I live in south Florida where it's hot as balls 9 months out of the year, warm 2 months out of the year and cool 1 month out of the year, anyways. I have a 15k race I'm doing next month and all my training i do is without a shirt. The other day i did a training run in a singlet and remembered quickly why i ditched wearing those back in March. So is it appropriate to wear a top of some nature during the longer races? I wear a singlet in 5ks as much as i hate it.