Biomechanical and ergonomic considerations on shoulder muscle load. Experimental studies

Work-related shoulder disorders represent a significant subset of work-related musculoskeletal disorders. Shoulder tendinitis has a high prevalence in major populations of employees. There is an urgent need for hints and directions on how to evaluate risks for developing chronic work-related shoulder disorders, as well as for methods of assessing hazardous working conditions.The aims of this work were to assess usability and accuracy in techniques and methods for exploring arm positions and shoulder muscle activity and to investigate the pattern of shoulder muscle interplay regarding voluntary control. The aims were also to elucidate the relations between the external physical demands originating from working tasks and internal load on different structures in the shoulder and to propose a model for estimating the risk of developing acute and chronic work-related musculoskeletal disorders of the shoulder, by using observable data which characterize the exposure.Electromyography (EMG) and intramuscular pressure (IMP) measurements were used to assess shoulder muscle activity. Bipolar electrodes were used for acquisition of EMG from the superficial muscles and for deep lying muscles indwelling wire electrodes were used. Acquisition of IMP was accomplished by microcapillary infusion technique. A 3D motion analysis system (MacReflex) has been used for control and registration of arm postures.The results indicate that IMP and EMG measurements produce similar estimates of muscle load and that there were substantial differences in IMP generation between shoulder muscles. Extremely high IMPs were recorded in the supraspinatus muscle. The MacReflex motion analysis system was found to produce position data with an angle error less than 1.8( in biomechanical and ergonomic application. It was demonstrated that the activity of the descending part of the trapezius muscle could be voluntarily reduced to 56% of the initial activity, without altering external conditions, and that the main part of the trapezius load was transferred to the rhomboid major and minor and the transverse part of the trapezius. IMP measurements showed that accumulated muscle fatigue might occur in the infra- and/or supraspinatus, if the upper arm exceeds 30( of arm elevation and that impaired muscle blood flow might occur if the upper arm exceeds 50(. In the validation of the biomechanical shoulder model, it was established that the shoulder muscle forces estimated by the model acceptably agree with the shoulder muscle forces estimated by the EMG measurements, except for the levator scapulae and the supraspinatus, where estimations from EMG measurements were 53% and 207%, respectively, of the activity calculated by the model. In conclusion: feedback assisted reduction of trapezius activity will affect other shoulder muscles, MacReflex motion analysis system possesses adequate accuracy for biomechanical and ergonomic purposes and IMP recordings from the infra- and supraspinatus indicate the necessity of restricted arm positions in static or repetitive work

Datorrelaterad muskuloskeletal ohälsa bland gymnasieelever 2005 - Intervju med datoransvarig på skolan

The data collection was performed in high schools in the counties of Stockholm, Södermanland, Uppsala and Västmanland during the autumn of 2005. The study consisted of two parts: 1. Questionnaires for the students. 2. Ergonomic evaluation of the schools computer workplaces and a short interview with the person responsible for the computers at the school. An information letter was sent to the school leaders where the setup and implementation of the study were explained. After that the school leaders were contacted by telephone and asked if their school wished to participate in the study. If they chose to take part, they were asked to send a record of all students in the second grade to Working Life Institute (Arbetslivsinstitutet). From these lists a selection of classes was made. Then a new contact with the school leader was made, where the leader was asked to inform the teachers concerned by the study. In addition, each teacher got a letter with information about the study. The students got information about the study from their teachers and from the first page in the questionnaire. The ambition was to have a researcher from the Working Life Institute present at the school when the students answered the questionnaire. The completed questionnaires were gathered by the teachers or the researcher and brought to the Working Life Institute where they were de-identified. After that the questionnaires were sent to the company "Tabell och Form AB" for scanning and a primary data preparation. Ergonomists from the Working Life Institute visited all selected schools to perform an ergonomic evaluation, according to a structured checklist, of the student's computer workplaces and to do a short interview with the person responsible for the computers at the school. Purpose: The aim of the study was to describe range of computer usage in school and in spear time and the prevalence of difficulties, especially in the locomotive organs, among high school students. The aim was also to examine if there is a connection between computer time and physical difficulties.Datainsamlingen genomfördes på gymnasieskolor i Stockholms, Södermanlands, Uppsala och Västmanlands län under hösten 2005. Studien bestod av två delar: 1. Frågeformulär till eleverna. 2. Ergonomisk bedömning av skolans datorarbetsplatser och kort intervju med datoransvarig på skolan. Ett informationsbrev skickades till skolledarna, där studiens upplägg och genomförande redovisades. Därefter kontaktades skolledarna per telefon och tillfrågades om skolan önskade medverka i studien. Om de valde att deltaga, ombads de skicka en förteckning på skolans samtliga klasser i ÅK2 till Arbetslivsinstitutet. Från dessa listor gjorde ett urval av klasser. En ny kontakt togs därefter med skolledaren, som då ombads att informera de lärare som skulle komma att bli berörda av studien. Varje lärare fick dessutom ett brev med information om studien. Eleverna fick information om studien via lärarna och första sidan på frågeformuläret. Ambitionen var att en försöksledare från Arbetslivsinstitutet skulle vara närvarande på skolan när eleverna besvarade frågeformuläret. De ifyllda frågeformulären samlades in av lärarna, alternativt av försöksledaren, och fördes till Arbetslivsinstitutet, där de avidentifierades. Därefter skickades de till företaget Tabell o Form AB för scanning och en primär databearbetning. Ergonomer från Arbetslivsinstitutet besökte samtliga utvalda skolor för att göra en ergonomisk bedömning, enligt en strukturerad checklista, av elevernas datorarbetsplatser samt en kort intervju med datoransvarig på skolan. Syfte: Syftet med studien var att beskriva omfattningen av datorarbete i skolan och på fritiden och förekomsten av besvär, särskilt i rörelseorganen, bland gymnasieelever. Syftet var också att undersöka om samband föreligger mellan datortid och kroppsliga besvär

Innovation and employee injury risk in automotive disassembly operations

<p>Engineering innovations in car disassembly systems are studied for affects on system operators’ risk of repetitive strain injury (RSI). Objective instrumented measures of injury risk factors with synchronised video-based task analyses were used to examine changes in operators’ RSI risk during two cases of engineering innovation: (1) a shift in industrial model from traditional extracting saleable parts to line-based full material recovery, and (2) the prospective effects of a simulated ‘Lean’-inspired process improvement in the line system. Both cases of innovation showed significantly increased movement speeds and reduced muscular recovery opportunities, implying increased RSI risk. This case study reveals a mechanism by which innovation may increase RSI risks for operators. Managers responsible for engineering innovation should ensure their teams have the tools and mandate necessary to control injury hazards as part of the development and design process. These cases suggest how failure to manage RSI hazards in the innovation process may allow increases of injury risks that can compromise operational performance. This ‘innovation pitfall’ has implications for operator health and organisational sustainability. Alternative pathways are discussed.</p

Datorrelaterad muskuloskeletal ohälsa bland gymnasieelever 2005 - Observation av datorarbetsplatser

The data collection was performed in high schools in the counties of Stockholm, Södermanland, Uppsala and Västmanland during the autumn of 2005. The study consisted of two parts: 1. Questionnaires for the students. 2. Ergonomic evaluation of the schools computer workplaces and a short interview with the person responsible for the computers at the school. An information letter was sent to the school leaders where the setup and implementation of the study were explained. After that the school leaders were contacted by telephone and asked if their school wished to participate in the study. If they chose to take part, they were asked to send a record of all students in the second grade to Working Life Institute (Arbetslivsinstitutet). From these lists a selection of classes was made. Then a new contact with the school leader was made, where the leader was asked to inform the teachers concerned by the study. In addition, each teacher got a letter with information about the study. The students got information about the study from their teachers and from the first page in the questionnaire. The ambition was to have a researcher from the Working Life Institute present at the school when the students answered the questionnaire. The completed questionnaires were gathered by the teachers or the researcher and brought to the Working Life Institute where they were de-identified. After that the questionnaires were sent to the company "Tabell och Form AB" for scanning and a primary data preparation. Ergonomists from the Working Life Institute visited all selected schools to perform an ergonomic evaluation, according to a structured checklist, of the student's computer workplaces and to do a short interview with the person responsible for the computers at the school. Purpose: The aim of the study was to describe range of computer usage in school and in spear time and the prevalence of difficulties, especially in the locomotive organs, among high school students. The aim was also to examine if there is a connection between computer time and physical difficulties.Datainsamlingen genomfördes på gymnasieskolor i Stockholms, Södermanlands, Uppsala och Västmanlands län under hösten 2005. Studien bestod av två delar: 1. Frågeformulär till eleverna. 2. Ergonomisk bedömning av skolans datorarbetsplatser och kort intervju med datoransvarig på skolan. Ett informationsbrev skickades till skolledarna, där studiens upplägg och genomförande redovisades. Därefter kontaktades skolledarna per telefon och tillfrågades om skolan önskade medverka i studien. Om de valde att deltaga, ombads de skicka en förteckning på skolans samtliga klasser i ÅK2 till Arbetslivsinstitutet. Från dessa listor gjorde ett urval av klasser. En ny kontakt togs därefter med skolledaren, som då ombads att informera de lärare som skulle komma att bli berörda av studien. Varje lärare fick dessutom ett brev med information om studien. Eleverna fick information om studien via lärarna och första sidan på frågeformuläret. Ambitionen var att en försöksledare från Arbetslivsinstitutet skulle vara närvarande på skolan när eleverna besvarade frågeformuläret. De ifyllda frågeformulären samlades in av lärarna, alternativt av försöksledaren, och fördes till Arbetslivsinstitutet, där de avidentifierades. Därefter skickades de till företaget Tabell o Form AB för scanning och en primär databearbetning. Ergonomer från Arbetslivsinstitutet besökte samtliga utvalda skolor för att göra en ergonomisk bedömning, enligt en strukturerad checklista, av elevernas datorarbetsplatser samt en kort intervju med datoransvarig på skolan. Syfte: Syftet med studien var att beskriva omfattningen av datorarbete i skolan och på fritiden och förekomsten av besvär, särskilt i rörelseorganen, bland gymnasieelever. Syftet var också att undersöka om samband föreligger mellan datortid och kroppsliga besvär

Datorrelaterad muskuloskeletal ohälsa bland gymnasieelever 2005 - Reliabilitetsdata-observationsdata

The data collection was performed in high schools in the counties of Stockholm, Södermanland, Uppsala and Västmanland during the autumn of 2005. The study consisted of two parts: 1. Questionnaires for the students. 2. Ergonomic evaluation of the schools computer workplaces and a short interview with the person responsible for the computers at the school. An information letter was sent to the school leaders where the setup and implementation of the study were explained. After that the school leaders were contacted by telephone and asked if their school wished to participate in the study. If they chose to take part, they were asked to send a record of all students in the second grade to Working Life Institute (Arbetslivsinstitutet). From these lists a selection of classes was made. Then a new contact with the school leader was made, where the leader was asked to inform the teachers concerned by the study. In addition, each teacher got a letter with information about the study. The students got information about the study from their teachers and from the first page in the questionnaire. The ambition was to have a researcher from the Working Life Institute present at the school when the students answered the questionnaire. The completed questionnaires were gathered by the teachers or the researcher and brought to the Working Life Institute where they were de-identified. After that the questionnaires were sent to the company "Tabell och Form AB" for scanning and a primary data preparation. Ergonomists from the Working Life Institute visited all selected schools to perform an ergonomic evaluation, according to a structured checklist, of the student's computer workplaces and to do a short interview with the person responsible for the computers at the school. Purpose: The aim of the study was to describe range of computer usage in school and in spear time and the prevalence of difficulties, especially in the locomotive organs, among high school students. The aim was also to examine if there is a connection between computer time and physical difficulties.Datainsamlingen genomfördes på gymnasieskolor i Stockholms, Södermanlands, Uppsala och Västmanlands län under hösten 2005. Studien bestod av två delar: 1. Frågeformulär till eleverna. 2. Ergonomisk bedömning av skolans datorarbetsplatser och kort intervju med datoransvarig på skolan. Ett informationsbrev skickades till skolledarna, där studiens upplägg och genomförande redovisades. Därefter kontaktades skolledarna per telefon och tillfrågades om skolan önskade medverka i studien. Om de valde att deltaga, ombads de skicka en förteckning på skolans samtliga klasser i ÅK2 till Arbetslivsinstitutet. Från dessa listor gjorde ett urval av klasser. En ny kontakt togs därefter med skolledaren, som då ombads att informera de lärare som skulle komma att bli berörda av studien. Varje lärare fick dessutom ett brev med information om studien. Eleverna fick information om studien via lärarna och första sidan på frågeformuläret. Ambitionen var att en försöksledare från Arbetslivsinstitutet skulle vara närvarande på skolan när eleverna besvarade frågeformuläret. De ifyllda frågeformulären samlades in av lärarna, alternativt av försöksledaren, och fördes till Arbetslivsinstitutet, där de avidentifierades. Därefter skickades de till företaget Tabell o Form AB för scanning och en primär databearbetning. Ergonomer från Arbetslivsinstitutet besökte samtliga utvalda skolor för att göra en ergonomisk bedömning, enligt en strukturerad checklista, av elevernas datorarbetsplatser samt en kort intervju med datoransvarig på skolan. Syfte: Syftet med studien var att beskriva omfattningen av datorarbete i skolan och på fritiden och förekomsten av besvär, särskilt i rörelseorganen, bland gymnasieelever. Syftet var också att undersöka om samband föreligger mellan datortid och kroppsliga besvär

Datorrelaterad muskuloskeletal ohälsa bland gymnasieelever 2005 - Enkät till elever

The data collection was performed in high schools in the counties of Stockholm, Södermanland, Uppsala and Västmanland during the autumn of 2005. The study consisted of two parts: 1. Questionnaires for the students. 2. Ergonomic evaluation of the schools computer workplaces and a short interview with the person responsible for the computers at the school. An information letter was sent to the school leaders where the setup and implementation of the study were explained. After that the school leaders were contacted by telephone and asked if their school wished to participate in the study. If they chose to take part, they were asked to send a record of all students in the second grade to Working Life Institute (Arbetslivsinstitutet). From these lists a selection of classes was made. Then a new contact with the school leader was made, where the leader was asked to inform the teachers concerned by the study. In addition, each teacher got a letter with information about the study. The students got information about the study from their teachers and from the first page in the questionnaire. The ambition was to have a researcher from the Working Life Institute present at the school when the students answered the questionnaire. The completed questionnaires were gathered by the teachers or the researcher and brought to the Working Life Institute where they were de-identified. After that the questionnaires were sent to the company "Tabell och Form AB" for scanning and a primary data preparation. Ergonomists from the Working Life Institute visited all selected schools to perform an ergonomic evaluation, according to a structured checklist, of the student's computer workplaces and to do a short interview with the person responsible for the computers at the school. Purpose: The aim of the study was to describe range of computer usage in school and in spear time and the prevalence of difficulties, especially in the locomotive organs, among high school students. The aim was also to examine if there is a connection between computer time and physical difficulties.Datainsamlingen genomfördes på gymnasieskolor i Stockholms, Södermanlands, Uppsala och Västmanlands län under hösten 2005. Studien bestod av två delar: 1. Frågeformulär till eleverna. 2. Ergonomisk bedömning av skolans datorarbetsplatser och kort intervju med datoransvarig på skolan. Ett informationsbrev skickades till skolledarna, där studiens upplägg och genomförande redovisades. Därefter kontaktades skolledarna per telefon och tillfrågades om skolan önskade medverka i studien. Om de valde att deltaga, ombads de skicka en förteckning på skolans samtliga klasser i ÅK2 till Arbetslivsinstitutet. Från dessa listor gjorde ett urval av klasser. En ny kontakt togs därefter med skolledaren, som då ombads att informera de lärare som skulle komma att bli berörda av studien. Varje lärare fick dessutom ett brev med information om studien. Eleverna fick information om studien via lärarna och första sidan på frågeformuläret. Ambitionen var att en försöksledare från Arbetslivsinstitutet skulle vara närvarande på skolan när eleverna besvarade frågeformuläret. De ifyllda frågeformulären samlades in av lärarna, alternativt av försöksledaren, och fördes till Arbetslivsinstitutet, där de avidentifierades. Därefter skickades de till företaget Tabell o Form AB för scanning och en primär databearbetning. Ergonomer från Arbetslivsinstitutet besökte samtliga utvalda skolor för att göra en ergonomisk bedömning, enligt en strukturerad checklista, av elevernas datorarbetsplatser samt en kort intervju med datoransvarig på skolan. Syfte: Syftet med studien var att beskriva omfattningen av datorarbete i skolan och på fritiden och förekomsten av besvär, särskilt i rörelseorganen, bland gymnasieelever. Syftet var också att undersöka om samband föreligger mellan datortid och kroppsliga besvär