Take this course for free. Do not submit them. Heavy workouts increase your body's need for protein. For fitness, you must engage in both aerobic and strength-training exercises. Warm-ups and stretching are the same thing.
Fitness is both an art and science.
As a science, the level of fitness can be measured and recorded. As you start your fitness program, it is important that you first evaluate your fitness level so that you can later note your progress. There are very many measures of the various aspects of physical fitness. The areas of fitness where you are low become your special targets of fitness improvement. The heart rate is measured by the pulse rate in beats per minute.