If you hang around people who exercise, you’re going to hear the word cardio or aerobics pretty often. Someone may say, “I do cardio four days a week,” or, “My gym has awesome cardio equipment.” Aerobics — a term coined in the 1960s by fitness pioneer Dr. Kenneth Cooper — refers to cardiovascular exercise, the kind that strengthens your heart and lungs and burns lots of calories.
After you read this article, you may be very excited about all the information and want to put it — and your feet — into action. On the other hand, with all this talk of maximum heart rate, anaerobic threshold, and heart-rate monitors, you may wonder whether cardio exercise is just too darned complicated to bother with. Trust us: It’s not! We provide all this information so that you understand the basics of how to determine your exercise intensity and set goals for your program.
Comparing Aerobic and Anaerobic Exercise
Aerobic exercise is any continuous, repetitive activity that you do long enough and hard enough to challenge your heart and lungs. To get this effect, you generally need to use your large muscles, including your butt, legs, back, and chest. Walking, bicycling, swimming, and climbing stairs count as aerobic exercise.
Movements that use your smaller muscles, like those leading into your wrists and hands, don’t burn as many calories. Channel surfing with your remote control can certainly be repetitive, sustained, and intense — particularly when performed by certain husbands we know — but it burns very few calories.
Aerobic means “with air.” When you exercise aerobically, your body needs an extra supply of oxygen, which your lungs extract from the air. Think of oxygen as the gasoline in your car: When you’re idling at a stoplight,
you don’t need as much fuel as when you’re zooming across Montana on Interstate 90. During your aerobic workouts, your body continuously delivers oxygen to your muscles.
However, if you push yourself hard enough, eventually you switch gears into using less oxygen: Your lungs can no longer suck in enough oxygen to keep up with your muscles’ demand for it. But you don’t collapse, at least not in the first 3 minutes. Instead, you begin to rely on your body’s limited capacity to keep going without oxygen. During this time, your individual muscles are exercising anaerobically, or without air.
Anaerobic exercise refers to high-intensity exercise like all-out sprinting or very heavy weight lifting. After about 90 seconds, you begin gasping for air, and you usually can’t sustain this activity for more than 3 minutes. That’s when your body forces you to stop.
You may still use large muscle groups, but you do so for only a short burst of time, and then you need to take a break before starting the next burst. Running a 30-minute loop around the neighborhood is aerobic, whereas doing all-out sprints around the track with a 2-minute break between them is anaerobic. Both count as cardio because they challenge your heart and lungs and burn lots of calories. You also may do hybrid activities referred to as “stop-and-go” sports, such as basketball, soccer, and tennis. These activities involve long periods of slow, sustained movement with some short bursts of high-intensity activity.