽  
System Usability Scale ◽  
Task Accomplishment

Objective To investigate the effect of using a passive back-support exoskeleton (Laevo V2.56) on muscle activity, posture, heart rate, performance, usability, and wearer comfort during a course of three industrial tasks (COU; exoskeleton worn, turned-on), stair climbing test (SCT; exoskeleton worn, turned-off), timed-up-and-go test (TUG; exoskeleton worn, turned-off) compared to no exoskeleton. Background Back-support exoskeletons have the potential to reduce work-related physical demands. Methods Thirty-six men participated. Activity of erector spinae (ES), biceps femoris (BF), rectus abdominis (RA), vastus lateralis (VL), gastrocnemius medialis (GM), trapezius descendens (TD) was recorded by electromyography; posture by trunk, hip, knee flexion angles; heart rate by electrocardiography; performance by time-to-task accomplishment (s) and perceived task difficulty (100-mm visual analogue scale; VAS); usability by the System Usability Scale (SUS) and all items belonging to domains skepticism and user-friendliness of the Technology Usage Inventory; wearer comfort by the 100-mm VAS. Results During parts of COU, using the exoskeleton decreased ES and BF activity and trunk flexion, and increased RA, GM, and TD activity, knee and hip flexion. Wearing the exoskeleton increased time-to-task accomplishment of SCT, TUG, and COU and perceived difficulty of SCT and TUG. Average SUS was 75.4, skepticism 11.5/28.0, user-friendliness 18.0/21.0, wearer comfort 31.1 mm. Conclusion Using the exoskeleton modified muscle activity and posture depending on the task applied, slightly impaired performance, and was evaluated mildly uncomfortable. Application These outcomes require investigating the effects of this passive back-supporting exoskeleton in longitudinal studies with longer operating times, providing better insights for guiding their application in real work settings.

Analysis of Muscle Activity Using Surface Electromyography for Muscle Performance in Manual Lifting Task

2014 ◽  
Vol 564 ◽  
pp. 644-649 ◽  
Author(s):  
Halim Isa ◽  
Rawaida ◽  
Seri Rahayu Kamat ◽  
A. Rohana ◽  
Adi Saptari ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Surface Electromyography ◽  
Biceps Brachii ◽  
Twist Angle ◽  
Erector Spinae ◽  
Manual Lifting ◽  
Experienced Fatigue ◽  
Left And Right ◽  
Lifting Task ◽  
Load Mass

In industries, manual lifting is commonly practiced even though mechanized material handling equipment are provided. Manual lifting is used to transport or move products and goods to a desired place.Improper lifting techniquescontribute to muscle fatigue and low back pain that can lead to work efficiency and low productivity.The objective of this study were to analyze muscle activity in the left and right Erector Spinae, and left and right Biceps Brachii of five female subjects while performing manual lifting taskwithdifferent load mass, lifting height and twist angle.The muscle activitywere measured and analyzed using surface electromyography (sEMG).This study found that the right Biceps Brachii, right and left Erector Spinae experienced fatigue while performingasymmetric lifting (twist angle = 90°) at lifting height of 75 cm and 140 cm with load mass of 5 kg and 10 kg. Meanwhile, the left Biceps Brachii experienced fatigue when the lifting task was set at lifting height of 75 cm, load mass of 5 kg and twist angle of 90°.The load mass and lifting height has a significant influence to Mean Power Frequency (MPF) for left Biceps Brachii, left and right Erector Spinae. This study concluded that reducing the load mass can increase the muscles performance which can extend the transition-to-fatigue stage in the left and right Biceps Brachii and Erector Spinae.

Deficits in anticipatory inhibition of postural muscle activity associated with load release while standing in individuals with spastic diplegic cerebral palsy

2013 ◽  
Vol 109 (8) ◽  
pp. 1996-2006 ◽  
Author(s):  
Hidehito Tomita ◽  
Yoshiki Fukaya ◽  
Kenji Totsuka ◽  
Yuri Tsukahara
Keyword(s):  
Cerebral Palsy ◽  
Lower Limb ◽  
Muscle Activity ◽  
Erector Spinae ◽  
Lower Limbs ◽  
Control Group ◽  
Lower Limb Muscles ◽  
Limb Muscles ◽  
Postural Muscle ◽  
Load Release

This study aimed to determine whether individuals with spastic diplegic cerebral palsy (SDCP) have deficits in anticipatory inhibition of postural muscle activity. Nine individuals with SDCP (SDCP group, 3 female and 6 male, 13–24 yr of age) and nine age- and sex-matched individuals without disability (control group) participated in this study. Participants stood on a force platform, which was used to measure the position of the center of pressure (CoP), while holding a light or heavy load in front of their bodies. They then released the load by abducting both shoulders. Surface electromyograms were recorded from the rectus abdominis, erector spinae (ES), rectus femoris (RF), medial hamstring (MH), tibialis anterior (TA), and gastrocnemius (GcM) muscles. In the control group, anticipatory inhibition before load release and load-related modulation of the inhibition were observed in all the dorsal muscles recorded (ES, MH, and GcM). In the SDCP group, similar results were obtained in the trunk muscle (ES) but not in the lower limb muscles (MH and GcM), although individual differences were seen, especially in MH. Anticipatory activation of the ventral lower limb muscles (RF and TA) and load-related modulation of the activation were observed in both participant groups. CoP path length during load release was longer in the SDCP group than in the control group. The present findings suggest that individuals with SDCP exhibit deficits in anticipatory inhibition of postural muscles at the dorsal part of the lower limbs, which is likely to result in a larger disturbance of postural equilibrium.

scholarly journals Changes in Cross-sectional Areas of Posterior Extensor Muscles in Thoracic Spine: A 10-year Longitudinal MRI Study

2021 ◽  
Author(s):  
Hitoshi Umezawa ◽  
Kenshi Daimon ◽  
Hirokazu Fujiwara ◽  
Yuji Nishiwaki ◽  
Takehiro Michikawa ◽  
...  
Keyword(s):  
Cross Section ◽  
Disc Degeneration ◽  
Thoracic Spine ◽  
Erector Spinae ◽  
Related Factors ◽  
Cross Sectional ◽  
Fat Infiltration ◽  
Extensor Muscles ◽  
The Cross ◽  
Muscle Fat Infiltration

Abstract This study aimed to examine changes in the cross-sectional areas (CSAs) of posterior extensor muscles in the thoracic spine over 10 years and identify related factors. The subjects of this study were 85 volunteers (mean age: 44.8 ± 11.5) and the average follow-up period was about 10 years. The CSAs of the transversospinalis muscles, erector spinae muscles, and total CSAs of the extensor muscles from T1/2 to T11/12 were measured on MRI. The extent of muscle fat infiltration was assessed by the signal intensity (luminance) of the extensor muscles’ total cross section compared to a section of pure muscle. Associations of age, sex, body mass index, lifestyle, back pain, neck pain, neck stiffness, and intervertebral disc degeneration with the 10-year CSAs changes and muscle fat infiltration were examined by Poisson regression analysis. The mean CSAs of all index muscles increased significantly. Exercise habit was associated with increased CSAs of the erector spinae muscles and the total area of the extensor muscles. The cross-section mean luminance increased significantly from baseline, indicating a significant increase of fat infiltration in the posterior extensor muscles. Progression of disc degeneration was negatively associated with the increase of fat infiltration in the total extensor muscles.

scholarly journals Surface Electromyography Based Core Muscle Fatigue Analysis During Repetitive Plank Using Multivariate Dimensionality Reduction Methods in Boys Aged 12-14

2021 ◽  
Vol 21 (3) ◽  
pp. 253-263
Author(s):  
Abir Samanta ◽  
Sabyasachi Mukherjee
Keyword(s):  
Discriminant Analysis ◽  
Muscle Fatigue ◽  
Muscle Activity ◽  
Principal Component ◽  
Erector Spinae ◽  
P Value ◽  
Recruitment Strategies ◽  
Structure Matrix ◽  
Spine Stability ◽  
Wilks Lambda

The aims of the study were: 1. To analyse the discriminative power of neuromuscular components for classifying the pre and post muscle fatigued states. 2. To examine whether the modification of neural recruitment strategies become more/less heterogeneous due to fatigue. 3. To research the effect of Erector Spinae (ES) muscle activity collectively with Rectus Abdominis (RA) and External Oblique (EO) muscle activity to identify the reduced spine stability during fatiguing Plank.  Material and methods. Twelve boys (age – 12-14 years, height 148.75 ± 10 cm, body mass 38.9 ± 7.9 kg) participated in the study. Multivariate Discriminant Analysis (DA) and Principal Component Analysis (PCA) were applied to identify the changes in the pattern of the electromyographic signals during muscle fatigue. In DA the Wilks’ lambda, p-value, canonical correlation, classification percentage and structure matrix were used. To evaluate the component validity the standard limit for Kaiser-Meyer-Olkin (KMO) was set at ≥0.529 and the p-value of Bartlett’s test was ≤0.001. The eigenvalues ≥1 were used to determine the number of Principal Components (PCs). The satisfactory percentage of non-redundant residuals were set at ≤50% with standard value >0.05. The absolute value of average communality (x̄ h2) and component loadings were set at ≥0.6, ≥0.4 respectively.  Results. Standardized canonical discriminant analysis showed that pre and post fatigued conditions were significantly different (p = 0.000, Wilks’ lambda = 0.297, χ2 = 24.914, df=3). The structure matrix showed that the parameter that correlated highly with the discriminant function was ES ARV (0.514). The results showed that the classification accuracy was 95.8% between fatigued conditions. In PCA the KMO values were reduced [0.547Pre fatigue vs. 0.264Post fatigue]; the value of Bartlett’s sphericity test was in pre χ2 = 90.72 (p = 0.000) and post fatigue χ2 = 85.32 (p = 0.000); The Promax criterion with Kaiser Normalization was applied because the component rotation was non-orthogonal [Component Correlation Matrix (rCCM) = 0.520 Pre fatigue >0.3Absolute<0.357Post fatigue]. In pre fatigue two PCs (cumulative s2 – 80.159%) and post fatigue three PCs (cumulative s2 – 83.845%) had eigenvalues ≥1. The x̄ h2 increased [0.802 Pre fatigue vs. 0.838 Post fatigue] and the percentage of nonredundant residuals reduced [50% Pre fatigue vs. 44% Post fatigue] from pre to post fatigue.  Conclusions. The variability and heterogeneity increase in the myoelectric signals due to fatigue. The co-activity of antagonist ES muscle is significantly sensitive to identify the deteriorating spine stability during the fatiguing Plank. Highly correlated motor unit recruitment strategies between ES and RA, providing supportive evidence to the concept of shared agonist-antagonist motoneuron pool or “Common Drive” phenomenon during fatigue.

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