Tag Archives: Fatigue

Chronic Fatigue Syndrome – Is This Contemporary Neurasthenia An Organic Neurological Or Psychiatric Disorder Associated With Childhood Trauma Related Chronic Anxiety And Resultant Ego Depletion

I was watching the Two Oceans running marathon in Cape Town yesterday on the square box, and marvelled not only at the aesthetic beauty of Cape Town, but also at how many folk of all ages ran the iconic race, and at their visible efforts to resist the sensations of fatigue they were clearly all feeling as the race reached its endpoint and as they laboured valiantly to reach the finish line in the fastest time possible for each of their abilities. Some recently published top-notch research articles on the mechanisms of fatigue by Roger Enoka, Romain Mueusen and Markus Amman, amongst others (surely with Simon Gandevia the scientists who have shaped our contemporary view of fatigue more than anyone else) have been doing the ’rounds’ amongst us science folk on research discussion groups the last while, and has ‘reignited’ an interest in the field in me. A large period of my research life was involved in trying to understand the mechanism behind the symptoms of fatigue, mainly in athletes, but also in those suffering from the clinical disorder known as chronic fatigue syndrome. As I come up quickly to the big age of 50 later this year, I notice that the daily physical and mental activity which I used to do with ease in my youth fatigue me more easily now. Because of this I have to ‘pace’ myself more carefully in all aspects of life to ‘preserve’ energy to ‘fight the good fight’ another day, in order to not run the risk of collapsing completely in the manner I witnessed in those folk with chronic fatigue syndrome I tried to assist both as a clinician and scientist during my earlier career, who pushed too hard and subsequently became moribund because of it. All of these recent observations have got me thinking of chronic fatigue syndrome (CFS), also known as myalgic encephalomyelitis (ME), what causes it, and why it manifests in some folk and not others.

Fatigue is a complex emotion which is felt by all folk on a daily basis, but paradoxically is very difficult to define. It has mental and physical symptoms and signs, and is often increased by and related to exertion of any kind. Fatigue can be either acute, where there is a direct correlation of the symptoms of fatigue to a specific task or activity and the symptoms attenuate when the activity ends, or can be chronic, when the symptoms of fatigue remain for a prolonged period and are not attenuated by a period of rest, and the reasons for these chronic symptoms remaining are very difficult to understand. In the sporting world, chronic fatigue is caused by pushing oneself too long and too hard in training and racing, and is known as over-training syndrome, and has a symptom complex which includes apart from the symptom of extreme fatigue also those of ‘heavy legs’, increased waking pulse rate, sleep disorders, weight loss (or weight gain), lack of motivation, depression and decreased libido, which do not improve unless there is a prolonged period of rest with no physical training. Working at the University of Cape Town with great scientists Mike Lambert, Liesl Grobler, Malcolm Collins, Karen Sharwood, Wayne Derman, and others, for my medical doctorate in the late 1990’s we examined athletes who were moribund from over-training, and found that a number of them had pushed themselves so hard and so long that they had developed skeletal muscle pathology (damaged mitochondria in particular) to go with all these chronic fatigue symptoms, and we called this symptom complex the fatigued athlete myopathic syndrome, and later acquired training intolerance. The words the athletes we examined used to describe their symptoms were classic and perhaps ‘explained’ the issues better than scientific or medical terms – with one sufferer declaring that they had ‘no spring in the legs’, another that ‘one kilometre now feels what equalled 100 km previously’, and another that ‘at its peak, the fatigue left me halfway between sleeping and waking most of the time’. Although there was perhaps a degree of hubris in these self-reported symptoms of fatigue, all these folk felt that the symptoms profoundly affected their exercise performance and lifestyle. Significantly, the majority of folk had evidence of suffering from depression, and also did not want to stop training and racing, and indeed found it almost impossible to stop training and racing despite these profound symptoms of chronic fatigue.

I carried on my interest in this field when moving to Northumbria University in the UK in 2006, and assisted Paula Robson Ansley and her PhD student Chris Toms, who did some great work examining causation, clinical testing of and exercise prescription for folk with classical chronic fatigue syndrome, as opposed to those with acquired training intolerance (though there is surely a relationship between these syndromes). Folk with CFS have symptoms of chronic and extreme fatigue which is persistent or relapsing, present for six months or longer, not resulting from ongoing exertion, not attenuated substantially by rest and causing impairment of activities which were previously easy to perform. They also have four or more ‘other’ diagnostic criteria, including impaired memory or concentration, sore throat, tender cervical / axillary lymph nodes, muscle pain, multi-joint pain, headaches, unrefreshing sleep or post-exercise malaise. It is importantly a diagnosis of exclusion of other medical causes of fatigue such as cancer, TB, endocrine or hormonal imbalances, or psychiatric or neurological disorders, and a clinician must always be careful to exclude these specific organic medical causes before diagnosing someone with CFS. The cause of CFS is unknown and hotly debated – it is usually precipitated by a viral infection such as Ebstein Barr Virus infection (glandular fever), and viral or infective causes, immune function issues, toxic pathogens or chemicals have all been suggested to be the cause of CFS, but not all folk who have CFS have any or all of these potential triggers or causal agents as part of their presenting history. It is notoriously difficult to treat, and some folk are left moribund and with significantly impaired lives for decades, although in some folk the syndrome seems to ‘burn out’ and they improve with time or learn to live with their symptoms by managing them carefully. Unfortunately there is a high level of suicide in folk suffering from CFS, though it is not clear if this is related to the underlying causation of the disorder or due to its long-term effect on lifestyle and physical capacity.

What is interesting (and of concern) for those folk studying CFS and trying to understand its aetiology and how to treat it, is the controversy and level of emotion attached to its diagnosis and treatment. Chronic fatigue syndrome used to be more well known as myalgic encephalomyelitis (ME), first diagnosed in the 1950’s after a group of doctors and nurses in a specific hospital developed post-viral syndrome with symptoms including chronic fatigue and with some neurological muscle and central nervous system related symptoms (hence the name ME) and it was first thought to be a neurological disorder. But with time, and as it was found that more folk who were diagnosed with ME did not have classic ‘organic’ neurological signs, it became thought of more as a psychiatric disorder and became more often described as CFS, due to the predominant symptomatology of fatigue as being the major ‘descriptor’ of the disorder. What is astonishing is that, as well described in a fascinating article by Wotjek Wojcic and colleagues at Kings College, London, in a survey of neurologist specialist members of the British Neurologist Association, 84% of respondents did not view CFS as a neurological disorder but rather as a psychiatric disorder. But, paradoxically, a number of patients with CFS would prefer it to be described as a neurological rather than a psychiatric disorder (and would prefer it to be still called ME), because of the social stigma of the label of having a psychiatric disorder. Somewhat astonishingly, as described by Michal Sharpe of the University of Edinburgh, there was even a negative response to a study of his which found that cognitive behavioural therapy and graded exercise therapy (the PACE trial) helped improved the symptoms of sufferers of CFS/ME, with several major patient organizations apparently dismissing the trial findings and being critical of them, because the findings could suggest that the syndrome was psychiatric in origin if cognitive behavioural therapy worked, rather than what would be the case if it was an organic neurological disorder, in which case such therapy should not work. As Sharpe concluded, in his own words it is a ‘funny old world’ when a study shows that a therapy works, but patients are angry because they didn’t want it to work, because of the stigma it would potentially create by it working.

Wojcic and colleagues also made the point that the majority of symptoms of CFS are almost identical to that of neurasthenia, a psychiatric disorder which was prominent in the 1800’s and early 1900’s, but has become almost unheard of as a diagnosis in contemporary times. Neurasthenia was described as a ‘weakness of nerves’ by George Beard in 1869, and as having symptoms of fatigue, anxiety, headache, heart palpitations, high blood pressure, neuralgia (pain along the course of a specific nerve) and depressed mood associated with it. The ICD-10 definition of neurasthenia is that of having fatigue or body weakness and exhaustion after minimal effort, which is persistent and distressing, along with depressive symptoms and two of the symptoms of either muscle aches and pains, dizziness, tension headaches, sleep disturbances, inability to relax, irritability and dyspepsia (indigestion). William James referred to neurasthenia as ‘Americanitis’ (he suffered from neurasthenia himself) as so many Americans in the 1800’s were diagnosed with it, particularly women, and it was a ‘popular’ diagnosis whose treatment was either a rest cure or electrotherapy. In world war one neurasthenia was a common diagnosis for and of ‘shell shock’, and folk with shell shock related neurasthenia were treated with prolonged rest. In the 20th century neurasthenia was increasingly thought of as a behavioural rather than a physical condition, and eventually it ‘fell out of favour’ and was ‘abandoned’ as a medical diagnosis. As Wojcic and colleagues suggest, not just the symptoms, but the ‘trajectory’ of the classification of the disorder have and follow a strikingly similar pattern to that of CFS/ME, which also started off as being diagnosed as an organic / neurological disorder and is now thought of a psychiatric disorder, which is (sadly) increasingly stigmatized by lay folk and indeed even some clinicians.

Neurasthenia was thought by Beard to being caused by ‘exhaustion’ of the central nervous system’s energy reserves, which he attributed to the (even in those days) stresses of urbanization, increasingly competitive business environment and social requirements – it was thought that neurasthenia was mostly associated with ‘upper class’ folk and with professionals working in stressful environments. Sigmund Freud thought there was a strong relationship to anxiety and to the basic ‘drives’, and as he almost always did, related neurasthenia to ‘insufficient libidinal discharge (ie not enough sex) that had a poisonous effect on the organism’. Both Freud and Carl Jung believed that drives were the result of the ‘ego’ state, and that disorders such as neurasthenia were a result of imbalances in this ego state. In their model, the ‘id’ was the basic component of the subconscious psyche which encompassed all our primitive needs and desires. The ‘ego’ was the portion of the psyche which maintains the sense of self, and recognizes and tests reality. A well-functioning ego perceives reality and differentiates the outer world from inner images and desires generated by the id, and ‘controls’ these. The ego develops in the first part of life, and is associated with a history of object cathexes. Cathexes are attachments of mental or emotional energy upon an idea or object. Object cathexes are generated by the id, which ‘feels’ erotic and other ‘trends’ as needs. The ego, which to begin with is feeble, becomes aware of these object cathexes, and either acquiesces or understands these needs and manages them (and thus becomes ‘strong’) or is disturbed by them and ‘fends’ them off by the process of repression (and becomes weak and ‘conflicted’). If weak, the ego deals with its inadequacy by either repressing unwanted thoughts (thrusting back by the ego from the conscious to the unconscious any ideas of a disagreeable nature) or developing a complex (a group of associated, partially or wholly represented ideas that can evoke emotional forces which influences an individual’s behaviour, usually ‘outside’ of their awareness). As a result of these complex developments, folk either use projection, which is a mental mechanism by which a repressed complex is disguised by being thought to be belonging to the external world or to someone else, or transference, which is the ‘shifting’ of an affect from one person to another or from one idea to another, either affection or hostility, based on unconscious identification, in order to deal with them at a subconscious level. Albert Adler described the inferiority complex as such – that a combination of emotionally charged feelings of inferiority operates in the unconscious to produce either timidity, or as a compensation, exaggerated aggression or paradoxical perception of superiority, and ones drives were a result of, or compensation for, feelings of inferiority derived from previous unpleasant experiences. For example, competing in extreme sport would be a compensation for being bullied in the past, or being abused as a child, or being ignored by a parent when young. Signs of such complexes included for Freud and Jung disturbing dreams and ‘slips of the tongue’, nervous tics and involuntary tremors, fanatical attachment to projects and goals, envy and dislike of individuals who are successful, falling apart when failing to successfully complete a challenge, desire for public acknowledgement and seeking of title and awards, compulsive exercising, and the development of neuroses and psychoses, all of which can be used to diagnosed the presence of ‘unsolved’ complexes, projections and transferences. Importantly for the development of neurasthenia (and chronic fatigue), Jung and Freud thought that there was an ‘energy cost’ to maintaining repressions and their associated complexes – Freud defined drives as the ‘psychical representative of the stimuli originating within the organism and reaching the mind, as a measure of the demand made for work in consequence of its connection to the body’ – and this energy cost eventually leads to the ‘breaking down of the will’ by the constant ‘fighting’ to maintain what was ‘hidden’ that was painful and not wanting to ‘come out’, and this breakdown of the will / ‘mental exhaustion’ lead to the signs and symptoms described above, which could in a circular way be used to diagnosed the presence of the underlying disorders. In a positive final observation, both Jung and Adler thought that the psyche was self-regulating, and that the development of these symptoms was purposive, and an attempt to ‘self-cure’ by compensation, and by bringing the destructive repressions, which exist at a subconscious level so are not directly perceived by the folk who have them, to their attention, or at least to that of their clinician or therapist, it would eventually lead to cure or at least ‘individuation’ and acknowledgement of the underlying issues, which to therapist of that era was the start of the cure.

Therefore, in this ‘id and ego’ model developed by Freud, Jung and their colleagues all those years ago, symptoms of chronic fatigue and burnout may be the psyche’s way of creating knowledge of and thereby attempting to cure latent psychic drives which lead to obsessive work or sporting goals and activity, created by past psychological trauma and a resultant ‘weak ego’, which results in chronic fatigue when the psyche cannot ‘cope’ with ‘fighting’ these often unperceived issues for a long period of time / for the life period up to the point when they collapse. Interestingly, while these theories have been mostly long forgotten or have fallen into disfavour, there has recently been an increase again in interest in the concept that mental and physical ‘energy’ is a finite commodity, with psychologist Roy Baumeister’s theory of ‘ego depletion’ gaining much traction recently, which suggests that a number of disorders of ‘self-regulation’, such as alcohol addiction, eating disorders and obesity, lack of exercise or excessive exercise, gambling problems and inability to save money and personal debt, may be related to one using up one’s ‘store of energy’ resisting the ‘deep’ urges which lead to these life imbalances, and eventually willpower decreases to a level where one cannot resist ‘doing’ them, or cannot raise the effort to continue resisting the desire to act out one’s wishes. In Baumeisters own words a tempting impulse may have some degree of strength, and so, to overcome it, the self must have a greater amount of strength, which can eventually be worn out or overcome, leading to adverse lifestyle choices in this ‘impaired mental energy state’. All lifestyle diseases and disorders may in his model therefore be related to an insufficiency of self-regulatory capacity, and there is an energy cost to resisting the ‘urges’ that lead to poor lifestyle choices, that may with time lead to either acute mental or physical fatigue, or in extreme cases to the development of chronic fatigue. Like with most contemporary psychology, the underlying reasons for such potential eventual failure of self-regulation were not deeply examined by Baumeister to the level that it was by Freud, Jung and colleagues, perhaps because so much of Freud, Jung and Adler’s theories are difficult to prove or disprove and therefore psychology and psychiatry have in the last few decades ‘turned against’ their theories and embraced neuroscience as having the best chance of understanding how the mechanisms underpinning self-regulation or the lack of it ‘work’, but neuroscience is currently far too ‘weak’ a discipline methodologically wise to be able to do such. Having said this, it is surely important that folk like Roy Baumeister are re-breaking such ground, and our understanding of such complex disorders such as CFS, and others such as fibromyalgia, which are also complex diagnostic dilemmas, is enhanced by the insight that mental energy ‘ego’ depletion may play a part in them. Sadly, there is evidence (described by Tracie Afifie and colleagues at Manitoba and MacMaster Universities) that folks who suffered physical or sexual abuse in childhood, or were exposed to between-parent physical violence at a young age, have an increased association with a number of chronic physical conditions (including arthritis, back problems, high blood pressure, migraine headaches, cancer, stroke, bowel disease, and significantly also CFS), and also a reduced self-perceived general health in adulthood, all of which would support the ‘ego and id’ psychopathology development theories of Freud and Jung to a degree, though of course surely not all folk who develop CFS have such childhood trauma issues.

Like the definition of neurasthenia and CFS, perhaps our understanding of their ‘deep causes’ is also moving in a ‘full circle’, and our knowledge of the underlying causes of CFS, if it does not have a specific organic or viral / toxic cause, needs to reconsider these basic concepts proposed by Jung, Freud and Adler more than one hundred years ago, and currently appears to be potentially re-occurring in a ‘repackaged’ version as suggested by Baumeister and his contemporaries theories in recent times. Perhaps the drive to keep on exercising that we found in all those athletes we examined in our studies at the University of Cape Town all those years ago was the key factor in the cause of their chronic fatigue, and was an ‘external’ manifestation of issues that they were not even aware of. We did not know enough about the subject back then to even ask them about it when we were trying to understand the causation of their symptoms. Perhaps a major component of CFS is mental exhaustion associated with continuously ‘fighting’ underlying past psychological trauma that the folk suffering from it are not even aware of, or at least this is part of the cause of the symptom complex along with other more organic or infective causes. Of course describing a disorder as either neurological or psychiatric is reductive, and indeed dualistic, and surely similar physical brain neural mechanisms underpin both ‘neurologic’ and ‘psychological’ disorders which we just cannot currently comprehend with the research techniques currently available. One has try to understand the reasons why one is ‘driven’ to do anything, particularly as one gets older and one’s physical (and perhaps mental) resources diminish and need to be ‘husbanded’ more carefully, though paradoxically CFS is a disorder which afflicts folk most often initially in their early twenties, and often ‘burns out’ / attenuates with increasing age, perhaps because part of growing older is often about understanding one’s issues to a greater degree, dealing with them, and living more ‘within one’s means’ all of materially, socially, physically, mentally and spiritually (although for some folk such learning never occurs). Aging may therefore be curative or protective from a CFS perspective (or one may die of ‘corollary damage’ such as heart attacks rather than developing CFS as a result of chronic stress related to unfulfilled drives).

Fatigue as a symptom is surely the body and mind ‘telling us’ that something is not ‘right’ and we need to rest – either acutely when we are doing sport, or chronically when we are ‘fighting’ something we do not understand or are aware of. The challenge is for us not just to rest, but to try and understand why we so often resist resting (well, those of us with complexes rather than those of us who are completely self-actuated and do not have stress or drives), and why life balance is so hard for many folk to find. The need (or unwanted requirement) for a prolonged rest / period of avoidance of one’s routine life / a ‘long sleep’ is often perhaps the last resort of those who are chronically fatigued and is nature’s way of ‘telling’ folk that they have ‘run out’ of responsive resources, and healing will not happen without it, though the healing may paradoxically be not of the fatigue itself, but of its underlying ‘deep’ causes. Now I am finished this its time to rest, and ponder what caused the need to write it in the first place, and why I have spent my holiday Easter period preparing for its writing, and ‘stoking the creative demon’ which never rests and which surely eventually damages one even as it creates, rather than just sitting in a coffee shop watching the world go by and thinking of nothing but how nice the next sip of coffee is sure to be. Demons of the past, away with you, before you lead to permanent mental and even physical damage, and tire folk out in the process!

Advertisements

The Sensation Of Fatigue – A Complex Emotion Which Is Vital For Human Survival

After a couple of weeks back at work after a great Christmas season break, I have noticed this week a greater than normal level of fatigue than I normally ‘feel’ at the end of a routine working week. After one of the hottest December months on record in my current home town, where temperatures for a while were consistently hovering around forty degrees Celsius, we have had a wonderful rainy, cool period, and I have noticed that I feel less fatigued in the cooler environment, and routine daily activities seem ‘easier’ to perform than when it was excessively hot. As part of a New Year’s resolution ‘action plan’ to improve my level of fitness, I have increased my level of endurance exercise, and as always have enjoyed the sensation of fatigue I feel towards the end of each long (though I know that ‘long’ is relative when compared to younger, more fitter folk) bike ride I do as part of this ‘fitness’ goal. All of these got me thinking of the sensation of fatigue, an emotional construct which I spent a great many years of my research career trying to understand, and which still is very difficult to define, let alone work out its origins and mechanisms of elicitation in our physical body structures and mental brain functions.

As described in these three very different examples from my own life, fatigue is experienced by all folk on a regular basis in a variety of different conditions and activities. Perhaps because of this, there are many different definitions of fatigue. In clinical medicine practice, fatigue is defined as a debilitating consequence of a number of different systemic diseases (or paradoxically the treatment by a variety of different drugs) or nutritional deficits. In exercise physiology, fatigue is defined as an acute impairment of exercise performance, which leads to an eventual inability to produce maximal force output as a consequence of metabolite accumulate or substrate depletion. In neurophysiology, fatigue is defined as a reduction of motor command from the brain to the active muscles resulting in a decrease in force or tension as part of a planned homeostatic process to prevent the body from damage which could result from too high a level of activity or too prolonged activity. In psychology, fatigue is defined as an emotional construct – a conscious ‘sensation’ generated by the cognitive appraisal of changing body or brain physiological activity which is influenced by the social environment in which the activity changes occur, and the mood status, temperament and background of the person ‘feeling’ these physiological changes. It will be evident from all of these different definitions how complex fatigue is an ‘entity’ / functional process, and how hard it is for even experts in the field to describe to someone asking about it what fatigue is, let alone understand it from a research perspective.

A number of different physical factors have been related to the development of the sensation of fatigue we all ‘feel’ during our daily life. During physical activity, it has been proposed that changes in the body related to the increased requirements of the physical exertion being performed cause the sensation of fatigue to ‘arise’. These include increased heart rate, increased respiratory rate, increased acid ‘build up’ in the muscles, reduced blood glucose or muscle or liver glycogen, or temperature changes in the body, particularly increased heat build-up – though for each study that shows one of these factors is ‘causal’ of the sensation of fatigue, one can find a study that shows that each of these specific factors is not related to the development of the sensation of fatigue. It has also been proposed that changes in the concentration of substrates in the brain structures associated with physical or mental activity are related to the sensation of fatigue – such as changes in neurotransmitter levels (for example serotonin, acetylcholine, glutamate), or changes in the nutrients supplied to the brain such as glucose, lactate or branched chain amino acids. But, again, for each study whose findings support these hypotheses, there are studies that refute such suggestions. It has also been suggested that a composite ‘aggregation’ of changes in all these body and brain factors may result in the development of the sensation of fatigue, via some brain process or function that ‘valences’ each in a fatigue ‘algorithm’, or via intermediate sensations such as the sensation of breathlessness associated with increased ventilation, the sensation of a ‘pounding’ heart from cardiac output increases, the sensation of being hot and sticky and sweating which result from temperature increases in the body, and / or the sensation of pain in muscles working hard, all of which are themselves ‘aggregated’ by brain structures or mental functions to create the complex sensation we know and describe as fatigue.

Which physical brain structures are involved in the creation of the sensation of fatigue is still not known, and given the complexity of the factors involved in its generation, as described above, large areas of the brain and a number of different brain systems are likely to be involved – the motor cortex as muscle activity is often involved, the sensory cortex as signals from changes in activity in numerous body ‘parts’ and functions are ‘picked up’ and assimilated by the brain, the frontal cortex as cognitive decision making on the validity of these changes and the need for potential changes in activity as a result of this ‘awareness’ of a changed state is required, the hippocampus / amygdala region as the current changes in physiological or mental activity must be ‘valenced’ against prior memories of similar changes in the past in order to make valid ‘sense’ of them as they currently occur, and the brainstem as this is the area where ventilation, heart function and a variety of other ‘basic’ life maintaining functions are primarily controlled, for example, amongst many other potential brain areas. We don’t know how the function of different brain areas is ‘integrated’ to give us the conscious ‘whole’ sensation we ‘feel’, and until we do so, it is difficult to understand how the physical brain structures ‘create’ the sensation of fatigue, let alone the ‘feeling’ of it.

How the mental ‘feeling’ of fatigue is related to these physical body and brain change ‘states’ is also challenging for us research folk to understand. Clearly some ‘change’ in structures, baseline physical values or mental states by whatever induces the fatigue process, be it physical or mental exertion or illness, is required for us to ‘sense’ these and for our brain and mental functions to ‘ascribe’ the sensation of fatigue to these changed states. It has previously been shown that the sensation of fatigue which arises during exercise is related to the distance to be covered, and increases as one gets closer to the finish line. While this sounds obvious, as one would expect the body to become more ‘changed’ as one exercises for a longer period, it has been shown that when folk run at the same pace for either five or ten kilometres, despite their pace being identical in both, at the 4km mark in the 5 km race the rating these folk give for the sensation of fatigue is higher than it is at 4km of the 10 km race, which is ‘impossible’ to explain physiologically, and suggests that folk ‘set’ their perceptual apparatus differently for the 5 and 10 km race, based on how far they have to go (what H-V Ulmer described as teleoanticipation), by changing the ‘gain’ of the relationship between the signals they get from their body depending on how far they plan to go. Two great South African scientists, Professor Ross Tucker of the University of Free State, and Dr Jeroen Swart of the University of Cape Town, have expanded on this by suggesting that there is a perceptual ‘template’ for the sensation of fatigue in the brain, and the sensation of fatigue is ‘created’ in an organized, pre-emptive ‘way’ by mental / cognitive processes in the brain, and the sensation of fatigue is ‘controlled’ by this template depending on the distance and / or duration of a sporting event. If something unexpected happens during an event, like a sudden drop in temperature, or a competitor that goes faster than expected, this will create an unexpected ‘change’ in signals from the body and requirements of the race, and the sensation of fatigue will become more pronounced and greater than what is expected at that point in the race, and one will slow down, or change plans accordingly. Ross and Jeroen’s fascinating work show how complex the mental component of the sensation of fatigue and its ‘creation’ by brain structures is.

There are multiple other factors which are involved in the generation of the sensation of fatigue, or of its modulation. I did my medical PhD (an MD) on chronic fatigue syndrome which developed in athletes who pushed themselves too hard until they eventually physically ‘broke down’ and developed the classical fatigue symptoms associated with chronic fatigue, where they felt fatigue even when not exercising, which was not relieved by prolonged periods of rest. These athletes clearly pushed themselves ‘through’ their fatigue symptoms on a regular basis until they damaged themselves. As one of the pioneer and world-leading experts in the fatigue field, Professor Sam Marcora, has pointed out, one’s ambitions and drives and ‘desire for success’ are a strong indicator both of the level of the symptom of fatigue folk will ‘feel’, and how they resist these symptoms. In these chronically fatigued folk we studied, something in their psychological makeup induced them either to constantly continue exercising despite the symptoms of fatigue, or made them ‘feel’ less sensations of fatigue for the same work-rate (assuming their fitness levels and physical capacity was similar) to most folk who do not experience this syndrome (the vast majority of folk). To make the matter even more complex, these folk with chronic fatigue described severe sensations of fatigue at rest, but when we put them on a treadmill, some of them paradoxically felt less, rather than more, sensations of fatigue when running as compared to resting, and their extreme sensations of fatigue returned (to an even greater degree) in the rest period after they completed the running bout. Furthermore, if one gives stimulants to folk when they exercise, such as caffeine, it appears to reduce the ‘awareness’ of the sensations of fatigue. Sam is doing some interesting work currently looking at the effect of caffeine on attenuating the sensation of fatigue – as did Dr Angus Hunter several years ago – and thereby using it as a ‘tool’ to get folk to exercise more ‘easily’ as they appear to ‘feel’ fatigue less after ingesting caffeine. All this shows again that the sensation of fatigue is both a very complex emotion, and a very ‘labile’ one at that, and can change, and be changed, by both external factors such as these stimulants, and internal factors such as one’s drive or ‘desire’ to resist the sensation of fatigue as they arise, or even ‘block them out’ before they are consciously generated. More research, and very advanced research techniques, will be required for us to clearly understand how and such potential ‘blockages’ of the sensation of fatigue happen, if they indeed occur.

The sensation of fatigue is therefore an immensely complex ‘derivative’ of a number of functions, behaviours, and psychological ‘filters’, and what we finally ‘feel’ as fatigue is ‘more’ than a simple one-to-one description of some underlying change in our physical body and brain that requires adjustment or attenuation. The sensation of fatigue is clearly a protective phenomenon designed to slow us down when we are exercising too hard or too long in a manner that may damage our body, or when we are working too hard or too long and need a ‘time out’, or when the environment one is performing activities of daily living in may be harming one. But there are usually more complex relationships and reasons for the occurrence of the sensation of fatigue than what on the surface may appear to be the case. For example, the increase in work related fatigue I feel is surely related not just to the fact that it is the end of a busy week – it is perhaps likely to be related to a ‘deep’ yearning to be back on holiday, or to the fact that my mind is not ‘hardened’ yet to my routine daily work requirements, or has been ‘softened’ by the holiday period so that now I feel fatigue ‘more’ than is usual. In a few weeks time this will surely be attenuated as the year progresses and my weekly routines, which have been ‘honed’ over many years of work, are re-established, and I will feel the ‘usual’ rather than excessive symptoms of fatigue as always on Thursdays and Fridays. The extreme feeling of fatigue I felt during the very hot December month may also be related to some subconscious ‘perception’ that my current living environment is perhaps not optimal for me lifestyle wise for a long term living basis, and this ‘valenced’ how I perceived the environment as one of extreme heat and therefore extreme (and greater than expected) fatigue last month. And that I am ‘enjoying’ the sensations of fatigue I feel when exercising may mean that I am perhaps not pushing my exercise bouts as hard as I could, and need to go harder, or that my mind and body is setting a pace that feels enjoyable both so I continue doing it, or to protect me from a potential heart attack if I go harder. All of these may be the case, or equally, all of these could be mere speculation – the science folk in the area of fatigue have a big mountain to climb, and many more hours in the lab, before we more fully understand the complex emotion which the sensation of fatigue is, and how and from where it arises and is controlled.

A time may come when Sam Marcora and other excellent research colleagues like him find the ‘magic bullet’ that will ‘banish’ the sensation of fatigue, and we will be able to work harder and exercise longer because of it. But then would the cold drink after exercise taste so good, or the feeling of accomplishment one gets at the end of a long exercise bout as a result of resisting the sensation of fatigue long enough to achieve one’s goals for the particular exercise bout one has just completed still occur? This is something to ponder on, when fatigued, as I am now after two hours of writing, as I sip my cup of coffee, and wait for my ‘energy’ to return so I can begin the next task of a routine Sunday, whether it be cycling with the kids, walking the dog, or any other fatigue-removing activity as I prepare for the next fatiguing cycle which is the work and sport week ahead!


The Capacity for Maximum Physical Performance In Humans – Do We Ever Really Go ‘All Out’

I read an article in the newspaper this week about a group of pedestrians who lifted a car off a lady that was trapped under it after the car crashed into her as they were walking by the scene of the accident. A few weeks ago I watched young world class cyclists in the Tour De France push themselves up miles of uphill road in some of the highest mountains in France, and who looked completely exhausted at the end of each stage. I have had some fun Twitter repartee recently with Samuele Marcora, Jeroen Swart, Andy Renfree, Ross Tucker and others – old science collaborators, friends and academic ‘sparring partners’ – regarding whether folk ever use their maximal physical capacity, and if not, whether their performances are regulated by processes in the body or brain, and if in the brain, whether algorithmic neural processes are involved, or rather more intangible mental motivation related processes are behind our maximal physical performances during races or athletic events. I spent a fair amount of time, particularly when working at the University of Cape Town a decade and more ago, examining these concepts, and developed a theory for them, along with colleagues Tim Noakes and Vicki Lambert, called the Central Governor theory, which caused some controversy then, and still does today, with folk either loving or hating it, as what happens with all theories in science.

For a long time, the concept of maximal performance, and what finally results in folk reaching the absolute limits of what they physically can do, could be described as a ‘catastrophic’ model of fatigue. In the catastrophic model, the body, when pushed hard during an athletic event, either runs out of key nutrients or energy fuels, or is ‘poisoned’ as a result of metabolites that cannot be cleared out of muscles quickly enough, either due to lack of oxygen delivery capacity of the lungs or blood supply which have been ‘overwhelmed’ by the demand placed on them by the physical activity. The lactic acid theory was the classical example of this – the ‘burning’ pain one feels in one’s muscle during extreme exercise was thought to be related to lactic acid build up, which eventually ‘poisoned’ the muscles to the point that they simply stopped working.

Most of these theories developed from animal studies, or isolated muscle studies, where muscles were removed from their normal anatomical environment and stimulated with electrical shocks until they stopped contracting completely (developed rigor for the scientists reading this). At this point of absolute fatigue, a variety of parameters such as lactic acid were measured, and given that the levels of these parameters were very high (or very low in the case of fuels), a cause / effect relationship between absolute fatigue in these isolated muscles and lactic acid for example was suggested to be occurring during these trials. But the action of muscles of human folk performing exercise does not occur in an isolated state or in a petri dish. We therefore did some work in the University of Cape Town labs, building on work by greats in the fatigue field such as Roger Enoka and Simon Gandevia, amongst others, and looked at how much muscle was recruited during real life endurance and sprint athletic activity, using fairly novel techniques (at least at that point in time!) such as electromyography (EMG), which indirectly measures muscle recruitment (though one could write a book on the merits of this technique to measure fatigue, or the lack thereof). In a breakthrough study for us, we found that the muscles of folks in the lab who pushed themselves to the point when they said they were absolutely exhausted still had reserve capacity / had not used their muscles absolutely maximally, which was both astonishing and exciting to us. We did muscle biopsies at the beginning and end of the trial, and also found that the levels of fuels such as muscle glycogen and glucose, essential fuels of the body, were low but not zero, indicating the presence of a fuel reserve capacity too. We repeated this type of study in a number of different population groups and types of athletic events, and found similar results, and concluded that the brain of an athlete ‘stopped’ an athlete in an anticipatory way prior to them ever being absolutely completely fatigued, even if they did ‘feel’ absolutely exhausted. So some process in the brain appears to ‘disconnect’ the sensation of fatigue from what exactly was happening in the body, likely as a protective mechanism to prevent the occurrence of either muscle damage or general circulatory failure which could (and occasionally does) occur during an athletic event in a very motivated athlete.

A number of other examples of this protective ‘central’ / brain protective mechanism came to light during our further experiments, or from experiments in other labs around the world. Derek Kay, Jack Cannon and Frank Marino in Australia found that in a lab study using race-like conditions, participants started fast, slowed down in the middle and sped up the last 10 percent (or so) of the trial. The EMG activity in their study tracked these increases and decreases in pace, which indicated that these changes were probably initiated and regulated by the brain. The increase in pace in the last 10 percent of the trial was described as an ‘endspurt’ – speeding up at the end of an event or activity – and of course if one’s muscles are being ‘poisoned’ by a continuous build-up of metabolites during a race, or if one did run out of a fuel completely, there would be no way that the trial participants could speed up and show an endspurt at the end of the race. A fascinating study performed in the 1960’s, which came to light when we investigated what we were finding, which perhaps would not have passed the muster these days from an ethical perspective, showed support for this concept. Trial participants were asked to contract their leg muscles as hard as possible in a leg strength testing device where the movement of the leg was resisted and the force output of the leg muscles recorded. The subjects were encouraged to keep on going until they claimed they were absolutely exhausted and could not continue for even a few seconds longer, and at this point a second researcher, who unknown to the participants had entered the room behind them, fired off a shotgun blank shell, without the participants seeing them do so. This obviously caused a massive shock to the participants, and the interesting finding from a study perspective was that the subjects put out between 20 and 30 percent more force after hearing the gunshot, despite saying prior to hearing the gunshot that they were absolutely exhausted. Again, this was strong evidence for the presence of the muscle reserve capacity at exhaustion and a ‘disconnect’ between the sensation of fatigue and the physical changes associated with the fatiguing process.

We, and other scientist folk, have had a long look at how this sensory / perceptual disconnect during the fatigue process and at the point of absolute ‘fatigue’ occurs. Clearly there is teleology behind this finding, and it is likely that it is a protective mechanism which uses ‘trickery’ to keep folk safe from their own motivational drives, but it is does ‘boggle the mind’ to think that one’s own brain in effect ‘lies’ to its own ‘self’ in order to protect ‘it’ from ‘itself’. The origin of sensations and the perception of emotional constructs such as fatigue, and how they develop in underlying brain structures (or indeed how they are even related to physical brain structures) is difficult to understand, given how little we unfortunately know about basic brain function, mental states, or indeed sensory awareness of anything. However, using indirect methods, we were able to show that the dissociation of the sensation of fatigue from the underlying physical fatigue processes can be fairly easily elicited. One of the most fun studies I have been involved with (though which has very relevant findings pertaining to this research area), was a study we (Rachel Winchester and others) did during my time at Northumbria University, where when young male participants who were running on a treadmill said they were feeling exhausted, we introduced either an attractive female or an athletic male into the lab who interacted with them while they were running. There were profound changes in the levels of reported sensation of fatigue by the athletes – when the attractive female interacted with them, they reported significant reductions in the level of fatigue they felt, but when an athletic male interacted with them, they reported being significantly more fatigued as a result of the interaction. So this was classic (and humour inducing) evidence showing that the sensation of fatigue can be actually fairly easily ‘dissociated’ from what is happening in the body itself, and that the sensation of fatigue has a psycho-social component, or at least can be ‘interfered with’ by psycho-social factors.

So what does all this tell us about the limits to performance and whether athletes, or indeed folk who perform recreational sport, ever really are ‘maximally’ fatigued, even if they do feel as if they are. The evidence described above would seem to clearly indicate that, at least in these scientific studies, one’s brain as a protective mechanism appears to limit ones activity to an always submaximal level, even if one ‘feels’ that one is pushing oneself to absolute maximum. How the brain (or mind) does this is currently not clear, but there is clearly some interplay or calculation between one’s motivations and desires for success, and one’s fear of damaging oneself during athletic, or indeed any, physical activity. Interestingly, in the wild, animals being chased by predators do occasionally push themselves so hard to not be eaten as prey, that even if they escape, they die as a result of their muscles becoming so damaged by overheating or over-exertion that they become necrotic, which results in kidney failure and death from multiple organ failure due to toxin build up from the badly damaged muscles. Clearly us humans are never in a situation in our routine lives that these animals face, and therefore perhaps this ‘reserve’ capacity is some relic of our ancestry where we were indeed potentially a larger animals prey, and there was benefit of always maintaining a reserve for this ‘death-defying’ challenge if it occurred, though of course it will always be nothing more than conjecture when speculating on ancestry or evolution as a cause for modern day behaviour or function, particularly when brain function or mental behaviour is involved. Though some athletes do collapse during and after events (and why they do so is still a mystery), the vast majority, even Tour De France winners, know that they need to leave a small level of physical capacity to allow them to be able to climb off the bike, have a shower, get their medal, or leave something ‘in the tank’ to race the next day. So when we think we are absolutely exhausted, we probably never are. When we see the person with the car on top of them in the middle of the road, we do have the capacity to perform life-saving feats (obviously within reason) and have ‘strength’ that we are not aware of. Whether it is wise to use this inherent reserve, and risk ‘all’, even one’s life, for that single instance of extreme use of strength or endurance capacity in whatever circumstance, is of course another story. As is persuading my scientific colleagues, who despite all this evidence described above, still think the concepts are baloney and nothing more than a good story!


%d bloggers like this: