DO WE REALLY NEED CARDIO?

I’m writing about cardiovascular health, partly because February is Heart Month, but more importantly because the American Heart Association in its 2019 update notes that 48 percent of all adults in the United States have some form of cardiovascular disease. We need to take better care of our hearts, but how? For me, I’ve found that the more you understand how your body works, the more “how to take care of it” makes sense—and the more it makes sense, the more you’re likely to actually do the work of taking care of your body.

Do humans need “cardio?” It depends. What do you mean by “cardio?” Do you think of cardio as a type (mode) of exercise? Or do you think of cardio as any movement that uses your heart and lungs more?

For many, “cardio” is a period of time where they move their body rhythmically and in a way that increases the demand for oxygen. (Running, mountain biking, Stairmaster, etc.) Specifically, the parts that are moving rhythmically need more oxygen to move in this repeated way. These moving parts get the oxygen they need, the heart and its vessels gets the movement they need, and your whole body completes a task (note: as explained in Move Your DNA and Movement Matters, moving used to have more purpose to it; now the physically demanding “tasks” we tend to complete are the exercises themselves, vs. getting our bodies fit while doing something that gets us the things we need, like food, water, shelter, etc.).

Increasing the movement of your heart and lungs (or as I think of it, taking them through a greater range of their possible motions) is essential, but I don’t believe this is a full “healthy heart” program. If we’re only doing cardio as it’s commonly thought of, we might not be doing all we can for our hearts.

While your feet and ankles are not included in the way we’ve classified the “cardiovascular system,” the motion of the feet supplements the work of the heart by helping blood pump back up against gravity. In this way, the various movements of the body are part of how your cardiovascular system works.

From Move Your DNA's Chapter Four: The Heart of the Matter and Why We May Not Need Cardio After All (although really, you should read the entire book):

If I had you create a mental image of the cardiovascular system, chances are you would come up with an image similar to those presented in anatomy and physiology textbooks throughout the world:

 

But this picture is incomplete. The arteries and veins are usually the main feature of drawings like these, but what this image leaves off are all the smaller vessels where oxygen delivery—the very reason the blood needs to circulate through the body—takes place. The final destination of oxygen is capillary beds—the teeny-tiny tubes that branch off the arterioles, which branch off the arteries. This is where the exchange between the body and blood occurs.

If you prefer pictures to words, it means that the blood flow to the hand pictured as this:

really looks more like this:

Even this picture hardly does justice to the dense network of your capillary system.

The capillary system is so prolific, most cells in your body (and there are a hundred trillion of them) are within fifty micrometers of a capillary. Don’t have your micrometer measurer handy? A human hair is about seventeen micrometers thick, which means almost every cell in your body is within a few hair-widths’ distance from a capillary.

ARTERIES ARE ONLY THE HIGHWAYS TRAVELED BY OXYGEN

Say you’re trying to visit a friend who lives a few states over from you. You hop in the car and head over on the fastest freeway to get as close to her house as you can before jumping onto a smaller but still crowded inner-city road, then to the slower routes through suburbia, and finally pull your car into the driveway of your friend’s home.

The process of going from being one in a thousand cars driving on megahighway to being the only car in a driveway is similar to the experience of a red blood cell traveling from your heart to a capillary bed. The function of the cardiovascular system is only “good” if it accomplishes the task of delivering oxygen everywhere in the body, and the state of your cells—your microhealth, if you will—is a better indication of the function of your cardiovascular system than is the ability to run five miles.

Breaking in to this excerpt to drop in a quick video to see this in action. Note the fuller, fast-moving vessels and the thinner capillaries carrying blood cells in a single-file line!

 

HOW DOES BLOOD-OXYGEN GET OUT OF THE ARTERIES AND INTO THE CAPILLARIES?

Blood moves like this: The mechanical stimulation of a muscle working causes the smooth-muscle walls of the arterioles to relax and open (this is called vasodilation), causing a drop in pressure that pulls blood from the arteries to the capillaries. Now I’m going to stop you here and have you recall the version of the cardiovascular system you are most familiar with. Do you remember any mention of the musculoskeletal system? Probably not. The cardiovascular system most of us are presented with is one in which the heart is essentially pushing the blood around your body. In reality, working muscles pull your blood to the tissues that need it.

The “heart-pump” model of the circulatory system is probably why the “strengthening your heart” paradigm has persisted. Within a sedentary culture, the heart becomes the sole mover of blood. This is not “how the body works,” but how the body operates in a movement drought.

**End section of Move Your DNA **

Do we need strong hearts? Absolutely. Aaaaaand I think we would benefit tremendously from an expanded view of a healthy cardiovascular system that is more holistic in nature.

How much resistance does your body place on your heart due to tight parts that aren’t doing their share of circulating the blood? How much resistance does your body place on your heart due to long bouts of not moving and thus not assisting the heart?

Here’s my healthy-heart movement checklist:

• Move with some intensity each day and use a variety of body shapes when you do, so that more parts are benefitting. I select modes of exercise that are more “whole-body,” and make sure I cross-train, i.e., use a variety of modes.
• Work on your body parts’ mobility, so that each part is able to contribute to circulating and delivering blood. #stretch
• Keep it moving. The body, that is. I don’t let more than thirty minutes go by without a short walking and stretching session. Even if these breaks are only a few minutes long, it’s beneficial!

So, do humans need “cardio”? No, I don’t believe humans need this type of exercise, isolated away from moving for things in their daily life (there are many humans who get necessary heart, lung, and limb motions without an exercise approach). “Cardio” exercise isn’t a biological requirement; using our bodies in a way that gets us these motions is. I’m not trying to make a semantic argument here; the fact is, the way we frame what we need (exercise vs. movement) can expand or limit the ways we attain our needs—or even whether we can attain them at all. But more on that another time...