Physical fitness is most easily understand by examining its components. There are four essential elements, and they are; Cardio-respiratory Endurance, Muscular Strength, Muscular Endurance and Flexibility.
Cardio-respiratory endurance: the ability to deliver oxygen and nutrients to tissues, and to remove wastes, over sustained periods of time. Long runs ans swims are among the methods employed in measuring this element.
Muscular-strength: the ability of a muscle to exert force for a brief period. Upper-body strength, for instance, can be measured by various weight-lifting exercises.
Muscular-endurance: the ability of a group of muscles is to do repeated contractions or to apply force to a fixed object. The push-up is often used to test the endurance of arm and shoulder muscles.
Flexibility: the ability to move joints and use muscles through their full range of motion. The sit and reach test is a good choice for the flexibility of the lower back and backs of the upper legs. Body composition is often considered a component of fitness. It refers to the makeup of the body regarding lean mass( muscle, heavy bone, tissue and organs) and fat mass. An optimal ratio of fat to lean mass is an indication of fitness, and the right types of exercise will help you decrease body fat and increase or maintain muscle mass.