I have been running, biking, backpacking, every day wearing these for Atleast 5 years. I became a 100% believer when i realized i could soak myself with ice in my hat, and let spectators soak me with a hose during the run portion of triathlons and never got a blister! It gets HOT racing in south FL. I have used these socks for ultramarathons, long haul fast packing weekends, 50-80 mile mountain bike races, everything.... you cannot beat these socks. I was backpacking the Maryland AT with my brother in February. About 1/2 way through. The first day (10 mi) he started talking about hot spots . We talked and i offered him my back up aspire 4 socks i brought to use the following day. I use these as a liner with the pursuit medium hiking sock. He put on the swiftwicks and became a believer! 30 miles in below freezing with howling wind became much more fun. These are great socks!