Cut-off points of quadriceps strength, declines and relationships of sarcopenia-related variables among Thai community-dwelling older adults.

To define quadriceps strength cut-off points for both sexes to be used in the working diagnosis of sarcopenia in older Asian people, and to investigate the age-related declines of sarcopenia-related variables and correlations between those variables among community-dwelling older adults.The present 3-year prospective study was a part of the Bangkok Longitudinal Study by Siriraj Hospital for Older Men and Women. Data on 2149 participants aged ≥ 60 years were included in this analysis.The quadriceps strength cut-off points, identified based on mobility decline over 2 years of follow up, were 18.0 kg for men and 16.0 kg for women. When these cut-off points were applied to the whole population aged ≥ 60 years (n = 950), the low quadriceps strength group had poorer results on all clinical variables when compared with the normal quadriceps strength group. Although nearly all of the sarcopenia-related variables declined over 2 years of follow up in both older men and women, more significant differences between age groups were seen in older women. Quadriceps strength had the highest degree of correlation with total lean body mass in all age groups (r = 0.550-0.584, P < 0.001), followed by the 6-min walk test in all age groups (r = 0.449-0.516, P < 0.001).The quadriceps strength cut-off points of 18.0 kg for older men and 16.0 kg for older women would be useful as a muscle strength measurement for use in any diagnostic algorithm; for example, sarcopenia diagnosis in older Asian people.