16 Mar

Coach Greg Glassman, the founder of CrossFit, has defined CrossFit as “constantly varied, high intensity, functional movements.” The focus of this definition being variance, intensity, and functionality.  Last week I listed three things that came to the forefront while assisting my staff members with their CrossFit L1 Certificate Course.  The last item listed was “The emphasis on neuroendocrine adaptation with functional movements and high-intensity interval training.”  Additionally, I touched on the neuroendocrine response as it relates to exercising on an empty stomach.  This week, we will talk more about how this effect relates to the type of exercise you choose (and typically what I choose for you).

The neuroendocrine response, as it pertains to physical activity, is the relationship between the nervous system (from your brain to your peripheral nerves) and the endocrine system (hormones). Hormones are what govern our body’s ability to grow and change, and can be conceptualized as the messengers between our brain/nervous system and tissues (e.g. muscles). They regulate how the body responds and changes in response to any given stimulus like lifting a weight or climbing a route. A few key hormones account for the majority of our body’s response to physical activity including testosterone, human growth hormone (HGH), insulin-like growth hormone (IGHF-1), insulin, glucagon, cortisol, and the catecholamines (i.e. dopamine and adrenaline, specifically). I discussed dopamine addictions in a previous blog regarding high fat, high sugar foods and caffeine. 

Coach Glassman is well aware of the vital role of neuroendocrine response in your training regimen. He described its importance succinctly in a 2002 article published in The CrossFit Journal:

“‘Neuroendocrine adaptation’ is a change in the body that affects you either neurologically or hormonally. Most important adaptations to exercise are in part or completely a result of a hormonal or neurological shift. Current research, much of it done by Dr. William Kraemer, Penn State University, has shown which exercise protocols maximize neuroendocrine responses. Earlier we faulted isolation movements as being ineffectual. Now we can tell you that one of the critical elements missing from these movements is that they invoke essentially no neuroendocrine response. 

Among the hormonal responses vital to athletic development are substantial increases in testosterone, insulin-like growth factor, and human growth hormone. Exercising with protocols known to elevate these hormones eerily mimics the hormonal changes sought in exogenous hormonal therapy (steroid use) with none of the deleterious effect. 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 (Glassman, 2002)” 

Why is this important?  Well, if you are interested in building muscle, the key then becomes to understand how the type of training we do does or does not trigger the body to activate this ideal neuroendocrine process. The best training causes your muscle to become more responsive to the growth-stimulating hormones known as the anabolic hormones (despite popular belief, these are important for both men and women). Less than ideal training may actually overly stress the body and muscles so that they become more responsive to the catabolic hormones, which stimulate muscle break down without the hypertrophic reaction. Of course if the training is not intense enough, you may not even activate any neuroendocrine response at all. If you think of strictly endurance athletes (marathon runners), you will realize that they often have smaller builds. This is a direct result of the type of training they do (long and low intensity).  This type of training does not elicit the ideal neuroendocrine response for muscle growth. For police officers of any jurisdictional boundaries (city, county, or state), it is critical that we strike a balance between efficiency and power.

Dr. Brett Osborn, author of Get Serious (2014) and a board-certified neurosurgeon, has also recognized the benefit of high-intensity interval training and specific weight lifting movements as they pertain to the neuroendocrine response in the body.  Specifically, Dr. Osborn states that “heavy squats generate a robust hormonal response as numerous muscular structures are traumatized during the movement (even your biceps).”  Dr. Osborn also urges his readers that proper form is necessary for this type of response in the body.  He relentlessly urges beginners “I’d rather see you squat deep with an unloaded bar (45 pounds) than do a half-squat with 95 pounds (Osborne, 2014 p. 55).”

Dr. Osborn’s strength training regimen is responsible for some, if not the majority, of the strength training involved in the weekly WODs.  In addition to his strength training regimen, we also utilize the training guidelines behind Korte’s 3x3.  This program was designed by Stephan Korte, a German powerlifting coach in the 90s.  Both Osborn’s strength training regimen and Korte’s 3x3 program are designed to fit your strength level.  They are based off percentage lifts, so it really doesn’t matter if you are a beginner or a distinguished lifter.

The important thing to remember when utilizing these programs, is that you should always warm up with an empty bar and build your weight up to the target weight for your rep scheme.  The warm-ups don’t count toward the programmed workout, but they should always be documented for your personal use.  I, personally, rep out a few back squats with an empty bar, jump up to 135 and execute several reps, then move my way up to the percentage total for the day.  Once I arrive at the percentage total, I perform one repetition to familiarize myself with the weight.  I then rest for a few minutes before starting my first programmed set.  Absent a cold gym, it’s fair to say you should be sweating by the time you start your programmed workout.       


Glassman, G. (2002). Foundations. CrossFit Journal, p. 1-8.

Osborn, B. (2014). Get serious. Bothell, WA: Book Publishers Network.

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