We do it, but why and how does it work?
We can break this down into two cases.
Athletic, healthy one.
Through a variety of training, we develop and strengthen our circulatory, respiratory and muscular systems. Workouts are not boring. We also train our motor skills. We have a goal, we improve our achievements and results. A fit and healthy human.
Theoretically, during training it is enough to reproduce everything that can happen to us during competition.
How will the body react when it is not in contact with a typical strength effort (in cycling it will be riding with high power and low cadence)?
In other words, how will your body (how will you) cope without prior strength training (at high intensity) when competing against other athletes on a steep climb?
The timing of fatigue between a trained athlete and an untrained athlete is frighteningly and drastically different. What for you untrained will be something unimaginable to drive, for another it will be practically a ride (by the way, in such situations there are often suspicions of doping, which can be and are usually missed).
The feeling of fatigue is mainly the need for oxygen. An untrained athlete will need more of it, he will not use it properly. He will breathe through his mouth, ears and legs, but it won’t do much.
How can you visualize it?
Trained: inhales “rich” air, exhales “empty” air
Untrained: inhales “rich” air, exhales still “rich”
As an example, I can describe my first starts in an individual time trial, during which I was not prepared for an interval trial. Theoretically, the time trial is not an interval ride, but a small uphill stretch appeared on the route, which made it impossible to return to the pace and feeling from before this short, several hundred meter long uphill stretch.
Later races where I was properly prepared and where all speed, strength and strength endurance trainings were done in the training plan were completely different. The return to the speed and power from before the uphill stretch is practically a dozen or so, maybe several dozen seconds.
Same with speed training. There will be a moment where you will have to ride with a very high cadence and if you do not have this element properly trained, the energy costs will be so high that you will not recover until the end of the competition.
Endurance? Here we are dealing with the economic management of oxygen, obtaining energy from other sources, but also with the endurance of the whole organism, which we also need to train. By the strength of the body, I do not mean only the strength of individual muscles, but I also mean the strength of the skin of the hands or other parts of the body. This is still training.