I bought some of these shirt last time they were offered. Nice shirts. Nice enough for casual wear on hot days too. (Too cold out to test that theory right now)
I'm 5'1" with narrow shoulders. I bought the small v-necks, though an extra small probably would have worked better. Also, for me, the shirts are a bit long.
I haven't actually worked out while wearing these shirts yet. Perhaps Woot is giving me a hint to get off the computer and get to the gym!