27th Apr 2024

Purpose
Continuous lifestyle, physical fitness, and physical activity (PA) surveys are conducted in Japan. This study aims to clarify the changes in PAT of Japanese children over 20 years, analyzing data from two representative continuous surveys.
Method
This study uses the following two survey results. One is the Student Health Status Surveillance (SHSS) conducted by the Japan School Health Association, which was conducted once every two years from 1992 to 2018. The target was 7,000 and 18,000 3rd- through 12th-grade students. PA time (PAT) survey was conducted based on the IPAC method in this survey. The distribution of PAT per week (DPAT) was obtained from 10 surveys from 1993 to 2010. The other is the Japanese national survey on physical fitness, motor abilities, and lifestyle (NSPML) conducted by MEXT, Japan, since 2008, which is a comprehensive survey targeting 5th- and 8th-grade students using the original PAT method. The DPAT was obtained from 2008 to 2016.
Results and discussion
In the initial SHSS survey, the DPAT had a left-skewed distribution with a peak of 4-10 hours. However, from around 2000, the proportion of inactive children showed a tendency to increase in all grades, shifting to a monotonically decreasing distribution. In addition, among high school boys, the 5-10 hours PA decreased, though the 10 hours or more PA increased, which indicated a polarization of active and inactive children. The trend has been observed among high school girls and middle school boys and girls since the 2004 survey. DPAT of NSPML also showed a similar trend to SHSS results. In the 2010s, the polarization of PAT became even stronger. Based on these results, DPAT on weekdays and weekends has been focused since 2017.
Conclusion
DPAT has changed over time, and a polarization between active and inactive children was confirmed, with these differences becoming more pronounced.