This post is about "perceived fatigue" which just like pain is about personal perception. What is now termed the psychobiological model of fatigue suggests that perception of effort is the ultimate determinant of performance, because this state is reached far earlier than actual physiological fatigue. Hence, the ability to sprint for the finish line after being seemingly at deaths door for the most part of the race.
This phenomenon has been shown time again to affect performance by experiments which have tricked people's perception of reality, such as rigging false room thermometers and giving incorrect time or distance feedback.
Central Fatigue Theory
This disparity between perceived fatigue and real physiological limits was coined "the central fatigue theory" by Tim Noakes, which he described in his book "The lore of Running".
The theory suggests that physiological parameters such as lactate accumulation and oxygen shortages are not the limiting factors to slowing you down but rather the brain's perception of these signals. In other words, fatigue is a psychological construct and the goal of feeling fatigued is a protective mechanism to make sure you don't actually reach those physiological limits and then literally kill youself.
Mental Fatigue
Mental fatigue which can occur from concentrating, studying, lack of sleep or working long hours is one such contributor to perceived effort. I think I may have experienced this trying to read Stephen Hawkins "A brief history of Time". I then ordered the children's version, which made no difference at all!
Samuele Marcora, an Italian exercise scientist primarily works on perception of effort and performance in endurance athletes. There is an interesting article in Runners World based around his research.
http://www.runnersworld.com/race-training/how-to-build-mental-muscle?page=single
He has shown repeatedly that mental fatigue affects physical performance. In one study, subjects spent 90 minutes either i) watching a film or ii) performing a cognitively challenging task. When both groups performed an exhaustive cycling test, those performing the task found the exercise harder and reached exhaustion 15% quicker.
Most of us will be suffering some form of mental fatigue at any one time, so what to do about it and can it be used as a training advantage?
As is the case for physiological systems, you overload (stress) and then get adaptation (compensation), the same applies for the brain. By becoming more resistant to mental fatigue, this should lower perceived effort. The classic book "The Stress of life" by Hans Selye elaborates on this really well.
Enter the era of brain training in Sport......
Endurance events require a submaximal effort for a (long!) sustained period of time. Tolerating fatigue and sustaining effort are therefore a huge part of this. Like most things physical which can be trained, this "grit" state can also be trained. I really do believe this although motivation plays a big part!
Training the brain to override these signals is essentially the essence of what is required to narrow the gap between perceived effort level and real physiological fatigue and like most things revolves around focus.
There are two ideas here:
1. To actually increase the threshold to fatigue, so it takes more before you feel it.
2. To learn to tolerate fatigue
Marcora is investigating the use of computer based cognitive skill games to facilitate brain training, to basically help grow neural networks through focused attention. Results of his first study, after 6 weeks of brain-endurance training, subjects had improved performance on a time-exhaustion cycling test by 23%.
The scientific hypothesis for this is mental exertion produces adenosine which gives us that tired feeling. By producing more adenosine, the bodies neural networks adapt and compensate, therefore increasing resistance. Caffeine is thought to work because it blocks adenosine.
The science bit
I am certainly not going to profess my competence in neuroscience and I do know the whole is greater than the sum of the parts! but the part of your brain needed for learning and memory is mainly in the hippocampus and is only active during uninterrupted focus. This interruption interferes with learning because focused attention is needed to grow neural connections in the hippocampus and build grey matter.
Neurophysiologists from Germany's Ruhr University Bochum (RUB) used MRI scans to look at the brains of 26 high performance athletes; half competed in judo or karate and half competed in marathon or triathlete. It was found there was more grey matter in the supplementary motor area (SMA) and the hippocampus in the athletes compared to non-athletes. You can't deduce cause or effect, i.e whether they started with that level or acquired it through training but it would seem to be important for performance.
What to do about it
Marcora advocates running once a week when you don't want to i.e when you are tired or after a gruelling work day. Because absolute speed are not so important to endurance running, the gains you make from training fatigue resistance are really relevant and done occasionally may outweigh the potential dangers of training tired.
Endurance athletes have often toyed with training in a fasted state or on tired legs to replicate this.
If you know why you are doing it and embrace that it will feel harder then perhaps the goal is appropriate, but I do feel it is one sure way to hate training - so to be done in small doses!
I have experienced often times a broken spirit doing this!! Not good for morale. I feel a better way of training "effort" is to learn to apply that focus whilst training.
Tolerance of fatigue
The ability to focus on the task at hand, without attachment to the "emotion" of fatigue is what I am talking about here. So this is where you are definitely are up there on the scale of perceived effort but you can learn to manage the sensation. Call it what you will, mindfulness, meditation, concentration etc.
Meditation and mindfulness are excellent ways of focusing the mind, but telling a complete beginner to sit cross legged and "try" to still the mind is a recipe for disaster and mental angst. Thoughts are of course inevitable and it is not the suppression of thoughts but the management that is the key. Allowing thoughts to happen but also to pass without trying to infer meaning to them is part of the skill of learning how to tolerate the discomfort of high effort. Thoughts are not facts in other words.
Usually concentrating on the physical senses is a good way of pacifying the mind. Senses such as breathing, sight, hearing, taste or sensation are examples and just choosing one to focus on in 5 minute blocks, I have found as a huge help to not engaging too much with pain/effort. It seems to be weather dependent though. In the rain and cold, the only pacifying thing for me will be stopping and a cup of tea....just saying.
So there you go... although you can't argue with genetics and what you were given, so much of physiology can be trained. Our environment and behaviour can make a huge difference to how those genes are expressed. Practice, practice, practice not just physical skills but mental skills is essentially what it is all about, to grow and establish new neural connections. It's never easy is it!
Or just have a giant cup of coffee.
References:
Blanchfield, A.W., Hardy, J., de Moree, H.M., Staiano, W. Marcora, S.M. (2013). Talking yourself out of Exhaustion: The effects of self-talk on Endurance Performance. Med Sci Sports Exercise. Epub ahead of print.
Marcora, S.M., Staiano, W. (2010). The limit to exercise tolerance in humans: mind over muscle?
European Journal of Applied Physiology. 109 (4): 763-70.
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