Differences in parameters of the explosive grip force test between young and older women.

BACKGROUND Decreases of strength and speed of muscle contraction are considered major causes of functional impairments in older people. However, the age-related changes in grip force-generating capacity are not clear. The purpose of this study was to measure the parameters of the explosive grip force test and to compare the differences between young and older women. METHODS Thirty healthy young women (mean age: 22.3 years) and 27 healthy older women (mean age: 78.5 years) participated in this study. All participants performed the maximal explosive grip test three times. Data were recorded as a force-time curve, and the maximal rate of grip force development (max RGFD) and RGFD at intervals of 10 ms up to 250 ms from the onset of contraction were calculated. RESULTS The majority of RGFDs of young women were higher than those of the older ones. The maximal grip strength, max RGFD, and max RGFD normalized by the maximal grip strength of older women were 28.3%, 52.4%, and 25.2% less than those of young women, respectively. RGFDs of the older women were not influenced by the maximal grip strength, whereas in young women, those in the late phase of explosive grip force generation showed a moderate correlation with the maximal grip strength. CONCLUSIONS The present results showed a decrease of the output parameters of the explosive grip force test in older women. Evaluation of explosive grip force generation using RGFD may be used as an assessment tool, providing more detailed information on the grip function.