By: Michael Beiter

Have you ever wondered what happens to your body when you encounter a stressor? Whether it's a tough workout, a difficult conversation, or a high-pressure work deadline, stressors can disrupt our homeostasis and trigger a physiological stress response. In this blog post, we'll take a closer look at what happens to your body during a stress response, using an intense workout as an example.

First, let's define homeostasis. Homeostasis is a state of comfortable and constant familiarity, stability, and/or predictability. It's that feeling of being in your comfort zone, where everything is familiar and predictable. Let's say you're walking into the gym feeling pretty relaxed a couple of hours after a good meal. You're in a state of homeostasis.

Then, you encounter a stressor that disrupts that homeostasis. In this case, the stressor is an intense workout. You hit the gym, and your body enters an "alarm phase," responding to the disruption. During this phase, you may feel temporarily worse as you try to manage the demands or threats. Or maintaining the same level of performance becomes challenging as fatigue from the exercises and activities accumulates.

During the workout, your body goes through a series of changes.

You need fuel, so you start mining your muscle, liver, and bloodstream for available nutrients.

Your heart beats faster to keep up with the demand for oxygen-rich blood to reach tissues.

You breathe faster and deeper.

Stress hormones such as epinephrine (adrenaline) and cortisol are released into the bloodstream. These free up stored fuels and activate your immune system to prepare you for any potential injury.

If the workout is particularly stressful or intimidating, you may get a "fight-or-flight" response as your sympathetic nervous system (SNS) amps you up. You may feel a burst of energy, nausea, or "shakiness."

Immediately after the workout, you may feel tired as metabolic byproducts build up, your body temperature increases, your fuel stores of glucose and glycogen are briefly depleted in your blood, liver, and muscles, and your muscular and central nervous systems put on the brakes to slow you down.

You may be thirsty if you've lost water through sweating and breathing more.

Your immune system is briefly activated (for a few minutes) but then becomes depressed for a few hours while you recover from the workout.

You may have micro damage to your muscles and other tissues that includes protein breakdown.

Inflammatory hormones and cytokines get to work as "early responders" who deal with this cellular damage by activating the inflammatory pathway so you can heal and regenerate tissues.

Over the next several days, your body will recover and rebuild any tissues that have been damaged, so long as you get enough sleep and enough nutrients, don't have too many other stressors accumulating, and have no other serious illness or deep health issues that makes regenerating difficult.

Your brain and nervous system will also adapt to the neurological demand of the workout. At times, this may mean grooving some motor learning (i.e., developing movement skills or teaching your motor neurons to produce force in particular patterns) as well. During this process, you get stronger and more resilient against future stressors.

Over the long term, you improve your energy transfer and, eventually, become more energetic as your mitochondrial efficiency and density go up.

Your immune system becomes more robust.

You build stronger muscles and replenish glycogen; you build new proteins and clear out the damaged old ones.

Inflammation decreases, and your body's "cleanup crew" (such as macrophages) clears out cellular wastes and debris.

You learn to move more efficiently and in more diverse ways. And so on.

Then, you enter a new homeostasis or baseline.

Now, you're slightly better than before.

In conclusion, stressors can disrupt our homeostasis and trigger a physiological stress response. During a stress response, our body goes through a series of changes, from an alarm phase to a recovery and rebuilding phase. If we recover and refuel, we adapt and improve, becoming stronger and more resilient against future stressors. Over time, this becomes a natural, growth-promoting pattern of up-and-down stress-then-recover.

My colleague of over a decade and I refer to this waving of increasingly better fitness levels as ‘The Tsunami Method.’