Rupert Hambly


Are you running and fighting too often?

Stress: Fight or Flight response, its effects on you and how to manage it.

Greetings from your friendly neighbourhood personal trainer!

This week, I’m going to talk about a well-known survival instinct commonly referred to as the ‘Fight or Flight’ response and the short term and long term effects this mechanism places upon the human body and psyche.

So I’m sure everyone has heard of the term ‘Fight or Flight’ before and most assume it is the adrenaline surge felt when you believe yourself to be in danger, often leading to remarkable feats of strength, speed or endurance. Well you’re not wrong but this is only a small part of the Fight or Flight response.


One of the reasons Humanity has survived for as long as it has is thanks to that big squishy thing between your ears. No not the nose (although mine has gotten me out of trouble before) but that fascinating bio-supercomputer known as the brain. Inside the brain we have a section called the Hypothalamus which deals with a variety of functions in the body; one of the more important functions it handles is that it links the nervous system to the endocrine system. The brain helps to regulate and control the release of hormones in your body.

In regards to the Fight of Flight response, when we perceive a threat (a stressor) our brain sends a signal via the central nervous system to two important structures in the body: the Pituitary gland and the Adrenal glands.

Now bear with me folks because things are about to get a little more technical.

The Pituitary gland releases a hormone known as Adrenocorticotropic Hormone, or ACTH for short (say that ten times really fast in a row. I dare you). Once ACTH has been released and begins to travel around the body, the adrenal glands become stimulated and release several other hormones, chief among them Epinephrine (Adrenaline) and Corticosteroid (Cortisol)

With these hormones flowing through the body several things starts to happen. The Liver starts to rapidly convert glycogen into glucose for energy. This glucose is used by the muscles to create Adenosine Triphosphate (ATP). ATP is responsible for the surge of power and speed in your muscles, being the primary energy source during intense actions (heavy lifting, sprints etc)

The breathing rate increases as your body starts to prepare for action requiring more oxygen. The heart starts to beat faster, increasing your heart rate and blood pressure, as it attempts to send as much oxygenated blood to the required muscles. Your digestive system is slowed down and blood flow from this area directed to more essential areas. The immune system is suppressed as the body focuses on spending energy on the more immediate concerns. All of this happens in the span of a few seconds. Seconds. By the time you’ve seen the danger and thought “oh s!£$” the body has prioritised which areas of your body need oxygen and blood the most and prepares for your muscles for action.
These are the short term effects, and it all seems rather beneficial as a response to an immediate threat. As soon as the threat has passed and we are safe our parasympathetic system kicks in and restores our body back to Homeostasis (normality/balance). Our heart rate slows, breathing rate calms, blood pressure and blood sugar levels drop back. Occasionally you’ll feel sweaty or clammy as your body attempts to cool your muscles down.

What about the long term effects and potential dangers this system has on our body? It may be surprising to hear but this survival mechanism isn’t solely used in “Life or Death” situations. The Fight or Flight response is a response to stress, something I’m sure you’re all familiar with. Whilst Humanity has made great leaps and bounds in regards to technology and “civilisation”, on a physiological scale we’ve not changed too much from our early ancestors. Sure we stand up a little straighter, some bones have lengthened and some have shortened but in regards to that big squishy bio-computer, especially the areas that deal with survival, have not really changed. We’re still wired to attack or in the words of Monty Python “RUN AWAY!” when we see danger. The phrase “if it ain’t broke don’t fix it” seems to be the go to rule with evolution.

Now surely if Fight or Flight has kept us alive this long, there’s nothing too bad about this system. Unfortunately that same wondrous marvel of nature that is the Human brain has a slight drawback. One of those “blessings and a curse” deals that all aspiring superheroes end up dealing with.

Our ability to think. Sure we can outwit and outthink natural predators, it is another reason we have survived as a species. Our ability to think can also be a cause of great distress and danger for some people. Aren’t we a paradoxical species?

As I’ve already stated, from a physiological perspective mankind’s survival mechanism has not evolved since early man. Our Fight or Flight instincts are still the same and if we still lived in a hunter/gather type of society I firmly believe the amount of stress people feel on a day to day level would be non-existent. Our bodies were made to deal with immediate threats: – See giant tiger – either kill giant tiger, run the other way or end up as a kitty snack.

The threats, the stressors, that modern man faces today are not the same as those of our ancestors. Our brain however still deals with them on the same level. Have a big meeting which is vital to the future of your career, your body goes into Fight or Flight mode. You have perceived a threat and your body wants to do its best to ensure you live to fight another day.
This continual strain of Fight or Flight, over-worrying and stress can pose several problems to the body:

  • Due to the heart beating faster and faster from all the perceived threats it can eventually lead to heart attacks, strokes or heart disease spending on the health of the individual.
  • The immune system is suppressed so frequently that chances of becoming ill from colds and viruses increase.
  • Suppression of the digestive system can lead to weight problems, digestive trouble and acid reflux.
  • Due to increased levels of blood sugar and continued production of glucose several problems can arise including diabetes, kidney failure, liver failure, nerve damage and vision problems.
  • Premature aging and loss of libido due to hormonal imbalances.

Now I’ll be handing over to the esteemed Dr Alex Fowke, Clinical Psychologist, for the second half of this blog to discuss the psychological dangers of prolonged stress and possible solutions to ease this stress…

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Like Nick says, the Fight or Flight system is our survival instinct, activated by the Sympathetic Nervous System (SNS) which is one branch of the Autonomic Nervous System (ANS). It’s the opposite to the Rest and Digest (or Feed and Breed) system which is activated by the other end of the ANS, the Parasympathetic Nervous System (PNS), which is that feeling of relaxation and satisfaction you get when you’re lounging on the sofa after a Sunday roast. Whereas the PNS encourages us to chill out and relax with friends, the SNS prepares us to respond to a stressful situation to keep ourselves safe and ultimately prolong the survival of the species.

Now, far be it from me to contradict Nick or be a pedant, but evolutionarily (and in terms of behaviour), it’s more accurate to describe the SNS response as ‘Flight or Fight’, rather than the usual way we think about it. Just watch any animal documentary and you’ll see that even the most vicious predator will most likely try to run away or escape as the first solution to a threatening situation. It’s only when they’re backed into a corner that they’ll attack.


We’re the same. If we’re stressed out it’s automatic to try to escape before facing the situation that’s stressing out, and generally speaking it’s futile trying to fight against this reaction, particularly because it’s a hard-wired part of the human experience. As a caveman wandering around the prehistoric scrubland, the physiological response to stress was vital to keep the species safe. Coming face-to-face with a sabre-toothed tiger, our ancestors didn’t have the time to consider all of the options. Instead, the release of ACTH focuses attention on the nearest tree to climb or rock to hide behind at a pre-cognitive level, that is, before your thoughts kick in and tell you what to do. Not only this, but the hormonal release set in motion all the physiological systems needed to run as fast as possible – heart beating fast to pump blood to the muscles in the legs, breathing rapidly to take in large amounts of air to oxygenate the blood, sweating to cool down the blood.

Even though we’re generally safe from these types of predators walking the streets, we’re surrounded by threat. Work pressures, deadlines, financial worries and relationship difficulties all trigger the same release of ACTH. Paradoxically however, we tend to remain in the threatening situation rather than respond in the way our body is urging us to, and this creates internal tension. This is why you’ll notice that sick feeling, those restless legs, that light-headedness and sweaty palms when you’re stressed out – your body is reacting in the way it’s hardwired to even though your intelligent self is probably telling you to sit still. It’s only when the threat is significant – like if you were about to be mugged for instance – that we turn and run.

Part of our sensitivity to threat is temperamental, i.e. it’s the result of genetics. That means that some people are more predisposed than others to experiencing situations as stressful, particularly if they have anxious parents. Psychologically, apart from imminently life-threatening situations, we would propose the SNS isn’t just an automatic response to whatever scenario we find ourselves in, but rather we would suggest that it is a physiological response to the interpretation of a situation as threatening. Indeed, as the Greek philosopher Epictetus (55AD-135AD) states: “Men are disturbed not by things, but by the view which they take of them”. So it’s not necessarily what happens to us, but rather it’s how we interpret situations that can make us anxious. So it’s not the work that makes you feel stressed, but rather the thought “This is too much, I can’t cope!”.


The role that cognition plays, along with temperament, helps us to understand why some people get more stressed than others to the same scenario. We would probably all have the same response to a sabre-tooth tiger because the response is pre-cognitive, but responses to less life-threatening situations generate wider variability of responses. So, for every person who thinks “This is too much, I can’t cope!” and freezes in response to having their boss dumping more work on their desk, there is a colleague sat somewhere thinking “Great! I love a challenge!” and can’t wait to get stuck in. The different thought processes generate different emotions, and hence different behavioural responses.

People with a lower tolerance to stress are likely to engage in a variety of coping strategies that have short-term positive effects but ultimately lead to longer-term problems. For example, ACTH released by the SNS can lead to emotional eating to cope with the pain of life stressors. Whilst comfort eating might be satisfying in the short-term, ultimately the types of food that we indulge in when eating emotionally will result in weight gain. Similarly, people who struggle to cope with stress are likely to have a poor diet because they’re constantly rushing and ‘fighting fires’, and hence eat poor quality junk food. Ironically, people who are easily stressed tend to crave food more than their less-stressed comrades, and find it harder to lose weight, even when they’re exercising and eating well!

Solving the problem of stress is easier said than done. Avoiding stressors seems preferable but is relatively impossible. There are some stressful situations that we can predict (Christmas, school holidays to name but a few) and therefore prepare for, but others are much-less predictable (an unexpected bereavement, redundancy, relationship breakdown). When stressed it’s useful to be aware of normally responses. It’s advisable to register whether these responses are ultimately helpful or not, and try to develop a more adaptive action plan. Rather than present a series of rules of how to respond to stress, I tend to advocate for greater degree of balance. As pressures increase, it can be helpful to work equally hard on activities that are calming and relaxing, but be mindful of excesses.


Indeed, whilst exercise is undoubtedly beneficial in the management of stress and anxiety, be mindful that it can also lead to greater vulnerability to stress! Getting enough (but not too much) sleep, looking after your physical health and avoiding too much alcohol, caffeine and other mood-altering chemicals are helpful, as is a balanced diet – a combination of what you ought to eat as well as some of what you want to eat – in reducing your vulnerability to stress and anxiety, as well as other negative emotional states.

Here’s to finding a healthy balance for all of us!

Nick and Alex

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