Components of Health-Related Physical Fitness
The first of five components of health-related fitness is cardiorespiratory endurance. This is simply the ability of your circulatory system—meaning your heart and your blood vessels and your respiratory system, or your lungs—to work together to supply the body with the fuel and the oxygen needed during sustained physical activity, so activity that occurs over a sustained period of time. This also includes the ability of the muscles to take up and use the oxygen that's been delivered during physical activity. Participating in aerobic activities such as biking, swimming, walking, running, are always to improve your cardiorespiratory fitness. These activities increase the demand on your cardiorespiratory system, or your heart and your lungs and your blood vessels, and over time these systems start to adapt to the increased load and become more efficient.