One of the beautiful things about a CrossFit workout is the length—meaning, CrossFit workouts tend to be short and sweet.

Minus the sweet.

No, really. Most workouts are 20 minutes or less. There are plenty of benchmark and Hero WODs that take us into 30, 45 and 60 minutes of work, but on the daily—less is more. In an hour-long class, we spend time on proper warm ups, accessory work, mobility work, strength training, and conclude with a killer, yet short, MetCon (metabolic conditioning).

Some days we might see a 7-minute burpee AMRAP programmed as the MetCon for the day and wonder, “That’s it? Am I getting a good enough workout? Is 7 or 12 or 18 minutes really enough?”

And we’re here to tell you, yes. It really is.

There are only two things you need to know that scientifically contribute to CrossFit’s shorter workouts with higher intensity. The first being our metabolic pathways and the second being neuroendocrine adaptation.

Without overwhelming you with the fancy jargon and research behind it all—CrossFit’s contrarian reputation stems from the scientifically-backed theory that CrossFit athletes can perform at an above average level across various fitness modalities because of the energy systems we utilize in our “short and intense” workouts.

First, the metabolic pathways—the energy systems I just mentioned—we have three of them. This is where the term “MetCon” comes from because the core of CrossFit’s version of “cardio” is adapted from these pathways that provide the energy for all human action. The three pathways are: phosphagen, glycolytic, and oxidative.

Greg Glassman, CrossFit’s founder and CEO, states:

Of the three metabolic pathways, the first two, the phosphagen and the glycolytic, are “anaerobic,” and the third, the oxidative, is “aerobic.” Just remember that efforts at moderate to high power and lasting less than several minutes are anaerobic and efforts at low power and lasting in excess of several minutes are aerobic.”

Did you catch that? Anaerobic is more intense exercise for a short period of time while aerobic is less intense for a longer period of time.

A central part of Glassman and CrossFit’s foundation lies in this: while aerobic exercise is beneficial to many athletes or those with fitness goals, it actually has the capability to decrease muscle mass, strength, speed, and power if it’s the only type of exercise we focus on.

He continues:

Anaerobic exercise is [actually] superior to aerobic exercise for fat loss! Anaerobic activity is unique in its capacity to dramatically improve power, speed, strength and muscle mass. Anaerobic conditioning allows us to exert tremendous forces over brief time intervals.

Still with us? So tapping into those first two energy systems—the anaerobic ones—it’s good. We promise.

So the next component is neuroendocrine adaptation. Defined as a change in the body that affects you either neurologically or hormonally.

And this is important because “most critical adaptations to exercise are in part or completely a result of a hormonal or neurological shift.”

Glassman tells us that isolation movements that we’d get from many of those machines at a typical gym are actually not initiating this necessary adaptation.

Exercise regimens that induce a high neuroendocrine response produce champions! Increased muscle mass and bone density are just two of many adaptive responses to exercises capable of producing a significant neuroendocrine response. 

It is impossible to overstate the importance of the neuroendocrine response to exercise protocols. This is why it is one of the four defining themes of the CrossFit Program. Heavy load weight training, short rest between sets, high heart rates, high intensity training, and short rest intervals, though not entirely distinct components, are all associated with a high neuroendocrine response.

So that 7-minute burpee AMRAP? Yes, it’s totally enough.

So we’ll leave you with this final statement from CrossFit’s fearless leader:

In CrossFit we work exclusively with compound movements and shorter high intensity cardiovascular sessions. We’ve replaced the lateral raise with pushpress, the curl with pull-ups, and the leg extension with squats. For every long distance effort our athletes will do five or six at short distance. Why? Because compound or functional movements and high intensity or anaerobic cardio is radically more effective at eliciting nearly any desired fitness result.

Glassman, G. (2002). Foundations. CrossFit Journal
Glassman, G. (2002). What Is Fitness? CrossFit Journal

About the Author

As a CrossFit Trainer & Content Writer at Solstice, Megan brings our experiences to life with her words. She strives to be a voice for the community, offering inspiration and advice for all our readers.