This is one of the questions that dog many an undergraduate physicist. The question of whether to run or walk in the rain. Now it is not as easy as you might think. Both Brainaic and Mythbusters have done this and come up with the conclusion that it is better to walk. Alas they are wrong. So first off what is the thinking that leads people to believe running is worse.

Basically the idea is that as you are running you are covering a larger area of rain. If you think of the rain falling down. imagine the rain that is falling on your head. When that rain falls on your head at a point directly in front there is the rain that is going to hit your feet