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.
Different exercises will affect your heart rate in different ways, and exercises that elevate your heart rate are a primary component of good cardiovascular health. The U.S. Department of Health & Human Services recommends 150 minutes of moderate aerobic activity or 75 minutes of intense aerobic activity a week.