The long and short of it: boys' heights unchanged

Saturday, Dec. 11, 2010

Kyodo News

The average height for boys between the ages of 5 and 17 dropped or remained the same for each age in the 2010 school year, marking the first time that has happened since the surveys began in 1948, the education ministry said Thursday.

The same happened with girls in all age groups except 13-year-olds and 17-year-olds, according to a preliminary report on the trend for children's physical conditions released by the Education, Culture, Sports, Science and Technology Ministry.

The ministry believes the average heights of children apparently peaked sometime from fiscal 1997 to fiscal 2001, after growing continuously since the end of World War II.

Children "are unlikely to grow taller any longer," a ministry official said, noting it has been some time since more nutritious meals became available and living standards improved in postwar Japan.

By tracking the growth of some 700,000 children from kindergarten through elementary and secondary schools across Japan from April to June, the ministry found that the average height for 15-year-old boys was 168.2 cm, down 3 mm, and down 1 mm among ages of 7 to 12, and 14 and 17.

The height of girls gained 1 mm among those aged 13 and 17, but dropped 1 to 2 mm for those aged 5, 8, 10, 11, 14 and 15.

Compared with 30 years ago, the height of 13-year-old boys rose 2.8 cm to 159.7 cm, and that of 10-year-old girls was up 1.9 cm to 140.2 cm.

"The growth in height among children has remained almost unchanged for a long time and is supposed to be close to the maximum point it can reach," said Yoshiteru Muto, professor in physical education and dean in the department of education at the University of Tokyo.

Muto also pointed out, however, that the recent lifestyle of children often involves a reduction in sleeping hours and this may have affected their growth.

"Many changes in the social environment created by adults may have effects on the balance of their nutrition, exercise and sleeping, each of which supports children's growth and development," he said. "If these problems are solved, their average height might grow again somewhat."