Five strategies for training a runner’s brain

In recent weeks I have been exploring ways of training my non-conscious brain to relax its apparently over-protective control of my cardiac output.  I think I have been successful, though at the price of straining a muscle – it is very difficult to get everything right.  Nonetheless, I am sufficiently encouraged by the gains to examine the way in which similar principles might be applied to other aspects of running.  The underlying principles that I have been employing are the principles of cognitive behavior therapy (CBT).  This is a form of therapy that has been widely used in recent years for treating a range of minor mental problems; some enthusiastic advocates see it as a technique for dealing with all sorts of everyday challenges.  In reality, panaceas don’t exist, but because some of the principles mesh with the growing evidence about the role of the brain in shaping our running, it is worth a closer look

 

Cognitions, behaviour and childhood development

CBT is a form of psychological therapy that deals with practical problems in the here and now, and  is often regarded with distain by psychotherapists who believe that change in human emotions and behavior is best achieved by dealing with deep rooted maladjustments that have their origins in early childhood.  It is almost certainly true that childhood experience shapes both our minds and our bodies – more striking than the genetic endowment of elite African distance runners is the observation that many of them ran to and from school every day in early childhood.  As someone who also had the good fortune to run to and from school each day for several years, I suspect that the long-term benefits were not merely increased development of heart and leg muscles, but also arose from both conscious and non-conscious memories. 

 

There is little evidence that it is effective to try to change the consequence of childhood development by regression to childhood.  That is the tortuous path mapped out by Woody Allen in his depictions of neurotic New Yorkers dependent on weekly visits to their therapists.   In contrast, CBT is short term and problem oriented.  There is good evidence that it works for treating depression and anxiety.  Of course when testing the effectiveness of psychological treatments, it is impossible to employ a ‘gold standard’ double blind controlled trial in which neither therapist nor patient know whether the patient is getting the treatment under test, or an inert comparison (placebo).  However the evidence from fairly well controlled but non-blinded studies does show that CBT works for mood disorders, and has efficacy similar to that of antidepressant medication (see for example the review by Cuijpers and colleagues, J Clin Psychiatry. 69(11):1675-85, 2008)  

Can the same principles be used to get the best out of our non-conscious brains when we run?  The core principle of cognitive therapy is that our conscious thoughts often involve us jumping to self-defeating negative judgment about ourselves that lower our mood and paralyze our performance.  That is the C part of CBT.  Just as important in the B part.  B denotes behavior therapy.  Thirty years ago, behavior therapy alone was in vogue.  It was a way of changing behavior based on observations of the ways in which laboratory rats or dogs can be trained. 

 

Similarities and differences between humans and other animals

The studies of animals demonstrated two common types of learning: Pavlovian conditioning which entails learning to respond to a new stimulus by associating it with an established stimulus that has an automatic effect (eg the smell of food producing salivation); and Skinnerian conditioning: learning a new pattern of behavior as a result of rewards for small steps in the right direction.  Skinnerian conditioning works well for training rats, and in fact can also be used to train humans, but pure behavior therapy went out of fashion as a form of psychological therapy, except for young children, for two reasons.  It does not fit well with contemporary society’s belief about the importance of being in charge of decisions about ones own life.  Secondly, and perhaps more importantly, it fails to utilize one the amazing things about the human mind and brain: our ability to make conscious decisions based not only on immediate rewards, but also on memories of the past and on plans for the future.

 

CBT attempts to incorporate conscious evaluation, planning and decision making with the type of automatic learning processes that work well in other animals.  In principle this makes sense: all of the basic building blocks of the human brain can be found in the brains of other animals and it is therefore likely that training strategies that work for rats in the laboratory, might also work for humans.  But despite being built of the same building blocks as the rat brain, the human brain has an immensely richer network of connections between the building blocks, and the richness of these connections endows us with what we experience as the ability to make conscious decisions.  But sometimes conscious thought can get in the way.

 

Pacing ourselves

In the domain of running, one of the unanswered mysteries is how we pace ourselves during a race.   It can scarcely be dependent entirely on conscious memory from previous races, but neither can it be a process of pushing our bodies to the limit throughout the race.   Tim Noakes and colleagues have developed the concept of the central governor which regulates effort by anticipation that is based at least in part on non-conscious processes.  The central governor hypothesis remains a hypothesis that has generated heated debate for almost 15 years.  So far, the studies designed to provide direct support of the hypothesis have not been convincing.  For example, the claim by Ross Tucker and colleagues from Noakes’ lab in Capetown that the rate of heat storage mediates an anticipatory reduction in exercise intensity during cycling (J Physiol 574: 905–915, 2006) has been criticized by Jay and Kenny on the grounds that the method of estimating the rate of heat storage was flawed (J Appl Physiol 107: 630-631, 2009). However, failure of experiments to establish the truth of the hypothesis does not prove that the hypothesis is invalid –the complexity of the human mind and body makes it difficult to obtain convincing evidence.  Nonetheless, there are many observations about the pacing of human performance that are difficult to explain by any hypothesis other than some form of anticipatory regulation, which is at least partly non-conscious. 

 

My own conclusion is that the central governor theory is a good framework for developing ideas, but the ideas must be tested out against experience.  Of course, many of the ideas that emerge from speculation based on science are things that our grandmothers might have told us – but if I had listened only to my grandmother, I would have given up running long before my mid sixties.  We now know enough about how the brain and mind works to justify trying to fit our own experience into a coherent framework, even though the immense complexity of the mind and brain means that the details are speculative and predictions need to be interpreted cautiously. 

 

So let us start by looking at the implications of principles that underpin CBT: First is the behavioral principle what is rewarded (for example, by success) will be reinforced by non-conscious mechanisms and become a part of our behavioral repertoire.  Second is the principle that cognitive responses shape human learning, but that our automatic cognitions are often self-destructive, and need to be tested against reality.  These two principles provide the basis for understanding some of the conscious and non-conscious mechanisms by which our brains set the pace when running

 

Five strategies

Here are five strategies that I have learned by testing my experiences against the general principles listed above.  All of these have no doubt been advanced previously by runners and coaches, purely on the basis of what experience has taught them, but over the years I have met coaches and runners who have expressed notions counter to these ideas – so at least for me, having a theoretical framework allows me to assemble a repertoire of training strategies that provide a coherent guide but nonetheless that I take with a pinch of salt:

 

1) Race often: racing is the best way to demonstrate to your brain just what your heart and skeletal muscles are capable of.  The excitement of the race maximizes dopamine release in the brain, and adrenaline release elsewhere in the body.  High dopamine levels (the principal  mediator of motivation) strengthen the signals the brain sends to the muscles; high adrenaline promotes strong contraction of heart muscle and efficient distribution of blood to the muscles.  So a race that is fairly hard but not totally exhausting race can be a great way to bring yourself to a peak.  However, it is essential to provide adequate time for recovery from the short term damage to muscles that racing produces.

 

2) Frequently run faster than target race pace in the sharpening- up phase, either by running shorter races, interval sessions or fartlek.  This teaches your brain that you still have plenty in reserve at race pace.  On the other hand, I do not regard ‘over-distance’ sessions as especially useful from the point of view of mental preparation.  Ever since childhood I have had a deeply embedded confidence that, barring a serious muscle injury, I can last the distance in any race; so at least for me, the more challenging issue is whether or not I can sustain the target pace.   Perhaps each individual needs to identify their own mental vulnerabilities.

 

3) Maintain conscious focus on the present:  In the mid stages of a long race, conscious focus on the distance remaining can undermine confidence of ones ability to sustain the planned pace.  Although pace judgment in a long race requires a sophisticated calculation by the brain, it is often better to leave the micromanagement of pace to the non-conscious brain.  When you focus purely on the sensations of breathing and the rhythm of running without consciously questioning how long you can sustain this, a fast pace often feels more exhilarating than daunting.  On the other hand, insidious negative thoughts can be destructive.

 

4) Make the most of bad days: When you body tells you that it cannot cope with a planned training session, it is generally better to aim to sustain the intended pace or even build up to a slightly faster pace for a shorter period; or maybe do some stride-outs at target race pace, but without forcing yourself; the aim is to demonstrate that there is a bit more in the tank than your brain believes, but not to wreck yourself.

 

5) Use you conscious brain to keep things in perspective: do not catastrophize if you have a bad session; make a mental list of the positive features of the session; be aware that the body has immense capacity to compensate for short-term minor disruptions, such as poor sleep; suboptimal food or fluid intake; minor injury – and accept that it is OK to stop if you have a definite injury – or to pause to deal with increasing local tension in a muscle.

Fatigue is a complex thing

I have been pre-occupied with fatigue in recent weeks, but I think that is now behind me.  For me, the most interesting thing as been the fairly clear evidence from my heart rate recordings that my non-conscious brain imposed a limit (mediated by the parasympathetic nervous system) on how much work my heart was able to do.   While I think that limit was initially based on a non-conscious but sensible protection strategy, it eventually because over-protective.   Furthermore, I think it is likely that my conscious strategy of graded exercise to teach the non-conscious part of my brain that regulates the autonomic nervous system, that it was safe to relax the limit, allowed me to recover fairly rapidly.

Ironically the final test of my recovery strategy was at the price of thrashing my legs beyond their current ability to cope in the Robin Hood half marathon.  So I am now nursing strained hip adductors.  However they are recovering. The bruising that tracked down the medial aspect of my thigh from near the point where adductor longus attaches to the femur has now turned yellowish-purple. In the past two days I have done very gentle runs of around 6Km without any sign of fresh bruising.  However it has been noteworthy that my legs are still tired, confirming that the adductor strain was merely a crunch that might have easily struck in any of the other major leg muscles.  In some ways I am pleased it was the adductors because shortening my stride allowed me to continue with relatively little further damage.  Maybe a tear of the hamstrings or quads would have stopped me from doing any further damage, but on balance, I am really pleased that I was able to finish.    For the next week or so, it will be gentle exercise to promote recovery while trying to avoid tearing the healing fibres apart.

 

Fatigue is a complex thing

While it appears that the parasympathetic action of the heart was the mechanism of my recent fatigue, I suspect that many instances of the more transient fatigue that sets in during long races are mediated by other mechanisms, especially by mechanisms that act directly on the leg muscles. 

One of the great things about the blogs by amateur runners is the insight they provide into what goes on in the mind and body during a long race.  I am cautious about expressing my thoughts about other people’s blogs in my own blog, but overall, I consider that what people have freely put into the public domain is legitimate material for comment.  I am therefore inclined to put down my speculations about the report on the Dingle marathon a week ago, by Thomas (Diary of a Rubbish Marathon Runner, http://rubbishrunner.blogspot.com/) though I should start with the caveat that my speculations  say more about me than about Thomas.  Nonetheless I will let Thomas know that I have written about him so he can correct any mis-perceptions on my part.

Thomas’ experience is especially informative because he is one of the most determined and motivated of those runners whose blogs I follow. Therefore I think it can be taken for granted that a far as conscious determination goes, few runners would approach a race with more dedication and determination than Thomas approached the Dingle marathon.  As the event unfolded, I think he ran an excellent race; his time and placing are, beyond doubt, great achievements.  He did not achieve a personal best, and one does not need to look far for the obvious explanations: an unseasonably warm day, and a brutal hill in the final few Km of the race. 

However, if one approaches the evidence with a mental bent towards understanding how it was that these two circumstances influenced Thomas’ race, several more intriguing thoughts arise.  

Background

But first we need to look at the background.  Thomas achieved 3:05:37 in the Dublin marathon last year and has trained very hard and very effectively since then.  He ran a creditable 3:10:36 in Boston under difficult conditions in April this year.  As he approached Dingle, his training paces demonstrated that he had the potential for a sub- 3 hour marathon under favorable circumstances.

At Dingle, circumstances were not favorable.  After miserable weather through July and August, Saturday 12^th September proved to be one of the most glorious days of summer for anyone except a marathon runner.  The temperature in Dingle was 22 degrees C (72 degrees Fahrenheit). 

Acclimatization to warm weather

There is no doubt that humans acclimatize to warm weather, though having spent my childhood in Adelaide, South Australia, I have often wondered about the mechanism of acclimatization.  Adelaide has cool winters and warm summers.  In early spring, when the temperatures first exceed 75 degrees Fahrenheit (we used the old units in those days) it felt great, but almost too hot for comfort.  A few months later,  we considered that we were being cheated of our summer if the temperature was not regularly in the upper 80’s or low 90’s,  and as children, we even took a perverse delight in times when the daily maximum temperature exceeded 100 degrees for several days on end.  I often trained in temperature well above 90 degrees and thought nothing of running a 5000m race on a mid-summer afternoon.

What had changed between the first days of spring and mid-summer only three months later?   There might have been changes in the function of our kidneys or sweat glands, but I suspect that the main change had been a change in what our brains accepted as normal. 

Jim Peters and Il Topolino

So what happens when we race on hot days?  Probably the winner of a long race on a hot day is the runner who is best acclimatized, but what does acclimatization entail?  Jim Peters’ collapse only yards from the line in the Vancouver marathon in 1954, while miles ahead of his rivals, suggests that the reason he was so far ahead was not due to a greater ability of his body to withstand heat, but rather an ability to over-ride his brain’s attempts to keep his body temperature within safe limits.

Don Thompson’s gold medal in the 50K walk in Rome in 1960 provides another thought provoking illustration.  Thompson, who was nick-named Il Topolino (‘mighty mouse’) by the Italian crowds, was diminutive in stature but mighty in his spirit.  He had trained for Rome in an improvised hothouse in the bathroom of his mother’s house in Middlesex.  He installed a stove in the room and put on a kettle to boil; closed the door and window; and switched on the electric wall heater to augment the effect of the steaming kettle.  Years later, when asked how Paula Radcliffe should prepare for the marathon in Athens in 2004 his reply was: ‘I trained in the bathroom about three times a week, from May to September, but I didn’t stay in there long each time and I think it was more about a boost to my confidence.’  Maybe Il Topolino had trained his brain to believe that keeping up the pace when the temperature was above 80 degrees F was possible, rather than adjusting the function of his kidneys or sweat glands.

The scientific evidence

Scientific studies confirm athletes tend respond to hot weather by slowing down to minimize the rise in core temperature; rather than by slowing down once core temperature has already risen.  In a comparison of African and Caucasian runners during self-paced 8K treadmill runs performed under cool and warm conditions, Marino and colleagues found that both groups ran at similar pace in the cool conditions.  The Caucasians ran more slowly under warm conditions, but sweated more profusely and maintained similar body temperature.  Marino concluded that the observation that the African runners ran faster only in the heat despite similar thermoregulatory responses to those of the Caucasian runners suggests that the larger Caucasians reduced their running speed to ensure an optimal rate of heat storage without developing dangerous hyperthermia (Marino et al., J Appl Physiol, 96: 124-130, 2004).

The diminutive Il Topolino demonstrated in Rome that it is possible to train the brain to over-ride this mechanism, but the case of Jim Peters in Vancouver perhaps illustrates that it can be difficult to get the balance right.  Fortunately, Peters recovered quite rapidly after re-hydration.

Back to Dingle

So what happened to Thomas at Dingle?  The temperature was warm by Irish standards, but in fact not really all that hot, at least by Australian standards. However, Thomas had been training in cold and windy weather around the shore of Caragh Lake in Kerry.  To both his conscious and non-conscious brain it seemed hot.  Nonetheless, he started with a first mile of 6:51, almost exactly in line with his 3 hour target pace and he reports that first few miles went very, very well. He was running  easily, feeling relaxed and happy.  For much of the first half, the race continued to go very well.  He was holding a pace of around  7:05 pace per mile which would have given him a finishing time near to his PB of 3:05:37.  However, it is of interest to note from the traces he presents in his blog that has pace tended to slow slightly throughout the first half, and his heart rate to fall very slightly from a mean around 168 bpm between miles 1 and 3 to a mean around 166 bpm from miles 10 to 13, despite greater undulations in the course after 6 miles.   Was his brain, either consciously or unconsciously, protecting him from undue exertion?   He reported that at 10 miles he started to feel some signs of fatigue.  Nonetheless he was still running well until mile 19, when the pace record shows he ‘lost it.’ He slowed from a pace of 7:10 per mile around mile 18 to slower than 7:30 per mile around mile 20.  The undulations in the road make the precise figure irrelevant but there was a definite trend towards slowing despite a net fall in altitude of approximately 50 feet between mile 18 and mile 21. 

Something else was looming on the horizon.  He reports that as he approached the drinks station at mile 21 he ‘could see the mountain looming ahead. It reminded me very much of Connemara’s “Hell off the West”, and I was in no illusion about the task ahead. This was going to be tough’    Starting in the 22^nd mile the road ascended 300 feet, at times with an incline of 13%.  He struggled gamely to the top, but shortly after the summit he was pole-axed by cramp.  His blog provides a graphic description of the pain in his calf muscles.  After a few protracted and excruciating moments he managed to apply a counter-tension that relieved the cramp, and he finished with an exultant wave to the crowd in 12^th place in a time of  3:12:44.   

It was a great performance, and I think it is unlikely that Thomas could have done any better on the day.  It is probable that some physiological process such as electrolyte imbalance was the coup that pole-axed him on the final hill, but his prospects of a PB were gone by 21 miles.  At that stage his heart rate had already fallen below 165.  We do not know how much his body temperature had risen, but Marino’s study suggests it unlikely that it had risen to dangerous levels.  More likely, his brain was protecting him from the heat and from the mountain ahead.  Some non-conscious part of that brain was probably also aware of his electrolyte status, and integrated this information with the message from his conscious brain that things were about to get very tough.  

While it is unlikely that there was anything Thomas could have done to have overcome the sensible response of his non-conscious brain at that time, no matter how determined he was, I suspect that if he had trained in an improvised hot-house, as Il Topolino had done almost 50 years previously, his brain might have allowed him to sustain a faster pace between 3 and 21 miles.  But whatever the physiological limit proved to be – electrolyte disturbance, core temperature or something else, it is probably just as well that his brain did not allow him to run himself to a state of exhaustion in Dingle.  That wasn’t the right day or place for a PB.  His more recent blogs indicate that he is recovering rapidly, and after a two week recovery phase, he is about to begin his preparation for the Dublin Marathon in 5 weeks time.  I think there is a very good chance he will record a PB in Dublin, and if the weather is good, his goal of a sub-3 hour marathon is within reach.

Recovery from fatigue

I appear to have recovered from the fatigue that had hamstrung me in mid August. In recent weeks I have described the way in which my return to training following the episode of illness in June and July was thwarted by a peculiar inability to raise my heart rate during exercise.  I found it very difficult to maintain a pace faster than around 6 min/Km. The most dramatic illustration of the problem occurred in the final stages of a staircase session on the elliptical cross –trainer, when I found it crushingly difficult to maintain an output of 240 watts for 4 minutes.  When I subsequently examined the record of my heart rate, I discovered that it had reached 143 bpm at the 200 watt step on the staircase, and had not risen at all when I increased the power output to 240 watts, resulting in the need to generate the additional power via anaerobic metabolism.  The Poincare plot of R-R intervals between successive heart beats demonstrated extensive spread of the points across the 45 degree line, confirming excessive parasympathetic output.  My parasympathetic nervous system was clamping my output in an apparently over-vigilant attempt to protect my heart from doing too much work 

The morning orthostatic tests corroborated the evidence of parasympathetic excess.  The rise in heart rate from resting to standing was typically only 2 or 3 beats per minute, compared with my more usual heart rate rise of around 9-10 BPM.  On one occasion, on the day following a very sluggish 16 KM run, my hear rate was actually lower while standing than when lying down, providing an additional illustration of an excessive parasympathetic response. 

 Today

Today, the pattern was much different. Here is a chart showing my heart rate during the orthostatic test, and also the Poincare plots representing R-R intervals in the 3 minutes before standing and during a 3 minute interval starting 30 seconds after standing (once the immediate heart rate variations associated with the work done in elevating by body had settled). 

 

Orthostatic test on 12th September 2009. The upper figure is the trace of heart rate while resting for 3.5 minutes and after standing for a similar period. The lower figures are Poincare plots of heart beat R-R intervals during the final three minutes of rest (left) and during a three minute period starting 30 sec after standing (right).

 

The features of note are:

1)      The orthostatic increase in heart rate is 14 bpm – a little greater than my normal increase of 9-10 bpm and much greater than the -1 to 3 bpm characteristic of the period when I was fatigued.

2)      There is much greater variability of heart rate while resting than while standing.

3)      While both resting and standing, the heart rate shows prominent fluctuation in time with my breathing.  I tend to breath naturally at a rate of around 6 to 7 breaths per minute when relaxing, a rate that corresponds to the 6 to 7 peaks per minute (0.1 – 0.12 Hz) in the heart rate trace.

4)      While resting, the breath by breath fluctuations exhibit a steady rise followed by a sharp descent.  I was aware of breathing out immediately prior to standing, a period in which the heart rate trace shows a sharp descent, confirming that the sharp descents arise as a result of the increase in parasympathetic output during expiration. These sharp descents are much less pronounced during standing.

5)      Comparison of the Poincare plots reveals not only a much greater variation in R-R intervals during rest (note the different scales marked on the axes) but also a different shape.  During the resting period, there is a cluster of points located far above the 45 degree line to the left side of the chart.  These points represent long intervals (ie slow heart beats) immediately following shorter intervals (faster beats), and reflect the sharp descents during expiration seen in the heart rate trace.   In contrast, the Poincare plot during standing is shaped like a comet with a flared tail.  It shows limited spread across the 45 degree line and relatively greater spread along the 45 degree line (though the actual extent is substantially less in both directions compared to the resting period).

 

Overall, today’s orthostatic test confirms that my parasympathetic nervous system is no longer over-active.  If anything, the balance has tipped further towards sympathetic activity compared with my usual state, though this degree of sympathetic output is well within the normal range.

 What led to recovery?

I am inclined to attribute my recovery over a period of 2-3 weeks to my program of low-volume, moderate intensity running.  I have done 3-5 runs per week, over distances of 3-6Km, either at an easy pace interspersed with a few moderate intensity stride-outs for a distance of 200-300 metres, or moderate intensity tempo runs. In addition I have done 1 or 2 staircase sessions on the elliptical cross trainer spanning the aerobic range (though on the one occasion noted previously, following an ill-advised attempt at a longer run the previous day, I found myself in the anaerobic zone at the top of the staircase, due to my parasympathetic system clamping my cardiac output).

 A decision about the Robin Hood half marathon

I am now ready to resume normal training.  This presents me with the need for a decision.  Tomorrow is the day of the Robin Hood half-marathon, which I had set as a target race four months ago.  The fact that I have not been able to train normally for the past twelve weeks has torpedoed any prospect of a fast time, and in any case, I would be unwise to push myself really hard on the first day back into normal training.

I am uncertain about what pace to set.  The greatest uncertainty is about how well my legs will cope with 21.1 Km, due to the marked truncation of training volume.  Here is a chart of my training volume in the period May to September this year, compared with the same period last year, when I ran the half-marathon in 101:50. 

 

Training volme (Km per week, averaged over 5 week intervals), May to September 2008 and 2009.

My training volume was greater last year, but most of that running was at low intensity.  This year, a higher proportion of the training sessions have included at least some moderate intensity running, and as a consequence, I think my aerobic capacity is probably not much less than last year despite my illness and its aftermath.   In several of my runs in the past two weeks, my heart rate has been around 650 beats per Km – over distances of 2-4 Km.  Last year, I rarely achieved lower rates than 650 beats/Km, though my endurance was much greater.

Although it is usually not sensible to set race pace according the heart rate on account of the risk of being misled by the higher sympathetic output associated with racing, in my present circumstances it is crucial that I avoid stressing my heart too much, to avoid precipitating another parasympathetic clampdown or perhaps an even more serious rhythm disturbance.  Hence, I think that the best strategy is to aim for a heart rate in the range 134-137 (upper part of the mid-aerobic zone) for the first 14 Km, and then adjust my pace according to how well I am coping at that stage.

Cautious optimism

The goal and the strategy

The evidence suggests that my strategy to overcome my recent acute fatigue syndrome with short sessions that include some moderate intensity running might be working.  The goal is to re-train my brain to accept that my body can safely cope with producing at least a moderate power output.  In my post last Monday (31^st Aug), I compared the Poincare plot of heart inter-beat intervals recorded during an elliptical staircase session during a mild setback on my path to recovery, with a plot from a similar session in mid-July before the onset of fatigue.  The feature of interest was the extensive spread of points across the 45 degree line on 31^st August, indicating excessive input from the parasympathetic nervous system.  This was apparently responsible for the fact that my heart rate could not rise above 143 bpm (averaged over 5 sec intervals), when I increased my power output from 200 to 240 watts.  I had to rely on anaerobic metabolism to generate the increase in power.  This was extremely demanding and in retrospect it was not surprising I found it very difficult to maintain 240 watts for more than a few minutes.  Clearly if I want to be able to produce a moderate power output, it was necessary to teach my non-conscious brain that it could relax the tight control at least a little.

Executing the strategy

During the past week I have done three elliptical sessions and two runs, each relatively short but each including a small amount of moderate intensity activity.  The increase in my heart rate from resting to standing during the orthostatic tests in the mornings has stabilized around 5 bpm – still a rather small increase, but probably within my normal range.  Encouraged by the signs of recovery, I repeated an elliptical staircase session on Friday.  To avoid the risk of stressing my heart too much, I spent only 2 minutes at each level of power output in contrast to 4 minutes at each level on previous occasions.  When I increased my power-out to 240 watts, my pulse rose to 147 bpm.  Although producing this power output required some effort, it was not so crushingly difficult as it had been when my maximum heart rate had been clamped at 143 bpm by my tyrannical parasympathetic nervous system, on 31^st August. 

Here are the Poincare plots for the three elliptical staircase sessions: mid-July, 31^st  August and Friday (4^th September).  The plot for Friday’s session is not fully comparable with the other two, because it was recorded after only 27 minutes of exercise, compared with 52 minutes in the other two sessions, and furthermore, the plot is based on a sample of heart beats over 1 minute rather than 2 minutes (because the plots can be misleading during a period of increasing heart rate immediately after an increase in power output).  Nonetheless, the three plots are as comparable as can be achieved in the circumstances.  The crucial point of interest is that the spread of points at right angles to the 45 degree line, which represents parasympathetic activity, is back to a level similar to that in mid-July.  This amount of spread is represented by the quantity, SD1, which was 4 ms  in mid-July; 13.4 ms on 31st August and 3.1 ms on 4^th September.   This provides further confirmation that the over-zealous parasympathetic nervous system that had clamped my cardiac output on 31^st Aug, forcing me to employ anaerobic metabolism to produce even a moderate power output, had learned by yesterday that it could safely allow the rise in heart rate necessary to generate 240 watts aerobically.         

Poincare plots of interbeat intervals in the upper aerobic zone during elliptical sessions before the onset of fatigue (July); during fatigue (August); and during recovery (September)

It is of course ironic that I am celebrating being able to push my heart rate to 147 in order to achieve a power output of 240 watts.  In June, I was pleased when I managed to produce 240 watts at a heart rate of 141.  However, in June my heart rate increased steadily as power output increased.  As I increased output from 200 to 240 watts, heart rate rose from 132 bpm to 141 bpm – in other words, in June, my relatively low heart rate was not due to clamping by the parasympathetic nervous system, but simply the result of being fitter.  ( It is not surprising that my aerobic fitness has decreased somewhat since early June, due to my illness and the fatigue that developed in its aftermath.  The increase in heart rate at 240 watts from 141 bpm in June to 147 bpm yesterday appears to reflect a decrease of around 4% in my aerobic capacity.  That is not too bad in light of the severity of my illness in June/July.)

A short tempo run

Encouraged by the apparent success of my strategy of short, moderately intense training sessions, yesterday (Saturday) I decided to do a 4Km tempo run.  In my only previous running session this week, I had done an easy 5Km including 4 stride-outs of 200-300m at a pace of around 4:45 /Km.  At the time, it would have required great effort to have increased to a pace any faster than this.  Nonetheless, because of my growing confidence, yesterday I decided to aim for a pace of 4:40 /Km for the 4Km run.

After warming up, I set off running comfortably with a gentle breeze behind me and reached the half-way point in 9:18 (4:39 min/Km) with an average heart rate of 138 bpm.  I anticipated that when I turned into the wind, it would no longer feel like a gentle breeze.  As expected, I had to increase the effort and my heart rate rose rapidly to 145, but I felt fine.  I covered the return journey in 9:20 despite the head-wind, giving a total of 18:38 (4:39.5 /Km).   I arrived home very pleased with my progress.

 The next day

However, the crucial question is whether or not today’s orthostatic test would show any evidence of a parasympathetic clampdown indicating over-exertion yesterday.  In fact, this morning the orthostatic difference was 5.4 bpm which is virtually identical to the average value of 5.3 bpm for the entire week. 

Thus, at this stage it appears that I am recovering from the excessive parasympathetic activity that had apparently produced the feelings of severe fatigue I had suffered two weeks ago.  Overall the evidence of the past few weeks is consistent with my previous suspicion that my parasympathetic nervous system tends to be over-active.  Furthermore, the evidence of the past week supports the hypothesis that the non-conscious part of the brain that regulates the parasympathetic system can be trained to relax the tightness of its  grip on the control of heart rate.  The question of whether or not I could have achieved the same outcome simply by resting remains unanswered, though the evidence from clinical studies that graded exercise can promote recovery from fatigue inclines me to think that the low volume, moderate intensity program was the right thing to do.

Caution

I remain aware that the parasympathetic nervous system serves a crucial protective role and therefore, I must be cautious in trying to modify it.  It is likely that the parasympathetic clampdown and the associated fatigue arose because I had been a little too vigorous in the attempts in early August to regain fitness after my illness in June and July.  Therefore, I will continue carefully, but I am cautiously optimistic.

Fatigue

After a few weeks of debilitating illness in June and July I wasn’t sure whether or not to stick to my plan of running the Robin Hood half-marathon in September.  When I started running again in late July I began with easy or moderate paced runs of around 5-6Km,  it became clear that I had lost a lot of fitness, but I was enjoying running.   Then at the beginning of August I decided to put matters to the test and ran 15Km, starting slowly but increasing the pace gradually.  I was pleased to find that I felt comfortable at a pace around 5 min/Km in the second half of the run.  That settled the question. I would run the half-marathon.  I was uncertain about the target time to set myself, but provisionally set a target time of 100 min – only one minute slower than the target I had set several months earlier.

As for training strategy, my first objective was to try to re-establish a reasonable level of endurance; so I planned to build up the distance with fairly easy paced running, up to around 60 Km per week. By mid-August, things were going according to plan.   I had three runs of 16-20Km behind me, and several ‘tempo’ runs – though at that stage, tempo pace was not much faster than 5 min/km.  I planned do two easy-paced longish runs in the third week of August followed by a few upper aerobic runs to confirm my choice of target race pace. Then something peculiar happened.

 

Malign alien force or guardian angel?

On the third Monday of the month, I set out on the first of the two planned easy-paced longish runs.  For about 5Km, things went well.  I felt very relaxed running at a pace of 5:45 min/Km with a heart rate in the lower aerobic zone (around 122).  And then quite unexpectedly, all the energy drained away from me.  I struggled to maintain a pace of 6:30 min per Km.  My heart rate dropped to around 115 and my legs felt very heavy.  It appeared that I was battling some alien force.  For the next few Km I made efforts to push the pace but then realized that it was a pointless struggle.  It was clear that I was losing the battle against the alien influence.  However, apart from the lethargy and heavy legs I was not experiencing any physical symptoms.  My pulse was regular and strong, though reluctant to increase much above 115 bpm.  So I kept on plodding along wondering what it all meant.   In the end I covered 16 Km, but at times my pace dropped to 8 min/Km.

The next day I did a short easy jog and felt OK, so on the Wednesday I again attempted the planned long easy paced run, though on this occasion, aiming only for a pace around 6 min/Km.  I felt sluggish though at least I was able to get my heart rate above 120.   Again I managed to do16 Km, but it appeared that I was in no shape to race a half-marathon within a few weeks.  I took it easy, doing only short easy runs for the rest of the week, and on the following Monday made yet another attempt at a longish run.  Yet a third time, the alien force was holding me back.  I eventually settled in for a slow plod at a pace in the range 6:30 to 6:45 min per Km and heart rate around 110.

What was going on?  I had been experimenting with various fitness measures using my new Polar RS80CX heart rate monitor, and after some experimenting, I have decided that the orthostatic test appears to be the most practical and useful test for monitoring my response to training.  What is clear is that during that third week of August I was experiencing an excessive parasympathetic drive that was keeping my heart rate down.   Maybe I am not struggling against an alien force; more likely it is a tyrannical guardian angel that is trying to protect me from myself.

 

The orthostatic test

In the orthostatic test, heart rate is recorded lying down for three minutes and then standing for a similar period.  Heart rate increases after standing, to elevate blood pressure sufficiently to combat pooling of blood in the lower extremities and thereby ensuring adequate perfusion of the brain.  This increase in heart rate is achieved by a shift in the balance between the activity of sympathetic nervous system  (the adrenaline-based fight or flight system) and the parasympathetic nervous system (which generally promotes relaxation and recovery).   On standing, sympathetic activity increases and in a fit person, an increase in heart rate of around 10 bpm can be expected (McGee and Abernethy, Journal of the American Medical Association. 1999;281:1022–1029.).  In an unfit or stressed person, the increase is usually greater.  

However, sometimes there is a paradoxical surge of parasympathetic activity – blood pressure falls and the person collapses in a faint.  Recovery usually follows quickly provided the person remains lying down.  This paradoxical surge of parasympathetic activity – a so-called vasovagal attack- appears to reflect an over-active compensation mechanism that exists to prevent us from over exerting ourselves.

While a faint is transient and harmless, it is interesting to speculate on the similarities between a transient vasovagal event and two enigmatic conditions that are very relevant to athletes: fatigue and over-training.   But first it is relevant to examine the results of a study of orthostatic test responses in marathon runners

 

Orthostatic responses after a marathon

Gratze and colleagues carried out an orthostatic test on 51 healthy amateur marathon runners the day before the Graz (Austria) marathon in 2007 and 2 hours after completion of the event (European Heart Journal vol 29, pp 1531–1541, 2008).  None of the runners exhibited a vaso-vagal attack on the day before the race, but 14 did so on testing after the event.  These runners were classified as orthostatic intolerant.  As expected, all runners exhibited evidence of increased sympathetic activity (indicative of stress) after the event, but the 14 who were orthostatic intolerant were unable to generate the required increase in sympathetic activity to compensate for pooling of blood in the lower extremities during the test.  Instead they demonstrated a paroxysmal increase  in parasympathetic activity, and developed signs of incipient collapse.

The only significant predictor of risk of orthostatic intolerance identified by Gratze and colleagues was having serum potassium levels in the lower part of the normal range before the race.  However there was also a trend towards a higher training volume in the preceding 4 weeks in the orthostatic intolerant group. (The probability that the difference between groups would have been as large as that observed purely by chance was 6.9%.  Thus the possibility of chance cannot be ignored, but weighing up all the evidence makes me think that the difference is unlikely to be due to chance).  The orthostatic intolerant group also had a higher training volume in their lightest week in the preceding month – in other words, they had not tapered to the same extent as those who did not develop orthostatic intolerance.  This invites the speculation that the runners who developed orthostatic intolerance were on the verge of over-training.

      

Over-training

Improving fitness necessarily demands over-reaching – the transient deterioration in performance following hard training that stimulates the development of increased fitness during the subsequent recovery phase.  If the athlete does not allow time for recovery following a hard training session, over-reaching develops into the early ‘sympathetic’ phase of the over-training syndrome, characterized by over-activity of the sympathetic nervous system – the adrenaline-related component of the autonomic nervous system that generates the fight or flight response.   Provided this sympathetic phase of the over-training syndrome is recognized in time, reduction in training volume or intensity for a few days is usually enough to promote recovery. 

However, if it is not recognized, non-conscious neural mechanisms intervene to protect us from our own fool-hardiness.   Perhaps this guardian angel within our non-conscious mind might be described as the central governor – though this is not quite the context which led Tim Noakes to develop the central governor hypothesis.  Whatever the true nature of our guardian, he/she is scarcely an angel and the consequences of his/her intervention are not quite what we might wish – the parasympathetic nervous system which normally promotes healthy relaxation and recovery becomes a tyrant. 

The balance between parasympathetic and sympathetic activity tilts strongly towards parasympathetic excess.  We no longer have any drive for fight or flight .   We become listless, apathetic and find that getting the heart rate up into the upper aerobic zone demands a major effort. The body is unable to mount an adequate defence against either injury or illness, and eventually either injury or illness forces a cessation of training.  This is the parasympathetic phase of the overtraining syndrome, and can last for weeks, months or even years.  If the 14 individuals from the sample of 51 marathon runners studied by Gratze were indeed on the verge of the parasympathetic phase of the over-training syndrome, then the risk of this problem is not uncommon.

 

Wrestling with an over-protective nanny

One of the reasons I have become especially interested in the over-training syndrome in recent times is the fact that despite life-long mild asthma which had caused me no problems since infancy, I have been increasingly hampered by broncho-constriction, the defining characteristic of asthma, in the past two years.  I have also been aware of having a rather low heart rate suggesting a tendency towards parasympathetic dominance.  Broncho-constriction can be precipitated by parasympathetic over-activity.   The sympathetic ‘fight or flight’ response opens the airways, while the parasympathetic ‘rest and recovery’ system has the opposite effect.

When I read Hadd’s well known account of his client Joe, who was training for a 2:20 marathon, I was intrigued to note for the first few levels of the Hadd test (a series of 2.4 Km runs at incrementally increasing heart rate) that I could run faster than Joe at a specified heart rate – though of course Joe could push his heart rate far higher than I could, and therefore he would have left me far behind in a race.  Perhaps I was a more efficient runner than Joe at slow paces, but efficiency is less important than VO2 max for all events other than ultra-marathons. 

I started to wonder whether or not the increased severity of my asthma and my low heart rate were evidence that some non-conscious part of my brain was taking action to prevent me over-exerting myself.  On balance, this apparently hypothetical tyrannical guardian angel appears to be acting in my best interests, and in particular, is protecting my heart, but the tyranny felt as irksome as an over-protective nanny.  It seemed worthwhile to get a heart rate monitor and try to wrestle some of the control back from this over-protective nanny.

 

Fatigue and the parasympathetic system

I hoped to use the monitor to maximse the efficiency of my training.  However, I had not anticipated the effects of my recent illness – a protracted bout of chicken pox accompanied by various complications.   In the aftermath of a viral illness there is risk of the enigmatic condition known variously as post-viral fatigue, myalgic encephalopathy (ME), or chronic fatigue.  The name used depends on the individual’s personal investment in the problem.  Many sufferers are adamant that it has a physical cause and tend to prefer terms like post-viral fatigue or ME; while skeptics tend to say it is all in the mind and prefer the term chronic fatigue. 

I suspect that multiple causes contribute: there are predisposing factors, precipitating factors and maintaining factors.  There is little doubt that viral illness can be a precipitating factor.  Possibly a tendency towards low parasympathetic activity is a predisposing factor, although paradoxically, excessive anxiety and sympathetic activity might also be a precursor.  There is a fairly large but inconsistent body of evidence indicating that the parasympathetic nervous system can be deranged in chronic fatigue – a confusing situation encapsulated in the title of a review article by Freeman ‘ The chronic fatigue syndrome is a disease of the autonomic nervous system: Sometimes.’ (Clinical Autonomic Research vol 12, pp. 231–233, 2002).  Typically, cases of chronic fatigue show evidence of an incipient vaso-vagal attack during orthostatic testing.

Although the literature on chronic fatigue is largely to be found in journals of cardiovascular medicine, immunology or psychiatry, while the literature on over-training is confined to sports medicine journals, it is probable that the two conditions have much in common. 

I also think there is little doubt that what I suffered in mid-August was the beginnings of a bout of post-viral fatigue.  Although I had attempted to return to training fairly cautiously after my illness, my decision to persist with my plan to run a half-marathon probably led me to push myself a little too hard.  I would not describe my present problem as an over-training syndrome yet, but I think I am on the edge.

Here is the record of my heart rate during the orthostatic test when my condition reached a nadir on 18^th August, together with a more typical recording performed on 2^nd  August.

 

On 18^th August, during the initial 3 minutes lying-down, my mean heart rate is 51 and there are high frequency fluctuations on a time scale of around 15 peaks /minute.  During the 30 seconds following standing my pulse rises to 71 bpm but then, while remain standing, an excessive parasympathetic surge produces a fall to a mean value slightly lower than the value when lying down, at times falling below 40 bpm.  It is noteworthy that the frequency of fluctuations decreases while standing relative to lying down, indicating greater sympathetic input, though the frequency while standing on 18^th Aug is still higher than on 2^nd  August.  The increase of 9 bpm from resting to standing on 2 August is typical

 

How is it best to manage the situation?

The management of chronic fatigue is a hot potato.  Many sufferers maintain that exercise is harmful (see for example: http://www.empowher.com/news/herarticle/2009/08/12/top-ten-list-recovery-chronic-fatigue-syndrome.  

In contrast, the evidence from clinical trials indicates that carefully graded exercise can be beneficial (Larun and colleagues, Cochrane Database of Systematic Reviews 2004, Issue 3)   The debate is heated because of the implication that if it can be cured by graded exercise, perhaps it was all in the mind after all.  However, I think that view underestimates the amazing nature of the mind, and the brain that under-pins it.  

The mind is no less real than the immune system or the cardiovascular system.  Almost certainly non-conscious mechanisms in the mind (and its brain) act to protect us from ourselves.  It is likely that the excess of parasympathetic activity that can occur in chronic fatigue is one such a mechanism.  However, despite being clever, the non-conscious mind is not always wise, because it is dependent on the information we feed to it.  If our conscious mind reinforces the need to be protective, it is possible to create a vicious circle in which conscious and non-conscious mechanisms get cemented into an over-defensive reaction.   By judicious conscious efforts to test the limits, we might be able to train the non-conscious mind to adjust the tightness of the leash in an optimal manner.    

If so, perhaps the most effective way of preventing incipient post-viral fatigue from becoming protracted debilitating chronic fatigue is to undertake carefully graded exercise so that the non-conscious mind/brain can adjust the tightness of the leash rather than consolidate the current status and create an intractable chronic problem.

Here is a graph showing the day-by-day variation in the difference between lying and standing heart rate during the orthostatic test. 

 

Orthostatic increase in heart rate showing nadir on 18th August. red arrows indicate long-run days; blue arrows indicate rest days

After the nadir in mid-August, there was a fairly steady improvement.  The red arrows mark days (both before and after the nadir) when I had increased training volume up to 15Km or more (albeit at a very easy pace).  On each occasion, there was a deterioration on the following day.  The blue arrows indicate days of complete rest.  These are followed by improvement, but perhaps even more importantly, during the period including runs of gradually increasing intensity over short distances, from 25-29^th August, the trend was strongly upwards.  Over this period, the Poincare plot ( a two dimensional scatter-plot that illustrates variation in inter-beat intervals, and in particlar allows as estimate of the rapid beat-by-beat changes in interbeat interval produced by activity of the parasympathetic nervous system) revealed that increasing orthostatic rise in heart rate was accompanied by decreasing parasympathetic drive during the standing phase.

 

Many a slip between cup and lip.

On Saturday (29^th August) I was sufficiently encouraged by my progress that I was tempted to increase training volume.  I ran 15 Km, starting slowly and gradually increasing up to a pace around 5 min/Km, achieving an overall average pace of 5:24.  This was a mistake.  On Sunday morning, the orthostatic difference was back down to 1 bpm.  This morning (Monday) it was 2 bpm.  It was clear that I still need to take things cautiously.

I decided that instead of running today I would repeat a session on the elliptical cross-trainer which I had done in mid July, at a time when I was gradually building up the training-load after my illness.   During the session, I increased the work-rate very gradually at 4 minute intervals, starting at 35 watts and increasing to 240 watts.  When I had done this session in mid-July, I had exceeded the ventilatory threshold (where breathing become very deep and rapid) during the final two levels.  My average heart rate in the final few minutes was 157 bpm (about 98% of maximum), but it had been an exhilarating rather than demanding session.  I anticipated that despite my recent fatigue, the training I had done since early July would be enough to allow me to achieve a 240 watt output while barely exceeding the ventilatory threshold. 

I felt reasonably relaxed during the early phases, though occasional glances at the heart rate monitor indicated that my pulse was rising at a similar rate to mid-July.  And then at 200 watts, I hit a very solid wall.   Suddenly I was gasping for breath.  I could scarcely believe how difficult it was.  However, it seemed that little harm could come from a few more minutes of exertion so I pushed on for the full 4 minutes of the 240 watt level.   When I examined the heart rate recording I was stunned to see that my heart rate had stopped rising after reaching 143 bpm at the 200 watt level.  The subsequent 240 watt level had felt so difficult because there had been no appreciable increase in cardiac output despite an increase in work-rate.  In the final few minutes I must have been utilizing almost purely anaerobic metabolism. No wonder it felt difficult.

The Poincare plot confirmed that it was the parasympathetic system that had blocked further rise in cardiac output beyond the level reached at 200watts.  A comparison of the Poincare plots in mid-July and today demonstrate that the variation along the 45 degree axis of the ellipse (largely due to sympathetic activity) was very similar on the two occasions: 6.9 ms in July compared with 5.6 ms today, but the variation across the 45 degree axis had increased more than threefold from 4.0 ms  to 13.4 ms, indicative of a relatively large amount of parasympathetic activity.  The consequence of this parasympathetic drive was a false ceiling on VO2max, and the sensation of hitting a solid wall.  I wonder does this mechanism play a part in creating the wall dreaded by ill-prepared marathoners?

Poincare plots of R-R intervals over a 2 minute period during the 200 watt level in the elliptical session on 18th July and 31st August

The future

I must now steer a course between Scylla and Charybdis, the mythical monsters that guarded the Straits of Messina.   If I push myself too hard the excessive stress will evoke an even more restrictive parasympathetic defense and I am likely to end up with protracted fatigue.  However, the evidence from studies of chronic fatigue indicates that the dangers of molly-coddling myself are almost as great.  Acute post viral fatigue can become very entrenched if the non-conscious mind/brain learns that the only safe path is low intensity activity.  

Previously in such circumstances I would have been inclined to opt for slowly re-building of aerobic base with a Maffetone-style program.  However, that would not be entirely logical as I think my aerobic base is still fairly robust.  The observations of the past 10 days suggest that short, moderate intensity sessions might be more effective for promoting recovery, whereas longer runs are likely to lead to further deterioration.

As for my half-marathon plans, I will simply have to see what unfolds in the next 10 days.  The Gratze study suggests that the two most crucial things to do in preparation are tapering, and ensuring that serum potassium level is not low.   Unfortunately, one of the side effects of my asthma inhaler is a decrease in serum potassium, so there are other less fearsome but nonetheless potentially troublesome monsters circling not far below the surface as I attempt to cajole my over-protective nanny through the gap between Scylla and Charybdis.  At this stage negotiating that gap is more important than the half-marathon, but provided my orthostatic test results show a moderate degree of normalization, I am inclined to at least present myself at the starting line.

Outwitting the governor

Performance is determined by physical fitness and by mental attitude. We devote a lot of mental effort to the challenge in deciding how to maximize physical fitness. The finer points in the debates between the different schools of training theory – Lydiard v Furman; Maffetone v Lydiard and many others – remain a topic for fertile discussion, but the re-assuring fact is that there are many ways to get physically fit. The finer points of the debates about the physical aspects of training only really matter when we get stuck in a rut and fail to improve.

In contrast, in my experience, the topic of mental attitude has been a less fruitful topic of debate. When I read articles about the psychology of sport I usually get the feeling that what is on offer is a set of fairly trite and uncontroversial observations that might be dismissed merely as common sense. However, as a young Australian growing up in the era when John Landy vied with Roger Bannister for the glory of breaking the barrier of four minutes for the mile, and a few years later, when Ron Clarke broke world record after world record but never won an Olympic gold medal, it was clear to me that the right mental attitude was crucial but also elusive.

The 1954 Vancouver mile provided the most graphic illustration that self-belief is paramount. The image of Landy looking over his left shoulder as he rounded the bend into the home straight while Bannister stormed past his right shoulder has been cast in bronze by the sculptor, Jack Harman, and serves as an enduring reminder that mental preparation is as important as physical preparation.

While much that has been written about sport psychology has left me uninspired, I have found Tim Noakes concept of the central governor very thought provoking. In formulating his central governor hypothesis, Noakes has developed an idea proposed many decades earlier by the celebrated muscle physiologist, A.V. Hill: performance is limited not by our lungs or muscles but by our brain, acting on the basis of physiological signals from the body to prevent us from damaging ourselves.

One of the most frustrating experiences in distance running is hitting the wall in the final few miles of a marathon. It feels as if every last muscle fibre has been exhausted; there is simply no more fuel left and it takes immense will power even to drag the legs onwards to the finish line at a pace scarcely faster than a jog. Mental tricks appear totally inadequate to mobilize the legs, yet when the finish line comes into sight, suddenly it is possible to lift those leaden legs and perhaps even raise a sprint. So the limiting factor is not total exhaustion of every muscle fibre; it is some barrier in the mind. This scenario vividly illustrates the machinations of Tim Noakes’ central governor.

One of the most compelling items of evidence supporting the concept of the central governor is the study of power output and muscle activation during a cycling time trial, by Kay and colleagues from Tim Noakes’ lab (Eur J Appl Physiol. 2001;84(1-2):115-21). The cyclists were required perform 6 maximal one minute sprints interspersed within a one hour time trial. Despite the cyclists’ attempts to perform to their maximum ability, power output and muscle activation decreased steadily from sprints 2 to 5. The decrease in muscle activation demonstrated that neural drive from brain to muscles was decreasing, not increasing as would be expected if the brain was acting to recruit additional muscles fibrils to compensate for the effects of fatigue. In contrast, during the 6th sprint, which was performed during the last minute of the time trial, power output and muscle activation increased significantly, similar to the pattern observed during the final sprint in endurance races.

This evidence indicates that slowing down due to fatigue is not due to reaching the limits of maximally recruited muscle fibres, but rather to a decreased recruitment of muscles by the brain. It is likely that this is a protective mechanism triggered by chemical messages released into the blood stream by stressed heart or leg muscles, or by signals from sensory nerves in the walls of blood vessels. However, the increase in neural drive to the muscles in the 6th sprint reveals that the brain does not merely act on an automatic response to signals from heart, blood vessels or leg muscles. Rather there is a computation of expected future demand that depends on input of information about future expectations from the conscious mind, as much as it does on chemical or neural messages from muscles, heart or blood vessels.

Thus our brain acts to protect us, using information from the periphery together with information from those parts of the brain that support conscious mental activity. We tinker with this mechanism at our peril. Nonetheless, it is clear from the fact that power output increased during the final sprint that under at least some circumstances, the central governor reaches a conservative decision, and we might improve performance with little risk if we could recognize when this is so, and take steps to override the governor.

However before rushing to devise schemes to over-ride the governor, it is worthwhile to look more carefully at the governor’s decisions under various circumstances. The study by Kay demonstrates that the governor acts conservatively when called upon to regulate a sprint in the midst of an endurance event. My own experience indicates that as I have grown older, my central governor also tends to act increasingly conservatively during interval training sessions. However this is not merely an issue for an aging athlete. The wily coach who announces after the eighth repetition in a planned 8 x 1Km session: ‘Well today we will make it ten’ is exploiting his knowledge that the governor tends to be conservative, in order to increase the mental toughness of his protégés.

We will return to the concept of mental toughness in a moment, but first we need to consider a common situation where the governor gets the computation wrong in the opposite direction. In endurance races, there are good physiological reasons to aim for a negative split: that is, to run faster in the second half than in the first half of the race. It is desirable to minimize the release of chemicals (calcium ions, potassium ions and muscle proteins) that indicate muscle damage, into the blood stream until as late as possible in the race to reduce the risk that the governor will order a premature shutdown. Also, in longer races where it is desirable to utilize fat as fuel, it is important to avoid premature switching off of fat metabolism by rising acidity.  However, one of the key mechanisms by which the brain prepares us for maximum performance on race day is the release of extra adrenaline. For the inexperienced athlete, this is a potential trap. The heart beats more strongly, the capillaries supplying the muscles dilate more readily and unless the athlete has the experience to rein in his or her supercharged body, he or she will set off at a profligate pace and pay a high price later.

Thus the central governor is not infallible. We can improve its reliability by providing it with more data upon which to base its computations of how much the body can safely stand under different circumstances. In fact the coach who says ‘Today we will make it ten’ after the eight repetition in the planned 8×1Km session is actually training the athlete’s governor to make a better estimate of the athlete’s capacity. Much of ‘mental toughness’ consists of establishing a preparedness to accept that a more demanding limit is achievable.

This mental toughness is closely related to self-belief. Although John Landy started the Vancouver mile as the current world record holder, he was acutely aware of the legendary final kick that Bannister had honed in training with his colleagues, Chris Brasher, Chris Chataway at Iffley Road in Oxford. As an Australian who had to travel far to participate in world class competition, Landy had limited opportunity to instill the necessary self-belief into his brain.

Training is not only a matter of increasing the efficiency of heart, lungs and muscles, but also about a program that trains the central governor to hone its judgment appropriately for the event in question – whether that be the need to produce a finely judged negative split in a marathon, or a devastating sprint in the final lap of a 5000m. Tempo runs, interval sessions, and low key races or time-trials are fertile sources of the raw the material required to train the governor.

However training the governor is not only a matter of preparing for races. It also has an important part to play is sustaining the quality of training sessions during a demanding schedule. It is commonplace to experience that sinking feeling during the warm-up for a planned tempo or interval session in the midst of a demanding schedule, that the body just cannot possibly cope with the intended pace, today. It is of course essential to evaluate the body’s complaints, but provided you have not embarked upon some unrealistic increase in training volume or intensity, and have been keeping track of recent performances to rule out the insidious development of the over-training syndrome, then the body’s anguish is probably a miscalculation by the central governor.

For me the trick that outwits the governor is banishing all thought about the intended distance of the run or the number of repetitions remaining, and focussing on running style, and on the immediate sensations from the body. Almost invariably, the sensation of lethargy diminishes. Each stride becomes an event to be savored with no thought about the number of strides remaining. Sometimes the lethargy disappears entirely; other times it persists but I am able to enjoy the sensation that comes from maintaining good form. However if the governor continues to provoke anguish, I know it is time to reformulate my goal for the session.

Getting out of a rut

This morning, I ran an easy paced 12 Km though the woods and along the river bank.  I had initially intended to do an interval session, but abandoned this plan when I continued to wheeze 15 minutes after using my salbutamol inhaler.  Running in the late winter woodland was a visual delight: the snowdrops, which have been in bloom for many weeks were still near their peak; the bluebell shoots were looking luxuriant though it is too early to expect the flower heads; a few clumps of daffodils that have escaped from the manicured village green into the wilder woodland were in bud.  After warming up, the wheezing diminished but I was still not running fluently.  My pace was only about 6 min/Km, and it felt as if I could not increase it.  Consciously I know that I am currently capable of a pace near to 4 min per Km, at least for a distance of a few Km.  However it appears that my continuing problem with asthma has sapped my confidence.

 

It is not uncommon for a runner to get into a rut in which performance falls below expectation based on current fitness.  This might be an indication of over-training, but if the usual signs of overtraining – lethargy, low mood, heavy legs, increased resting heart rate, erratic sleeping patterns etc are absent, it is more likely that the problem is psychological.  There is no doubt that I am not at present suffering from over-training.  So the challenge was to deal with the psychological issues. 

 

It is worthwhile stepping back from the particular circumstances of my run this morning and speculating about the psychological processes that influence running.  I am inclined to think that the mental mechanisms that govern running are no harder to understand the physical mechanics of running.  Of course, even the physical mechanics is complex and at present we understand only the rudiments – hence the debates between the various schools of efficient running.  Similarly, we understand only the rudiments of the mental mechanisms, but it is potentially profitable to examine these rudiments.

 

Our mind regulates how fast we run, and this regulation is only partially under voluntary control.  Tim Noakes has proposed the concept of the central governor that steps in to stop us over-exerting ourselves.  It is probable that the decisions of the central governor are based on the non-conscious monitoring of physiological variables such as stress hormone levels, proteins released from damaged tissues, hydration status, blood glucose level, core temperature and other indicators of potentially dangerous changes in the state of our internal milieu.  We would be playing with fire to over-ride these indicators.

 

However, the commonplace observation that a marathon runner can rise to a sprint when the finish is in sight, despite being utterly unable to lift his or her pace after ‘hitting the wall’ around the 20-23 mile mark, suggests that the central governor not only reacts to the indicators of the current internal milieu but also takes account of expectations for the future.  In general it appears that the central governor can be re-set according to our level of confidence.  Once we are fully confident of reaching the finish line, the central governor relaxes its restraining grip. 

 

If self-confidence can over-ride the restraint imposed  by the governor, it is also plausible that loss of self confidence due to prior bad experiences might have the opposite effect and cause the governor to be unduly restrictive.  Under these circumstances we need to find strategies to rebuild confidence before we can perform at our full potential.

 

The rise of running as a sport in which your main opponent is yourself and the main goal is to achieve a PB, rather than to beat an opponent has created an somewhat unnatural situation that we are not well adapted to deal with.  If at some point in pre-history the main reason to run fast was either to escape from a predator or to pursue prey , it is likely that the central governor evolved in manner best suited to adjust priorities according the needs of these situations.  When escaping a predator, the need to avoid being eaten assumes a higher priority than the risk of muscle damage, dehydration, heat stroke or exhaustion of glycogen stores at some future time-point.  On the other hand when chasing prey somewhat different priorities apply.  As long as we are gaining on the prey, or at least not losing ground, it is worth running the risks associated with pushing our physiological state at least modest degree beyond the usual limits.  On the other hand, once it is clear that the prey is faster than we are, a well adapted central governor would be expected to halt the chase.

 

I believe this might account for the well know phenomenon of the snapping of the contact with the front runner in a race.  Whilst our perceptions provide continuous evidence that we are succeeding in maintaining our place on the shoulder of the runner in front, the running feels easy, even though we might be near our physiological limit. However as soon as we drop back more than a few metres, our confidence evaporates, the bond snaps and we lose pace.  Thus, perhaps the experiences of our forebears chasing prey on the African savannah prepared us well for the challenge of racing an opponent. 

 

But when we are running to achieve a PB, the circumstances are quite different.  At best we get feedback from a stop-watch every few minutes.  Our central governor does not get the benefit of a continuous update on progress, and we must rely on mental mechanisms to sustain our confidence.  If we are going through a phase in which we have been struggling to achieve our self imposed targets in recent races, we are prey to doubt and self-questioning that saps our confidence.  The central governor is more likely to step in and restrain us.

 

How can we overcome this?  There are two potentially good strategies.  The first is to stop focusing on the target finishing time, and focus instead on our current internal milieu.  If we focus on breathing and/or the rhythms of our muscles, and cease worrying about how much longer we can sustain the current pace, we usually find that we are coping adequately for the time being.  By avoiding worry about the future, we avoid the crisis of confidence.  Strategies such as counting steps or counting breaths can distract us from worrying about our ability to maintain the pace until the finish line.

 

The other strategy is to recreate a situation similar to that of our forebears in pursuit of prey on the savannah.  Concentrate on racing an opponent.  As long as we are in fact running within our physiological limit, holding pace on the shoulder of our chosen opponent feels relatively easy. On the other hand; if we have been too ambitious in our choice of opponent, the psychological string that binds us to our opponent will stretch until it snaps, but at least we will have run to the best of our current physiological limit.

 

Returning to the situation I faced this morning, after a few brief bursts in which I increased my pace a little only to drop back to a sluggish 6 min/Km pace as soon as I stopped pushing myself, I decided to adopt the strategy of focusing on my breathing and running style.  Within a few minutes I was feeling much more fluent.  I did not measure my pace, but know from a rough estimate of the total time that I had picked up pace by about half a minute per Km in the second half of the run.  So I returned home feeling mildly exhilarated, and with renewed confidence. However, I am still a bit oppressed by the fact that I have not been able to do regular interval sessions since last November.

Dancing with the Devil: More about the mind of the dancer

Many of us accept in an abstract manner that the mind controls the body, but in everyday life, we do not usually act as if we believe it. We aim to get fit by stressing our bodies. We focus on miles or kilometres run; or on repetition times recorded on the stop watch. In September I described evidence from a study of hotel cleaners who were advised about the health benefits of their daily work. In comparison with their colleagues who did similar work without information about its health benefits, they showed significant improvements in physiological variables such as blood pressure. Mental approach to physical activity influences the physiological benefits derived. Today I found myself wondering about the interaction between psychological and physiological processes for a different reason.

In the past 10 days, as I have attempted to throw off the lingering symptoms of a bout of flu, I have been unable to train even at moderate intensity because my airways have become excessively sensitive to any stresses. Deeply breathing air at temperatures near to zero brings on an asthma attack. So I have increased the volume of my training but kept the intensity low. In fact, I have run more kilometres in the past 10 days than in any consecutive 10 days in almost forty years. Mostly I have really enjoyed being outside in the fine but bracing weather. I have listened carefully to my body to make sure that I was not overdoing things. Today, I set out for an easy 10 K run, but my muscles felt tired. There was no sign of any focal musculo-skeletal problem, so there was no reason to abandon my run, but I faced the challenge of how to make the most of my run on very tired legs.

A digression

I will start with a brief(ish) digression about tired legs. Before taking up running again in my sixties, I had made one previous ‘come-back’ to running. In my late 50’s I ran one race, a marathon. I had done 16 weeks of training that had been fairly consistent, but the weekly volume was less than half of that more typical of my younger days. I started the race with little idea what pace I should set. According to the age grading tables of the World Masters Athletics Association, the performances of my heyday suggested that as a 58 year old, I might be capable of around 2 hours 50 minutes if fully fit, but I was far from fully fit. So I set myself a choice of three goals: a gold standard of 3 hours, but I realised this was little more than a dream; a silver standard of 3:15 – I considered that this was possible but I would nonetheless have been extremely pleased to have achieved it; and a bronze standard of 3:30, which I was fairly confident was within my reach.

I lined up with thousands of others; a strange and unsettling experience compared with the races of my youth when even a major international marathon field was rarely larger than a few hundred. The start was complete bedlam. In an attempt to break clear of the melee I ran far too fast, and covered the first three miles in a little over 20 minutes, which was somewhat faster than my ‘dream’ gold standard pace and definitely not sustainable. I reached the halfway mark in about 93 minutes. My legs were starting to feel a little tired but my silver target appeared still to be within reach.

On the basis of my marathon running practice from several decades previously, I did not replenish glucose supplies along the way. Nor had I pre-loaded with carbohydrate the day before. In the 1960’s we didn’t entertain such notions. Maybe this old dog should have tried to learn some new tricks. By 20 miles, I was in serious trouble. My running action degenerated to a shuffle. My pace slowed to somewhere around 6 min/Km or even slower, but my mind was too fuzzy to read my watch and calculate times properly.

At the 23 mile marker, I was able to read my watch well enough to see that I had been running for three hours, and my befuddled brain was able to work out that I needed to maintain a pace a little faster than 10 minutes per mile to achieve my bronze target. I could hear a runner behind slowly closing the gap between us, and I realised that perhaps my only chance to achieve my target was to tuck myself in behind him and let him pace me to my 3:30 deadline. However, he went past and I simply could not lift my speed by the small margin required. My legs just would not obey the command. I was flabbergasted, but nonetheless was able to keep putting one foot in front of the other, and I plodded on. More runners passed me, and within the final kilometre a young man, perhaps about 30 years my junior, went by but I simply could not increase my speed.

When I turned into the home straight with about 100 metres to go I could make out most of the numbers on the huge digital clock over the finish line. It read 3 hours twenty something. I did not take in the minutes exactly, but my brain registered that there was still a chance of achieving the bronze standard. Suddenly I was sprinting. It wasn’t merely a delusion created in a glucose-deficient brain. I was gaining on the young man who was now about 40 metres ahead. At that point even time didn’t matter; it was a race to the finish. The spectators in the grand stand were shouting encouragement and it was only their shouts (or perhaps my gasping breath) that alerted my quarry. With a few metres to go he looked over his shoulder and scampered across the line just in front of me. My finishing time was 3:27:35. A few years later I met an acquaintance who told me he had been there that day and remarked on what a spectacular finish it had been.

For me the memory is vivid though the observation is commonplace: with an appropriate trigger, we can mobilise reserves that are ordinarily inaccessible. It is worth pondering several issues. At 20 miles I was conscious of the fact that I could no longer maintain the pace of the first twenty miles. At that point I was not capable of computing the pace required for my bronze target, but my unconscious brain selected a pace for me. I doubt that it was based on a non-conscious calculation of the requirement for the bronze target; more likely it was simply an estimate of the output my muscles could sustain without some metabolic catastrophe, perhaps a serious fall in blood glucose. At 23 miles, when I attempted to increase the pace marginally, I simply could not do so despite my conscious judgment that I would be unlikely to achieve even my bronze target unless I could tuck in behind a suitable pace-setter. Nonetheless, in the final 100 metres, I was able to muster a sprint that had the spectators in the grand stand buzzing. My brain was quite prepared to let me build up a small deficit of oxygen and burn up an extra few grams of glucose, now the end was in sight.

The central governor

So my experience confirms Tim Noakes proposal that the final arbiter of performance is a central governor in the brain. Is it worth exploring the possibility that we might train our brains to re-set the central governor? Mat Fitzgerald has recently published a book on Brain Training for Runners that makes suggestions for how we might do this. But is it a sensible thing to do?

I suspect that the central governor is not merely whimsical, but makes its decisions on the basis of data about the metabolic status of the body. There are many possible messengers that the brain should heed. Microscopic damage of skeletal muscles or of heart muscle releases enzymes into the blood stream. Maybe the brain might detect these and order a shut-down before serious damage is done. Maybe the kidney signals when electrolyte imbalance is developing, or pressure receptors in the large blood vessels might signal a fall in blood volume due to dehydration. The temperature regulator in the hypothalamus might order a shut down when body temperature increases too far beyond 40 degrees C (Nybo & Neilson, (Hyperthermia and central fatigue during prolonged exercise in humans. J Appl Physiol. 2001;91(3):1055-60). It s likely that the brain itself would take action to prevent a fall in glucose which is essential to the brain’s own continued function. Clearly, if we decide to reset the criteria by which the central governor reacts to such messages, we are tinkering at our peril.

However, it is probable that the criteria set by the central governor are cautious criteria and it is likely that among elite endurance athletes it is those with less cautious central governors that win gold medals. The image of Jim Peters staggering into the arena and collapsing from heat stroke 200 metres before the end of the Commonwealth and Empire Games marathon in Vancouver in 1954 suggests that one of the factors that made him the pre-eminent marathon runner of his era was the ability to tolerate a high body temperature. Maybe some training to produce small adjustments of the central governor’s physiological criteria is sensible, but it is difficult to know where to draw the line.

Mental influence on the Governor

It is also likely that there are there are largely psychological mechanisms that activate the central governor. One of these is our perception of how much longer we are required to sustain a stressful effort. When doing 8×1Km repetitions in training it is often possible to squeeze out a little more speed on the 7^th and 8^th repetition than would have seemed possible on the 6^th. Machiavelian coaches sometimes announce after the 7^th repetition that ‘today we will do 10’ just to build up the mental toughness necessary to cope with an unexpected challenge in the final stages of a race.

Seeing the end in sight mobilises reserves; it is probable that awareness of just how much further there is to go at the twenty mile mark in marathon has the opposite effect, via a mechanism that has more to do with mental perceptions than it has to do with physiological danger signals from the body. How can we prevent these self-defeating perceptions from causing premature shut-down?

Paula Radcliffe reports that she does it by distraction. She counts to 100, or as in the New York in 2007, in her first marathon after the birth of baby Isla, she recites ‘I love you Isla’

However, for a generation whose bible was Robert Pirsig’s ‘Zen and the Art of Motorcycle Maintenance’ there is another approach. Live wholly in the present and banish any temptation to create self-defeating perceptions of the length of the road ahead. Focus on every breath; on every step. Maintain a brisk cadence in the range 170-180 steps per minute. Lift the foot from stance with a short and sweet pull that directs it smartly up and forwards, but not too far forwards. Tip the rim of pelvis up at the front to facilitate a well coordinated swing and footfall. The goal is to achieve that zone of all encompassing bodily awareness where effort becomes effortless.

As I set out on my 10K run today I switched on my heat rate monitor, but apart from checking that it had started recording (it has a wonky switch), I didn’t look at it again until the end. I was aiming for pace in the mid-aerobic zone, a zone sometimes disparaging described as ‘junk miles’ by runners familiar with the excellent physiological principles of Daniels, because it is not fast enough to place a heavy demand on the biochemical pathways that deal with lactate, but too fast to be described as recovery. However, I think that point of view under-estimates the valuable role of that pace for developing a sense of effortless efficient running. In my youth, my most frequent training run was a distance of 15-20 Km at a pace around 3:20-3:30 per Km. That was pace that I felt I could maintain for ever, or at least for as long as I ever wanted to run. In those days it was slightly slower than my marathon racing pace. Allowing for the extra adrenaline of race day, it felt similar to racing a marathon, so it was no doubt a good mental preparation for a marathon runner. However that mental preparation for effortless running also stood me in good stead over shorter distances. I only ever ran one 10K race and I have no record of my time, but that race sticks in my mind for two reasons: it felt effortless and I won it (quite a memorable feature because I rarely ever won races on the track).

This morning, I easily found the same zone, though of course at a much slower pace than 40 years ago. My breathing was just audible at a rate between 40 and 45 breaths per minute. I felt I was being stretched without strain. In the language of materials science where stretch is synonymous with strain and both are proportional to stress, being stretched without strain is nonsense, but for me the concept evokes the right mental image. I think it is similar to what Sebastian Coe describes as the pace of a therapeutic run.

Holme Pit in May 2008

I focused on brisk cadence and lifting my foot from stance with a short sweet pull. I was not wearing gloves and at first I was aware of tingling fingers, which was scarcely surprising as Holme Pit was frozen. However, after a short while the tingling faded into the background. Visually I focused on the next bend in the path though I imagined that beyond the bend was an endless series of twists and turns stretching to infinity. When I got home I checked my heart rate monitor. The recorded mean heart rate was 136, which for me is about 85% of maximum, and somewhat lower than I would expect to maintain in a marathon. I didn’t measure the distance exactly, but my pace was around 5 min per Km. It was my most enjoyable run of the week, apart perhaps from my unplanned ‘race’ with the family of cyclists on New Years Day

I do not intend to test this mental approach in the final miles a marathon in the near future. In the next few weeks I have a more mundane goal. Because I do not think I will be able to push myself into the upper reaches of the aerobic zone outdoors until the air temperature increases a bit on account of my asthma, it would be good to develop a mental strategy to make upper aerobic workouts on the Elliptical cross trainer seem effortless.

Signals from the unconsious mind

It has taken a week to shake off the cold that I developed last weekend, and even now the last vestiges persist. However, compared with some of my friends who suffered the same bug, I did not suffer too badly. Some of my work colleagues who had developed symptoms a few days before me were still off work yesterday. For me the worst symptoms were painful throat and ears that kept me awake at night, and pain in the shoulders. By today those symptoms have disappeared, though my upper airways are still a bit congested.

This morning when I was in the garage sorting the household waste for re-cycling, I decided to do a few pull-ups to the rafters. I have a distance runner’s skinny arms and do not do any regular upper body strength training, though I occasionally do a few pull-ups or press-ups. I remember being pleased when on my 60th birthday I found I could still do 10 consecutive pull-ups. (I hadn’t recommenced running at that time and in general was feeling quite unfit). Today, I was struggling to get my chin above the cross-beam even on the first pull-up and after the second I decided to desist. It appeared that my unconscious mind was sending a signal that my recently painful shoulders were not yet ready for the task.

However, my conscious mind was eager for a run, and my unconscious mind did not signal any disapproval as I set out for an easy paced 8 Km run along the river bank. The weather was misty but mild compared with recent weeks, and it felt really good to be out running. I am eager to get back to systematic training soon, but nonetheless, I will continue to be guided by how comfortable things feel few more days.

The mind of the dancer: Does mind-set influence the benefit of training?

In a recent post in mid-July I had mentioned the evidence from brain imaging studies showing that merely imagining an action activates the brain cells that are engaged when performing that action. It follows that merely imaging good running style might establish and strengthen the patterns of brain activity that are required to achieve good running form.

This raises an even more speculative question. What influence does mind-set have on non-voluntary actions such as the activity of the heart and metabolic processes. I do not know of any evidence that imagination alone will make you fit, but maybe the way we think about our training can increase the benefits of training. Alia Crum and Helen Langer of Harvard University carried out a study of the effect of merely informing hotel cleaning staff that their daily cleaning work is good exercise. Four weeks later, their blood pressure and body fat had decreased, even though they did not increase the amount of cleaning they performed. In contrast a comparison group who carried on cleaning as usual without being told that cleaning is good exercise, did not show improvements in fitness. (Crum and Langer, ‘Mind-Set Matters: Exercise and the Placebo Effect’, Psychological Science, 18:165-171;2007). Maybe the practical conclusion is that developing a training plan that makes sense to you increases the benefit of that training compared with performing the same training without knowing why.