With this post I am beginning a series of post’s entitled “Things a Wise Zebra Once Taught Me.” The series is an attempt to look deeply at the bodies physiological response to stress caused by physical exertion, and to better understand how this knowledge can help athletes to train smarter. I hope my summary of Sapolsky’s work is of help to you.
Any public school educated second grader has learned that as they begin to run, there heart beat begins to race. Any second grade PE teacher could tell you that the reason this occurs is to allow the heart to pump more blood, through the lungs, faster, so the blood can be delivered to the working musculature to keep up the good work. While this answer is enough to suffice the inquisitive mind of the average second grader, it doesn’t explain the physiological reaction that occurs, and how it is remarkably similar to what’s going on in the body of a zebra being chased by a hungry lion. While these two stressors are definitely different types of stressors, your body’s response is not.
When your body senses a stressor (physical or psychological) the message is immediately sent to your brain (hypothalamus to be exact). Once your brain understands what is going on it makes a quick call over to the pituitary gland which initiates the Sympathetic Nervous System which is responsible for getting the body ready for one of four functions: fight, flight, fright, or sex. First, the body increases the stimulation rate of the accelerator nerve, which is responsible for regulating heart rate. Next, the body triggers hormonal secretions to prepare the body for one of the four previously stated functions. Most of the hormones secreted are the same no matter which stress response function you chose, there are however minute differences depending on the function chosen. Epinephrine (adrenaline), norepinephrine, and later glucocorticoid’s are allways released into your blood stream to allow your body to kick into ready mode.
So this stuff is already pretty cool, but it gets better. Your body is actually capable of instantly prioritizing which functions are necessary and which ones can wait. Do you think the zebra is spending massive amounts of energy on digesting that yummy grass it just ate? Or taking brakes to stop, and hide behind a tree so it can use the restroom? No the zebra is sending as much nutrient rich blood as it can to the working musculature, and turning as many functions off as it can, digestion included. One can easily see how if this stress was to become prolonged how big of a toll it would take on the body. Fortunately for the zebra, it lacks the cognitive ability to realize that in reality there are probably always lions within a few miles. To the zebra, the lion is out of sight, out of mind. To the human it is easy to stay up at night wondering if that minor headache you’re having could be the beginning of an onset of chronic migraines, or maybe a brain tumor? Because of humans increased cognitive ability we are prone to initiating our sympathetic nervous system (stress response) and being unable to turn it off.
This last paragraph is something we will continue to explore in the upcoming posts. When your stressed your body does turn of functions, some of these are extremely important for healthy living (i.e. immune system). I hope this post has at least peaked your curiosity and will lead you to come back and learn a few more “Things A Wise Zebra Once Taught Me.”
- Will Hawkins
Sapolsky, Robert M.. Why Zebras Don't Get Ulcers, Third Edition. 3rd ed. New York: Holt Paperbacks, 2004. Print.
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