Physical and Psychological Stressors (The Autonomic Nervous System)

-Post inspired by “Why Zebras Don’t Get Ulcers”


Stress is a part of everybody’s life. Regardless of the type of stress, our body typically handles the subconscious response the same way (Fight or Flight). In short, our mind (hypothalamus) perceives a stress, communicates this stress to our pituitary gland, which then releases hormones to the adrenal glads, which in turn releases more hormones to communicate with other cells and organs within the body (HPA Axis). This flight or flight response activates the sympathetic nervous system, inhibits the parasympathetic nervous system, and mobilizes the necessary energies to overcome theses stressors.

This type of stress response is critical in the animal kingdom. You are a zebra, you see a lion, you need to mobilize all the energy you can to get the hell out of its way before you get eaten. However, thanks to opposable thumbs and our higher order thought processes, we have out innovated the food chain. We no longer run away from animals trying to eat us. Instead, we get stressed out over someone not texting us back, our favorite sports team losing a game, or school work.

The point is, our mind perceives stress the same, regardless if the following outcome is going to involve the physical process of running away from a wild animal trying to eat us or not. So, while the flight or flight response is necessary in the animal kingdom and other physical events, it is not always necessary for some of the “common” stressors we face day to day.

Why Does This Matter?

Well, the body kind of has a simple on off switch in side of it (not really, but kind of). While on, the body’s goal is to mobilize energies. During this “on” state, the body is breaking down energy stores in the body via catabolism. This is obviously important for performance, as energies are what drive our bodily functions to higher capacities, but if this process takes place in a non-functional way, we can get in trouble. The “on switch” in short, is your sympathetic nervous system.

The body also has an “off switch”. While the body is “off”, it goes into rebuild and repair mode. It takes energies and instead of breaking them down, it builds them into new structures. This is how muscle get built, bones heal and tendons repair. This “off switch”, also known as the “rest and digest” state and is governed by your parasympathetic nervous system.

To sum it up, when one is “on” the other is not working. Your body doesn’t like to try to build up and breakdown at the same time (yes, I am sure there are some specific exceptions). However, in general this idea holds true. When talking about athletic development, the relationship between the sympathetic and parasympathetic is critical. If the system is always breaking down, how do you expect to rebuild?

Side note: Sympathetic activation is not bad, just too much of it at the wrong time is. 


The key here is not just to focus on physical stress, but also physiological stress. Remember, both types of stress initiate the same flight or fight, sympathetic nervous system response. This is why injuries spike during finals week. The system is on all go, all the time, with no room for rebuilding.

As a coach, we cannot look at workouts in isolation. Understanding the grander scheme of stress and how it influences athletic development is critical for success. Remember, not all athletes are going through the same psychological stressors in life. Because of this, response to exercise and stress accumulation can vary from one to another. This is why talking to your athletes, using subjective questionaries, and objective measurements can help you get an understanding of how much stress is going on and whether or not training needs to be modified.

follow up post soon to come


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