Normally, when someone wants to start learning to play guitar, we start buying the most economical one in the market. Not even the most exalted guitarist could play his high-speed solos with that instrument. For those who want to reach a high or professional level, you must start at least with a mid-range guitar, otherwise, to try to achieve speed you have to force your fingers and develop a bad technique that will avoid getting effectiveness, and unlearning or removing those vices acquired with a cheap guitar is more difficult than learning from the beginning.
I consider that in order to have the possibility of being quick in the solos, two aspects that are the most important must be kept in mind: THE RELAXATION OF THE MUSCLES AND THINKING OF THE NEXT MOVEMENTS IN ADVANCE. Of course, talent, practice and other factors affect performance, but they are not as decisive as the ones I mentioned earlier.
THE RELAXATION OF MUSCLES.
When we see our favorite guitarist performing a complex song, especially if it is Metal or Rock, we see in them certain postures and facial expressions that make it seem that they cling to the instrument with aggression and strength, however they are gestures to make the concert spectacular. If you look carefully at your fingers or arms you will realize that they are totally relaxed. The reason is simple: If you are tense, the muscles opposed to the movement that must be done will hinder the work of the finger that should go to one direction. If you have to press a string quickly, the muscle that "closes" the finger will move slowly because the tension of the muscle dedicated to opening it will offer resistance. This slows down the agility, besides that it generates an extreme fatigue and even injuries if you play for long times. And as I mentioned earlier, getting rid of that vice is more difficult than learning a precise movement for the first time.
It is important, therefore, to learn to isolate only the muscle that is going to be used so that the opposite does not hinder its movement. It takes a lot of practice and concentration for that. In addition, the fact that we are going to play a fast solo, involuntarily causes us to stiffen without realizing it, especially the shoulders and neck. To practice fast shredding correctly, it is not advisable to do it for a long time without stopping. After a minute, we rested for a moment and went through a kind of monitoring checking the muscles were unintentionally tensed, then we relaxed and practice again, always thinking about loosening the muscles that do not need to be applied. There are even people who in their concentration and tension begin to breathe choppy, which further affects the tension and nerves.
The thumb of the left hand is also a finger that forgets that it must be relaxed. It should be simply supported behind the fretboard, and should only offer adequate resistance when pressure is applied in the moment of stepping on a note with one of the other fingers of that hand.
Another very difficult defect to eradicate is the pressure that must be applied on the strings on the fretboard. Many people squeeze with unnecessary force, tensing and obstructing the execution of the other fingers. You must experiment what is the right pressure: For example, we press with the index finger the first fret of the first string very lightly and we make it sound. If a clean note is not heard, then the string must be pressed a little more with that finger until the correct sound is already obtained. That pressure is what you should always keep in mind to begin to be aware of the necessary pressure. Many times that pressure is less than you thought. It is convenient that the finger that play is just behind the fret to minimize the effort, but never above it, because, an unwanted buzzing happens. There are quite a few exercises on the internet to speed up the fingers with some scales, and we can also invent ours based on our deficiencies.
THINK IN ADVANCE THE NEXT MOVEMENTS.
This part is interesting, because after a while the practice will get used to doing the work automatically. Often the amateur guitar player only thinks about the movement that the hands should do at the moment, however, if he is also aware of the next movements that are going to happen (at least the next two notes), the other fingers will be preparing and positioning, ready for only a small movement to be made. If you do not think in advance, it is possible that the finger of the next movement will be far from the place it should be, and that is enough to delay your arrival in the fast passages, besides that it diminishes your precision by being far away. Always try that the fingers of the left hand (in the case of the right guitarists) are always close to the strings.
When begin to play, We must be focused and not do many repetitions without always thinking about each movement. It is worth one hour more than ten while watching TV or watching something else. Sooner rather than later, we will get the results we want, and when they become a habit they will not need to concentrate so much to play as we want.
Thanks for reading, dear friends. Any additional contribution You want to make is welcome. Happy day ;-)
Images:
https://www.guitarworld.com/lessons/tips-guitarists-how-build-shredding-speed
https://elitemusic.ca/guitar-shredding-playing-slow-to-play-fast/
https://angelsguitar.com/dominar-cejilla-guitarra/