I realized yesterday that maybe not everybody on this site has access to $80 running shoes, or even a run store to learn about the appropriate fit.

I don't know a lot, but I thought I might share what I've learned.

- The purpose of any shoe is to protect your foot from stuff on the ground. In addition running shoes absorb the impact of your foot hitting the ground in a running motion (which is what makes them different from cross-trainers, etc). Every manufacturer has their own way of doing this: gel, shoe structure, what have you. That's what makes the different manufacturers different.

- A running shoe should be about one shoe size larger than your street size (I wear an 8 1/2 normally, and have worn a size 10 running shoe). This is because your feet will slightly swell when running. They will also spread out slightly when you land on them. If your foot doesn't have room inside the shoe, your toes will hit the front. You may not necessarily realize that is happening because you will unconsciously change your stride to protect your toes. This will cause calf pain because your calves will take on the work of balancing that your toes are supposed to do.

- Running shoes can also help you with any problems you might have with foot motion. For instance, I pronate (roll in toward my arch) on my left foot. A shoe with a wide base or a little roll bar in the arch helps keep my foot stable.

- There is a guy here in Atlanta that does a lot of the 10ks in jeans and bare feet to prove that you don't need hundreds of dollars in equipment to be fast. And his point is good. However, most of us find that the dollars spent on a quality running shoe is worth it, if we can afford it.

Here is a link for more expert information: http://www.roadrunnersports.com/rrs/content/content.jsp?contentId=200098

I hope this helps!