The pulse in the arteries is directly related to the heart rate. The left ventricle in the heart pushes the blood to all parts of the body through the arteries. During periods of relaxation, most of the blood flow supplies the brain at 18%, liver at 25%, kidneys at 20% and muscles at 20%, with the rest going to the skin, bone marrow, and heart. However, during exercise, the need for oxygen is greater and the heart rate speeds up as does the pulse within the arteries. During these times, the muscles get 87% of the blood flow. This will allow the muscle cells during the period of greater activity to have an increased amount of oxygen and glucose to maintain the higher metabolic rate while exercising. Therefore, as the heart rate and the pulse increase, the circulatory system will supply more blood flow to the leg muscles during periods of activity.