During my fascinating meeting with Prof. Noakes, I still had time to discuss his stance on one of his more recent publications, the re-invigoration of the Central Govenor Model or Hypothesis (CGM) which I wanted to share as a conclusion to my time spent at the SSISA. The theory exposes A.V. Hills 1923 traditional ‘peripheral fatigue model’ of the physiological limitations to exercise which has sculpted modern science beliefs, and undermines the utility and concept of VO2max as an indicator of performance. This is defined, as we know it, simply that during maximal exercise the exercising muscles requirement for blood flow exceeds a maximal rate. Which in turn forces the muscles to function ‘anaerobically’ with the production of lactate and muscle acidosis in excess.
Noakes’ premise that the brain regulates performance is ‘justified’ because fewer than 100% of skeletal muscle fibres are recruited in exercising muscles to meet the demand for greater oxygen processing. He logically states that 100% use should be the case to fulfil Hills original model, if performance was limited by the peripheral capacity. Instead ‘the brain may serve to protect organs and prevent death under demanding environmental conditions’.
In his model, the brain works as an anticipatory control to prevent irreversible myocardial damage, in communication with the heart once catastrophic failure has begun. This mechanism was originally perceived by Hill, as Noakes believed that homeostasis is maintained in all organ systems by the brain in a ‘feed-forward’ manner. Further, peripheral sensory feedback from the muscles to the brain has been included in these more up-to-date models, thereby assessing both physiological and psychological factors which determine the athletes initial pace, based on expected distance and duration and their level of motivation. Noakes logically suggests that these will be influenced by the level of external competition and the importance the athlete ascribes to the event, plus the athletes level of self-belief. He goes on to highlight that during exercise, there is continuous feedback from all the organs of the body, which will inform the central command of the state of the fuel reserves, the rate of heat accumulation, and the hydration state amongst other factors.
During our chat, Noakes touched on how the CGM could interact with the peripheral system (muscles, heart and lungs etc) with the most successful athletes experiencing the least ‘pain’, itself suggesting a minimal pain model. This perspective would be quite refreshing, not because we know that the same athlete would also be the fittest, but in terms of how we approach training. Instead of an athlete under taking the most suffering, which seems to be a common view amongst amateur endurance athletes, the focus is to create the most adaption with a minimum effective dose of discomfort from training. These two perspectives seem to be associated but crucially different. Pain can manifest in different forms. But continuous pain is destructive. In this case the anticipatory feedback mechanism (muscle spindle pain receptors or ‘nociceptors’) suggesting that organ homeostasis is close to failure and the brain causes early termination of exercise, which we know if challenged too often leads to over-training and poor performance. This is the reason why many centrally acting performance enhancing drugs (PEDs) are so effective, increasing the threshold to pain.
Even Alex Dowsett said that ‘the first 30min felt easy’ on his recent WR hour performance. Again, I can underline this mechanism by highlighting the deep set mentality of amateurs consistently racing ‘because others do’ only to end up with flat or unproductive seasons.
Noakes goes on to suggest that RPE otherwise known as the Borg scale (established by Dr.Gunnar Borg), the subjective rate of perceived exertion could be more accurately defined in relation to CGM as a measure of exercise intensity that has been completed or that still remains. Practically I have found RPE to vary widely between my clients, but also the range of RPE changes with objective measurements in performance progression, emphasising the link between the peripheral sensors and centrally acting regulator of muscle recruitment and cardio-respiratory function, the brain. Some of you may think that none of this is really news….but reading Prof.Noakes review is still very enlightening and may underline just how much mind over matter really counts!Leave a reply →