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It’s not long after you pick up the sport of running that you begin to figure things out for yourself. It’s part of discovering the enjoyment of running and growing as a runner overtime. There will always be certain foods, training sessions and types of terrain that you both works for you and you enjoy, which positively helps in your development as a runner. When errors in our training, such as physical imbalances, digestion issues and fatigue occur, we look to correct course and address the issue.

But one thing seems to go unchecked…

In fact, we often as runners even go out of our way to martyr ourselves in the belief that running through the metaphorical mental sh*t-storm will have us emerging out the other side, tougher and stronger individuals.

That may be true, but not in the long run – and can in fact have quite the opposite effect.

As runners, we embrace the idea of ‘enduring’ difficult and stressful times as it’s often what we’re signing ourselves up to do at the weekend. We talk ourselves into it, often even wearing it as a badge of honour and hold a sense of pride in enduring a day full of stress. On the flip side, we see it as a sign of weakness to admit that we’re coping poorly with stress. If we can endure the mentally tough times in running, we should be able endure equally tough times mentally in other situations right? And if we can’t, it makes us appear ‘weak’, or at least feel like we’re mentally weaker in other aspects of life. But must we carry the endurance capabilities of stress over from our hobby into every day life to prove to ourselves, or others, of our strong mental fortitude?

Unlike other factors that may disrupt our running, the topic of stress becomes taboo due to the expectations either ourselves, or society, places on us. So we endure what life throws at us, then get out in the evening and relieve the stress on the trails.

Quite rightly too, as trail running is a great stress reliever, but what happens when the enduring of stress takes it’s toll? You’ll likely have met the sense of ‘running on fumes’ after a tough, stressful day, and there’s a reason for it, one that you’d rather not make chronic.



But also wrong, and potentially incredibly detrimentally so.

It is true that to progress in running, you must introduce ‘stresses’ to allow your body to adapt and overcome to progress and be robust enough to endure increasingly more stress.


So it would seem the daily stresses we not only willingly endure, but sometimes even seek out, will make us tougher over time.

And the theory would hold true, if it wasn’t for the hardware in your bodies system running in the background having the complete opposite desired effect. It’s not so much what chronic stress does to us in the presence, but what continuous activation of the stress response does to bodily systems as a whole that becomes problematic over time.


When we endure ‘stress’ from a purely mental and psychological aspect, our ‘fight or flight’ system, the sympathetic nervous system ramps up. From an evolutionary aspect, this was used infrequently and only in life or death situations. Think ‘out running a lion’, or some other monster our ancestors met in a dark alley.

We all have that response, and some of us multiple times a day. That sinking heart feeling and butterflies in the stomach, with the pulse racing and heart beating hard. Alertness and awareness is heightened, that’s cortisol pumping through your veins and can certainly be beneficial on the start line of a race! After all, our body is prepped and ready to race in these circumstances and is a natural response.

Physiologically, the body’s reaction when the sympathetic nervous system is activated is to prompt your adrenal glands to release a surge of hormones, including adrenaline and cortisol.

This hormone response causes:

  • Increased heart rate to supply the body with oxygenated blood
  • Increase more airflow to the lungs
  • Decreases motility and sphincter contraction in the stomach and intestines, slowing down digestion to divert energy to other sections of the body, eg. legs, arms (literally fight or flight)
  • Increases glucose production and inhibits insulin secretion

All great for the beginning of a race. However, nowadays the same response can be elicited through the subject line of an email, the daily commute, the price of living, highly stressful jobs and long hours trying to balance family life with the time to fit in training.

Think of it as a ‘death by a thousand cuts’, but instead, it’s your nervous system enduring the ‘cuts’, and eventually it’ll take its toll.

Living in the constant state of ‘fight or flight’ leaves the body unable to switch off, making us sympathetic nervous system driven. Once this occurs, it can have cascading negative effects of the body, and now those daily stresses in your training that were once improving your fitness are potentially having the opposite effect.


Being chronically stressed doesn’t automatically mean you will see the effects of everything below (there’s even more not addressed here too). At least not instantly. One issue arising will eventually cause problems in other areas if left to continue in this way.


Once the digestive system loses its ability to function as normal due to the chronic reduction of motility, the stomach becomes partially paralysed and unable to process food as before, causing diarrhoea and/or constipation (yes, both can occur at the same time).

The effect of the body’s ability to process food as normal leads to the inability to absorb nutrients and minerals. With the body’s lack of ability to absorb nutrients, malnutrition occurs, potentially leading to issues such as decreased thyroid function and low iron anaemia.

The microbiome, which is the gut’s colony of millions of different types of bacteria, viruses and fungi, also begins to endure negative effects. The biome is (ideally) balanced, allowing the good bacteria to stave off the bad bacteria, digest nutrients to repair and strengthen the lining of the intestinal wall, as well as help fight off free-radicals in the body.

Stress impacts the good bacteria, and in drastic cases eliminates them completely, allowing the bad bacteria to overgrow and have serious long term effects on our health. Our gut bacteria can even impact our mood, and even what we eat. Bad gut bacteria can cause negative thoughts and cause us to crave unhealthy food thats feeds them, causing a feedback loop that keeps us in an increasingly worsening spiral.


Overtime, stress will begin to weaken the gut lining of your stomach, which is integral to keeping gut bacteria from passing into your blood stream.

Thankfully, your immune system, which is 70% located in your gut takes care of most of the bacteria. The immune response to constantly fighting off bacteria that would normally be restricted to the gut is now causing a constant inflammatory response and causing the immune system to work over time.


The stress response also introduces ‘cytokines’ into the body. Cytokines are a protein intended to deescalate inflammation, as well as regulate the immune response to invading pathogens to stimulate, recruit, and increase immune cells. When the body is in a chronic state of stress, these proteins are constantly in circulation, causing the immune system to ultimately be working 24/7. Without rest, the immune system once again becomes weakened, but also looks at ways to try and root out and find the source of stress, seeking out methods that once worked before.

When you’re injured, you open pain pathways from your brain to the injured area. These learned pathways, especially on your more extreme, long-lasting injuries, are ingrained in the body’s neuromuscular response.

Whether it’s through the decreased lining in your gut causing the immune system to fight off bacteria more often, or due to the cytokines circulating the system trying to root out the cause of the stress, the constant state of inflammation and the immune response can open up old pain pathways in an attempt to rid your body of the stress. Unfortunately, the stress is coming from an outside source, but your body can only recognise stress in one form and cannot differentiate.

This is often the reason old niggles never seem to go away and often reemerge when we’re feeling ‘rundown’, especially when our lives are at our most busiest and stressful.


If several times a day your parasympathetic nervous response pumps glucose into the body and inhibits insulin production, but there isn’t an actual physical response needed, the body is unable to burn off and reduce blood glucose levels. The result of constantly high levels of stress stopping insulin from working efficiently means our glucose response is negatively effected.

Without an efficiently working glucose/insulin response, our bodies cannot regulate our glucose levels and can cause issues maintaining regular energy levels, leading to chronic cases of fatigue. It can also lead to type 2 diabetes too, even in seemingly healthy individuals.

As runners, we call upon our body’s ability to draw glucose from the blood to help pump energy into our muscles. Without the body’s ability to regulate the glucose response, we are left feeling tired, fatigued and with the handbrake constantly on.


Once your brain signals the body to produce the hormones to induce the sympathetic response, it’s then up to the vagus nerve to drive up the opposite response, using the parasympathetic system and returning your body to normal levels. The vagus nerve is the main nerve between the brain and gut, signalling the nervous system of the occurrence of a stressful situation. This is why you have ‘gut feelings’ and the feeling of anxiety from within your gut region.

When you live in a constant state of ‘fight or flight’, calling upon and stimulating the vagus nerve to work overtime to bring hormone levels back down can effectively wear down the body’s ability to use its parasympathetic response system, or possibly cause it to have extreme responses.

The vagus nerve directly affects heart rate as it’s needed to bring the heart rate back down when in a stress induced state. An out-of-whack parasympathetic response can cause heart rate levels to plummet, even causing fainting.

We use the parasympathetic response to return breathing and heart rate levels to return to normal once we stop exercising. Without a fully functioning parasympathetic nervous system, heart rate levels can be difficult to return to normal after exercising, or even plummet so much it can cause you to faint. The term of which is called ‘post-exercise syncope’.

The vagus nerve also controls acid levels in the stomach. Having less vagus nerve activation can increase the chances of irritable bowel syndrome (IBS),  but also enhances the release of ‘histamine’ in stomach cells, which releases stomach acid.

The chronic term for acid reflux is called ‘GERD’, and although it won’t stop you running, it can cause you to have a somewhat unpleasant time…


Somewhat topical with the current pandemic crisis, stress can cause your response to viruses to be that much worse.

If you have lived your life in an endlessly stressful way, your body will have regressed and degenerated with the impact of having done so. The chronic stress response is a gradual, cascading effect. One thing falls first, leading to the next, and onto the next.

If you think of yourself as a loaded gun, ready to fall apart at any second under these constant set of circumstances, then a nasty virus will be the trigger that exasperates and fast tracks you into a chronically unwell state.

It’s not always apparent, or at least, you may have been ignoring the red flags that were warning you about your bodies failing systems. Your body in its run down state, from your immune health to your microbiome, is now unable to effectively fight off the infection as it normally would. Even causing the symptoms to last for months.

We’re keen as runners to return to our schedules as soon as possible after being hit with a virus, but the added stress only adds to the body’s inability to rest and recover, further plummeting our health and causing the nosedive to continue.


It’d be easy to suggest to ‘remove all stress’ from your day. It’s simply impossible to avoid.

Stress is a part of life, but it is possible to reduce and avoid stressful scenarios. When it comes to running there are steps you can take. Is there a particular toxic coach making your running more stressful than necessary? Is your club dynamic not working for you?

Your running circle should include support, friendship and a place to relax and unwind on your easy days, but also push you in a constructive manner when the time’s right. The ability to separate the day’s stresses and your training is essential to keeping the sport fun and not adding to your stress, therefore causing further burdens to endure.

Outside of your running, it’s also wise to switch off and unwind. An ‘always on’ mind can only hinder stress levels and lead to more problems. Getting out into nature has been scientifically proven to help reduce stress levels, whether that’s going out for a run or a walk is your choice. It might sound silly to some, but meditation and yoga can also help. Meditation trains the mind to identify negative thought patterns, helps switch off from overthinking and eases the body into a parasympathetic state.

The food we eat will also help. Inflammatory foods exacerbates issues, whereas healthy, whole foods can help soothe and heal the body – ‘Food is medicine’ after all!

Mostly, it’s crucial you don’t fall into the trap of believing stress is something we have to put up with. It’s not healthy, and you’ll never win any awards for how much you can endure, and in the end, you’ll lose a whole lot more. If you’ve ever watched marathoner Eliud Kipchoge run, you’ll know he runs with a smile, and his results are evidence enough to prove the benefits of stress-free running.

About the author

Endurance State Coach, specialising in long distance and trail running disciplines. As an all round runner with a successful background in a variety of running disciplines, from 5k to Ultramarathons. Chris has competed internationally for Great Britain and England in various mountain running disciplines.

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