Managing fatigue after training, after each training session, is one of our top priorities as runners. And I'm not going to talk to you about techniques to improve its recovery. I have already covered this subject at length in this article. Here, I want to lead you to a better understanding of the notion of fatigue according to the type of training you will do. And above all, understand how to manage recovery time according to each type of training.
To progress is to voluntarily generate fatigue
Because yes, the basis is that to progress in running, you have to stress your body. It forces him to adapt and therefore to strengthen himself. In itself, we can even say that the more stress we generate, the more we progress! Unfortunately, if it were that simple, it would be known and the words injuries and overtraining would be unknown to runners! This is not the case because the more you train, the more you get tired and progress is to manage this fatigue well. To do this well, it also means managing your level of fatigue so that it is not higher than what your body can handle.
Each type of training induces a different level of fatigue
I won't tell you anything if I tell you that a jogging is less tiring than a split session. For those who run their jogging in fundamental endurance, this is obvious. We come back from a jogging session with very little fatigue. On the contrary, you feel in great shape. When you come back from an intense split session like a 30/30, you're empty! Managing fatigue after training means adapting your recovery time to the training you have done.
Concept of total and sufficient recovery
In the rest of this article, I will use two terms that must be clearly distinguished. The first: total recovery. No need for much explanation, it's just the time needed to completely erase the fatigue associated with a workout.
Sufficient recovery is much more interesting. It represents the minimum recovery time to be taken before moving on to a new workout. We will not have recovered completely, but we will have reduced the fatigue to a level low enough for the next training to be profitable.
The different types of fatigue in detail
A workout can generate fatigue in several ways. And each type of fatigue is to be taken into account when managing fatigue after training.
Muscle fatigue :
Our muscles are made up of multiple muscle fibers that are not all used at the same time. Depending on the intensity required, the number of muscle fibres required is more or less important. Logically enough, the more you use your muscle fibres, the more likely they are to tire.
Everything is controlled by the brain. He is the master of all our movements, he is the one who sends electrical signals to the muscles to ask them to create energy. Fatigue here consists of a decrease in the quality of signal transmission and reception. The motor neurons that control the muscle fibres are tired and have difficulty doing their coordination work properly.
The creation of energy in the muscles requires that a whole bunch of chemical reactions be carried out continuously. If, in itself, the body has the ability to create energy "to infinity" if we feed it properly, gradually the system will tire and disrupt the reactions that occur in our muscles.
It is the one that feels the most. General fatigue is in fact the sum of all the types of fatigue I mentioned above + those of daily life which has a major role. General fatigue is like our energy bar in a video game. And this energy bar is obviously limited. We start with a more or less full bar every day depending on the fatigue we keep from the previous ones. And our daily activity will gradually drain this energy bar.
The more we give ourselves in a day, the more rest we need to recover our initial energy level. And that counts for both physical and mental activity. If we had a very stressful day on all aspects of our professional or personal lives, fatigue is important before we even start our training. This counts in the quality of the progress that it can generate. But also in the amount of fatigue that we will store by doing it!
Fatigue = Volume x Intensity !
A fundamental notion to understand is that the calculation of fatigue after each training session is unique! The only real way to quantify the fatigue generated by a training session is to use the formula Fatigue = Volume x Intensity. The most tiring sessions are to be found in the extremes.
A 2h30 long outing at the end of marathon preparation (often including a marathon pace!) includes a large volume and intensity. It is therefore a session that induces a lot of fatigue. High intensity sessions will not be at high volume but will still induce a lot of fatigue. And of course, the worst is still the competitions. It runs at the maximum intensity that can be held over the running distance. The fatigue calculation therefore explodes the counters, especially from the half marathon!
Some simple rules for calculating fatigue
Many paragraphs before arriving in the concrete... but I think it was essential. To manage fatigue after training, you have to be able to understand what it means, what it is made of, how it is generated. Fortunately, from there, I will provide you with something simple. A classification of training at three different levels of fatigue. The recovery time indicated corresponds to the two "limits" mentioned above. We talk about sufficient recovery time with the first duration and we go up to total recovery time with the second duration.
Easy training = Minimal fatigue = 6 to 24 hours of recovery:
We are mainly talking about slow footings. They are relatively short (depending on the overall volume of the runner and the race he is preparing). For the non-beginner runner who trains regularly, a simple jog is not a training that is supposed to generate fatigue. It's supposed to be easy and we feel easy from start to finish. The recovery time is therefore minimal and can be as little as 6 hours before another training session (for runners who use the bi-daily in their training).
Cross training also falls into this category. As I mentioned in this article, intense swimming training will remain light on the legs. It will therefore enter the "easy" if we are interested in quantifying our fatigue specific to running (but not if we look at the general fatigue). For the bike, it's a little different because it's the legs that work. Only easy, non-invasive bike rides are included in this category.
Average training = Fatigue to consider = 24 to 48 hours of recovery:
As its name suggests, we have here all the training that does not generate enormous fatigue... but a fatigue that, when accumulated, is often the one that leads to overtraining/injuries if we are not careful... This is the trap category where some will unconsciously put many more training sessions than they imagine.
The average training sessions are all a little long compared to what we are used to doing (if your standard training sessions are 45′, a 1 hour jog for example). They are also the footings running at the aerobic threshold for example. If it is voluntary, no problem, but it must be taken into account when looking at the recovery time. Finally, we will find all the "light" split or tempo sessions. By light, I mean the maintenance sessions of a quality where we will not necessarily give 100% / that we will end up with a little bit under our feet. These easy split sessions are not very useful but can be very useful!
Difficult training = Fatigue not to be neglected = 48 to 72 hours of recovery:
It's not complicated, so all that's left goes here. These are all fractionated sessions where you give yourself 100%, where you go all the way. But they are also the ones that generate the most progress. They are also the ones who ask for the most recovery behind so that overcompensation can happen and progress can be made. (To find out what overcompensation is, click here). Doing a big session is great, but without the right level of recovery, it's unnecessary fatigue. Give the body time to do what it has to do and you will progress more, sometimes by doing less!
As I said earlier, fatigue is not just about intensity, it is also about volume. A long outing (longer than the one we usually do all year round). The classic 1h15 if repeated every week becomes a "medium" training. I know that 48 to 72 hours of recovery may seem like a long time, but it's what the body needs after these very intense training sessions. That's also why we have to play intelligently with intensity and long outings. To use them too much is a lot of fatigue and a lot of fatigue can be harmful.
Can we train before sufficient recovery time?
Of course! Of course! First of all, because the times given here are arbitrary. These recovery times will differ from one runner to another depending on his experience but also on his natural ability to recover. Sufficient recovery time does not therefore mean minimum recovery time. But training before reaching sufficient recovery must be done in full knowledge of the facts.
The more incomplete the recovery, the higher the level of fatigue remains and the less time the progress of the previous training had to materialize. If a training is carried out within this time frame, it must be adapted. Adapted training may mean limiting yourself to a recovery jog (short and slow jogging, see here). Or to be a training in a carried sport such as cycling or swimming without great stress on the legs.
Voluntary fatigue training
Of course, you can also voluntarily try to train with a high level of fatigue. Linking several intense workouts or fairly long workouts closely together can be a very interesting strategy when used properly. It can generate an even greater progression than a simple isolated training. It works very well but you have to be doubly careful about the recovery you take after this sequence! Because the level of fatigue then climbs to the red and the risk (of injury or overtraining) becomes significant.
This is a method that marathon runners use a lot, especially to work on long endurance. We start by pre-fatiguing the body with an intense session. And the next morning we make a long trip to work on endurance on fatigue. Perfect to simulate the second part of the marathon!
Below I have put a graph showing the effect of training too close together. Fatigue climbs faster than our level and the overall effect on our performance is therefore negative! The full article to understand this is available here.
Fatigue level management with running watches
It is on a system similar to everything I have told you here that today's running watches work. Whether it is Garmin or Suunto with their "Recovery Time" indicators, the system is the same. They compare your session data with your profile data, mainly your Maximum Heart Rate. Based on the time spent in the different cardio areas, the watch calculates how long it takes you to recover from a session.
5 rules to adjust fatigue to your profile
Fatigue will generally be less if you train regularly
Fatigue will generally be less important if you are in a period of form
The recovery time will be minimized if the runner is serious about the recovery aspect (and vice versa)
Fatigue will be less important on a type of training to which we are accustomed (the body adapts in a specific way so if we reproduce the same training, it has prepared itself specifically for that one)
The fatigue of a session done in a pre-fatigue / incomplete recovery state is added to the fatigue of the previous training.
Use fatigue well to improve!
In the end, the interest of all this is clearly to find a balance in your running practice. A balance that allows you to progress and blossom as you run. But also, and above all, a balance with daily life and professional or family obligations. Putting too much energy into the race is a dangerous game. Wanting to improve is good, but you have to make sure that it is worth it. Prioritize the right places and define sports objectives that are consistent with what energy is left to achieve them... that's the challenge!
But once you "agree with yourself" on what is realistic to do, you can train accordingly and use fatigue to improve your progress!