As they sprint around the playground with boundless energy, it might seem like kids are impervious to the heat.

And in general, doctors say kids are healthier than adults.

But one important difference that parents might not know is that children do not sweat as much as adults, and so they can't regulate their body temperature as efficiently.

Dr. Patrick Daley with St. John Medical Center says hydration is vital, and not just AFTER the kids play outside.

"Be sure we're drinking before and after we do activities is so important," Daley said.

He said it depends on the activity, but he says when temperatures are 100 degrees and above,  a good rule-of-thumb is to have the kids come inside and cool off after about 30 minutes of playing outside.