Muscle strength and muscle endurance in groups with different occupational muscular load was studied among 60 women and 69 men. The mean age of the subjects was 52.0 +/- 3.4 years. Isometric grip and trunk strength were measured on dynamometers, and dynamic muscle endurance by sit-ups. A job analysis was done with the AET method including the assessment of intensity, duration and type of muscular work of each subject. According to the job analysis, the subjects were classified into groups with low or high muscular load at work. The maximal isometric hand grip strength of women with a load classified as long duration of static or dynamic load on the hands at work was 86 and 88%, respectively of the strength of those with a load of short duration. The women with high intensity in static work had a grip strength of 86% of those with low intensity. These differences in strength among women between the high and low load groups were statistically significant (P less than 0.05). No other statistically significant differences in muscle strength or muscle endurance between the high and low work load groups were found, although the high work load group had systematically the lowest muscle strength and muscle endurance in almost all comparisons. Muscle strength and muscle endurance was, however, not a discriminating factor between the group classifications of static and dynamic work. The results indicated that the muscle strength and muscle endurance of middle-aged employees was systematically lower among those with high muscular load compared to those with low load at work.
This study is part of a comprehensive multidisciplinary project aimed at determining criteria for retirement ages in municipal occupations in Finland. Musculoskeletal load at work was studied in eight different occupational groups to see what differences between occupational groups exist. A job analysis of the work of 116 subjects was made with the ergonomic job description analysis method (AET). The work of 116 men and women, mean age 52 years, was studied in the work place. The study revealed three levels of overall musculoskeletal load. The groups with high musculoskeletal load worked in installation, auxiliary, home care and transport groups, with an assessed load of on average about one third of the maximal on the AET scale. Both quantitative and qualitative loading problems were concentrated in these groups. In contrast, teaching and administration groups had low musculoskeletal load averaging about 10% of the maximal. The nursing and office groups were between these two levels with a load of approximately 20% of the maximal. However, with the same overall quantity, the quality of the musculoskeletal load varied. In the transport group, monotonous static work with both arms (about 60% of workshift) and legs (30%) was most common, while the musculoskeletal load of the auxiliary and home care groups consisted of heavy dynamic muscular work with arms (60% of workshift) and legs (70%). On the other hand, the administration group alone had a static load of the arms (about 15% of workshift) and legs (2%) and also a low dynamic load with arms (0%) and legs (33%), which could have hypokinetic effects. In conclusion, there are significant differences between the profile groups in both the quantitative and qualitative load of the musculoskeletal system. The differences are even more pronounced when aging employees are studied. These facts support different retirement ages for the profile groups, at least when the musculoskeletal system is concerned.
The occupational stress factors related to specific cardiovascular diseases were studied by a questionnaire mailed to 6213 municipal employees aged 45 to 58 years, (response rate 85%) and by a specific job analysis of certain municipal occupations. The highest prevalences of self-reported chronic hypertension were found among male transport workers (19%), technical supervisors (19%) and auxiliary workers (15%), as well as among female domestic helpers (18%) and auxiliary workers (18%). Among men the prevalence of coronary heart disease varied from 9% for dump workers to 0% for dentists (mean 5%) and among women from 4% for kitchen supervisors to 0% for physicians (mean 3%). In the work profile groups with the highest rates of reported, specific cardiovascular diseases, the stress factors of women's work (domestic help and auxiliary work) were high energy demands, heavy dynamic and static work with high application of strength, poor postures, and uncomfortable climatic conditions. These stress factors were also typical among men doing auxiliary work. Other common stress factors among men included sensory-motor work done alone in static, monotonous sitting postures, exposured to vibration, drafts, and continuous alertness of the senses (transport work) and to processing and organization of information together with time pressure linked to decision-making and the need for accurate sensory perception (technical supervision work).
The effects of musculoskeletal work load and muscle strength on strain at work were analysed among 60 women and 69 men (mean age 52 +/- 3.4) in municipal jobs in Finland. The musculoskeletal work load was determined by analysing the jobs by a job description method. The maximal isometric hand grip strength was assessed with a manometer, trunk flexion and trunk extension strength with a dynamometer, and dynamic trunk flexion endurance strength with a sit-up test. Heart rate was registered continuously and ratings of perceived exertion were determined 4 times during the work shift. The results revealed that high musculoskeletal work load was systematically and significantly related to high strain at work in both sexes. A high mean heart rate related to an individual's range in women was an interaction effect of high work load and low hand grip strength or low trunk flexion strength. Among men, both high mean and maximal heart rates in relation to the heart rate range was due to the interaction effects of high work load and low trunk extension strength. The interaction of work load and strength was not systematically related to the ratings of perceived exertion during work. It was concluded that the musculoskeletal work load exerted the main effects on the cardiorespiratory and perceived strains at work. The interaction effects of work load and strength on strain depended on the sex and the muscle group in the studied work load level of elderly municipal employees.
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