Normative reference values of the handgrip strength for the Portuguese workers

The active workforce is increasingly aging. However workload, as well as working time and intensity, sometimes remains unchanged. This can be an even more critical situation in older people, since occupational exposure associated with aging, will further reduce the muscle's ability to generate energy, which in turn facilitates the development of these age-related syndromes. This study aims to identify the normative values of handgrip strength for Portuguese workers in the automotive industry.

About 1225 employees were invited to participate in the study. The final sample consisted of 656 employees in the assembly area. The handgrip strength was measured in kilograms (kg) using the Jamar digital dynamometer. Sex-specific profiles of handgrip strength were designed by the Ordinary Least Square regression (OLS) analysis, where height, age, age squared, and height squared are entered into the models as determining factors of the maximum grip strength in both female and male groups.

The peak mean values of handgrip strength in the group of women was 34 kg in the age group of 35-39 years, and in the group of men the peak mean was 52 kg in the age group of 25-34 years. The most pronounced decline in the female group appears in the age of 30-34 years of about 4 kg and the male group the decline occurs at 2kg below the peak force, in the age group of 40-57 year-olds. This study used a cut-off at 2 SD below by the sex-specific peak mean.

Normative values can help delineate the career path of workers because they portray risk values according to age, height, and gender. The normative values assist health and engineering professionals and ergonomists in adjusting task demands to the morphological and strength characteristics of the workers.