While you're sitting still, your heart is beating at 70 to 80 contractions per minute (unless you're extremely fit). With each contraction, the right ventricle discharges about three-quarters of the blood it contains into the vessels of the lungs where it receives oxygen. At the same time, the left ventricle is discharging about three-quarters of the blood that it contains into the aorta and arterial system to feed the oxygen to all the organs and muscles. All four heart valves work together to control blood flow into and out of the heart, making sure that no blood flows in the wrong direction. Wouldn't it be nice if traffic systems were so efficient!
The arterial system dilates, or expands, each time the left ventricle empties into it and speeds blood on its way to the various working tissues. How much blood goes to each tissue is determined by what that particular muscle or organ needs to do. When you eat a big meal, for example, the heart, brain, parasympathetic nervous system, and arteries all decide that more blood needs to go to the organs in the gastrointestinal tract to help them with the work of digesting that low-fat, cardiac-healthy meal you just ate.
Say you decide that you're going to exercise regularly. (Good idea!) Exercise poses a different challenge to the heart compared to rest. Extra blood flow must go to muscles used in exercising and to the coronary arteries that feed the heart muscle itself so that it can pump out the extra blood required during your exercise exertion.
Fortunately, this extra work is no problem for a healthy heart. Once again, all systems work in concert. Extra blood is pumped from the heart, and extra blood flows down the coronary arteries, which dilate to accept this extra flow. The heart valves continue to direct the blood in the proper direction, and the electrical system, with a little boost from the nervous system, starts generating more beats per minute. At the same time, the cardiac muscle relaxes a little bit, enabling more blood to be pumped out during each beat.
In addition, the nervous system, in conjunction with the arterial system, causes
- Some parts of the arterial circulation to expand or dilate, sending more blood to the working muscles that need it
- Other parts to constrict or narrow, diverting blood away from areas where it is not as active during exertion
The good news is that if you exert yourself on a regular basis, your heart and the rest of your cardiovascular system begin to become more efficient and prepare for the regular exercise sessions. That's true even if you've been diagnosed with heart disease or had a heart attack or other heart event. For that reason, physicians prescribe specific types of carefully monitored activities and exercises as part of treatment and rehabilitation programs for heart disease.
When all parts of the heart and cardiovascular system are healthy and functioning well together, it is a beautiful system. But the heart is a muscle. And like any muscle, it works best when you keep it in shape and avoid injury.
The conditioned heart
A conditioned heart is stronger and better able to meet the demands the body places on it. Human bodies were designed to be in motion. And the motion of physical activity keeps the heart well tuned, the benefits of which are numerous:
- Literally hundreds of studies have shown that individuals who adopt the simple habit of daily physical activity substantially reduce their risk of developing various heart problems, most notably coronary artery disease.
- The conditioned heart enables individuals to accomplish the activities of daily living with comfort and without running out of breath and energy.
- The more conditioned the heart, the lower the resting heart rate, and the less work the heart has to do in a lifetime.
- Studies also show that, with appropriate activity, hearts damaged by disease or injury can regain conditioning that enhances health and function and may even contribute to the reversal of some aspects of disease.
The deconditioned heart
In contrast to the active individual, the individual who leads a sedentary lifestyle can actually experience a deconditioned heart. The deconditioned heart is less efficient at doing its work and has to work harder to get adequate blood flow throughout the body. You're a prime candidate for a deconditioned heart if you answer "yes" to these questions or others like them:
- Do you avoid the stairs because climbing two or three flights leaves you extremely short of breath?
- Do you circle a parking lot numerous times looking for a space right in front of the store to make sure that you don't have to walk much?
- Do you watch sports on television rather than participate in them with friends and family?
- On a nice day, do you pop a DVD into the player rather than take a walk?
For many people a deconditioned heart is the first step in a slow slide down the long slope toward a sick heart.
The diseased heart
A sedentary lifestyle coupled with unhealthy practices such as poor nutrition, weight gain, cigarette smoking, or certain other health conditions, such as high blood pressure, high cholesterol, or diabetes, can severely alter the basic cardiac structures and lead to a disordered anatomy that can create a very unhappy destiny. A short list of the things that can go wrong includes blocked arteries, high cholesterol, high blood pressure, angina, heart attack, heart failure, and sudden death. The bottom line: Many of the cardiac problems that people experience are brought on by years of neglect and failure to abide by even the most basic of cardiac-healthy lifestyle principles. (Nature makes a few mistakes, too, but even in those cases, personal choices often complicate the problem.)
The good news is that even if you've been diagnosed as at risk for heart disease or as having it, and even if you've experienced specific heart problems, paying attention to the basic principles of a cardiac-healthy lifestyle in conjunction with the medications and procedures of your treatment plan can help you turn things around.
