I am 53, 5'7, 68 kilos. I am a serious runner and cyclist. I run all distances; no ultra marathons and train 6 days/wk. Also, I have used compression socks for the last year or so, and these tights blew them away hands down. These tights are top notch and well worth the investment. They fit like a glove and perform beautifully.  I put in 2 .30 hours last sunday and my legs felt fresh, springy and ready to hammer. I picked up the pace in the last 3 km to 4:15/km (garmin 310 xt) and didn't feel sore nor any impediment to do so. Awesome!!! There's only one caveat, they aren't easy to get into, specially when it comes to getting them thru your feet (recommend you do this sitting down); same is true when taking them off. So, put them on without socks. Otherwise, go for it and have a blast.