Estimation of reference intervals for physical fitness indicators in healthy community-dwelling older adults

BACKGROUND: The aim of this study was to estimate reference intervals for physical fitness indicators in healthy community-dwelling older adults.METHODS: The subjects were community-dwelling adults aged 65 years or older who were independent in their daily lives. A healthy older adult was defined as one without locomotive syndrome (LS). The participants’ grip strength and 5m-walking time were measured. Additionally, they underwent the Single Leg Stance (SLS) test and Timed-Up and Go (TUG) test. The values obtained were evaluated for normality, and if a normal distribution was found, the bootstrap method was used to estimate the 95% confidence interval (CI). The values that did not show a normal distribution were evaluated again for normality using the Box-Cox transformation. The bootstrap method was used to estimate the 95% CI for the physical fitness indicators that showed a normal distribution after the Box-Cox transformation, and an inverse transformation of the estimated value was performed.RESULTS: A total of 330 subjects were included in the study (84 men). Only grip strength was found to be normally distributed in both sexes. The other values were Box-Cox transformed and normality tests were conducted again. The physical fitness indicators that ultimately showed a normal distribution were grip strength, preferred walking time, fast walking time, and TUG.CONCLUSIONS: These reference intervals can serve as a guide for determining whether an older adult can be considered physically healthy.