I spent an entire week fretting over what to wear to this mud run I was attending. When I found out it was going to be 30 or 40 degrees, I researched, and researched, and had a hard time coming up with any information on what to wear. I went to the thrift store on Friday afternoon, when the mud run was on Saturday. In my head, I envisioned a long sleeve pink shirt, but knowing how thrifting goes, I was ready to settle for a pilled, losing-stretch-everywhere, loose-around-the-neck castoff. But! Lo and behold I happened to find this beautiful, brand-new-looking Reebok mock-turtleneck in my preferred shade of hot pink. Score! I also purchased some trashed tennis shoes, intending to wear those. The morning of the race I put them on and realized they had absolutely no traction and they had a plastic piece from the heel coming through that would have given me intense blisters.
So I ditched those in favor of my Merrell Trail Runners (which often get muddy anyway) and the rest I had already.
Here's the breakdown:
Spandex sports bra: American Eagle
Underwear: Spandex sports underwear from Patagonia
Long-Sleeve Turtleneck sports top (stretchy and easy to clean): Reebok/thrifted
Shorts: Adidas/thrifted (if you feel comfortable in just running tights, rock it, but I wanted another layer!)
Running Tights: Nike/tag sale
Socks: Dollar store (these will get kind of trashed unless you have synthetic socks, but those make it easier to slip out of your shoe)
Shoes: Merrell trail runners/gift (make sure they're washable and tie them really tightly!)
Spandex or another sporty material is best because the mud will slide off and won't cake in the fibers to stain. You'll want to bring a towel and dry clothes (including underthings), as well as a trash bag or two to put the dirty things into after you change.
I did not wear my vest, gloves or sunglasses for the race. The key is to keep moving! If you stand still too long you'll get cold no matter what you're wearing. I think there was less mud though, since the ground was very cold.
At the end of the run, I took the whole lot home and threw it in the washing machine immediately. It all came out just fine!
Have fun, be safe, and enjoy!