The amount of O2 used by the body during a training session is referred to as ______.

The term that best describes the amount of oxygen utilized by the body during a training session is oxygen uptake. This concept refers to the total volume of oxygen that is consumed by the body, specifically during physical activity. Oxygen uptake is a crucial measure, particularly in exercise physiology, as it indicates how effectively the body is able to utilize oxygen to produce energy, reflecting both cardiovascular and muscular function.

When the body engages in exercise, oxygen uptake increases to meet the heightened energy demands of the working muscles. This process can be quantitatively expressed as VO2, where "V" stands for volume and "O2" represents oxygen. Understanding oxygen uptake helps in assessing cardiorespiratory fitness and the overall efficiency of the aerobic energy system.

Other terms that could potentially be confused with oxygen uptake include VO2max, which represents the maximum rate of oxygen consumption during intense exercise, and (a-v)O2 difference, which indicates the difference in oxygen concentration between arterial and venous blood, reflecting how much oxygen is extracted by the tissues. Ejection fraction refers to the percentage of blood that is pumped out of the heart with each contraction, measuring cardiac efficiency rather than oxygen utilization during exercise. Thus, oxygen uptake is the most appropriate term for the amount of O2