system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5; How does tearing a muscle while working out suddenly give it space to regenerate and make MORE muscle. Why do muscles get bigger?
gpt
You do not increase the number of tissues in your muscles. Instead, when you exercise a muscle a random selection of fibers in that muscle break down (but do not disappear). Depending on the extent of effort a varying number will do so. 

Afterward, those muscle fibers will rebuild and will be a bit larger. Depending on the energy source for the muscular effort there may be some soreness. This is why most training varies from day to day emphasizing different muscle groups. It's better to allow muscles to rebuild while they're (comparatively) resting.

Thus, more frequent break-down and rebuilding event will cause muscles fibers to get bigger and bigger each cycle.