Final answer:
The age-related decline in VO2 max is due to decreased maximal stroke volume, decreased maximal heart rate, and decreased maximal a-v O2 difference.
Step-by-step explanation:
The age-related decline in VO2 max is due to all of the following factors: decreased maximal stroke volume, decreased maximal heart rate, and decreased maximal a-v O2 difference.
Decreased maximal stroke volume means that the heart is unable to pump as much blood with each contraction, resulting in a lower amount of oxygen being delivered to the muscles. Decreased maximal heart rate means that the heart is not able to beat as fast, limiting the amount of blood and oxygen that can be transported to the muscles. Decreased maximal a-v O2 difference means that there is a smaller difference in oxygen content between the arterial blood and the venous blood returning to the heart, indicating that the muscles are not extracting as much oxygen from the blood.
Therefore, all of these factors contribute to the age-related decline in VO2 max.