What do exercise and a diet high in fibre have in common? We’ve known for some time now that both of these are good for our gut health and decrease our risk of colon cancer. However, it seems as though there may something extra that fibre and exercise have in common, and it comes as a fatty acid called butyrate. This link between exercise, fibre and gut health will be explored, and you’ll see that the effects travel as far as the brain.
What actually is butyrate and what does it do?
Butyrate is a short chain fatty acid produced by our gut bacteria as they break down foods that are high in fibre. Resistant starches are a type of fibre, that are some of the best fuels for these butyrate producing bacteria (Bourassa 2016). These starches come in foods such as legumes, oats and starches that are cooked and cooled like potato and rice salads.
Now butyrate is an important fuel for the cells of our colon. In fact it supplies up to 70% of their energy (Bourassa 2016). Keeping your colon cells healthy is thought to be one of the reasons why higher butyrate levels decrease your risk of colon cancer by 50% (Matsumoto et al, 2008).
However, the benefits of butyrate go well beyond reducing our risk of colon cancer. This is because healthier gut membranes improve their integrity (how closely they bond together) allowing them to act as a better barrier, which has flow on effects to improving our immunity and reducing inflammation (Ji Wang et al, 2018).
What’s the evidence on exercise and gut health?
Most of the interest on the effect of exercise on butyrate levels started back in 2008. Matsumoto and colleagues showed that butyrate levels, and the bacteria that produce butyrate, were higher in rats that exercised versus a sedentary control.
In 2014 a group of Irish researchers found that professional rugby players had a greater diversity of gut microbiota than a group of sedentary controls (Clarke et al, 2014). However a signifiant limitation in this study was that professional athletes eat very differently than the general population. And these results could possibly be related to their diet and not their activity.
We had to wait until late last year when a group from the University of Illinois designed a study that looked at the impact of aerobic exercise on butyrate. Previously sedentary individuals were asked to exercise three times a week for a 6 week period (Allen et al 2017). What they found was that there is a link between butyrate, exercise, and gut health in humans.
Much like the rodent study back in 2008 they found that aerobic exercise increases the levels of butyrate along with the colonies of bacteria that produce butyrate. Interestingly this effect was most pronounced in lean subjects. The overweight group did still increase the colonies of the butyrate producing bacteria (not to the extent of the lean group) but they didn’t see an increase in butyrate levels in their stools.
Exercise and gut health can also improve your brain!
Now here is where it really gets interesting. The term “your gut is your second brain” has been well used over the last decade. This has been used to explain that the enteric nervous system of the gut is not only quite complex, but it also has the capacity to signal the brain via many neurotransmitters.
We know that butyrate can cross the blood brain barrier and it is well known to suppress HDAC (Histone deacetylase; Bourassa 2016). Now HDAC inhibitors will increase the expression of BDNF (Brain-derived neurotrophic factor) in the brain. This is important for memory and learning as BDNF is like fertiliser for the brain. It helps your brain cells grow in number and connections!
So where’s the research at?
An interesting experiment, albeit in mice, was published back in 2013 where mice were given an object recognition memory task that is usually not enough to form in either their short or long term memory (Intlekofer et al, 2013). They had a sedentary group and a group that was exercising 3 weeks before the task. They also had a sedentary and exercising group that was injected with butyrate.
The non-butyrate injected sedentary mice could not successfully remember the task 24 hours post initial exposure However, both the sedentary/butyrate injected group and the exercise group could. And when it came to remembering the task 7 days after the initial exposure, it was only the butyrate group that could.
It is important to know that the exercise group only did so for the 3 weeks leading up to the task, and not during the 7 days after the task. This highlights that to get the improved learning outcome, continual exercise exposure is needed.
This mechanism of increased BDNF release via butyrate is probably why we see that children who are fed a high fibre diet perform better in cognitive tasks than those on a low fibre diet (Bourassa 2016). And it could also be the reason why it shows promise in the treatment of neurodegenerative diseases (Bourassa 2016).
We also know that aerobic exercise has an effect on increasing BDNF levels, and this may be why individuals have a 20% improvement in learning tasks (Winter et al, 2007). So it makes sense to eat a high fibre diet and exercise at the same time right?
Take home points about exercise and gut health:
- It appears as though aerobic exercise continues to benefit our health in many different ways, and improving our gut health is another reason to be active. Aerobic exercise of around 30 to 60 minutes a few times a week can give you this benefit to your gut.
- Improve the diversity of your microbiota through eating foods that are high in butyrate producing fibre such as legumes, oats and potato salads.
- Combine this with regular exercise to improve the butyrate production of your gut as this have effects that travel to your brain.
- And while there is still much more research to be done, it seems to indicate that by doing this you are improving your capacity to learn and remember things, along with decreasing your risk of developing neurodegenerative conditions such as Alzheimer’s.
About the Author
Everybody feels stressed at some point. But how do we deal with it? 75% of Australians admit that stress adversely effects their physical health and 64% report an impact on their mental health (APA, 2014). For 86% of us, watching TV or movies is our chosen coping strategy for stress and only 55% of us are getting an adequate amount of physical activity (Australian Health Survey 2011-12). So exercise, mood and stress; what’s the link? Here’s the science to support why exercise should be our go-to for those stressful situations.
You know those days where you wake up in the morning, a bunch of crazy happens and then you go to sleep (way too late)… Maybe some of this feels familiar; you’re up to your eye balls in reports at work. The kids have basketball training tonight. You forgot to get dinner out. It’s your mum’s birthday next week. You said you would help the school with their fundraiser this Friday. You promised your friend you would catch up for lunch on the weekend. You still haven’t found time to exercise, like you planned. Feeling stressed? How’s your mood?
A Brief Bio About Stress
Stress comes in many shapes and sizes, acute and chronic; social stress, physical stress, metabolic stress… just to name a few.
There is a psychological state of stress, and a physiological response to stress – it’s important to distinguish these. One is the external stressors of life, such as a looming deadline at work. The other is our internal state of stress, like when we feel we are stressed out of our minds and cannot think straight!
I want to talk about how we can manipulate one by manipulating the other.
The body’s stress response is a built-in gift from evolution, without it we wouldn’t be here today. This complex alarm system (the panic button being the amygdala), is more commonly known as the fight of flight response.
I’m going to try and explain how this process actually works in our brain using cute pictures, it gets a bit nerdy, but stick with me.
The Neurophysiology of Stress (the simple version)
Basically, the short version is: our amygdala signals the adrenal gland to release a few different hormones, such as adrenaline, which causes increases in blood pressure, heart rate, and breathing. These hormones also act on the pituitary gland which triggers the release of cortisol into our immune system. The amygdala then signals the hippocampus to start recording memories (so we remember to avoid this in future), and the prefrontal cortex assesses whether this is an actual threat requiring action.
Humans are unique in the fact that danger doesn’t have to be clear and present to illicit a stress response, we can create it ourselves. The mind is so powerful we can actually set off our stress response just by imagining we’re in a stressful situation. You see how this can start to get unhealthy…
But just as we can get ourselves into a stressful state, we can get ourselves out.
The purpose of the fight-or-flight response is to mobilise us to act, so physical activity is the natural way to prevent the negative consequences of stress. When we exercise in response to stress, we’re doing what human beings have evolved to do over the past several million years.
Your Prescription for exercise, mood and stress
If I prescribe you 1 x exercise session per day, you should see a reduction in stress symptoms and an improvement in mood immediately…
Why is that?
Now that you’re all over the neurophysiological mechanisms that are behind the stress we feel, how exactly does exercise improve our mood and reduce our stress?
- Exercise triggers the production of more insulin receptors, thus lowering blood glucose levels
- Exercise produces FGF-2 and VEGF which build new capillaries and expand the vascular system in the brain
- Exercise increases BDNF production, which is responsible for neurogenesis: the creation of new neurons
- Exercise increases serotonin, norepinephrine and dopamine (feel good hormones!)
And on a physiological level, exercise can improve the stress we feel in our bodies by:
- Relaxing the resting tension of muscle spindles, breaking the stress-feedback loop to the brain
- Increasing the efficiency of the cardiovascular system, lowering blood pressure
Exercise does a whole range of juicy things to our body and our mind, and it’s virtually impossible to impact one without impacting the other – now you see why!
Just keep in mind that the more stress you have, the more your body needs to move to keep your brain running smoothly.
If you’re interested in reading more about this, pick up a copy of Psychiatrist, John Ratey’s book: SPARK; the revolutionary new science of exercise and the brain. This blog is based on the concepts discussed in Chapter 3; Stress. It’s full of stories and fascinating information about the connections between exercise and your brain, in an easily digestible format.
About the author
Blue Mind: A mildly meditative state characterized by calm, peace, unity, and a sense of general happiness and satisfaction with life in the moment.
We can all agree that modern life is tough. We experience chronic stress, struggle with constant monkey mind and are probably all too familiar with directed attention fatigue. We live a lifestyle where we are “always on”, and this can eventually result in burn out, memory problems, poor judgement, anxiety, and depression. Physically, chronic stress damages the cardiovascular, immune, digestive, nervous and musculoskeletal systems. It does this by lowering levels of serotonin and dopamine (our neurotransmitters responsible for making us happy) and leaves us feeling exhausted and down. And yet, the knowledge that our lifestyles have some room for improvement is just another source of stress! “Red Mind” is a term coined by neuroscientist Catherine Franssen, and is described as an “edgy high, characterized by stress, anxiety, fear and maybe even a little bit of anger and despair”. Whilst Red Mind can have its perks and be healthy at times, like everything, it should be experienced in moderation. This blog will show you how exercise in water can provide a much needed balance to “red mind” for your mental health!
Our brains are wired to constantly scan for danger, which makes sense historically. But now we’re faced with busy streets and email alerts, not lions.
Our brains like being around water because there is a high degree of predictability. This allows the amygdala (an emotions centre of the brain) to relax. However, small disturbances such as waves breaking or birds flying past give enough sense of surprise that we receive a pleasurable hit of dopamine. Because of this simultaneous sameness and change, we get a soothing familiarity and stimulating novelty when we look over the water. It’s the perfect recipe for triggering a state of involuntary attention in which the brain’s default network, essential to creativity and problem solving, is activated.
Studies have even shown that being at the beach, where there is an abundance of negatively charged ions in the atmosphere, lowers blood lactate levels and elevates mood.
Blue looks good on you
‘So how do I access my Blue Mind?’ I hear you ask. There is a very fitting quote from poet Sylvia Plath; “There must be quite a few things that a hot bath won’t cure, but I don’t know many of them”.
It seems way too simple, but by simply being around, in, on or under water – we trigger our Blue Mind.
There are now studies that show being immersed in water reduces stress, partly by balancing the flux between the sympathetic and parasympathetic nervous systems. Or that taking a spa bath can significantly lower your salivary cortisol levels. Feeling anxious? Taking a hot 5-minute shower can measurably lower anxiety levels.
So… I can just drink mimosas next to the pool?
Technically yes. But! There’s an extra level of Zen that water can offer you. And the answer has something to do with Exercise.
We’re well aware of the wonderful things exercise does to our brain on a neuro-chemical level, like release endorphins and endocannabinoids (the brain’s natural cannabis-like substances), which reduce the brain’s response to stress and anxiety.
The feel-good effects of swimming have actually been assimilated to the “relaxation response” triggered by yoga. When we swim, our muscles are constantly stretching and relaxing, and this movement is accompanied by deep, rhythmic breathing. All of which put us in a quasi-meditative state. On top of this we have to use a level of cognitive effort to learn and coordinate swimming strokes. This cognitive and aerobic combination can provide the brain with the satisfying stress-reducing feeling of “flow”.
Meet the power couple – Exercise in water for mental health
So when you feel yourself getting stressed, tense and a bit tightly wound why not utilise the powerful effects of exercise AND water?
So why not go for a run along the beach each week? Or go for a swim at your local pool? You could even learn to surf with the kids next weekend? Or how about simply going fishing? Perhaps paddle-boarding is more your style?
Now in part one of this blog we learnt that pain is a vital part of our survival but sometimes it can persist for longer than we need. So now I’d like to share with you some of the longer term changes that can occur as discovered by pain scientists (Hodges & Tucker, 2011). These adaptations give us a road-map on how to use exercise and movement to free ourselves from pain.
Pain leads to changes in the way we move
Think of a time when you may have hurt yourself and you were in pain. A very common occurrence is twisting your ankle. Sometimes this doesn’t create much tissue damage but it can have a very significant pain response. What you’ll notice is that you’ll limp, maybe just for a little while, as the pain changes the way we move so that we don’t load the affected area too much.
Our muscles around the area will “splint” to stiffen the area up and we’ll subconsciously take load off of the affected side. Now as I stated in part 1 of this blog, this is really useful during the first few months of tissue healing. But long term this can have other consequences. Some common examples are that if we were to injure a joint (let’s stay with the ankle). It can increase the load in joints further up the chain (such as the knee or hip). Alternately, let’s say that we injured our right ankle, if we don’t correct the way we are limping, we’ll place more weight through our left side making it work harder. This could then make the left leg more predisposed to injury.
Now many of these changes in how we move are subconscious. A lot of people don’t realise they are limping long after their initial injury. So sometimes we need to retrain our body to move freely and more evenly again. This is where specific corrective exercise can be useful.
Pain changes the way our muscles fire!
Not only does pain change the way we move, in doing so it also changes the way our muscles fire.
Some muscles will become facilitated
That is, they increase their tone to help protect and splint a particular area. Again while this might be useful for the first few months, these muscles tend to get tight and overworked in the long term.
They also become over-sensitised to pain to the point where even a gentle stretch, well below the threshold that would create tissue damage, creates a pain response. This is where it is important to get these muscles moving freely again, even if it is a little uncomfortable at first. In doing so we are retraining our protective response. Over time our brain no longer deems the use of these muscles as threatening and our pain will gradually decrease.
Some muscles will become inhibited
Now interestingly, while some muscles increase in tone others will “go to sleep”. These are quite often called inhibitions and the long term consequence of these muscles not firing properly can place undue stress on other tissues.
I don’t know whether anyone really knows why this occurs. Perhaps it is part of our short term protective response to prevent us from using a particular area and allow for healing. However we do know that in the brain the areas that fire a particular area become “smudged”. That is when we try to fire a particular muscle we might get a whole group of muscles firing (quite often the protective facilitated ones).
What we find is that we need to “wake up” these inhibited muscles which are quite often muscles that are important for the long term use of our past injured joints. And it is not until these muscles are firing properly again that our pain will subside.
Everyone’s protective pain response is individual
Finally, and most importantly, what we know is that our response to an injury and pain is unique and individual. How we move after an injury depends on what we were doing to cause the injury. How we splint and what muscles tighten up is very individual. And what muscles go to sleep and lose their capacity to fire can be different as well.
Interestingly, all of these people though may have the exact pain in the same location. So it is important that we don’t just focus on the area of pain. In fact, sometimes this can just feed our pain response as it make this area even more sensitive. We need to assess the way you move to see if you are still protecting an area long after it has fully healed. And we also need to identify what muscles are not firing appropriately and what muscles are still stiff and tight trying to protect.
Now this detective work is not always straightforward, particularly if like many of use you’ve accumulated multiple injuries over the years. But unraveling this tangled rope might be one of the best ways to do this and it is probably why good quality movement and exercise is shown to be one of the best ways to free yourself from pain.
Hodges, PW & Tucker, K (2011). Moving differently in pain: A new theory to explain the adaptation to pain. Pain 152 S90-S98
Quite often when we injure or hurt ourselves we tend to go back into our shells and stop our usual activities to prevent pain. This can often mean limiting our movement and exercise, as doing so creates more pain. This is normal and something that shouldn’t be feared.
Pain is a protective response to keep us alive!
Let’s think back to our hunter and gatherer days when our main goals were to eat, sleep and procreate. Back then our survival was dependant on how successful we were in finding our food. This, of course, required a lot of movement. In fact, modern day hunters and gatherers such as the !Kung and Ache tribes average 15-20 km per day. (Cordain et al, 1998). That’s over 20,000 steps a day!
Now obviously if we were to injure ourselves this would severely limit our capacity to hunt and gather. So our in built pain response was designed to allow for tissue healing and conserve energy while our capacity to get food reduces. This protective response in our paleolithic environment was vital to keep us alive. Now pain science can get a bit heavy so I’ve tried to reduce some of the key points for us to understand:
1. Pain tags the brain with the circumstances that lead to creating it.
A toddler only needs to touch a hot stove once to remember that it is not safe to do so again! Back in the hunter and gathering days this might have included the location of dangerous terrain or the time and place of an aggressive animal. Research has shown that the pain response will improve our memory of these specific details.
2. Pain prevents us from moving the affected area for a short period of time.
This is incredibly useful as depending on the tissue that has been injured. It can take around 2 to 12 weeks for the area to heal. Pain can prevent us from loading the particular tissue too much and too soon and allow for recovery.
3. The protective pain response triggers metabolic responses in the body to conserve energy.
Inflammation and cortisol (part of the stress response) both have been shown to increase insulin resistance. This both triggers the body to increase your blood sugar levels for energy and also store your body fat. This is a perfect response for when you didn’t know if or when you would get your next meal. Unfortunately today food is at an abundance and many of us put on weight after an injury. So nowadays we don’t find this too useful!
Pain has short term benefits but can have longer term consequences
As I stated above our protective pain response is really useful for those first few months after the initial injury. However, for many of us pain can go on for much longer than that or we may not have actually had a trauma to create an injury. Long term pain is quite often diagnosed as non-specific pain as doctors can not find any tissue damage or pathology. Sometimes this pain might be the remnants of a past injury that has fully healed. But for some reason our protective pain response remains.
Going into the scientific reasons as to why this occurs is not something we can quickly delve into. However, in part 2 of this blog I’d like to share with you some of the longer term adaptations that occur to us. These adaptations will give us a roadmap as to how to best free ourselves from pain for good.
Cordain, L., Gotshall, R.W., Boyd Eaton, S., & Boyd Eaton III, S. (1998). Physical activity, energy expenditure and fitness: An evolutionary perspective. International Journal of Sports Medicine, 19, 328-335.