I found out what it is...

 Ok, the marathon is not trying to dope me. It was killing me not knowing so I took it down to the front desk to ask for translation. Turns out its a very popular Chinese Medicine...the front desk receptionist couldn't explain what was in it (ginseng was all she knew) but was impressed that I had it (probably b/c I am a foreigner). It's good for the heart and muscle aches which makes sense why the marathon committee was giving it out.

I might try taking this after the run.