What is happening in your heart during aerobic exercise.

             I know your first thought when it pertains towards running. Why I am I doing this? Outside of long-distance enthusiastic runners who are also known as psychopaths (kidding!) most of us dislike running, however I am betting that you don't like running. The part you dislike is the gasping for air, that burning sensation in your lungs. The pain. 

                Two things happen when you run. There are acute (or short term) and chronic (not Dr. Dre's album or that other chronic....) in this case chronic means long term adaptations. Within acute aerobic exercise two systems of the body are working simultaneously. The circulatory system and the Respiratory system. Circulatory and Respiratory system working together is the cardiovascular system; primarily the cardiovascular system is to provide nutrients and remove waste. The acute effects on the circulatory system involve your heart (duh) and your blood (duh). The measure of how hard your heart is working is called Rate-Pressure product. Rate pressure product is your heart rate times your systolic blood pressure. Heart rate is how many times your heart beats. This can be calculated by either counting the thumps for sixty seconds at your neck, wrist, ankle or groin area (I would recommend sticking with the wrist or neck) or counting to ten at multiplying by six. The amount of blood pump with each beat is called stroke volume. Stroke volume depends on end-diastolic volume (amount of blood pumped by the left ventricle of the heart) and a chemical called catecholamines. Catecholamines goes hand in hand with the sympathetic nervous system. manipulating catecholamines can be either through drugs (stimulants) or natural responses to stimuli (flight or fight response). Think about the last time you were scared or jumpy and how your heart felt like it was going to jump out of your chest? Thats your flight or fight response. With more blood being pumped through the circulatory systems it all has to return to the heart. Increased blood flow leads to increased fibers within the muscle walls (vasodilation). This expansion is called the Frank -Starling Mechanism. Multiplying your stroke volume and your heart rate is called Cardiac Output and is labeled by the letter Q. When you're resting approximately 15%-20% of cardiac output goes to the skeletal muscle. With vigorous exercise (aka running) cardiac output may rise to 90% to the skeletal muscle. This is why after an intense training run your extremities become cold and clammy. You may see competitive long distance runners wearing arm sleeves or beanies in mild temperature. this is to negate the loss of blood flow to the extremities. Another example of the Frank Starling Mechanism is the: pump" although this is more of a resistance training effect the same principles apply. More blood flow goes to the active muscles causing vasodilation then temporary larger muscles.

             Ok, back to rate pressure product. Now we know all about heart rate and stroke volume, but what about the other half of the rate pressure product. Your blood pressure is depicted in two numbers: Systolic and Diastolic. Systolic blood pressure is the pressure exerted against the arterial walls as blood is forced by each contraction. Diastolic blood pressure on the other hand is the pressure exerted against the arterial walls when no blood is forcibly ejected through blood vessels. Systolic is the number on top and diastolic is the number on the bottom when taking blood pressure reading. Generally, at rest blood pressure could read of 110-139 over 60-89 is fine. Systolic blood pressure can almost double with exercise.