If you exercise often, you undoubtedly keep track of the number of minutes you spend exercising, the number of calories you burn, and your heart rate. However, there is another metric that can assist you in improving your aerobic fitness. VO² max, also known as oxygen uptake, is a measurement of how much oxygen your body takes and uses while exercising. The letters V, O², and max stand for volume, oxygen, and maximum, respectively. When you breathe, oxygen enters your bloodstream. The blood is pumped into your muscles by your heart. That oxygen powers molecular reactions that provide energy to your muscles. When you exercise, you breathe more swiftly and deeply because your muscles require more energy to work harder. The amount of oxygen (typically in milliliters) you breathe in while exercising as hard as you can is measured by your VO² max. Your body may use more energy if you inhale more oxygen. Physical fitness is frequently associated with a higher VO² max.