Guide To The Central Nervous System And Exercise

The brain is the body’s most complex organ.[1] Part of that complexity arises from its unique architecture and function and part of it is the result of the complex bi-directional list of interactions that go on all the time between the brain and the body and the external world. 

While firmly locked inside the protective casing of the skull, the brain is actively involved in everything the body experiences and everything the body does, through the massive network of nerves running from it to every part of the body. This network of nerves is divided into the Central Nervous System (CNS for short) that consists of the brain itself and the spinal cord[2] and the peripheral nervous system which consists of everything else that carries a neural network. 

The brain controls how we think, feel, think and move and the spinal cord is the primary conduit through which billions of cells called neurons carry messages from the brain to the body via a complex interaction of chemical and electrical signals.[3] The chemical signals are the result of neurotransmitters and the electrical ones are the result of electrical impulses that occur when the presence of charged particles accumulates[4] in specific regions of the brain that have to do with executive control and decision-making. 

Super-simplified as this picture we’ve just painted may be, it is still breathtaking. It gives you some idea of the complexities involved where a seemingly small change in one element such as the environment or our internal state (let’s say we get indigestion) triggers a cascade of events that end up influencing everything we do and he way we feel. 

It stands to reason that if we understand how our Central Nervous System (CNS) functions we are better situated to influence it to our benefit. Because we are a living organism, we are viewed as an open system that is in a constant state of change. Our body and brain are constantly adapting to our environment as we aim to maintain a stable, sustainable state of being. This is called homeostasis.[5]   

The easier we can maintain that stable state of being, the more resources we have to devote to functions such as decision-making, cell repair and cell-building all of which affect our happiness and our health. One of the easiest means we have to intervene in all this complexity and control it to our benefit is through physical activity and exercise. 

In the next six sections we review just how exercise factors into the function of the Central Nervous System (CNS) and how the CNS, in turn, affects how much we can exercise and often determines the kind of physical activity we engage in. 

The Central Nervous System And Genetics

Nature is never fair, at least not in the way we expect it to be, and this case is no exception. Just like there are people who are naturally stronger or naturally faster because of the way their body has been put together there are also people who are naturally stronger, more agile and coordinated because of the way their Central Nervous System has been wired.[6] 

Most of the research has been carried out on rodents, however, it is a fair assumption (though still an assumption at this stage) to think that at an elite level of athletic performance there will be a percentage of athletes who possess genetic traits that allow their Central Nervous System to process pain differently and regulate emotions and thermogenesis (the metabolic process during which the body burns calories to produce heat) better. 

Just like with visible physical advantages such as height, weight or reach, just because there is a predisposition doesn’t mean that it is an automatic win. Our current understanding of the body and its interaction with the environment suggests that it is our physical activity that triggers epigenetic changes that switch genes on or off and contribute to unlocking abilities we have (i.e. predispositions) or developing new ones. 

What this means is that while at an elite level of performance predispositions provide a competitive advantage, at all other levels prior to the absolutely topmost, everyone has a more or less equal chance if they put in the work and have the necessary focus. 

Exercise And The Brain Soup 

The moment we start to do any kind of physical activity we change the body’s internal state. Adenosine Triphosphate (ATP) is used up in the muscles and depending on how long and how intensively we exercise the body goes through a process where it sequentially uses up blood sugar, a.k.a. glucose, breaks down glycogen stored in the muscles via a process known as glycolysis and then goes on to use up stored fat supplies in the body through a process called lipolysis. Lipolysis is also part of the Krebs Cycle through which the body uses up oxygen as part of aerobic respiration and produces water and carbon dioxide, amongst other byproducts.  

At the same time it raises the temperature of the muscles and starts the cooling down process. Our ability to sweat is part of the thermoregulatory bag of tools we use to maintain homeostasis when we engage in vigorous exercise. 

While all these things are going on a number of parallel and consecutive biochemical changes involving in excess of 9,000 molecules,[7] also take place at cellular level throughout the body and in the blood. These changes, in turn, affect how genes are switched on and off in our body turning down some predispositions to, let’s say, high blood pressure and cardiovascular disease and turning on more beneficial attributes such as lower base heart rate and a resilience to inflammation. 

What is truly remarkable about this is that the body experiences these changes even after one minute of exercise. Despite this relatively short time of physical activity the internal changes we experience are sufficient to mitigate all-mortality risks and even reduce the incidence of cancer.[8]  

In addition, the chemicals released in our blood when we engage in physical activity create corresponding releases of neurochemicals in the brain[9] that affect our moods, safeguard our cognitive capabilities[10]  and maintain our mental health. 

Finally, there is a mounting body of scientific evidence on how physical activity unlocks neural pathways that affect everything from the body’s immune response to our decision-making,[11] problem-solving and planning capabilities which means that exercise makes us functionally better and energetically more efficient. 

Exercise And Central Nervous System Functions 

The brain is an organ. Just like every other organ in the body it is made up of tissue and requires healthy cells and a good flow of oxygen-rich blood to function properly. Unlike any other organ in the body the brain has no pain receptors.[12]  This, alongside the fact that it doesn’t seem to do something that requires a visible action (like digesting food or beating loudly to move blood around the body) often makes it the forgotten organ when it comes to pathologies. 

Again, just like any other organ in the body, the brain suffers from pathologies that originate from poor lifestyle choices. “Neuroinflammation, blood-brain barrier (BBB) dysfunction, neuron and glia injury/death and myelin damage”[13] are just some of the most common ones and they can all be mitigated by exercise.[14]   

Exercise helps safeguard brain health by maintaining a stable, sustainable and sustaining environment (i.e. the internal physical state of the body) for the brain to exist in.[15]  As a result, exercise helps us improve cognitive attributes such as resilience,[16]  stress management,[17] emotional regulation,[18] executive function and attention.[19]  

These are all necessary components for living a long, productive, healthy and happy life in the modern world. 

Social Cognition And Exercise

Social cognition is a set of complex and adaptive abilities that guide information processing, choices, decision-making and behavior in a social setting. From an evolutionary perspective social cognition has been key to our survival because it allows us to identify threats, recognize opportunities and optimize operative behavior through cooperative agreements with others. In other words, we need social cognition in order to hold down a job, live in society and function in the community settings of our towns and cities. The brain, therefore, ascribes a sizeable amount of resources to it. 

The moment we do anything physical we basically make the body send a signal to the brain that it needs to allocate energy and resources so it can help build whatever physical attribute we are exercising for: strength, speed, agility or endurance. The brain, in turn, is engaged in a constant and complex dialogue with the body via its Central Nervous System and the microbiome. 

It is through its effect on neural and neurochemical pathways[20] that exercise becomes the tool we can use to intervene in the dialogue between our gut microbiome and our brain and use the intervention to improve our mental health.[21]    

Neurogenesis And Rewiring The Brain Through Exercise

We’ve known for some time now that complex moves such as combat-based workouts increase our IQ as well as our physical fitness. There is now additional scientific evidence that shows how martial arts-based workouts contribute to improved attention,[22]  better emotional control and improved decision-making. 

In addition, there is also evidence that shows that exercise and, in particular, exercise that involves moving the body in complex ways through three-dimensional space has neuroprotective benefits, helps improve both memory and learning and helps the brain generate fresh neurons through an exercise-activated process known as neurogenesis.[23]  

Strength-training, aerobic workouts and complex moves play a key role in slowing down the aging process of the brain and rejuvenating its structures.[24] This means that physical exercise is central in our efforts to slow down aging both inside and outside our body’s organs and increase our healthspan and general wellbeing. 

CNS Fatigue During Exercise

We’ve seen, so far the various ways through which the central nervous system (CNS) contributes to fitness and health and is affected, in turn, by the states experienced by the body. What is less obvious however despite the fact that it is key to maintaining our health and fitness, is the way the central nervous system (CNS) is itself influenced by exercise, experiences fatigue and changes the body’s performance parameters as a result. 

The role of the brain is to protect itself and the body. One of the ways it does this is by creating specific parameters that define the body’s physical capability so that the body does not exceed its limitations and does permanent injury to itself. If we, for instance, ran at our fullest capacity or jumped, kicked or punched in an unchecked manner we’d soon hyper-extend our joints, wear out cartilage, tear muscles and detach tendons rendering us physically useless.  

The flip side of that protection is where CNS fatigue is experienced. CNS fatigue, or central fatigue, is defined as task-failure because of weakened or interrupted messaging from the CNS to the muscles. Whereas peripheral fatigue is defined as task-failure when the muscles themselves are unable to adequately respond despite messaging from the brain via the CNS.

When the task requires lifting something heavy or running fast or running for a long time or playing a match where concentration is required for long periods, we realize just how important it is to avoid CNS fatigue in order to maintain optimum function. 

This is an area of research that is hard to undertake ethically (because we cannot place experimental subjects in a situation where they could be harmed) so it remains somewhat theoretical still. The current theory, known as The Central Governor Theory or The Integrative Governor Theory[25] suggests that the brain, in its effort to protect the body from harm artificially restricts what it can do by placing a relatively arbitrary limit. 

For sure, there are anecdotal instances of seemingly ordinary people exhibiting extraordinary physical capabilities under extreme conditions. The suggestion is that when our emotions, attention, thoughts and actions align we can exceed parts or the whole of this self-imposed limitation and, in our case, workout longer, increase the intensity of our workout and, generally, get fitter more easily. 

Because of the difficulties of experimenting with this there is some pushback against this theory.[26] On the whole, however, the theory retains a lot of value. It is shored up by studies that correlate perceived effort when exercising (a subjective, self-reported experience) and objective muscle fatigue (as evidenced by objective, measurable task-failure).[27] Other studies[28] that look into how mental fatigue and anticipated effort (a mental component) affect perceived effort thresholds (a physiological component) also seem to support the Integrative Governor Model.  

On a more practical basis, it appears that the central nervous system can and does experience fatigue during exercise which affects its signalling and leads to muscle task-failure. It also needs a recovery period from one physical training session to the next which is why back-to-back high-intensity workouts are not advised. 

Summary

As comprehensive as this piece may be we’ve only just scratched the surface of the effects of the CNS in the body and the way the body affects the CNS and the brain. What is an established fact I that the brain lives in the body and it is affected by aging and poor systemic health like every other organ in the body if we don’t eat well, exercise enough and get adequate sleep to recover. Unlike any other organ in the body, the brain is involved in everything we do, think and imagine and it has the capacity to unlock our physical potential and improve our emotional control by harnessing the power of our imagination.

As we age it is a sustainable, lifelong exercise regime that helps our brain remain young and sharp and healthy. 

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