Physical loads and aspects of physical performance in middle-aged men and women

Abstract: This investigation aimed at a description of different aspects of physical loads during a 24 year follow-up (1970-1993) in 484 men and women born between 1935 and 1952, in relation to different aspects of physical performance, as measured at follow-up. The subjects were originally recruited in 1969 from the Stockholm county generalpopulation. Quality aspects of questionnaire data on physical loads in the past were also examined.Test-retest reliability, for physical activities at work exceeded that for leisure time and physical training activities, and correlation did not differ markedly between past and present activities. No distinct influence of gender or low back health on one-year reproducibility was found. Six-year reproducibility, showed highest values for theproportion of the working day spent sitting and for perceived general exertion and the lowest values for trunk and neck flexion.Validity of questionnaire responses on physical work loads six year back in time in relation to work-place measurements performed six years ago at these work-places showed the highest values for items sitting and repetitive work and the lowest, unacceptable values for head rotation and neck flexion. Misclassification of exposure did not appear to be differential with regard to musculoskeletal symptom status, asjudged by calculated risk estimates.During the follow-up period (1970 to 1993) the proportion of subjects in blue-collar occupations and the physical work loads decreased among men, but both increased among women. Physical work loads were in general higher among men than among women at younger ages (below 30 years), but the difference was smaller at higher ages. Expert evaluations of the musculoskeletal load showed a pattern similar to that of self-reported work loads.Consistently with previous reports, but mainly among the women, prolonged physically heavy demands showed associations with low trunk flexion strength, squatting endurance and aerobic power. In contrast, low isometric hand grip strength and low weight-lifting endurance were seldom seen among those with high physicalwork loads, indicating a possible maintaining or training effect on the hand/arm/shoulder muscle groups.A consistent covariation between muscle strength and pain thresholds was found in both men and women. Increased sensory thresholds with age were observed even within the limited age span of this study. The sensory thresholds showed only slight covariation with physical work load.