What variable primarily contributes to increased VO2 max with training?

The variable that primarily contributes to increased VO2 max with training is increased stroke volume. VO2 max, which represents the maximum amount of oxygen the body can utilize during intense exercise, is influenced significantly by the cardiovascular system's efficiency. Stroke volume refers to the amount of blood pumped by the heart with each beat.

As a person engages in regular aerobic training, the heart becomes stronger and more efficient, allowing it to pump a greater volume of blood with each contraction. This increase in stroke volume means that more oxygen-rich blood is delivered to the muscles, which is crucial during exercise.

The enhancements in stroke volume effectively improve the capacity to transport and utilize oxygen, which directly results in a higher VO2 max. While other factors may play a role in cardiovascular adaptation, the increase in stroke volume from training is recognized as the most significant contributor to improvements in VO2 max.