You may lie on your back, or you may lie face-down with your chin raised. Once you are inside the scanner, the machine's x-ray beam rotates around you. (Modern spiral scanners can perform the exam without stopping.) A computer creates separate images of the body area. These are called slices.
Circuit training builds muscular and cardiovascular endurance. It alternates intense cardiovascular activities, such as jumping rope and running, with strength-training activities, such as pushups, crunches and squats. With circuit training, you can focus on building endurance for a specific muscle group or your entire body, depending on the strength-training exercise you choose.
Aerobic exercise increases the breathing rate and ultimately raises heart and lung efficiency. Prolonged aerobic exercise (at least 20 minutes five times a week) is recommended for the maintenance of a healthy cardiovascular system.