One tiny question for my English paper.

Hi, I'm Japanese. I'm learning English.

I have a tiny question for my English paper.

I hope you can help.

I think I have the entire paper finished. I had to write the short story in present tense. Except for one sentence I need help on.

Here it is:

-----I am aware of the people surrounding me, nimble runners whom I can never aspire to beat in a race, their bodies conditioned for the event.-----

Is "whom" correct?

Or should I use "who?"

I'll thank this website on my paper for your help.

Thank you.

- Asuna