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Stress & Exercise. Its not as simple as you think.

Jade Teta ND, CSCS

When ancient humans were presented with a stressful event, i.e. the saber toothed tiger, they either had to run for their lives or stay and fight. The acts of running or fighting were essentially a priming mechanism for human growth. As Neitchze said, “That which does not kill us makes us stronger”. Every time our ancestors narrowly escaped becoming a predator’s dinner or fell just short of catching the next meal, their bodies were pushed to the physical limit. This intense exertion forced the body to respond by becoming leaner, faster and stronger so the chance of success was more likely next time around. This same concept is one of the most important aspects of weight training. It is called progressive resistance.

In order for the muscles to respond they must be pushed with ever-greater intensities. Contrast the above scenario with what is common today. A car cuts out in front of you on the highway, you just got into a fight with your boyfriend, or your boss decides to give you a difficult project to complete by end of day. In the natural world you might jump up, break into an all out sprint, and run away from the car, tackle your boyfriend, or hurl your boss across the room. But the real world is more about “sit and seethe,” than “fight or flight.”

Today when confronted with stress, the options are to just sit there and endure or get up and move. Exercise is definitely your best choice, but what kind of exercise is most beneficial? Should you go to a restorative yoga class, burn through an hour on the treadmill, or is there a more appropriate way to fight stress with exercise?

The Effects of Chronic Stress:

Before we discuss optimizing exercise for stress, it may be helpful to review why repeated stress and tension followed by improper movement is damaging to the body. It damages DNA, degenerates collagen, disrupts fuel metabolism, and affects virtually every system in the body. The negative impact of chronic stress is derived in part from hormones. Adrenaline, noradrenalin, and cortisol are three hormones released when the body encounters stress. When these hormones are released day after day, in large amounts, and without the countering effects of appropriate exercise their signals become disruptive to our physiology.

This is analogous to revving a car engine to an excessive degree while it is in park. The car may not be in motion but the wear and tear on the engine still occurs. One of the major effects of stress is a disruption in the hormonal network of the body. Human physiology is a closely orchestrated dance between environmental inputs, hormonal signaling, and metabolic output. When the hormonal system becomes damaged because of chronic stress, the metabolism no longer works correctly, creating many of the problems associated with aging and disease.

Consistently high levels of stress hormones lead to changes in other hormones like insulin, leptin, growth hormone, and reproductive hormones. It is not uncommon for this hormonal dysfunction to reach the point of hormone resistance where the body requires more and more hormonal inputs to induce the same effects. A similar mechanism can be seen in the adaptive response to stimulants. Just as the body will adapt to chronic caffeine intake by requiring more and more to have the same stimulant effect, the body can also develop resistance to the mechanisms of its own hormones.

One of the areas this problem becomes evident is with the female reproductive hormones. Excess cortisol and stress has the effect of lowering progesterone levels and raising estrogen. Although, the exact mechanism of this effect is unknown, some holistic doctors believe progesterone is sequestered by the adrenal glands to make more cortisol (progesterone in the adrenal glands is a required precursor for cortisol production). This creates an “estrogen dominant” state leaving an increased risk for hormonally related cancers and other estrogen related health issues.

The Hormonal effects of stress and exercise:

The body’s ancient physiological programming is designed to deal with tension in a very specific manner. When the body encounters a challenge, the first action is the release of hormones like adrenaline, noradrenalin, and cortisol as described above. These hormones act like a turbo-charger causing the body to release large amounts of sugar into the blood stream. The body releases sugar because unlike fat, sugar can be burned quickly and is able to provide the body with exceptional performance. If fat is like diesel for the body (poor performance, but increased mileage), sugar is like high-octane jet fuel (blazing performance, but poor staying power).

The large increase in blood sugar is meant to be followed by movement. However, not just any type of movement will suffice. Intense exercise is what the body needs and it is the only tool available to use up all that jet fuel and cool down the engine. Here is how it works: As the stress hormones rise, the body is flooded with high-performance fuel (sugar). This large rise of sugar and surging adrenaline elevate heart rate, dilate the eyes, engorge the blood vessels, and increase lung function. All of this is designed to prime the body for intense movement which uses far more sugar than lower intensity exercise. As the intense movement continues, sugar stores become depleted and oxygen is used at an accelerated rate.

Soon the body is faced with limited oxygen supply to fire its engine and anaerobic metabolism begins (sugar burning without oxygen). This leads to a large increase in lactic acid and a muscular signaling molecule called IL-6. When the intensity reaches a threshold, these two molecules build up in large quantities and signal the release of human growth hormone and testosterone. This is when the magic happens. The chemical soup created by this combination of biochemicals (adrenaline, cortisol, HGH, and testosterone) make the body a fat-burning, muscle-building machine.

When the threat is over, these hormones work synergistically to burn fat, build muscle, and make you leaner, faster and stronger. In addition, the intense movement signals other changes in the body including a compensatory parasympathetic response creating the feeling of energized relaxation. In addition, the perception of stress is altered for the better. This is the body’s innate ancestral response to combating stress. Breaking into a relaxing yoga pose or going for a long jog when confronted with a stressful event cannot duplicate this response because the intensity threshold needed to signal the appropriate growth response is inadequate. While each can lower cortisol levels and burn off some sugar respectively, they are less effective substitutes for the effects of high intensity exercise.