Normative percentile curves of accelerometer-measured daily step counts in Korean older adults

[Purpose] The objective of this study was to quantify daily physical activity levels in Korean older adults using accelerometers and establish sex-and age-specific normative percentile reference values for daily step counts. [Methods] A total of 375 community-dwelling older adults aged ≥ 65 years (182 males and 193 females) were enrolled. Physical activity was measured over one week using triaxial accelerometers. Participants were instructed to wear the device for ≥ 10 h per day on four or more valid days, including at least one weekend day. Normative percentile curve for step counts was estimated using a simple smoothing method after calculating sample quantiles by sex and age group by selecting a sample smoothing method. [Results] No significant differences in step counts were observed among older adults across the days of the week. Males had higher average step counts than females. At the 50th percentile, males aged 6574 years recorded 8, 272 steps/day, while those aged ≥ 75 recorded 7, 634 steps/day; corresponding values for females were 6, 631 and 5, 706 steps/day, respectively, indicating a more pronounced decline in females than in males. [Conclusion] This study provides objective sex- and age-specific normative reference values for daily step counts in older Korean adults. These values can be used to evaluate physical activity levels, guide personalized goal setting, and inform national health promotion strategies for aging populations. The limitations of this study include its cross-sectional design and the potential underestimation of non-ambulatory activity by accelerometers.