(AP) — Today’s kids can’t keep up with their parents. An analysis of studies on 250 million children around the world finds they don’t run as fast or as far as their parents did when they were young.

Researchers say that on average, children 9 to 17 take 90 seconds longer to run a mile than their counterparts did 30 years ago. Heart-related fitness has declined 5 percent per decade since 1975.

The American Heart Association featured the research at its annual conference in Dallas on Tuesday. The group says the study is the first to show that children’s cardiovascular fitness has declined worldwide over the last three decades.