Validity Evidence of Objective Physical Activity Measures for Early Childhood

Background/Purpose: Even though interests of participating in physical activity have been tremendously increased, there was lack of evidences of physical activity effects for the early childhood. One of possible reasons can be the lack of accuracy of physical activity measurers. Therefore, the purpose of this study was to validate objective physical activity measures for the early childhood in Korea.

Method:  A total of 131 children (aged 3-6yrs n=25, 32, 26, & 48, respectively) was participated (Height: 3yrs95.56±3.11, 4yrs110.81±6.01, 5yrs116.00± 5.50, & 6yrs114.67±7.76 / Weight: 3yrs16.26±1.51, 4yrs19.18±2.62, 5yrs21.33±3.86, & 6yrs22.66±5.74). Each child was wearing an accelerometer (Actigraph GT3X, USA) and a pedometer (Omron HJ-720ITC, JAPAN)for 7 consecutive days (at least 10 hours per day) in free-living including weekdays and weekend.

Analysis/Results: Descriptive analysis (mean±SD) was employed to calculate the walking steps measured by the pedometers and moderate-vigorous physical activity (MVPA) levels (min) measured by the accelerometers. Two-way ANOVA was applied to examine group differences of gender and age with Tukey post-hoc (a<.05). Pearson’s correlation coefficients were calculated to determine the convergent validity of the objective measures utilizing IBM SPSS 20.0. There was no interaction effect between gender and age. Also, walking steps did not show statistical difference between gender (Boys 6421.80±2018.43 vs. Girls 6186.07±2025.70), but age groups (3yrs 5402.25±2426.84, 4yers 5933.53±1883.05, 5yrs 6665.21±1870.06, & 6yrs 7206.99±2330.34 with F=13.31, p < .001. From Tuky post-hoc, it showed the group difference as follows: 3yrs<5yrs & 6yrs and 4yrs<6yrs, p<.001. MVPA showed age group difference only with F=3.287, p<.05 (3yrs 180.00±59.41, 4yrs138.22±49.58, 5yrs167.35±55.71, & 6yrs169.76±54.11 / boys161.88±57.17 vs. girls 166.19±54.21, p>.05), and MVPA of 3 years old children was statistically higher than 4 years old (p<.05). Convergent validity coefficients between total steps and MVPA were moderate, which were 7days r=.594, weekday r=.551, weekend r=.373, respectively. Lower age group (3-4yrs) showed higher correlation coefficients than higher age group (5-6yrs), which were 7days .668 vs. .540, weekday .603 vs. .520, & weekend .562 vs. .377, respectively.

 Conclusions: As age increased, the physical activity level was increased from 3yrs to 6year except for MVPA of 3yrs. The employed pedometer and accelerometer showed moderately high validity coefficients for the early childhood, especially 3-4yrs. The discrepancy between walking steps and MVPA should be further investigated with more sophisticated research design for the early childhood.

 Note: The study was supported by the Korea Research Foundation Grant funded by the Korean Government (MOEHRD, Basic Research Promotion Fund) (KRF-2011-G00082) and Seoul City