(or Why We Don’t Program “Murph” Every Day)

For today’s bite, let’s take on the elephant in the room: cardio.

The mainstream fitness prescription calls for spending hours and hours “burning calories” on the treadmill (or elliptical, or exercise bike, or whatever the cardio machine du jour happens to be.)

We do not like this. Here’s why.

Long duration “cardio” is exclusively aerobic training, utilizing the oxidative pathway (we’ll talk more about this in a future Bite-Sized CrossFit Concept.) Aerobic training improves cardiovascular function and decreases body fat. However, it also decreases muscle mass, strength, speed, and power. This is why you find marathon runners who can only jump a couple of inches off the ground!

We want to produce athletes who are equal parts track athlete, gymnast, and Olympic weightlifter: strong, fast, and powerful. We want to decrease your body fat and give you a huge strength to bodyweight ratio so that you can win American Ninja Warrior and look amazing doing it!

Anaerobic training — short duration, high intensity intervals — is the only way to achieve this. It improves cardiovascular function, decreases body fat more effectively than aerobic training, and dramatically improves power, speed, strength, and muscle mass. In addition, anaerobic training can be used to develop a very high level of aerobic fitness. In English, this means that short duration interval training will develop your ability to take a nice long run as well as PR your “Fran” time.

To summarize: stop worrying about how long you’re spending working out, and start worrying about finding that intensity in every session!

Food For Thought

Do you often find yourself lying on the floor gasping for breath after a workout? If not, why not?

Learn More

Forget The Fat-Burn Zone: High Intensity Aerobics Amazingly Effective by Clarence Bass

What Is Fitness? by Greg Glassman

Have Questions?

Ask them in the comments!

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Bite-Sized CrossFit Concepts is our series of quick primers on some of the fundamental principles of CrossFit, as well as common misconceptions and frequently asked questions. We hope that they will help you understand why we do things the way we do, and train smarter!