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.
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 8x1Km repetitions in training it is often possible to squeeze out a little more speed on the 7th and 8th repetition than would have seemed possible on the 6th. Machiavelian coaches sometimes announce after the 7th 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.