PHOENIX - Concave or funnel chest occurs in one out of every 300 to 400 kids. It's more common in boys than girls, but how can you tell?

"The first symptom that parents usually notice is that they're on the field with other kids and they're getting more winded than the other children that they're playing with," said Dr. David M. Notrica, a pediatric surgeon at Phoenix Children's Hospital.

This could lead to chest pain, rapid heartbeat, coughing and fatigue. According to Boston Children's Hospital, symptoms could show up by the age of one, but Notrica recommends waiting to go see the doctor.

"The typical age that we'll first see a patient with pectus excavatum is maybe 10 or 11 years of age," Notrica continued.

Ways to improve the conditions of this disorder include exercise.

"A lot of kids we will put on an exercise program if they're simply having mild excavatum or mild indent," Notrica said.

If the symptoms are more than mild, surgery may be required. The surgery can take up to six hours for a child. Also, there is no way to prevent the disorder, as the main cause is still unknown, but kids with Poland syndrome, scoliosis or rickets could develop the disorder. It is believed to run in families.