The Influence of Load Handling Height on Shoulder Biomechanics during Sudden Loading

2018 ◽  
Vol 62 (1) ◽  
pp. 828-832
Author(s):  
Hossein Motabar ◽  
Saman Madinei ◽  
Xiaopeng Ning
Keyword(s):  
Muscle Activity ◽  
Material Handling ◽  
Travel Distance ◽  
Body Parts ◽  
Occupational Risk Factors ◽  
Shoulder Muscles ◽  
Proprioceptive Deficit ◽  
Shoulder Disorders ◽  
Sudden Loading ◽  
Load Handling

Shoulder disorders have been reported as the most severe musculoskeletal disorders among all body parts. Multiple occupational risk factors such as manual material handling, repetitive motion, overexertion, fatigue, and overhead tasks have been reported to be associated with the development of shoulder disorders. The objective of this study was to investigate the effect of height (low, middle, high) on shoulder muscles during sudden loading. Kinematics and Electromyography (EMG) was recorded from 14 male participants. Effect of height found to be significant on normalized EMG and load travel distance. Bilateral shoulder muscles indicated higher NEMG with the increase of the load’s altitude. This increase of muscle activity could have resulted from the greater potential energy of the load at higher altitudes which required extra muscle activity to maintain the biomechanical stability of the shoulder. Reduced stability of shoulder at higher altitudes caused proprioceptive deficit which resulted in higher load travel distance.

scholarly journals Back-Support Exoskeleton Control Strategy for Pulling Activities: Design and Preliminary Evaluation

Designs ◽  
2021 ◽  
Vol 5 (3) ◽  
pp. 39
Author(s):  
Maria Lazzaroni ◽  
Tommaso Poliero ◽  
Matteo Sposito ◽  
Stefano Toxiri ◽  
Darwin G. Caldwell ◽  
...  
Keyword(s):  
Control Strategy ◽  
Muscle Activity ◽  
Material Handling ◽  
Ease Of Use ◽  
Biomechanical Analysis ◽  
Perceived Support ◽  
Preliminary Evaluation ◽  
Subjective Measurements ◽  
Spinal Muscles ◽  
Forearm Muscle

The execution of manual material handling activities in the workplace exposes workers to large lumbar loads that increase the risk of musculoskeletal disorders and low back pain. In particular, the redesign of the workplace is making the execution of pulling activities more common, as an alternative to lifting and carrying tasks. The biomechanical analysis of the task revealed a substantial activation of the spinal muscles. This suggests that the user may benefit from the assistance of a back-support exoskeleton that reduces the spinal muscle activity and their contribution to lumbar compression. This work addresses this challenge by exploiting the versatility of an active back-support exoskeleton. A control strategy was specifically designed for assisting pulling that modulates the assistive torques using the forearm muscle activity. These torques are expected to adapt to the user’s assistance needs and the pulled object mass, as forearm muscle activity is considered an indicator of grip strength. We devised laboratory experiments to assess the feasibility and effectiveness of the proposed strategy. We found that, for the majority of the subjects, back muscle activity reductions were associated with the exoskeleton use. Furthermore, subjective measurements reveal advantages in terms of perceived support, comfort, ease of use, and intuitiveness.

scholarly journals Analysis of trunk muscle EMG during rotational motion

2021 ◽  
Author(s):  
Nika Zolfaghari
Keyword(s):  
Rotational Motion ◽  
Muscle Activity ◽  
Trunk Muscle ◽  
Trunk Muscles ◽  
Wheelchair Users ◽  
Area Of Interest ◽  
Shoulder Muscles ◽  
Seated Balance ◽  
The Subject ◽  
Rotational Direction

The study of seated balance, specifically for the application of wheelchair users, has been an area of interest for quite some time. Unfortunately, most of the available studies to date have focused on upper limb and shoulder muscles, and little has been done analyzing the activity of trunk muscles (abdominal and back). For the purpose of this study, motorized rotational motion in the forward and backward directions at ±45 degrees was simulated, and the corresponding trunk muscle activity of nine healthy subjects was recorded by surface electromyography (EMG) for eight muscles, including an analysis on the effect of holding on to a harness for support, coupled with the presence of a visual input. The collected raw data was filtered, and the produced results illustrated that the muscle activity was greatest in the forward rotational direction, when the subject was holding on to a harness for support, with visuals present.

A questionnaire-based musculoskeletal disorder assessment for aircraft maintenance technicians

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ebru Yazgan ◽  
Necmettin Firat Ozkan ◽  
Berna Haktanirlar Ulutas
Keyword(s):  
Environmental Factors ◽  
Working Conditions ◽  
Material Handling ◽  
Musculoskeletal Disorder ◽  
Aircraft Maintenance ◽  
Body Parts ◽  
Hand Tools ◽  
Content Type ◽  
Manual Material Handling ◽  
Fall Protection

Purpose Aircraft maintenance technician (AMT) is the most critical profession in the aircraft maintenance system. The tasks of a licensed AMT require expertise and involve repetitive physical tasks such as tightening or loosening aircraft parts, carrying or removing parts during long working hours under time pressure and day/night shifts. This study aims to attract attention to the difficult working conditions of AMTs and identify the body parts that are at risk of musculoskeletal disorder (MSD). Design/methodology/approach A questionnaire is developed by the authors to gather demographic information, use of hand tools, equipment, use of fall protection, manual material handling (lifting, pushing, pulling), load weight, environmental factors, and MSD discomfort level perceptions. The questionnaire is applied to 150 AMTs during six months period, and the obtained data are analyzed by sequential ordinal logistic regression (OLR) models. Findings The ORL results confirm that the use of equipment (lift platform, scissors lift), safety belt attached to the platform, manual material handling, environmental factors (humidity, vibration and illumination) and resting periods have a significant effect on MSD risks. On the contrary, age, experience level, use of small hand tools, temperature and noise are not identified as statistically significant. Originality/value The study is original for it considers the working conditions and perceived discomfort levels of AMTs. A questionnaire is introduced to assess the consequences of the use of tools, equipment, fall protection equipment, environmental conditions and work organization on various body parts (neck, shoulder, elbow, back, lower back, wrist-hand, hip, knee, and ankle-feet), and strain level is identified. The study contributes to the theoretical aircraft maintenance literature and managers in practice.

scholarly journals Occupational risk factors for shoulder chronic tendinous pathology in the Spanish automotive manufacturing sector: a case-control study

2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Beatriz Rodriguez Diez-Caballero ◽  
Joaquín Alfonso-Beltrán ◽  
Iker J. Bautista ◽  
Carlos Barrios
Keyword(s):  
Risk Factors ◽  
Psychosocial Factors ◽  
Musculoskeletal Diseases ◽  
Manufacturing Sector ◽  
Individual Risk ◽  
Predictive Values ◽  
Occupational Risk Factors ◽  
Automotive Manufacturing ◽  
Multiple Variables ◽  
Load Handling

Abstract Background Musculoskeletal Diseases (MSDs) are among the most prevalent health problems encountered in the workforce in Europe. Multiple risk factors contribute to their onset. In the present study, different individual risk factors for chronic tendinous pathology affecting the shoulder were analysed in a sample of workers from the automotive manufacturing sector. Methods An observational retrospective study was conducted with 73 cases of officially recognised and compensated occupational diseases and 94 aleatory cases of healthy workers from the same car assembly company. The experimental group comprised individuals with tendinous chronic pathology of the rotator cuff. Multiple variables that identified the risks present in the job were assessed along with participants clinical evaluation. Furthermore, two standardised guidelines for risk factors assessment were also used: the Spanish National Institute of Social Security (INSS) and the American Occupational Information Network (O*Net). Both descriptive statistical analysis and Odds ratios calculations considering the occupational disease as a dependent variable were performed. Results The use of hand tools, exposure to mechanical pressure in the upper limbs and awkward postures were the most prevalent risk factors. Pressure on the palm of the hand and the hand tool impacting the hand were also important risk factors. Some psychosocial factors such as lack of autonomy and mental workload were also associated shoulder tendinous diseases. The association of age, load handling, and awkward postures were the core risk factors responsible for most of the tendinous chronic injuries of the shoulder in this sample of car assembly workers. Conclusions Both ergonomic and psychosocial factors were present and increased the risk of developing occupational chronic tendinopathies at the shoulder in this sample of workers. Aging, load handling, and awkward postures showed the strongest predictive values. Greater knowledge of how risk factors interact would facilitate the design of better preventive workplace strategies.

scholarly journals Manual material handling in the supermarket sector. Part 1: Joint angles and muscle activity of trapezius descendens and erector spinae longissimus

2021 ◽  
Vol 92 ◽  
pp. 103340
Author(s):  
Sebastian Skals ◽  
Rúni Bláfoss ◽  
Michael Skipper Andersen ◽  
Mark de Zee ◽  
Lars Louis Andersen
Keyword(s):  
Muscle Activity ◽  
Material Handling ◽  
Erector Spinae ◽  
Joint Angles ◽  
Manual Material Handling ◽  
Sector Part

scholarly journals Altered visual feedback from an embodied avatar unconsciously influences movement amplitude and muscle activity

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Pierre Bourdin ◽  
Matteo Martini ◽  
Maria V. Sanchez-Vives
Keyword(s):  
Visual Feedback ◽  
Muscle Activity ◽  
Motor Performance ◽  
Muscular Activity ◽  
Arm Movement ◽  
Body Ownership ◽  
Immersive Virtual Reality ◽  
Body Parts ◽  
Elastic Band ◽  
Visual Inputs

AbstractEvidence suggests that the sense of the position of our body parts can be surreptitiously deceived, for instance through illusory visual inputs. However, whether altered visual feedback during limb movement can induce substantial unconscious motor and muscular adjustments is not known. To address this question, we covertly manipulated virtual body movements in immersive virtual reality. Participants were instructed to flex their elbow to 90° while tensing an elastic band, as their virtual arm reproduced the same, a reduced (75°), or an amplified (105°) movement. We recorded muscle activity using electromyography, and assessed body ownership, agency and proprioception of the arm. Our results not only show that participants compensated for the avatar’s manipulated arm movement while being completely unaware of it, but also that it is possible to induce unconscious motor adaptations requiring significant changes in muscular activity. Altered visual feedback through body ownership illusions can influence motor performance in a process that bypasses awareness.

Use of a Shoulder Rest for Playing the Violin Revisited: An Analysis of the Effect of Shoulder Rest Height on Muscle Activity, Violin Fixation Force, and Player Comfort

2019 ◽  
Vol 34 (1) ◽  
pp. 39-46 ◽  
Author(s):  
Laura M Kok ◽  
Jim Schrijvers ◽  
Marta Fiocco ◽  
Barend van Royen ◽  
Jaap Harlaar
Keyword(s):  
Muscle Activity ◽  
Anterior Part ◽  
Activity Patterns ◽  
Deltoid Muscle ◽  
Surface Emg ◽  
Emg Activity ◽  
Linear Regression Models ◽  
Upper Trapezius ◽  
Shoulder Muscles ◽  
Rest Condition

AIMS: For violinists, the shoulder rest is an ergonomic adaptation to reduce musculoskeletal load. In this study, we aimed to evaluate how the height of the shoulder rest affects the violin fixation force and electromyographic (EMG) activity of the superficial neck and shoulder muscles. METHODS: In professional violinists, four different shoulder rest heights during five playing conditions were evaluated. Outcome variables included the jaw-shoulder violin fixation force and bilateral surface EMG of the upper trapezius (mTP), sternocleidomastoid (mSCM), and left anterior part of the left deltoid muscle (mDTA). Playing comfort was subjectively rated on a visual analogue scale (VAS). Linear regression models were estimated to investigate the influence of the shoulder rest height on muscle activity and violin fixation force as well as the muscle activity of the five evaluated muscles on violin fixation force. RESULTS: 20 professional violinists (4 males, 16 females, mean age 29.4 yrs) participated in this study. The shoulder rest condition had a significant effect on playing comfort (p<0.001), with higher shoulder rest conditions associated with decreased subjective playing comfort. The mean violin fixation force for each shoulder rest condition ranged between 2.92 and 3.39 N; higher shoulder rests were related to a higher violin fixation force (p<0.001). CONCLUSION: In this study, violin fixation force and muscle activity of the left mDTA increased while playing with an increasing height of the shoulder rest. As the shoulder rest influences muscle activity patterns and violin fixation force, adjustment of the shoulder rest and positioning of the violin need to be carefully optimized.

scholarly journals Determining Changes in Electromyography Indices when Measuring Maximum Acceptable Weight of Lift in Iranian Male Students

2018 ◽  
Vol 8 (1Mar) ◽  
Author(s):  
A Salehi Sahl Abadi ◽  
A Mazloumi ◽  
G Nasl Saraji ◽  
H Zeraati ◽  
M R Hadian ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Material Handling ◽  
Objective Assessment ◽  
Wilcoxon Test ◽  
Male Students ◽  
Spearman Correlation ◽  
Lifting Technique ◽  
Spearman Correlation Test ◽  
Left And Right ◽  
External Oblique

Background: In spite of the increasing degree of automation in industry, manual material handling (MMH) is still performed in many occupational settings. The aim of the current study was to determine the maximum acceptable weight of lift using psychophysical and electromyography indices.Methods: This experimental study was conducted among 15 male students recruited from Tehran University of Medical Sciences. Each participant performed 18 different lifting tasks which involved three lifting frequencies, three lifting heights and two box sizes. Each set of experiments was conducted during the 20 min work period using free-style lifting technique and subjective as well as objective assessment methodologies. SPSS version 18 software was used for descriptive and analytical analyses by Friedman, Wilcoxon and Spearman correlation techniques.Results: The results demonstrated that muscle activity increased with increasing frequency, height of lift and box size (P<0.05). Meanwhile, MAWLs obtained in this study are lower than those in Snook table (P<0.05). In this study, the level of muscle activity in percent MVC in relation to the erector spine muscles in L3 and T9 regions as well as left and right abdominal external oblique muscles were at 38.89%, 27.78%, 11.11% and 5.55% in terms of muscle activity is more than 70% MVC, respectively. The results of Wilcoxon test revealed that for both small and large boxes under all conditions, significant differences were detected between the beginning and end of the test values for MPF of erector spine in L3 and T9 regions, and left and right abdominal external oblique muscles (P<0.05). The results of Spearman correlation test showed that there was a significant relation between the MAWL, RMS and MPF of the muscles in all test conditions (P<0.05).Conclusion: Based on the results of this study, it was concluded if muscle activity is more than 70% of MVC, the values of Snook tables should be revisited. Furthermore, the biomechanical perspective should receive special attention in determining the standards for MMH 

scholarly journals Analysis of trunk muscle EMG during rotational motion

2021 ◽  
Author(s):  
Nika Zolfaghari
Keyword(s):  
Rotational Motion ◽  
Muscle Activity ◽  
Trunk Muscle ◽  
Trunk Muscles ◽  
Wheelchair Users ◽  
Area Of Interest ◽  
Shoulder Muscles ◽  
Seated Balance ◽  
The Subject ◽  
Rotational Direction

The study of seated balance, specifically for the application of wheelchair users, has been an area of interest for quite some time. Unfortunately, most of the available studies to date have focused on upper limb and shoulder muscles, and little has been done analyzing the activity of trunk muscles (abdominal and back). For the purpose of this study, motorized rotational motion in the forward and backward directions at ±45 degrees was simulated, and the corresponding trunk muscle activity of nine healthy subjects was recorded by surface electromyography (EMG) for eight muscles, including an analysis on the effect of holding on to a harness for support, coupled with the presence of a visual input. The collected raw data was filtered, and the produced results illustrated that the muscle activity was greatest in the forward rotational direction, when the subject was holding on to a harness for support, with visuals present.

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