OK, let’s talk physiology!!! You probably learned that ” While at rest, your muscles do not need much energy. Your heart and lungs are able to deliver enough oxygen to meet energy needs using aerobic metabolism. To increase the amount of energy produced by aerobic metabolism you must increase the amount of oxygen available at the muscle. To do this your breathing and heart rate must increase, but this takes time. When you first begin to exercise your breathing and heart rate have not yet had enough time to increase the amount of oxygen available at the muscle.”
Our cardiovascular system main objective is to deliver oxygen to the tissues, and pick up carbon dioxide. Both are carried by hemoglobin (a protein found in red blood cells). Our heart beats and pumps blood in the arteries, in accordance with the needs of oxygen by the tissues. Athletes heart beat, can be as low as 35 beats per minute (heart rate), an average person’s heart rate is around 75-80 BPM. The reason athletes, heart rate is much lower, is a matter of efficiency. Their cardiac output (amount of blood pumped out from the heart per minute) is much higher, since the tissues are well perfused with blood (well irrigated with blood), the heart does not need to beat as fast. Tissues need oxygen; they use oxygen as fuel in order to manufacture ATP (a high energy compound). When oxygen is absent, muscle tissue undergoes a process known as “oxidative phosphorylation” (a process of making ATP without oxygen). In this process, the end product is “Lactic Acid“, the compound responsible for muscle cramps.
So, it’s all about efficiency, when our metabolic needs are high, our heart has to work harder to deliver oxygen. More fit you are, and less the heart has to work ( the reason you get tired is that your heart works too hard to accommodate your tissues need for oxygen)….Any thoughts?
Dr. Zachary Lahlou