There's no requirement that you have both. I don't have a non-clinical volunteer activity. Its better to have 1 or 2 things (like EMS) that you put a lot of time into than to pick up some stuff that doesn't matter. 2 years as an EMT is a whole lotta volunteer hours, and a whole lotta clinical experience. I'd just make sure you get some shadowing or hospital volunteering so you can see what PHYSICIANS do. Maybe you could pick up a non-clinical if you find something that you want to get involved in, but if you show you've committed 12 hours a week to EMS I don't see how they can expect you to find too much more time to volunteer elsewhere.