system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why muscle soreness takes till the next day to kick in why not right after training?
gpt
Muscle soreness is caused by microtears in the muscles which appear during exercise. These microtears lead to inflammation in the muscles (that’s what causes the pain), but the inflammatory process needs some time to start, hence the delay.

The previous mechanism based on lactic acid accumulation has been rejected in light of new evidence. We now know that lactic acid is released during exercise and stops being released about one hour post-exercise, so it couldn’t cause delayed soreness.