Shoulder and neck muscle activities during typing with articulating forearm support at different heights

The Ergonomic Association between Shoulder, Neck/Head Disorders and Sedentary Activity: A Systematic Review

Background

Work-associated upper limb and neck disorders are common occupational disorders throughout the world. These disorders are usually observed more in workers who spend a long time sitting, referred to as sedentary activity (SA). The immediate and distorted risk of sedentary-related problems was considered high in Europe, Australia, and the United States. Even though mediation is convenient, it is likely to reduce office workers' risks of developing cervical and upper body pain due to sedentary work. This systematic review addresses risk factors and evaluates the relationship between SA and upper body disorders in office workers (i.e., shoulder and neck/head).

Methods

PubMed, Scopus, and Web of Science were searched for articles published between January 2010 and August 2021 in the English language. The three keywords “sedentary,” “upper body elements,” and “work” (and their derivatives) were searched to identify studies and carry out this systematic review. The articles were searched so that all three keywords or at least a derivation of each keyword should appear. Findings. Of the 40 articles that met the enclosure criteria, 32 studies examined the association of SA and upper body elements during both office and computer work. However, three articles were evaluated in the sit-stand work environment, and in the remaining five studies, one was evaluated during teaching, two during hospital work, and two during mixed working conditions.

Conclusions

Research related to SA focuses mainly on extended risk factors, but there was no focus on other aspects, such as muscle and tendon contractions. As there is a convincing connection between SA and the upper body, our close examination identifies the need to institutionalize a system for collecting, analyzing, and describing the impact and short-term effects of SA on the upper body. Additionally, some suggestions were made to minimize the risk in a sedentary working environment.

Pandemia de COVID-19 e as atividades de ensino remotas: riscos ergonômicos e sintomas musculoesqueléticos dos docentes do Instituto Federal Catarinense

RESUMO O objetivo da pesquisa foi avaliar os sintomas osteomusculares e os riscos ergonômicos dos ambientes de trabalho dos docentes do Instituto Federal Catarinense (IFC). Participaram 140 docentes, que responderam a um questionário online sobre informações sociodemográficas, realização de tarefas, ambiente de trabalho e dor musculoesquelética. Os dados foram analisados por meio de uma regressão logística binária separadamente para cada desfecho, utilizando como variáveis dependentes: dores no pescoço, no ombro direito e na coluna lombar. A prevalência de dor entre os professores foi de 94,7%, e as regiões mais frequentes foram o pescoço, a coluna lombar e o ombro direito. Os principais riscos ergonômicos observados foram: sobrecarga mental (estresse), mesa de trabalho e monitor inadequados. Foi observada associação entre dor no pescoço e docentes que apresentaram maior sobrecarga mental (estresse), não fazem atividade física e usam o computador por mais de 20 horas por semana; dor no ombro direito e docentes que não fazem atividade física, usam o computador por mais de 20 horas por semana, cuja mesa de trabalho não estava ao nível do cotovelo e sem espaço para apoiar os antebraços. Ainda, a dor na coluna lombar foi associada ao grupo de mulheres com carga horária de aula semanal maior que 15 horas e com doença crônica. Os resultados encontrados possibilitam a adaptação dos ambientes de trabalho dos docentes para a prevenção de dor, a melhoria da qualidade de vida e do ensino.

Posture and musculoskeletal implications for students using mobile phones because of learning at home policy

There is an increasing trend of awkward postures due to smartphone use among students learning from home. Previous research in several countries has shown that the use of smartphones during a pandemic impacts musculoskeletal complaints. This study aimed to determine the postures performed by the students when using mobile phones and their implications for musculoskeletal complaints. A total of 709 students who learned from home voluntarily completed an online questionnaire regarding identity, work posture, and duration, while muscle and bone complaints experienced when using mobile phones were obtained through the Nordic Musculoskeletal Questionnaire. Furthermore, a bivariate analysis of body postures was carried out to identify perceived complaints using the chi-square method. The results showed a significant relationship between standing and leaning on a table posture (p-value: 0.026) with elbow, knee, and ankle complaints.

COVID-19 pandemic and remote teaching activities: ergonomic risks and musculoskeletal symptoms of professors at Instituto Federal Catarinense

ABSTRACT This study aimed to evaluate the musculoskeletal symptoms and the ergonomic risks in the workplaces of the professors of the Instituto Federal Catarinense (IFC). 140 professors participated by answering an online questionnaire on sociodemographic information, task performance, work environment, and musculoskeletal pain. Data were analyzed using binary logistic regression for each outcome separately, using neck, right shoulder, and low back pain as dependent variables. The prevalence of pain among professors was 94.7% and the most frequent regions were the neck, lumbar spine, and right shoulder. The main ergonomic risks were mental overload (stress) and inadequate worktable and monitor. An association between neck pain and professors who had greater mental overload (stress), who do not engage in physical activity, and who use the computer for more than 20 hours a week was observed; also, between pain in the right shoulder and the professors who do not engage in physical activity, who use the computer for more than 20 hours a week, who had an inadequate workspace. Low back pain was associated with women, weekly course workload greater than 15 hours, and chronic disease. The results found indicate the need to adapt the workplace of the professors with in order to prevent pain and improve the quality of life and the quality of teaching.

Ergonomic arm support prototype device for smartphone users reduces neck and shoulder musculoskeletal loading and fatigue

Smartphone use is a risk factor for both neck and shoulder musculoskeletal disorders. The objective of this study was to evaluate an ergonomic arm support prototype device, which may help improve posture while using a smartphone, by determining its effect on muscle activity, muscle fatigue, and neck and shoulder discomfort. Twenty-four healthy young adult smartphone users performed 20 min of smartphone game playing under two different conditions, smartphone use with support prototype device (i.e. intervention condition) and without (i.e. control condition), while neck and shoulder posture were controlled at 0° neck flexion and 30° shoulder flexion. Activity and fatigue of four muscles were measured using surface electromyography (sEMG), these were: anterior deltoid (AD), cervical erector spinae (CES), upper trapezius (UT) and lower trapezius (LT). The intervention condition showed significantly decreased activity of all muscles. Fatigue of all muscles, except LT, significantly increased over time compared to the start point in the control condition. There was no significant difference in muscle fatigue between each time point in the intervention condition. In conclusion, the ergonomic arm support prototype device can be used as ergonomic intervention to reduce neck and shoulder muscle loading and fatigue.

Mouse with your arm™: Facilitating forearm support using the chair armrest to prevent and mitigate musculoskeletal disorders

BACKGROUND

Musculoskeletal disorders (MSDs) can be prevented by avoiding trauma caused by poor posture, compression, force, and repetition. Neutral postures are recommended to avoid MSDs.

OBJECTIVE

This study introduces Mouse With Your Arm™ (MWYA) methodology which promotes sitting back in a chair, using the chair's armrest for forearm support at relaxed elbow height, matching surface and armrest height, and keeping the mouse on the surface edge. This position allows optimal task chair use, facilitates movement and neutral postures, avoids compression and contact stress, and is effective in mitigating MSDs.

METHOD

MWYA was applied and measured in the field for more 23 years providing over 3,500 individualized assessments to integrate a participant's unique characteristics, reported health concerns, tasks, tools, and environment to achieve and sustain whole-body neutral and comfortable working postures.

RESULTS

Previous research has consistently recommended use of forearm support by a desk, apparatus, or wrist rest, and resulted in non-neutral, static postures and measured health consequences. By using armrests for support, MWYA avoids the potential of MSDs as can be caused by these previously endorsed postures.

CONCLUSION

By applying the five MWYA principles, computer users comprehend neutral posture and put forth the effort essential to creating healthy human computer relationships.

Armrests and back support reduced biomechanical loading in the neck and upper extremities during mobile phone use

Mobile phone use is known to be associated with musculoskeletal pain in the neck and upper extremities because of related physical risk factors, including awkward postures. A chair that provides adequate support (armrests and back support) may reduce biomechanical loading in the neck and shoulder regions. Therefore, we conducted a repeated-measures laboratory study with 20 participants (23 ± 1.9 years; 10 males) to determine whether armrests and back support during mobile phone use reduced head/neck flexion, gravitational moment, and muscle activity in the neck and shoulder regions. The results showed that the chair support (armrests and back support) reduced head/neck flexion (p < 0.001), gravitational moment (p < 0.001), and muscle activity (p < 0.01) in the neck and shoulder regions significantly compared to no chair support. These results indicate that a chair with adequate support can be an effective intervention to reduce the biomechanical exposures and associated muscular pain in the neck and shoulders during mobile phone use.

Glasses-type wearable computer displays: usability considerations examined with a 3D glasses case study

This study presents usability considerations and solutions for the design of glasses-type wearable computer displays and examines their effectiveness in a case study. Design countermeasures were investigated by a four-step design process: (1) preliminary design analysis; (2) design idea generation; (3) final design selection; and (4) virtual fitting trial. Three design interventions were devised from the design process: (1) weight balance to reduce pressure concentrated on the nose, (2) compliant temples to accommodate diverse head sizes and (3) a hanger mechanism to help spectacle users hang their wearable display on their eye glasses. To investigate their effectiveness, in the case study, the novel 3D glasses adopting the three interventions were compared with two existing 3D glasses in terms of neck muscle fatigue and subjective discomfort rating. While neck muscle fatigue was not significantly different among the three glasses (p = 0.467), the novel glasses had significantly smaller discomfort ratings (p = 0.009). Relevance to Industry: A four-step design process identified usability considerations and solutions for the design of glasses-type wearable computer displays. A novel 3D glasses was proposed through the process and its effectiveness was validated. The results identify design considerations and opportunities relevant to the emerging wearable display industry.

The effects of forearm support and shoulder posture on upper trapezius and anterior deltoid activity

[Purpose] To assess the effects of forearm support and shoulder posture on upper trapezius and anterior deltoid activity. [Subjects and Methods] Twenty-three female university students were evaluated. Muscle activity was assessed by a portable surface electromyography (sEMG) system (Myomonitor IV, Delsys, USA). Upper trapezius and anterior deltoid activity were recorded in five shoulder flexion postures: 0°, 15°, 30°, 45° and 60° and in two conditions: with the forearm supported and unsupported. Descriptive data analysis was performed and statistical analysis was conducted by a multivariate analysis of variance with three repeated factors (posture, support and side). [Results] Three-way interactions were not significant. Two-way interaction was significant for support and posture for both muscles, indicating that the muscular activity depends on the forearm support and shoulder posture. The forearm support reduced upper trapezius and anterior deltoid activity for all shoulder flexion angles. The mean and standard deviation for this decrease was 7.8 (SD=4.6)% of the maximal voluntary contraction for anterior deltoid and 3.8 (SD=2.0)% of the maximal voluntary contraction for upper trapezius. In the unsupported condition, increasing the shoulder flexion angle caused an increase in the upper trapezius and anterior deltoid activation. [Conclusion] These results highlight the importance of using forearm support and to maintain neutral shoulder posture, when the upper arms are not supported, to reduce muscle activation. Thus, this study provides evidence about the effect of these recommendations to reduce muscular activity.

Effects of touch target location on performance and physical demands of computer touchscreen use

Touchscreen interfaces for computers are known to cause greater physical stress compared to traditional computer interfaces. The objective of this study was to evaluate how physical demands and task performance of a tap gesture on a computer touchscreen vary between target locations and display positions. Twenty-three healthy participants conducted reach-tap-return trials with touch targets at fifteen locations in three display positions. Mean completion time, touch accuracy and electromyography of the shoulder and neck extensor muscles were compared between the target locations and display positions. The results demonstrated that participants completed the trial 12%-27% faster with 13%-39% less muscle activity when interacting with targets in the lower area of the display compared to when tapping upper targets (p < 0.05). The findings suggest that proper target placement and display positioning can improve task performance and lessen physical demands of computer touchscreen interface use.

Hand usage pattern and upper body discomfort of desktop touchscreen users

A laboratory study was conducted to determine how users of different handedness interact with desktop touchscreen displays and how the hand usage pattern influences their body discomfort development. Twenty-one participants in three different handedness groups conducted simple web-browsing for 30 minutes using a 23″ touchscreen display while their subjective body discomfort, frequency of use of each hand and touch area preference were periodically quantified. Participants reported a gradual increase in body discomfort during web-browsing, and the increments in body discomfort varied between handedness groups for some body parts. Results also show that right-handed participants had stronger laterality than the left-handed, and ambidextrous participants used both hands more evenly than other participants, suggesting associations between the hand usage pattern and body discomfort development. Findings of the current study suggest that body discomfort of desktop touchscreen display users could be moderated by user-interface improvements and user training.

PRACTITIONER SUMMARY

Body discomfort development of desktop touchscreen users may be influenced by their hand usage pattern. Findings of this laboratory study suggest that user discomfort may be moderated by placing menu items in the lower area within the display or training users to alternate hands when conducting touch gestures.

Touch displays: the effects of palm rejection technology on productivity, comfort, biomechanics and positioning

Direct touch displays can improve the human-computer experience and productivity; however, the higher hand locations may increase shoulder fatigue. Palm rejection (PR) technology may reduce shoulder loads by allowing the palms to rest on the display and increase productivity by registering the touched content and fingertips through the palms rather than shoulders. The effects of PR were evaluated by having participants perform touch tasks while posture and reaction force on the display were measured. Enabling PR, during which the subjects could place the palms on the display (but were not required to), resulted in increased wrist extension, force applied to the display and productivity, and less discomfort, but had no effect on the self-selected positioning of the display. Participants did not deliberately place their palms on the display; therefore, there was no reduction in shoulder load and the increased productivity was not due to improved hand registration. The increased productivity may have been due to reduced interruptions from palm contacts or reduced motor control demands.