I bought these for my husband who works out consistently, but also works outdoors. My husband is also hot-natured so he doesn’t like to wear heavy clothing that will make him sweat when it is cold. These are perfect because they allow him to stay warm, without causing him to sweat. He said they are very comfortable and he wears them when the temperature is expected to drop. He buys the normal version of these (no thermal lining) for the spring/summer. He is 5’8 , 205lbs with solid muscular thighs and the XL fit nicely.