Studies on millions of children around the world has found that kids don't run as fast or as far as their parents did when they were young.
On average, it takes children 90 seconds longer to run a mile than their counterparts did 30 years ago, Fox News reported.
Heart-related fitness has declined 5 percent per decade since 1975 for children ages 9 to 17.
The American Heart Association, whose conference featured the research on Tuesday, says it's the first to show that children's fitness has declined worldwide over the last three decades.
Dr. Stephen Daniels, a University of Colorado pediatrician and spokesman for the heart association said that kids that are less active than before.
Health experts recommend that children 6 and older get 60 minutes of moderately vigorous activity accumulated over a day. Only one-third of American kids do now.
