Riding on a high

At the first sign of spring, many people start thinking about pulling their bicycles out of the garage and getting in shape.

"Along with hiking, swimming and jogging, cycling is a classic outdoor endurance activity," says Theodor Stemper, a sports scientist at the University of Wuppertal, Germany, adding: "It brings about all kinds of desirable effects."

These benefits include improved heart muscle, better circulation and lower blood pressure. The motion is also easy on the joints as the cyclist's weight is supported by the bike.