A concussion, whether it is mild or severe, is common in contact sports; unfortunately, it can go unnoticed by coaches, teammates, even the athlete themselves.

  To view our videos, you need to
enable JavaScript. Learn how.
install Adobe Flash 9 or above. Install now.

Then come back here and refresh the page.

Concussion can happen in most sports and bumps on the head for most kids are certain. When is it time to worry?

"Any time anyone seems dazed or confused or somehow startled by something that happens, I think it is always, anybody overseeing those athletes, to check and make sure that they are 100 percent it and ready to be engaged fully not only physically but also neurological in the competition," Cirenza said.

If a child seems disoriented, dizzy, vomits or complains of a headache, it's worry time.

"Any time a child sustains a concussion you really need to pull them out, give them a period at least around ten or fifteen minutes to assess what is going on and really see whether or not they are clear or oriented," said Cirenza.

After one serious hit to the head, the doctor warns, the worst things you can do is put the child back in on the field. In the event, if the child would suffer a second head injury, the results could be severe.

"It is not so much getting the concussion it is getting another one while you are still recovering for the first concussion so while your brain is still recovering is in a vulnerable state, if you then sustain second concussion while you are recovering from the first the result can be dramatic, sudden death, shock, brain damage," said Cirenza.

If football is the sport of choice, you may want to consider a helmets like this one, its designed to reduce the risk of head injury. They're made with special protective padding, the shape is less round, and the facemask is larger, the price? They cost, a few hundred dollars and parents must be prepared to pay for it. Companies claim that the helmets can reduce the number or concussions by 31 percent, but more studies are needed.