The Great East Japan Earthquake occurred in 2011, bringing unprecedented damage to the Tohoku region of Japan. Today, after 11 years, the scars from that tremendous damage remain. The health damage to young school children has been particularly great. One may imagine a slowing trend in physical growth from the effects of that disaster, but no clear findings have been reported. Certain trends for obesity and decreased physical strength due to a lack of physical exercise have been reported, but there are no clear reports for the entire disaster area. In this study, we analyzed the delay in the age at MPV of weight due to the poor and stressful environment following the Great East Japan Earthquake from the relationship between the ages at maximum peak velocity (MPV) for height and weight, which are thought to be natural growth mechanisms, and examined the risk to physical growth that emerges as a result of earthquake disasters. We first conducted an analysis using data on national averages for height and weight since before World War 2, and height and weight growth data from age 6 to 17 from 1955 to 2011 for Miyagi and Iwate prefectures, which were both affected by the earthquake, which were published in the School Health Statistics Research Reports. We then identified the age at MPV of height and weight and, by analyzing the secular trends in age at MPV of weight, investigated the slowing trend in the MPV age for weight that emerged in the earthquake disaster environment. The results showed that in the national average the age at MPV gradually become younger overall for both boys and girls, while in Miyagi and Iwate prefectures the age at MPV of weight tended to be somewhat delayed starting in the 2000s for both boys and girls. This trend was particularly noticeable in boys. From this, one of the effects of the earthquake is conjectured to have been an unnatural weight gain caused by the stress and lack of activity resulting from the disaster.
In Japan, cross-sectional data on physical growth (height, weight) from age 6 (first grade of elementary school) to 17 (final year of high school) have been published in School Health Statistics Research from 1900 to 2022. While the results are averages, they are derived from 700,000 pieces of data gathered from across the nation, and are recognized to have sufficient meaning for analyses of cross-sectional data. In the past, Kawahata  and Matsuura  analyzed these data and examined the age at the maximum growth velocity in height (age at the pubertal peak) and the postwar growth acceleration phenomenon. Kudo et al  arranged these average data into cohorts and examined the trends over time in the age at the pubertal peak for height based on cohort data. Similarly, in recent years Fujii  applied the wavelet interpolation method and identified the age at the maximum growth velocity during puberty (maximum peak velocity; MPV) from the described height growth velocity curve, and examined the secular trends from before World War 2 until around 1990. He reported that during the war the age at MPV was considerably later and that after the war a trend was seen for earlier maturity together with high economic growth, which then slowed from around 1990. From these trends one may conjecture that in Japan the poor wartime environment had the effect of significantly inhibiting physical growth, and that there was acceleration in physical growth from a postwar catch-up phenomenon with the development of infrastructure associated with high economic growth.