Your extracurriculars are all about continuity, longevity, and most importantly your ability to swing things if you need to. I did research with monkeys and I'm sure if I get an interview they'll ask me why and I'll do a good job of convincing them that A) it was relevant to medicine and B) that I did it because it meant something to me and wasn't just about filling up space. This is an important distinction. If I have to talk about being an EMT, I'll mention that I was interested in being an EMT before I even considered medicine and it was working with paramedics that helped push me towards medicine.