Why are distance runners seen as nerdy by society?

That’s interesting. I’ve heard that’s somewhat true at other schools, but when I was HS (a few years ago) it was mainly socially normal kids who were on the smaller side when they started 9th grade.

“Running many hours each week” is almost as pointless as frequenting message boards for topics you think are pointless. But not quite.

Running has the highest proportion of mentally retarded people in any sport. That's probably why. If you hang with them, you become them.

At least you appear self-aware

The two are similar in the only point being entertainment, just like video games, masturbation, watching tv etc. but unlike running many hours a week, the others have far lower injury risk, nutritional cost, equipment cost, post-activity rest/stretching time etc., and it’s trivial to quickly drop the activity to attend to household or family matters if any that might need immediate attention.

Everyone deserves to be viewed as what they are not what they want to be. In the real world (not on the internet), I have never experienced what you speak of. Many times it is the opposite experience: someone somehow gets word that I am a runner, and we converse, and they think it is cool. Maybe they wouldn't do it, but they usually respect the drive. It's been this way as long as I can remember.

I also don't make a big deal about being "a runner", -- most runners do. This is annoying, and draws people to view you as a "nerd"; most "nerds" make their hobbies or activities so central to their identities that you cannot disentangle the two. One could say that this is an apt way to define nerds, as people whose hobbies become their "personality". This is the same reason why for many of these folks references become very important in their lexicon.

Next time you meet someone new, try not mentioning that you are a runner, and see how long it is until this naturally comes up, you might be surprised.

What I'm saying is this: most runners are nerds not because they are runners, but because they are nerds. You might be a nerd, -- and the fact that you are asking this question makes me think that you are! Most runners, however, are of the visage, the pale of an academic brunt. I will not belabor this point here.

Lastly, -- Life isn't a popularity contest, nor is High School. It's an open system where, if people don't think that you are cool, you can leave.

That’s quite the performative prose, the semantic analogue of onomatopoeia, patently evincing nerdery.