Understanding the Cardiovascular System, Part 1

Although there are more than 600 muscles in your body making up almost 40 percent of your total body weight, there is one muscle that stands out as more important than all the rest. Without it, you can’t live, and each year its failure kills close to one out of every three Americans. I’m sure by now you’ve guessed that the muscle I’m talking about is your heart.

Over the course of an average lifetime, the heart will beat over an estimated three billion times! Think about that for a minute. It really is an amazing number. When you consider that the heart is really just an elegantly designed pump, it should come as no surprise that sooner or later, along with the pipeline of vessels it supplies blood through, it can wear out.

How long your cardiovascular system does its job of pumping blood throughout your body is the result of a great many factors that we’ll discuss throughout this article. However, at the simplest level, the more stress you put your heart through, the more likely you are to wear out the pump (your heart) or plug up and damage the network of hoses (your blood vessels).

The cardiovascular system and fitness

One of the fundamental reasons exercise is so important to your overall health and wellness is its ability to strengthen the heart and supporting network of tissues as well as improve the heart’s regulatory mechanisms. Make your pump stronger and more effectively regulated, and it will last longer. It’s that simple. Even more, a healthy heart is able to more efficiently deal with the daily stresses you put it through and allows you to exercise more frequently, which means your work capacity is improved and you get better results!

As you know, we can think of fitness as how well your body is prepared to deal with the demands you place upon it. Because your heart is the engine that drives your body, constantly pumping oxygenated blood and vital nutrients to all the tissues of your body, your heart’s health and function plays a major role in your body’s ability to deal with stress. By stress, I mean both mental and physical. It is because of this principle that your heart’s health and regulation is a powerful reflection of your overall health and wellness.

Through regular, consistent, and directed exercise, you are able to strengthen and condition the heart to more effectively deal with the stress of everyday life by making sure it is properly regulated and fit. Instead of having chronically high blood pressure and chest pains, you get a healthy heart, you feel great, your performance is better than ever, and you dramatically slow down the aging process. Intelligently designed cardiovascular and resistance exercise should be used as a powerful tool to improve the regulation and strength of your heart.

In order to understand just how exercise is able to accomplish this, we need to first look at how the body regulates the heart and how the heart responds to stress.

Function of the cardiovascular system

The function and regulation of your heart largely comes down to the interplay between two opposing branches of what is called the autonomic nervous system and the hormones they release. The role of the autonomic nervous system (ANS) is simple—to act as a control system within the body and regulate many processes within the body in an effort to maintain stability or homeostasis. In other words, its job is to keep things working smoothly. It works without conscious effort (in most cases) to control things such as heart rate, digestion, and perspiration. It works through two opposing branches known as the sympathetic and the parasympathetic.

The sympathetic system can be thought of as the accelerator and is what gets turned on rapidly during periods of stress. It is responsible for the “fight or flight” response, also known as the stress response. It activates a series of chemical and hormonal processes that prepare the body to deal with the stress it is facing. Without going into too much boring detail, these processes infuse your body with powerful hormones such as adrenaline and cortisol that set off a cascade of reactions to increase blood and energy supply to your muscles, heighten your reflexes and arousal, and get your body ready to perform in high gear.

The parasympathetic system can be thought of as the body’s break, the proverbial yin to the sympathetic system’s yang. It works to slow the heart rate down, promote storage of energy and fat, stimulate appetite and digestion, and return everything back to its normal state following periods of stress. At rest, this system promotes the rebuilding and storage of nutrients. It performs the counter functions of the sympathetic system, and together, the two systems work in elegant opposition to regulate the body to maintain homeostasis.

When the sympathetic system is activated and turned on, the parasympathetic system is turned down. Thus, activities of the sympathetic functions dominate and vice versa. Part of this regulation comes through the act of breathing. When you inhale and take a breath, the parasympathetic system is momentarily muted and the sympathetic system takes control. When you exhale, the exact opposite happens and the parasympathetic branch is stimulated. It is through this yin and yang system that a healthy heart is largely regulated. As your respiration speeds up in response to physical exercise or psychological stress, your heart rate is therefore increased as well. When you slow your breathing down, such as when you sleep, meditate, or get a relaxing message, your heart rate drops accordingly. Your body uses this constant back and forth process of activation and suppression to manage tension between the two systems and maintain the proper heart rate to provide your tissues with the right amount of oxygen, hormones, nutrients, and so on, depending on your body’s needs. Unfortunately, it’s not as difficult as you might think to throw this auto regulatory system out of balance and set yourself up for cardiovascular problems.

The cardiovascular system and stress

Stress is something we all face in everyday life, and yet few of us ever stop to realize the dramatic impact it has on our health and wellness. Perhaps nowhere is this more evident than when it comes to our cardiovascular system. When we start to examine the mechanisms of stress and the stress response, it becomes obvious why cardiovascular disease and its many related conditions are so prevalent in today’s society.

In order to understand why excessive stress, both psychological and physical, can be so damaging to our health, we need to consider for a moment what exactly happens in the face of stress. Think back to your first big job interview, your first college final, your first kiss, or your first presentation at a new job. Remember how you could practically feel your heart beating through your chest as beads of sweat rolled down your forehead in nervous anticipation?

Although you didn’t realize it at the time, your mental anxiety had set off a chain of events inside your body causing the sympathetic nervous system to do its job of releasing powerful hormones and neurotransmitters to increase heart rate, drive up perspiration, divert blood flow to your muscles, and stimulate the release of energy into the bloodstream. The scientific term for this specific set of physiological events is the “stress response.” (It’s also sometimes referred to as the “fight or flight response.”) It is without a doubt one of the most important concepts to understand in health and wellness. It’s also an amazingly similar process regardless of whether the stress is mental or physical.

If you’re an animal living in the wild, the stress response is often needed to save your life and keep you from being eaten. The increased heart rate, powerful hormones, and newly released energy racing through your blood gives your body just what it needs to speed away and escape capture by the dangerous predator.  If you’re a person facing the daily stress that comes from managing a busy workweek, family life, and school, however, the stress response can slowly kill you. The difference between saving your life and slowly leading you down the path of heart disease comes from what happens after the system is turned on and how well the heart’s function is regulated.

A path to disease

We can better understand how the stress response can be either beneficial and protect us from danger or harmful and set us up for disease if we look a little deeper underneath the surface of what’s happening inside our body after the stress response has been turned on. If we were to take a virtual field trip inside our body, the first thing we’d notice is our heart is beating much more rapidly than at rest, often up to more than double our resting heart rate or even higher. Because of this, our blood pressure has also skyrocketed because blood is now being pumped out much more rapidly and with more force from the left ventricle of our heart. In order to deal with this increased pressure, our blood vessels have become more rigid and less elastic.

Next, we’d also see much higher levels than normal of powerful hormones such as cortisol and adrenaline racing through our bloodstream along with a rush of glucose and fatty acids, the raw materials used by our muscles to produce power. Other hormones, such as insulin and those that stimulate appetite, would be lower than normal, and we’d notice that blood flow has been diverted away from organs to active muscles to provide them with increased oxygen and energy.

In the case of the animal in the wild, all these changes in the body serve a vital, biological purpose and give it the capacity for an explosive getaway. In our daily lives, however, we rarely use the powerful physical capacity the stress response has prepared us for, and instead, we sit in front of a computer typing away to try to meet a deadline or we sit and worry about how we’re going to pay our bills if we don’t get a new job. Our body is left confused. It’s got everything it needs to fight or flight, and yet it’s just sitting there.

Once the stress and anxiety have passed and our body realizes we’re not actually going anywhere or doing anything physical at all, it’s now time to return everything to normal. The parasympathetic system gets turned up as the sympathetic drive comes back down, and all the neurochemical processes start to reverse themselves. Our heart rate starts to come back down, our blood pressure heads back to normal, we stop sweating, insulin levels rise and start storing energy back in our muscle and fat cells, and blood flow gets redistributed. Most of the hormones return to normal pretty quickly, although some produced during the stress response can stay elevated for hours afterwards depending on how much the system was turned on and how long it was turned on for.

While this whole process may not seem dangerous to your health at first and it obviously serves a vital biological purpose, the trouble starts to materialize when the stress response becomes activated over and over again and when it isn’t properly regulated. In this case, stress goes from being a relatively routine passing event to being a chronic condition, and dangerous changes start to take place in our bodies that damage our health and set us up for a whole range of cardiovascular and other health problems.

To give you an example of how this can happen, let’s look at how cardiovascular disease can develop over time. As we discussed previously, when the sympathetic system is dominant, it means blood pressure is elevated because more blood is being pumped throughout the body. If blood pressure is chronically elevated—clinically known as hypertension—then over time our blood vessels begin to change and develop thicker more muscular walls because they’ve had to work harder to regulate the increased blood volume. These thicker more muscular walls means the blood vessels are more rigid and less elastic. These thicker walls are also more resistant to blood flow which creates a vicious cycle because it will elevate blood pressure even more.

As a result of the scenario I’ve just described, your cardiovascular system is now at a much greater risk of developing disease for a few different reasons. First, as a result of the chronically elevated heart rate and blood pressure, the heart begins to undergo physiological changes to its structure—more specifically to the mass of the left ventricle—that put it at risk for irregular heart rhythms. Second, the thicker less elastic blood vessels are now at a greater risk of developing small tears in their smooth inner linings. These tears then become chronically inflamed and a place where circulating junk such as fat, blood platelets, and cholesterol can begin to clump up and form what is known as an atherosclerotic plaque.

Now that you’ve got an unhealthy heart and plaques forming throughout your blood vessels, you’re really in trouble. These dangerous plaques clog up your arteries and restrict blood flow, which only serves to raise blood pressure even more once again. Pretty soon, the blood flow is restricted enough that vital organs and parts of the body are not receiving the blood supply that they need to be healthy, and they become damaged. You’re also at risk to have the plaques break loose and travel into smaller blood vessels where they can block blood flow completely.

Your cardiovascular system is now a ticking time bomb. It’s not a question of whether or not you’ll end up needing bypass surgery, having a heart attack, or becoming another statistic but rather when it’ll happen. Any stress you face only serves to accelerate the disease process even more. Eventually, your compromised cardiovascular system will fail unless something changes.

The road to health and wellness

I wish I could say the example illustrated above was farfetched or highly unlikely, but the statistics don’t lie. Each year close to one million people in the U.S. die from various cardiovascular diseases and more than seven million die worldwide! Fortunately, you don’t have to be part of the statistics. There is another path to take that leads to health and wellness rather than disease.

By now this article covered a great deal about how the heart works, how it’s functionally regulated, and how it responds to stress. As a result, you’ve no doubt come to a whole new understanding about the importance of fitness, the ability of your body to meet the demands you’re asking of it, and its role in your health and wellness. The example we just discussed was a perfect example of what happens when your heart is unfit and can’t meet the demands you place on it through daily mental and physical stress. In the face of stress, a lack of fitness leads to negative changes in structure, function, and regulation, and inevitably, this is the path to disease.

A well-designed cardiovascular training program can take you down a much different road, a road that leads to health, wellness, and performance. Through very precise training methods based on science, your cardiovascular system can be properly developed to deal with the stresses it will invariably face throughout your life.

Cardiovascular system training principles, part 2

As we’ve already alluded to, there are three main components of cardiovascular health that we must improve in order to raise your specific level of cardiovascular fitness—structure, function, and regulation.

To be continued…