Neck Muscular Load When Using a Smartphone While Sitting, Standing, and Walking

2020 ◽  
pp. 001872082090423 ◽  
Author(s):  
Woojin Yoon ◽  
Seobin Choi ◽  
Hyeseon Han ◽  
Gwanseob Shin
Keyword(s):  
Muscle Activation ◽  
Myoelectric Activity ◽  
Activation Level ◽  
Extensor Muscles ◽  
Musculoskeletal Problems ◽  
Muscular Load ◽  
Smartphone Use ◽  
Neck Musculature

Objective Myoelectric activity of neck extensor muscles and head kinematic variables, when using a smartphone for one-handed browsing and two-handed texting while sitting, standing, and walking, were evaluated to compare the neck muscular load during these tasks and across the posture conditions. Background There has been limited research on the relation between head-down postures and the muscular load on the neck of smartphone users. Methods Twenty-one asymptomatic young users were asked to perform one-handed browsing and two-handed texting tasks in each of the posture conditions, and the myoelectric activities of the neck extensor muscles, head kinematic variables, and upper back posture were quantified. Results The muscle activation level when using a phone during walking was 21.2% and 41.7% higher than that of sitting and standing on average ( p < .01). Head vertical and angular accelerations were also significantly greater ( p < .01) for walking than for sitting and standing conditions. Between the two conducted tasks, participants flexed their heads more significantly ( p < .01) with higher activation of the neck extensor muscles ( p < .01) when texting as compared to when browsing. Conclusion Results indicate that two-handed texting while walking would be the most physically demanding scenario for neck musculature, and it might be attributable to the dynamics of the head while walking with the head facing downwards. Application These findings can be used to better understand the potential relation between smartphone use and the occurrence of neck musculoskeletal problems and to inform the users of the ergonomic risks of using smartphones while walking.

scholarly journals Neck muscle activation and head kinematics when using a smartphone while walking

2019 ◽  
Vol 63 (1) ◽  
pp. 957-961 ◽  
Author(s):  
Woojin Yoon ◽  
Hyeseon Han ◽  
Seobin Choi ◽  
Gwanseob Shin
Keyword(s):  
Tilt Angle ◽  
Muscle Activation ◽  
Head Tilt ◽  
Neck Muscle ◽  
Safety Issues ◽  
Activation Level ◽  
Extensor Muscles ◽  
Muscular Load ◽  
Smartphone Use ◽  
The One

Using a smartphone while walking has been common in countries with high smartphone penetration rates. While pedestrian safety issues have been studied frequently, research regarding ergonomics issues such as neck discomfort of smartphone use while walking has been limited. An experimental study was conducted to evaluate the neck muscular load of smartphone use while walking. Twenty-one asymptomatic young smartphone owners conducted one-handed browsing and two-handed texting while walking on a treadmill. Their neck muscle activation level, head and upper back posture were quantified. Compared to when walking upright without using a smartphone, the two smartphone-use tasks demanded 33.3% to 101.8% more activation of the neck extensor muscles. Mean head tilt angles (relative to upright standing) were 28.9° and 36.9° for the one-handed browsing and two-handed texting, respectively. Between the two smartphone tasks, the head tilt angle and the muscle activation level were significantly greater for texting than for browsing. Results indicated that conducting two-handed texting while walking would pose larger muscular load to the neck extensor muscles compared to when conducting one-handed browsing while walking due to the larger head tilt angle.

Low back muscle activity when using a smartphone while walking

2019 ◽  
Vol 63 (1) ◽  
pp. 1099-1102 ◽  
Author(s):  
Seobin Choi ◽  
Misol Kim ◽  
Eunjee Kim ◽  
Gwanseob Shin
Keyword(s):  
Muscle Activation ◽  
Erector Spinae ◽  
Myoelectric Activity ◽  
Low Back ◽  
Back Muscle ◽  
Muscle Activation Patterns ◽  
Concurrent Use ◽  
Extensor Muscles ◽  
Smartphone Use ◽  
Back Extensor

Concurrent use of a smartphone while walking may influence low back muscle activation patterns due to restricted arm motions, limited trunk rotation and walking with the head in a flexed position. The objective of this study was to quantitatively determine the effects of smartphone use while walking on the level of myoelectric activity of the low back extensor muscles. Fifteen asymptomatic young smartphone users who were familiar with smartphone use while walking participated in this experiment. The electromyography (EMG) of the lumbar erector spinae muscles were collected bilaterally when they were conducting three walking tasks on a treadmill: 1) walking without smartphone use (upright walking); 2) web-browsing while walking; and, 3) texting while walking. Results found that the normalized EMG of the lumbar erector spinae muscles were significantly (p<0.05) greater when using a smartphone while walking as compared to when walking without using the phone. It indicates that using a smartphone while walking could pose larger muscular load to the low back extensor muscles than that of walking without using a phone.

Reflexive Response of Neck Muscle to Sudden Perturbation after Prolonged Smartphone Use

2021 ◽  
Vol 65 (1) ◽  
pp. 1250-1253
Author(s):  
Eunjee Kim ◽  
Donghyun Song ◽  
Dasom Park ◽  
Hyorim Kim ◽  
Gwanseob Shin
Keyword(s):  
Cervical Spine ◽  
Muscle Activation ◽  
Neck Muscle ◽  
Spinal Stability ◽  
Delayed Onset ◽  
Activation Level ◽  
Before And After ◽  
Smartphone Use ◽  
Head Stability ◽  
Passive Stretch

Prolonged smartphone use induces passive stretch of neck tissues and muscle fatigue, affecting spinal stability and pain. It is necessary to evaluate the effect of smartphone use on the reflexive response to detect the changes in neck tissues and head stability. A laboratory experiment (n=10) was conducted to investigate the reflexive response of neck muscle to perturbation after 30 minutes of smartphone use. Neck extensor muscle activation and its activation timing to perturbation were investigated before and after smartphone use. Head angle and muscle activation level were collected during smartphone use. During smartphone use, muscle activation gradually increased. After smartphone use, neck muscles showed a higher activation level and significantly delayed onset to perturbation. Smartphone use changed the reflexive response of the neck muscle. Further study is needed to investigate the association between smartphone use and neuromuscular changes to the tissues of the cervical spine.

Strength training counteracts motor performance losses during bed rest

2003 ◽  
Vol 95 (4) ◽  
pp. 1485-1492 ◽  
Author(s):  
Minoru Shinohara ◽  
Yasuhide Yoshitake ◽  
Motoki Kouzaki ◽  
Hideoki Fukuoka ◽  
Tetsuo Fukunaga
Keyword(s):  
Strength Training ◽  
Muscle Activation ◽  
Vastus Lateralis ◽  
Knee Extensor ◽  
Bed Rest ◽  
Training Group ◽  
Medial Gastrocnemius ◽  
Knee Extensors ◽  
Extensor Muscles ◽  
Muscle Groups

The purpose of the study was to determine the effect of bed rest with or without strength training on torque fluctuations and activation strategy of the muscles. Twelve young men participated in a 20-day bed rest study. Subjects were divided into a non-training group (BRCon) and a strength-training group (BRTr). The training comprised dynamic calf-raise and leg-press exercises. Before and after bed rest, subjects performed maximal contractions and steady submaximal isometric contractions of the ankle extensor muscles and of the knee extensor muscles (2.5-10% of maximal torque). Maximal torque decreased for both the ankle extensors (9%, P < 0.05) and knee extensors (16%, P < 0.05) in BRCon but not in BRTr. For the ankle extensors, the coefficient of variation (CV) for torque increased in both groups ( P < 0.05), with a greater amount ( P < 0.05) in BRCon (88%) compared with BRTr (41%). For the knee extensors, an increase in the CV for torque was observed only in BRCon (22%). The increase in the CV for torque in BRCon accompanied the greater changes in electromyogram amplitude of medial gastrocnemius (122%) and vastus lateralis (59%) compared with BRTr ( P < 0.05). The results indicate that fluctuations in torque during submaximal contractions of the extensor muscles in the leg increase after bed rest and that strength training counteracted the decline in performance. The response varied across muscle groups. Alterations in muscle activation may lead to an increase in fluctuations in motor output after bed rest.

scholarly journals Determining the optimal maximal and submaximal voluntary contraction tests for normalizing the erector spinae muscles

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7824
Author(s):  
Gemma Biviá-Roig ◽  
Juan Francisco Lisón ◽  
Daniel Sánchez-Zuriaga
Keyword(s):  
Muscle Activation ◽  
Individual Variability ◽  
Erector Spinae ◽  
Emg Activity ◽  
Horizontal Position ◽  
Maximum Voluntary Isometric Contraction ◽  
Emg Signal ◽  
Activation Level ◽  
Flexion Extension ◽  
Maximal Activation

Background This study aimed to identify which maximum voluntary isometric contraction (MVIC) and sub-MVIC tests produce the highest activation of the erector spinae muscles and the greatest reduction in inter-individual variability, to put them forward as reference normalization maneuvers for future studies. Methods Erector spinae EMG activity was recorded in 38 healthy women during five submaximal and three maximal exercises. Results None of the three MVIC tests generated the maximal activation level in all the participants. The maximal activation level was achieved in 68.4% of cases with the test performed on the roman chair in the horizontal position (96.3 ± 7.3; p < 0.01). Of the five submaximal maneuvers, the one in the horizontal position on the roman chair produced the highest percentage of activation (61.1 ± 16.7; p < 0.01), and one of the lowest inter-individual variability values in the normalized signal of a trunk flexion-extension task. Conclusions A modified Sorensen MVIC test in a horizontal position on a roman chair and against resistance produced the highest erector spinae activation, but not in 100% of participants, so the execution of several normalization maneuvers with the trunk at different inclinations should be considered to normalize the erector spinae EMG signal. A modified Sorensen test in a horizontal position without resistance is the submaximal maneuver that produces the highest muscle activation and the greatest reduction in inter-individual variability, and could be considered a good reference test for normalization.

scholarly journals Nutrient sensitivity of gastric emptying of digesta in the preruminant calf

1988 ◽  
Vol 59 (2) ◽  
pp. 335-343 ◽  
Author(s):  
J. W. Sissons ◽  
F. R. Bell ◽  
C. L. Girard ◽  
J. A. H. Wass
Keyword(s):  
Smooth Muscle ◽  
Gastric Emptying ◽  
Motor Activity ◽  
Muscle Activation ◽  
Venous Blood ◽  
Inhibitory Response ◽  
Myoelectric Activity ◽  
Hyperosmolar Solutions ◽  
Osmotic Stimuli ◽  
Made In

1. Studies of gastric function were made in preruminant calves fitted with a single abomasal cannula, re-entrant cannulas in the duodenum close to the pylorus and recording electrodes on the pyloric antrum and proximal duodenum.2. Simultaneous measurements were made of gastric emptying of a saline (9 g sodium chloride/1) meal, myoelectric activity of antral muscle and plasma concentration of somatostatin in jugular blood whilst infusing the duodenum with different solutions. The duodenal infusates were isotonic sodium bicarbonate (300 mosmol/kg), hyperosmolar solutions of NaCl (1000 mosmol/kg), sodium carbonate (500 mosmol/kg), sucrose (1000 mosmol/kg), 41 g emulsified butterfat/kg or 60 mM-hydrochloric acid.3. Infusing the duodenum with isotonic NaHCO3 stimulated intense myoelectric activity of the antral smooth muscle and rapid emptying of the test meal. In contrast, infusions of 60 mM-HCl reduced antral motility and inhibited gastric emptying of digesta. This inhibitory response to HCl infusion was related to a significant (P < 0·05) increase of somatostatin in peripheral venous blood.4. The Na2CO3 infusate, like HC1, inhibited gastric motor activity and digesta emptying, but the concentration of circulating somatostatin was only slightly elevated above pre-infusion levels.5. Compared with the effects of infusing HCl, infusions of emulsified butterfat or hyperosmolar NaCl and sucrose induced a greater intensity of antral motor activity and faster outflow of gastric effluent, although not to the same extent as with isotonic NaHCO3. However, as with isotonic NaHCO3, these infusates did not evoke the release of somatostatin.6. The results support the concept of duodenal receptors which, in response to a variety of stimuli in gastric chyme, modulate stomach emptying of digesta through actions on contractile processes of antral smooth muscle. Activation of such receptors by fat or osmotic stimuli, both ionic and non-ionic, do not appear to involve the release of somatostatin. However, the hormone appears to have an entero-gastrone role in mediating the inhibitory action of HCI on gastric motor function.

Effect of Simulated Muscle Activation Level on Driver Neck Response in Frontal Motor Vehicle Crashes

2021 ◽  
Author(s):  
Gongxun Deng ◽  
Shun Gan ◽  
Wentao Chen ◽  
Qing Zhou ◽  
Yong Peng ◽  
...  
Keyword(s):  
Muscle Activation ◽  
Motor Vehicle ◽  
Motor Vehicle Crashes ◽  
Vehicle Crashes ◽  
Activation Level

Muscular loads associated with floor vacuuming with cordless stick cleaners

2021 ◽  
Vol 65 (1) ◽  
pp. 1381-1384
Author(s):  
Yujin Kwon ◽  
Gwanseob Shin
Keyword(s):  
Upper Extremity ◽  
Muscle Activation ◽  
Upper Extremities ◽  
Myoelectric Activity ◽  
Shoulder Muscles ◽  
Occupational Tasks ◽  
The Mean ◽  
House Painting ◽  
User Friendly ◽  
Ergonomic Interventions

The muscular loads of the upper extremity and chest muscles were assessed during floor vacuuming with stick vacuum cleaners. Ten participants conducted vacuuming with two stick cleaners (weight: 3.03 kg, 3.56 kg) on tiled and carpeted floors while the myoelectric activity of the upper extremity and chest muscles were collected. The mean muscle activation levels ranged from 15.5% to 45.7% of the maximum voluntary capacity. Greater muscular loads were observed on the forearm and shoulder muscles when vacuuming with repeated curved strokes (vs. straight storkes), and on the chest muscle when vacuuming the carpeted floor. The range of muscular loads were higher than that of occupational tasks such as house painting and dental drilling, which have been known as intensive activities for upper extremities. The results suggest that floor vacuuming with stick vacuum cleaners is physically demanding for household consumers. Ergonomic interventions such as more user-friendly design should be considered.

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