sport certificate of completion for high school?

[Madoka-chan]

Hey, I'm a high school student and last spring I completed the season for swim. I never got a certificate of completion, but at that time, I didn't know you were supposed to get one; it was my first time joining a sport and I assumed that they would put it in my record that I was on the swim team. But quite recently, my friend told me that he heard that colleges are now requiring certificates of completion for sports as proof that they actually participated in that sport. That makes me SUPER worried because I didn't get a certificate of completion and it's probably too late to ask my coaches about this now.

Is it true that colleges now require you to have a certificate as proof? Can anyone clear this up for me? What should I do? Thanks in advance for any suggestions and advice.