General Adaption Syndrome (GAS Theory) is something that Hans Selye first outlined when researching the effects of stress on lab mice in Montreal. Upon further research (and subsequent elaboration and expansion by many other individuals) he concluded that your body will deal with stress in three different stages (which is the ‘GAS Theory’):

1) Alarm

2) Resistance

3) Exhaustion

To kick things off, your body must first prepare itself. The ‘Alarm stage’ is perhaps the most well known, as this is where your fight or flight response will take place. If you are unaware, this is your body’s natural response to a perceived threat or danger. Various physiological changes are made by jumpstarting a cascade of hormones to flood your system. This is done via secretions from at the adrenal gland, and will prepare your body for whatever may come next.

The physiological changes that usually occur are:

— increased heart rate,

— increased blood pressure,

— increased blood glucose, and

— increased respiration

These changes help to prepare you by:

— allowing better oxygen absorption,

— improving hearing,

— making muscles more responsive, and

— dilating pupils

If preparation was the name of the game in the alarm stage, now it is time to deal with the issue at hand. The ‘Resistance stage’ is essentially your bodies way of resisting the stressor(s). Not to make this confusing, but some people may also say that the last sentence takes place between the alarm and resistance stages, and instead during the resistance stage your body is walking a line between high-alert and recovery.

In this notion of “high-alert”, it would be  maintaining the readiness of your body. Opposite to this line of thinking is that once your physiological changes have spiked, your body will start to even out those changes. But I think it is important to note that it takes a bit of time for your body to normalize… and this may be what others refer to as “high-alert”. By this I mean that because it is taking longer for your blood pressure or breathing rate to normalize, you have a better change of dealing with the stressor(s) if they arise again.

There are a few notable effects while in this stage of the GAS Theory:

— poor concentration,

— irritability, and

— frustration

Finally, the ‘Exhaustion stage’ will happen when the above physiological changes remain constant or too high for too long. As harmless as this may sound to have faster breathing and quicker muscle reflexes, it can actually result in single organ or entire organ systems succumbing to chronic stress / illness (just all-around general unpleasantness – to put it lightly).

Chronic stress can have major adverse reactions to your: brain function, nervous system, endocrine system, respiratory system, cardiovascular system, and even your reproductive system. For a more complete break down of how chronic stress affects those body systems checkout this fascinating article by the American Psychological Association.

To return to our post on fatigue, overreaching, and overtraining, click here.