[j1o1h1n]

"Science for more than a half-century has found ways to complicate the matter ..."

Peterson, T. C. and Wallis, T. W. R. (1997), Running in the rain. Weather, 52: 93–96. doi: 10.1002/j.1477-8696.1997.tb06281.x

http://onlinelibrary.wiley.com/doi/10.1002/j.1477-8696.1997....

  But all this is model and theory. What about reality? To predict the weather four 
  days in advance you may want to use a model, but to truly determine whether a walker 
  or a runner would get wetter in the rain one can simply conduct an experiment. ... 
  we purchased two identical pairs of hats, sweat shirts and pants, ... Departing 
  at the same time, Dr Wallis ran the lOOm at a velocity of 4.0ms-' while Dr Peterson 
  walked the same distance at 1.4ms-'. The total water absorbed by the walker was 
  0.217kg and by the runner 0.130 kg. 
  Running, therefore, produced a decrease in wetting of 40 per cent.

[delazeur]

This calls for follow-up research on how the absorption ratio varies with distance traveled. Please excuse me while I apply for some grant money.

[giardini]

Argumentum de evolution:

I find it intriguing but also somewhat self-satisfying that the natural response (to run), placed in our DNA by evolution, is confirmed by both mathematics and experiment. One wonders why one should have asked at all!8-))

[logicrook]

Actually, if you run fast enough, you can get wetter because of water projections by you legs/feet. You can end up with a wet back, wet lower legs, and nearly dry front.

As delazeur said lower, this calls for follow-up research!