Neuromuscular assessment in elderly workers with and without work related shoulder/neck trouble: the NEW-study design and physiological findings

Abstract

Musculoskeletal disorders in the neck and shoulder area are a major occupational concern in the European countries especially among elderly females. The aim was to assess these disorders based on quantitative EMG indicators and functional tests. 252 female computer users (45-68 years) were recruited from four European countries in two contrast groups: (1) 88 neck/shoulder (NS) cases reporting trouble in the neck and/or shoulder region for more than 30 days during the last year, and (2) 164 NS-controls reporting such trouble for no more than 7 days. Questionnaires, functional/clinical tests, and physiological recordings were performed in workplace related field studies. The results showed no differences in anthropometrics but NS-cases reported more strained head positions and more eye problems than controls. The psychosocial working factors were similar, although, NS-controls had slightly better scores on working conditions, general health, and vitality compared to cases. The NS-cases had lower maximal voluntary contraction (MVC) during shoulder elevation (mean (SD) 310 (122) N) compared to the controls (364 (122) N). During 30% MVC electromyography (EMGrms) in the trapezius muscle was lower in NS-cases (194 (105) muV) than in controls (256 (169) muV), while no differences were found regarding endurance time. Estimated conduction velocity was not different between NS-cases and -controls. Four functional computer tests were performed equally well by NS-cases and -controls, and the corresponding EMG variables also did not differ. A major finding in this large-scale epidemiological study is the significantly lower MVC in NS-cases compared with NS-controls together with lower EMGrms value at 30% MVC, while computer tasks were performed at similar relative muscle activation. The study was unable to reveal quantitative EMG indicators and functional tests that could objectively assess disorders in NS-cases.

Trapezius muscle rest time during standardised computer work – A comparison of female computer users with and without self-reported neck/shoulder complaints

“…All subjects were fully informed about the experimental procedures before giving their consent, and were fully allowed to interrupt or leave the study whenever they wanted to. These subjects constitute a sub-sample of the subjects with general EMG results previously reported by Sjøgaard et al (2006).…”

“…If the third MVC recording was more than 5% higher than the previous two recordings, a fourth test was performed; a maximum of 5 tests were performed. For further details, see Sjøgaard et al (2006). The maximum voluntary electrical (MVE) activity was computed according to recommendations by Mathiassen et al (1995).…”

Perceived work demands, felt stress, and musculoskeletal neck/shoulder symptoms among elderly female computer users. The NEW study

“…The importance of aspects of the psychosocial work environment, such as perceived work demands, influence at work, skill discretion, social support, and appraised workload, as risk factors for musculoskeletal symptoms has been demonstrated in a vast number of studies, although the results are not consistent (Ariens et al 2001b;Bongers et al 1993Bongers et al , 2002Hoogendorn et al 2000;van der Windt et al 2000;Bystro¨m et al 2004). As regards the psychosocial work environment, the present study is focused on one specific aspect thereof-perceived work demands.…”

Clinical signs and physical function in neck and upper extremities among elderly female computer users: the NEW study

“…A neck/shoulder control (NS control) was defined as reporting a maximum of 7 days of trouble in both the neck and the two shoulders within the last 12 months, and a maximum of three areas in total with more than 30 days of trouble within the last 12 months. The present study group is a subgroup of the NEW (neuromuscular assessment in elderly workers) study population (Sjøgaard et al 2004), representing only those subjects who also participated in a clinical examination of the neck and upper extremities, comprising a total of 50 subjects from Denmark and 53 from Sweden. In total, 42 NS cases and 61 NS controls from four workplaces, representing both public and private organizations, were included.…”