No matter what degree we want to achieve, we need professional and targeted training. Will muscle growth reduce the flexibility and speed of the body? I think this is mainly related to your targeted training. There is a proverb that as you sow, you reap. Where you work hard, there will be a flower, and so will fitness.
If you only want to grow muscles for nothing else, you can really meet your requirements in body shape, but it is likely to reduce your flexibility and speed, because you have not received professional training in these two aspects, and your natural ability will be relatively poor. Moreover, in our real life, many people exercise only for the pursuit of shaping, and do not have professional and targeted training for muscles.
So it will only lead to a great increase in your muscles, but your speed and explosive power have not been well trained, so whether you will reduce your flexibility and speed depends on whether you have made some efforts in this regard. Fitness is a rewarding process. Although the process is slow, as long as you persist patiently, it will definitely have an effect. Therefore, it is necessary to find a fitness method that adapts to oneself and makes oneself feel comfortable in life.