Physical activity in South Korea measured by accelerometer: The Korea National Health and Nutrition Examination Survey VI 2014-2015

Abstract

Purpose The purpose of this study was to evaluate the moderate to vigorous physical activity(MVPA) and sedentary time measured by accelerometer. Furthermore, the level of physical activity and adherence rate of physical activity guideline(PAG) were compared with the self-reported questionnaire. Methods The MVPA, sedentary time, and adherence rate of PAG according to age and sex were examined to people who agreed to wear accelerometers among the participants of the 2014-2015 Korea National Health and Nutrition Examination Survey. To compare the relationship between accelerometer and self-reported questionnaire, Chi-squared test and Spearman correlation analysis were performed. Results The MVPA of the accelerometer-total(AT) was 40.6 minutes/day for men and 31.1 minutes/day for women. Sedentary time was 502.9 minutes/day for men and 498.9 minutes/day for women. The MVPA of accelerometer-bout(AB) estimates was 16.4 minutes/day for men and 14.2 minutes for women. On the other hand, the MVPA of the self-report was 95.8 minutes for men and 64.3 minutes for women, and the sedentary time was 471.2 minutes for men and 455.2 minutes for women. The adherence rate of PAG was 55.6% of the self-report, 56.1% of the AT, and 21.4% of the AB. The correlation between self-report and accelerometer was statistically significant(p < 0.01), but showed a weak correlation coefficient(rho=0.112-0.351). There was no association between AB and self-report(p < 0.01). The sensitivity and specificity of the self-report were 71.3% and 48.6%, respectively. The positive and negative predictive values of the self-report were 27.5% and 86.1%, respectively. Conclusions As a result of this study, self-reported physical activity level by questionnaire had more MVPA and less sedentary time than the accelerometer-determined physical activity. In addition, the adherence rate of the PAG differed from accelerometer and self-report. The difference was significantly increased when comparing AB with the self-report. Therefore, great care must be taken when interpreting accelerometer and self-report questionnaire. Further research will be needed on specific methods that can be used by complementing the two measurement tools.