Muscle strength and muscle endurance of middle-aged women and men associated to type, duration and intensity of muscular load at work

Abstract

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.

Physical demands in working life and individual physical capacity

“…Furthermore, most of the ''cases'' were also found to have low muscle endurance (which correlates to aerobic capacity), as well as poor balance and coordination. Earlier studies have shown a negative relationship between capacity (both aerobic and muscular strength) and long-lasting physical activity at work (Nyga˚rd et al 1987(Nyga˚rd et al , 1988Era 1992;Torge´n et al 1999). Females in the highest quartile of TWA-MET work had, however, lower muscle endurance in their abdomen and legs and worse coordination than subjects in the lowest quartile of TWA-MET work .…”

“…A positive relationship between physical capacity and physical workload among young workers has been documented (Schibye et al 2001). In studies among middle-aged and elderly workers who have had physically strenuous jobs during their careers, a negative relationship between capacity and physical activities at work has been observed (Nyga˚rd et al 1987(Nyga˚rd et al , 1988Era 1992;Miettinen and Louhevaara 1994). In contrast to these findings, other studies find a positive relationship between muscle strength and workload among elderly workers (e.g.…”

Does a history of physical exposures at work affect hand-grip strength in midlife? A retrospective cohort study in Denmark

“…The influence of work-related exposures on muscle strength has been discussed since the 1980s, where occuhas been discussed since the 1980s, where occupational physical activity was thought to strengthen manual workers (1). Since then the focus has been on the deteriorating effects of physical exposures, which are now known to be important risk factors in the development of musculoskeletal symptoms and diseases (2,3).…”

Excessive physical demands in modern worklife and characteristics of work and living conditions of persons at risk

“…A positive relationship between physical aerobic capacity and physical workload has been documented for young workers (20). In studies among middle-aged and elderly workers who have had physically strenuous jobs during their careers, a negative relationship has been observed between aerobic capacity and physical activities at work (21)(22)(23)(24). In contrast to these findings, other studies have found a positive relationship between muscle strength and workload among elderly workers (20).…”