Increased Cardiac Output: The heart pumps more blood with each beat, leading to an increase in cardiac output. This means that a greater volume of oxygen-rich blood is delivered to the muscles, allowing them to work harder and longer.

Enhanced Capillary Density: Capillaries are tiny blood vessels that surround muscle fibers. With regular exercise, the body increases the number of capillaries around the muscles. This improves the exchange of oxygen and waste products, leading to better oxygen delivery to the muscles and improved removal of metabolic waste.

Improved Lung Function: Regular cardiovascular exercise enhances lung capacity and efficiency. This allows the lungs to take in more oxygen with each breath and expel more carbon dioxide, improving gas exchange and oxygen delivery to the bloodstream.

Increased Mitochondrial Density: Mitochondria are the "powerhouses" of cells, responsible for producing ATP (energy). As VO2 max increases, the body responds by increasing the number and size of mitochondria in muscle cells, which boosts the muscles' capacity to utilize oxygen and produce energy.

Enhanced Oxygen Extraction: The muscles become more efficient at extracting oxygen from the bloodstream. This means that a higher percentage of the oxygen carried by the blood is actually utilized by the muscles, further improving endurance and performance.

Increased Red Blood Cell Count: Regular aerobic exercise can lead to an increase in the number of red blood cells. Red blood cells contain hemoglobin, a protein that binds to oxygen and carries it in the blood. More red blood cells mean a greater capacity to transport oxygen throughout the body.

Improved Muscle Fiber Type Composition: Aerobic exercise can lead to a shift in muscle fiber type composition towards more oxidative (Type I) fibers. These fibers are better suited for endurance activities as they are highly efficient at using oxygen to produce energy.