system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why stretching the body without warming up is bad? Is it that bad, that an athlete's career can be sabotaged by not properly warming up?
gpt
The simplest ELI5 way i can explain it is: imagine you have a cold rubber band. Imagine you stretch it right away and it breaks. 

Next time, you’ll think to warm the rubber band up and ease it into stretching. In the case of the human body, your muscles, tendons and ligaments are the rubber bands.