Well ‘tis the week of Valentine’s Day, and all it’s hearty associations. Here are some ways to show love to the most important heart in your life - your own.
How does exercise improve our heart health? In so many ways. Here are three biggies.
Cardio means heart, and vascular means vessel. Therefore, the cardiovascular system includes both the heart muscle itself, and all the vessels (arteries, veins and capillaries) through which the blood flows. Exercise affects many things that improve the function of this system of pumps and tubes, and the hormonal milieu in which it works.
We’ll start with the main pumping station - the heart itself. Made of specialized muscle - cardiac muscle - composed of cardiomyocytes (cardio = heart, myo = muscle, cyte = cell), spontaneously generate their own electrical impulses. Heart cells in Petri dish will beat by themselves, and when they grow to touch each other, they beat in synchrony by sharing their electrical waves across their cell membranes. In our own hearts, we have an inner pacemaker poetically called “The Bundle of His” and the “Purkinje fibers”. Go and nerd out on these terms , but for now, I’ll simply say these structures coordinate our cardiomyocytes and keep our heart beating regularly day in, day out until we die (or need an artificial replacement pacemaker). Fibrillation is when our inner pacemaker loses control and all the cardiomyocytes start beating independently. The heart just quivers uselessly, and the owner suffers a heart attack. A defibrillator shocks and resets the inner pacemaker to reorganize synchronicity, keeping the owner alive until the paramedics get there. This is why first aid classes now involve training on an AED or an Automated External Defibrillator.
Strong muscles are more efficient and squeeze more powerfully. By performing aerobic (with air/oxygen) exercise that challenges us past our comfort zone, we forcibly require our cardiac muscle to pump more blood through the lungs and thence to outlying tissues meeting the increased oxygen and nutrient requirements. The heart, like any muscle, will rise to repeated challenges and hypertrophy (become larger). Unchallenged muscles atrophy (become smaller), and cardiac muscle is no different. Cardiac atrophy is not a good idea, so regular exercise is needed to maintain cardiac muscle mass and performance. A general indicator of good heart health is a low resting heart rate (50 - 60 beats per minute), indicative of powerful and efficient cardiac muscle. Take your resting heart rate when you have just woken up and are still lying in bed - here’s how, and here’s a comparison chart. There are exceptions due to medications like beta blockers and various medical conditions.
Take home message #1; perform daily aerobic exercise that challenges your heart muscle to maintain it’s size and efficiency.
The other part of the system are the blood vessels. Arteries move oxygenated and nutrient-filled blood outwards to the peripheral tissues. Capillaries in the tissues are so delicate that O2 and nutrients filter out toward the cells and cellular waste products and CO2 diffuse back in. Veins collect blood with CO2 and waste products and return to the core for purification via lungs, kidneys and liver. Then the whole process starts again. This is a massively simplified overview of course, but you get the idea of circulation.
As with any system of pipes, restriction of flow causes problems, so maintenance of smooth healthy vascular tubing is crucial. Your arteries are muscular (a variety called “smooth muscle”) and complex triple-layered tubes that contract, dilate and secrete slippery substances to keep their inner walls clean. Exercise increases the level of nitric oxide in the arteries, maintaining a flexible and open lumen, thus enhancing blood flow. Aerobic exercise causes the heart to push more blood through the tubes and flushes the system, cleaning the insides of the vessels and reducing risk of build-up. What might build up? Sticky substances like Low Density Lipoproteins (LDL), platelets (clotting factors) and trapped blood cells may collect inside the vessels if they are damaged due to inflammation. Consistent flushing helps keep things flowing. These principles apply especially to the little arteries that feed the heart muscle itself - the coronary arteries. Constriction of the coronary arteries is called Coronary Artery Disease, or CAD and can lead to heart attacks. Exercise decreases this risk.
Take home message #2: daily exercise boosts blood flow by flushing our blood vessels and increases the presence of nitric oxide which keeps vessels open and slippery.
A more general effect of exercise on our system involves stress reduction. Exercise is shown to reduce the amount of stress humans typically perceive. Whether is it’s due to a reorganization of our hormonal response (cortisol/adrenaline) or simply the feeling that we have “done something” (which is mentally relieving) is still up for debate. Our sleep improves when we physically tire our bodies from regular exercise, and sleep is when we repair ourselves to become stronger and more able to face our challenges; mental, physical and emotional. Stress hormones released during negatively stressful situations can depress the nitric oxide in our arteries and increase other inflammatory substances that may rub away at our inner vessel linings to increase the risk of cardiovascular injury and events.
Take home message # 3: daily exercise is a way of inhibiting stress-response chemicals, lowering the risk of damage to our cardiovascular structures.
Make a daily date for 30 - 60 minutes of heart-rate boosting exercise for a long, happy and heart-felt commitment to your cardiovascular system.
Every day is Valentines Day when it comes to your heart!
