Everyone understands that muscles benefit from exercise. Their achievements are visible: flat abs, steely glutes and biceps. Less visible but more significant are the vast victories you experience elsewhere in your body. Exercise is a particularly potent prescription for your lungs, heart, and blood. You upgrade these when you do aerobic exercise—any activity that uses large muscles in a rhythmic way, such as running, walking, cycling, dance, swimming, and so on.
You breathe in, you breathe out, your heart beats, your blood fl ows. You don’t really need to think about this much. So what’s to improve? A lot. The truth is, with a little movement, your breathing, your lungs, your heart, and your blood become breathtakingly better. And with these improvements you can go from chugging along like a junker car to purring at top speed like a Ferrari.
Better circulation starts with your lungs. Your lungs don’t grow bigger or harder with exercise like your muscles do, but with exercise your lungs perform the same work using less energy. It’s almost as if your lungs get smarter.
Exercise also spawns greater efficiency in moving air in and out of your chest, and in exchanging oxygen and carbon dioxide with your blood. Trained athletes tend to breathe slower and deeper. This reduces what’s called the “functional dead space” in your lungs. This dead space resides in the tube between your lungs (where oxygen is transferred to your blood) and your mouth (where you get oxygen from the environment). If you have ever inhaled air through a snorkel, you know that it’s harder to breathe. That’s because the snorkel extends the dead space between your lungs and the air. You have to put more energy into sucking air in and out to move all of the air in the snorkel. Only the air that makes it deep into your lungs will bring oxygen to your blood, but you have to move all of the air in the tube to get new air down there. When you are active and need oxygen pronto, your body quickly realizes that dealing with the dead- space air between your lungs and mouth is like breathing through a snorkel. When you breathe faster, you have to suck in the air that’s not contributing—that dead- space air—more times. You quickly discover that breathing slower and deeper is easier than breathing faster.
Dead- space air constitutes about a third of each breath you take in resting conditions. For every breath you can save, you reserve the energy it takes to move that amount. When resting, you suck in that useless air ten to sixteen times a minute. When you are aerobically fit, you draw it in fewer times a minute. That totals more than a quart of useless air you avoid sucking in every minute. Imagine a quart-size balloon filled with air and the energy it would take to suck that air out. That’s the amount of energy you save every minute when you are fit, and you save even more while exercising.
This savings in respiratory work following training is substantial. Research demonstrates that when exercising at the upper limit you spend up to 8 percent of your total energy just on breathing (expanding your lungs and so on). The energy you save with better breathing is total gain; your body sends some of that energy to other muscles that are working hard, like your leg muscles. Thus by breathing deeply and less frequently, any given activity—walking, running, dancing, or swimming—is easier for you to do. You can sustain it longer; you feel less fatigue.
Another change in the breathing technique of fit people is that they keep less air in their lungs at the end of each breath. Basically they squeeze out more air. The changes in pressure that happen inside the chest during the respiratory movement help your blood return to your heart, favoring your circulation. With training, your respiratory pattern changes. Think of marathon runners: They are always relaxing their breathing. Their shoulders drop; each exhalation is very deliberate; they become veritable exhaling machines. This is an automatic, unconscious breathing pattern that allows for more air to come in at each new breath. This washes out more carbon dioxide (and you produce a lot of carbon dioxide when you exercise). It is, in a sense, a recyclable that gets tossed out at the energy factories in your muscles. At your muscles, blood delivers oxygen and picks up carbon dioxide, then returns to your lungs to dump carbon dioxide and retrieve fresh oxygen. When carbon dioxide accumulates, your blood becomes more acidic. It can’t pick up as much carbon dioxide at the cells—and what it does pick up it can’t drop off at the lungs. By exhaling more deeply when you exercise, you are washing out more carbon dioxide from your lungs with each breath.
Training benefits circulation even more. When you’re fit, your lungs open up their “spare rooms,” so to speak, so you use more of your lungs for air exchange. When you exercise you also distribute both the blood and the air in your lungs more evenly. At rest, when you are standing, a lot of blood stays in the basement of your lungs (due to gravity); most of the air keeps to itself at the top of your lungs, or in the attic, as it were. If you lie on your back, the same thing occurs—you have more blood at the back of your lungs, more air on top. When you exercise, however, the balance shifts and the two mingle better. They both filter into all of the rooms on all the floors of your lungs, in more equal proportions. This way, more blood comes in contact with more oxygen, and your blood is essentially better oxygenated when it returns to the heart and is pumped to the rest of your body.