What, Exactly, is Aerobic Exercise?

Having served as a high school cross country and track coach for the past 20 years, this topic is near and dear to my heart…get the “heart” reference?…aerobic exercise…heart…get it? Of course you do! Even if you only have a rudimentary understanding of aerobic exercise, you probably understand it’s somehow related to heart health. Well, actually, it’s more related to oxygen, but the heart is certainly involved with oxygen. Well, actually, the heart is more involved with transporting oxygen to your muscles, but that’s still a link between your heart and oxygen, is it not? Just go with it.

The rough translation of “aerobic” to common, easy to understand English is “with oxygen” as opposed to anerobic which means “without oxygen.” Therefore, think of aerobic activity as exercise during which your breathing rate remains at a manageable level. In other words, you’re not out of breath. You can still speak without too much difficulty. You can maintain your current activity level for an extended period of time, say ten minutes or so. If you’re participating in anerobic activity, on the other hand, you get out of breath very quickly. When you talk, it’s in short, single-word, staccato bursts. You can maintain your current activity level for a very short period of time. Think sprinting versus jogging.

Without getting too technical or using esoteric terminology, before we go any further, let’s try to get a basic understanding of how our bodies generate energy to better understand what aerobic exercise is and why it differs from anerobic. Our muscles burn fuel, just like a car’s engine burns fuel. However, our muscles do not burn gasoline, they burn a combination of fat, glycogen (broken down sugars or carbs) and oxygen. And, just like a car, the faster we go, the more fuel we burn until our tanks are empty. Muscle activity is limited by their access to fuel, i.e. fat, glycogen and oxygen. Just like a fuel tank, our bodies can only store so much glycogen and fat and our bodies burn glycogen prior to burning fat. Oxygen, on the other hand, cannot be stored in our bodies. Hence our constant breathing to replenish our oxygen levels.

When our activity level increases, so too does our breathing rate as our muscles demand more fuel (glycogen, fat and oxygen) to meet our energy demands. So long as our activity level is low or moderate, our increased breathing level is able to meet our muscles’ demands. Yes, we will eventually deplete our stores of glycogen (after a few hours of moderate activity) and fat (after days of moderate activity), but let’s focus on oxygen for now.

So, if our muscles demand more oxygen as we exercise, how do they get it? Through our blood, that’s how. You might not notice it a first, but as your breathing rate increases due to exercise, so too does your heart rate. Your heart starts pumping faster in order to meet your muscles demand for more oxygen. However, your heart can only beat so fast (maximum heart rate) for so long. That is why Usain Bolt can only maintain his 27-mph pace for only 100 meters or so. His heart can’t pump fast enough to get the necessary oxygen to his muscles. It’s also why we struggle in the oxygen depleted air of high-altitude environments. There’s less oxygen in the air, therefore, there’s less oxygen available for our muscles.

So, aerobic exercise is an activity during which our heart and lungs can provide the necessary oxygen your muscles demand for an extended period of time. That “period of time” generally depends on the intensity level of the activity and how efficiently your heart and lungs work and that varies by individual. Generally speaking, that period of time should be, at a minimum, ten to twenty minutes without a break. And there are a variety of exercises that qualify as aerobic and they include, but are not limited to: walking, jogging, swimming, biking, cardio machines, dancing, kick boxing, jazzercise, tae bo, stair climbing, hiking, etc.

If you participate in aerobic exercise most days of the week, you’ll reap the benefits of strengthening the muscles involved in respiration, a more efficient heart muscle, reduced blood pressure, increased number of red blood cells, reduced risk of diabetes, reduced stress levels, and, if it’s high-impact aerobic exercise like jogging or skipping rope, increased bone growth and a reduced risk of osteoporosis.

Well, I could go on forever about this subject, but I probably should save some for a future post. Now get out there and exercise…aerobically.