Feel the tightness of the shoulder muscles after half an hour of rest without straining them. What has changed?

Muscles after playing sports or doing hard work look larger, tense and quite dense. All due to the tension of muscle fibers and blood flow. When some time passes, the muscles become soft, they are not tense and lose their previous volume, since blood circulation is restored during rest and leaves tense muscles. But still, muscles develop and gradually grow due to the fact that muscle fibers are torn and restored. Therefore, when playing sports, you need to take breaks for several days so that the muscles can regenerate normally.