WHAT IS VO2 MAX?
Maximal oxygen uptake is a measurement of the amount of blood the body uses for useful work. It is a function of the amount of blood pumped by the heart and the working cell's ability to extract oxygen from the blood. The greater one's fitness level, the longer one can exercise at maximum aerobic capacity.
WHAT FACTORS AFFECT MAXIMUM OXYGEN UPTAKE?
The physiological factors affecting maximal oxygen uptake are both central and peripheral. Central factors include the heart's ability to efficiently pump blood through the cardiovascular system. Efficiency of the heart depends upon the amount of blood pumped by the heart (stroke volume, which is essentially the force of strength of the heart's contraction), or heart rate.The result of stroke volume x heart rate determines cardiac output. Cardiac output can be enhanced by aerobic training which primarily impacts the stroke volume of the heart. In oner words, the heart becomes stronger and is able to pump more blood per beat, performing a given workload at a lower heart rate. This leads to greater efficiency.
The peripheral factor affecting maximum oxygen uptake is the arterio-venous difference, or the difference in the amount of oxygen in the arterial blood going from heart to the muscle cells and the venous blood going to the muscle cells back to the heart. This difference is the amount of oxygen the muscle cells have extracted from the blood and used for energy production. Aerobic training will also improve the cellular capability to extract oxygen from the blood. Other factors enhanced by aerobic training are increased capillary density, aerobic enzyme development, and muscle cell fluid volume (myoglobin).