If I had to choose what I felt was the most important aspect behind any of the principles of applied exercise physiology, then without doubt I would pick Supercompensation above the rest. Supercompensation explains the mechanism behind how we, as organisms, adapt and respond to any physical stimulus, and is therefore fundamental to performance progression.
Elite and professional athletes have mastered their interpretation of how their bodies respond to a training stimulus, and hence optimise duration, intensity and recovery accordingly. This ensures there is a minimum effective dose which impacts on the right systems at the right time to create strength and endurance adaptions so that system is capable of performing the same task but with more efficiency.
Throughout all life forms, biological rates and reactions dictate the kinetics of growth, survival and even death. The dose response curve, or concentration effect curve represents how inter- and intra-cellular messengers, hormones, growth factors, neurotransmitters and other mediators are found to ‘communicate’ between organs, cells and sub-cellular structures. So, every reaction in our bodies has a minimum and a maximum limit. For instance…. there is a minimum amount of light required to see, and there is also a maximum before we are blinded, the same with sound, taste, smell, touch. Pain is a limiter for a reason…it stops the body from damaging itself beyond repair when a stimulus is too intense. Perceived pain from exercise is no different from the five senses. Enduring the right amount of pain will result in optimal strength adapations, too much though will break down the body beyond repair.
Often training can be thought as relying on the inner voice constantly appraising our performance, pushing us to continue or stop, based on prior experience and future ambitions and the level of pain needed to endure. Knowing if that voice has a sound understanding of what we are capable of is a different matter. This is sometimes the case if our perception is skewed for some reason by injury, stress, illness, fatigue and over-training. We won’t properly adapt to the training we are doing, as we maybe doing too much or too little for the phase in our training when other factors influence our well-being.
On regular occasions in our training we should assess if we are optmising the magnitude, duration and frequency of each session to maximise training effect in accordance with the natural compensation mechanism, ie is the timing of our training sessions optimally aligned with our physiology? The basic impulse-response model of training maybe applied to a single session as well as to a complete mesocycle (seasonal period) of training and competition. Every movement we make adds towards the overall response we expect after each phase of training.
Briefly as depicted in the diagram below, a training load, whether a resistance session in the gym or endurance session on the bike will create an initial period of fatigue following cessation of the session. This fatigue then dissipates as the system returns towards normal, although the baseline state is surpassed for a period proportional to the intensity of that training load as well as the initial fitness status. This part is termed the supercompensation phase, which will also occur at the end of a block of training or racing. This is an improvement in fitness of the system to attempt to compensate for any inefficiencies exposed. However, this response is saturable, ie it has a maximum effect, which if surpassed will have no positive effect on fitness (dotted line).
The time required for your body to recover from an individual training session depends on the exertion level applied (training load) and your training history. For the best development of performance, the optimal time window for the next training impulse to occur is highly variable. However the window is longer the higher the exertion level of the training. Any subsequent training should ideally be performed during this phase, so that the athlete is in a stronger position to cope with what could be a greater training load intensity or training of a different system (which may require greater effort). If no further training is undertaken at this point then the fitness level will return to its baseline after a definite period of time before further decline in fitness. So from this simple mechanism we can see there can be a few situations, with rest intervals between sequential training periods resulting in totally different outcomes in performance gains. These are shown below.
From the scenarios depicted above we can see that the first sequence of training stimuli (timing of stimulus depicted by arrows) result in a slight positive gain as the frequency of training falls within the supercompensation period.
The second sequence depicts a similar optimal scenario as the first but with a greater intensity of training load.
The third sequence shows what happens if successive training sessions are performed within the recovery phase, before supercompensation, and if the training is continued in this fashion.
The fourth sequence demonstrates the same as the third, but if recovery is then allowed a greater supercompensation phase maybe experienced.
The final scenario depicts no overall performance gains if training sessions are scheduled after the end of the supercompensation phase.
The mechanism explains why you should sometimes go slow to get faster, as to allow muscular transformations, biochemical changes and adaptations to catch-up if frequency and intensity has been too severe for a prolonged period. Active recovery or rest periods would allow the athlete to have a forced supercompensation period and prevent further over-training.
Heart rate recovery has been known to be a good indicator for scheduling blocks of training, predicting performance and avoiding over-training by adjusting training load and frequency as reported by Lambert. The Lambert sub-maximal cycle test was developed to assess changes in response to training and help diagnose over-training syndrome. Although this test requires baseline measurements to show any change in heart rate recovery, and power to heart rate ratios over time.
More advanced technology has taken advantage of heart rate variability (HRV) as an indicator of adequate recovery or potential over-training as part of the adaptation/ supercompensation mechanism. When the heart rate comes under the control of the autonomic nervous system due to stress, fatigue, temperature, drugs and illness results in a more regular heart rate with less variability in time between contractions. This may be monitored over longer periods, days or weeks, to determine a trend in variability, eg entering a period of over training (reduced HRV) or becoming more well rested (increased HRV).
Different monitoring devices can only allow a certain amount of confidence for predicting real changes. I came across this company based in Finland called FirstBeat who have only just started in the UK. I managed to catch up with their new UK representative and distributer at the Tri-show at Sandown, Esher. They have taken this area on as their specialty, and explained the science behind HRV a bit better than I can, with research references. It looks to me like their products include proprietary algorithms to estimate EPOC and training effect in what is robust wireless technology. I would advocate using HRV to anyone who is looking to optimise their training response, as the physiological principles are totally sound, although I will include one caveat in that HRV alone cannot steer periodisation. Clearly, you will still need to follow an adequate periodisation programme, knowing which systems and intensities to train at, customised to your unique physiology. Incorporating HRV tracking will streamline this process even further.
Going back to the first diagram above, the typical impulse-response curve is extremely interesting because it can also be read in reverse as well as corresponding to the influence of a single work out over time. We can see this in the influence response curve which can be used as a tool to optimise training, shown below in a graphical form. T=0 on the lower x-axis indicates an event. Training on any of the days prior to the event will have a negative effect on performance up to 12 days before, after which they will have a positive effect, peaking at 40 days prior. This suggests that any training 12 days before a race should be avoided, however in practice athletes may use this point at which their taper should well be under way, ie reducing volume and keeping intensity.
So we can see how there is a multi-layer approach to biological adaptions. Not only should we be concerned by individual training sessions and how they influence acute performance, but also how they may affect the chronic build-up of fitness and whether or not we achieve a true peak performance in time for our planned events or series of competitions. This can be tracked efficiently using heart rate recovery assessment or even looking at trends in heart rate variability during your periodisation. Once you master your own adaptations and supercompensation periods, then you soon realise how much less training time you may actually need to reach your goals.
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