Training, the art of doing just enough
We love our sport, whether it is running, cycling or something else. To become better at it, we invest a lot of time and energy. We train regularly, if not daily or even twice a day. So it only makes sense to discuss the concept of training, why we do it and how to do it safely. We will discuss the topics of supercompensation (or why rest and not training itself makes you stronger), detraining, overreaching and overtraining.
Supercompensation
The human body is a remarkable machine, capable of performing incredible feats. The most impressive of which might be the ability to heal and adapt, to the point of becoming stronger and more resilient than before. In 1936, this led the endocrinologist Hans Selye to developing his General Adaptation Syndrome (GAS) theory. He identified three phases in the body’s reaction to a stressor or a stimulus: the alarm phase, adaptation phase and exhaustion phase. By 1967, Russian researcher Nikolai Yakovlev applied this theory to the field of sports science, leading to the development of the supercompensation theory.
The body’s tendency to adapt to stimuli forms the basis of modern training theory. In his initial work, Yakovlev divided the process of adaptation into four phases. During phase 1, acute fatigue sets in immediately after a training session, lasting approximately one to two hours. Phase 2 is the rest or compensation phase. Yakovlev stated that during 24 to 48 hours following exercise, and prior to a new training stimulus, we give our body the rest needed to compensate for the stress that was incurred. This is followed by the supercompensation phase (phase 3). The reaction to the stimulus leads to improvements, elevating performance to a higher level than before the exercise. If a new stimulus does not follow within 36 to 72 hours of entering the supercompensation phase, we transition into phase 4: a decrease of the benefits that were gained in the previous phase.
Figure 1: the phases of Yakovlev’s supercompensation theory
By now, we understand that the duration of each phase is not fixed, but rather varies based on the type and intensity of each training stimulus. For example, as you go out for a medium-intensity long run, it might take around 7 hours for the supercompensation phase to set in. However, it might take up to 48 hours following a hard interval workout, especially if the central nervous system has been highly challenged. The application of the supercompensation theory is further complicated when multiple stimuli are introduced in a short timeframe (for example during a twice-a-day training strategy), convoluting a clear distinction between the phases.
So what is training? I define it as:
The deliberate application of domain-relevant stimuli with the objective of eliciting an adaptation that drives an increased performance level in that specific domain.
For its application in sports, training can only be considered true training if it is relevant to your sport of choice. So if you want to become a better runner or track cyclist, there are little to no benefits to be gained from training to become a chess master or dart player. The correlation, let alone causation, between these modalities is too low to provide cross-domain performance gains. However, incorporating regular cycling can constitute a great complement to your running training. Even though the sports are different, their cross-section is large enough that the spill-over effects from one modality to the other can prove very useful indeed.
The other keyword is deliberate. This sets training apart from any other life activity that might be linked to your sport of choice. For example, going to bed at 3 A.M. after a party is not considered sleep deprivation training. However, a sleep deprivation training strategy within the context of a multiday ultramarathon might very well incorporate going to bed at 3 A.M. and having your next run at 5 A.M. For the same reason, mowing your lawn does not constitute endurance training. But, again in the context of ultramarathon training, an appropriate endurance training strategy will probably include a focus on increasing time-on-feet, a characteristic you might increase by mowing your lawn. In each of these cases, the activity (going to bed late or mowing your lawn) are stressors you or your coach should take into account as stressors when building a training program, but they can only be considered training when they are deliberated prescribed and executed.
This leads us to the question of how to optimize a training program – the architecture of all training activities with the goal of meeting or exceeding event demand –, so that we can build off of the supercompensation phase of a previous training stimulus. This is a complicated question, as our recovery needs depend not only on the stress of an exercise stimulus, but are also influenced by any stressor that we could categorize as general “life stress”. It does take a trained eye, and a lot of trial-and-error to find out what combination of stress and rest fits each athlete’s individual needs.
Another topic of discussion is what happens when we exceed the tolerances of training within the supercompensation model. In other words: what are the consequences of, on the one hand, not introducing a new or adequate training stimulus in time (or at all), or on the other hand a too rapid sequence of too intense training stimuli. This brings us to the concepts of detraining, overreaching and overtraining.
Detraining
Phase 4 of the supercompensation model is intricately linked to the concept of detraining. In effect, both describe a decrease of our current performance potential, our training level, or, more colloquially, fitness. We train to become better at our sport. However, as our maturity level within our sport increases, it is natural for our rate of improvement to slow down, eventually converging to our individual maximum performance potential. Detraining occurs from the point in time at which our performance level stagnates and starts to decline, either due to the body reaching certain plateaus, or because of a reduction or cessation of training. The rate of decline is high in early stages, slowing down later on to a plateau of untrained performance level.
Figure 2: expected rates of performance growth/ decline with training or detraining
I would like to focus on what the reduction and cessation of training mean in practice? Well, in short, don’t worry. Not being able to train for three days because you’re on a holiday or because work gets in the way probably won’t change your fitness level for the worse. To the contrary, in some cases such a non-voluntary abstention of sports can be highly beneficial, as it presents a much needed break from training that could provide both a mental and a physical recovery period.
Current literature suggests that very few noticeable changes happen within the first two weeks of exercise cessation. After about two weeks, the cardiovascular system – responsible for transporting oxygen throughout the body – is one of the first systems contributing to a decline in performance level. This is mainly due to a reduction of blood volume, leading to a reduced stroke volume and therefore limiting the maximum volume of oxygen uptake (VO2max), even though other factors start to decline and negatively affect sports performance. As detraining continues beyond two to four weeks, further reductions in the cardiovascular system, carbohydrate oxidation, and lactate production continue to limit our performance level.
The good news is that mitigation strategies are easy to implement. Maintaining at least one-third of training volume and two-thirds of training intensity could provide sufficient stimulus to postpone a reduction in fitness. So, an athlete who normally runs six sessions per week, two of which are high-intensity, might see little to no changes in maximum performance for an extended period of time when reducing training to two to three weekly running sessions, one of which is at high-intensity. Of course, this training load will not be sufficient to enable further performance improvements, nor to maintain performance indefinitely. But it will postpone the point of detraining.
Overreaching and overtraining
On the other end of the spectrum is the case of doing too much, too soon or going too hard. By not giving your body the time it needs to rest and recover (phases 2 and 3 of the supercompensation model), or by consistently introducing training loads you are not ready for, you will give up on the steady increase of your fitness. You will not allow for the supercompensation effect to take place, because you will present new stressors and stimuli to your body before it has had the chance to adapt to the previous ones.
I would like to present three stages of doing too much: functional overreaching, non-functional overreaching, and overtraining.
By introducing training stimuli to our body, we simultaneously introduce fatigue. For the purpose of better understanding this concept, it might be useful to distinguish between acute fatigue (on the short term), and chronic fatigue (long-term fatigue).
An example might clarify this: during a multiday training camp, you will inevitably increase your training load. You might train twice a day for three or five days on end, even though you normally would never have such a high training load. This will lead to increased levels of fatigue, necessitating adequate and prolonged recovery time. If the acute fatigue and muscle damage were to manifest as heavy and sore legs, three days of rest might be enough to recover and feel ready for more training. However, the effect of the training camp will not have faded away completely during these three days. That might happen only over the course of four or five weeks. It would not be prudent to organize such a training camp every two weeks, as this will increase your chronic fatigue levels to unhealthy levels.
In the context of the training camp, you will deviate markedly from your average training load, resulting in a state of overreaching. As you diligently recover over the next couple of days, your acute fatigue will have subsided, but you might have missed the window of opportunity for building on the supercompensation phase of your last training session. However, the overall result (the gains from the training camp minus the losses from the days off) could still result in a net performance gain. Your recovery days would constitute the prolonged rest phase of the supercompensation model for the training camp as a whole, allowing you to regain fitness, even though you haven’t trained for a few days. Your state of overreaching resulted in a net positive effect, that is to say, it was functional.
Another example is that of a recovery period after a high-priority race. Having complete the marathon race of your dreams, you might take two weeks off of training, forfeiting some immediate fitness gains for the sake of a recovered and healthy body and mind that are ready to take on more training. The overall result is a stronger body and a net positive effect of your functional overreaching on race day.
On the other hand, non-functional overreaching is an increase in training load that is so consequential that the required recovery period will not allow you to come back stronger. You have gone too far, if you will, and reaching a healthy physical state will take so long that you will have to incorporate a decent amount of recovery and base training to first get you back to your initial performance level. So if you were to participate in biweekly training camps, I’m pretty sure that after about six weeks, you will notice negative health effects that set you back too much, and the overall result will be a net negative.
Overtraining is the final stage of doing too much, which happens when you repeatedly ignore your body’s signals during the states of overreaching. Overtraining is a clinical diagnosis that presents as an extreme form of non-functional overreaching, with the addition of a longer performance decrement, and severe symptoms and physiological maladaptation, from which full recovery is long and difficult. True overtraining syndrome prevalence is rather low, and might even be related to other factors such as general stress management and low energy availability.
If you want to safely start training or continue improving, it might be helpful to get the support of a coach. They can help you progress safely, based on your individual needs. However, you should not consider your coach as a medical professional. Even though they can partly take on the role of a nutritionist, doctor, physiologist or psychologist (and should do so if they are worth their salt), they should refer you to the adequate domain specialist with your specific health-related questions.
