What is a key indicator of overall physical fitness?

Cardiovascular endurance is a key indicator of overall physical fitness because it reflects the efficiency of the heart, lungs, and muscles in delivering oxygen to the body during prolonged physical activity. This aspect of fitness is essential for sustaining energy levels and performance in various activities, whether they are sports or everyday tasks. High cardiovascular endurance generally contributes to better health outcomes, such as lower risks of heart disease and improved stamina.

While body mass index is a common measure, it does not specifically assess fitness levels or the ability to perform physical activities. Bone density is important for skeletal health, particularly in aging populations, but it does not measure overall fitness directly. Flexibility plays a role in physical fitness by enhancing range of motion and reducing injury risk, but like the other two options, it is only one component of the broader picture concerning overall physical fitness. Cardiovascular endurance encompasses multiple systems within the body, making it a more comprehensive measure of fitness.