One obvious point to make is that most marathon winners are from East Africa. Participants in these races are mostly white people.
One of my favorite books on running is What I Talk About When I Talk About Running by Haruki Murakami, which is kind of about writing too. I was happy to see you mention Japan in this piece.
One thing we can do about it is to offer free entry to young people of color, or maybe a sponsorship program to encourage more people to run. Those entry fees are definitely a barrier for the sport.
But also educating young people so they get hooked on it. An athlete like Kenya’s Eliud Kipchoge should be touted, and would make a good addition to the other black athletes that young people idolize.
Do you take your students out for a run? Do they know you are a runner?