According to a MSNBC article, Tour de France bikers have large hearts. Not in a giving since, but literally. Dr. Francois Carre of the Centre Hospitalier Universitaire de Rennes, France, said the hearts of former Tour bikers were 20 to 40 percent larger than normal. Now if someone would just research the brains of former Tour riders who have taken steroids......

The difference is attributable largely to rigorous training that expands the cyclists' hearts. But researchers have not yet determined whether the athletes' hearts were larger to begin with.

"They are a special breed," said Dr. Richard Becker, a professor of medicine at Duke University and spokesman for the American Heart Association. Becker was not connected to Carre's study.

Scientists have long noticed the phenomenon of the "athlete's heart." Athletes who train hard in aerobic sports, such as cycling, running or swimming, tend to have a bigger heart that pumps more blood throughout the body.

The heart's walls become thicker to be able to handle the increased blood volume. That gives the athletes an edge by increasing their oxygen levels and improving their endurance.

Carre's study, funded by the Brittany provincial government in France, is perhaps the first to track what happens to athletes' hearts when they stop training.

Medical tests done on all Tour de France cyclists before the race begins showed virtually all have enlarged hearts, Carre said.

"When you see an athlete's heart test, you know right away that it's not a normal person," he said.

In his study, Carre tracked seven former professional cyclists through their final year of competition and three years of retirement.