I am a 40 year-old female, 5'6" and 117 lbs. I have run 14 marathons in the last dozen years.
I bought these tights in a size Small a few days before my last marathon in May. Wore them only once for a short 3 mile run, before the marathon.
Overall, I liked the tights and felt that they provided good support around the knees and prevented my quads for getting cramped in the last few miles of the marathon. The only that that bothered me a bit was the tightness around the calves. It felt like my circulation was being restricted too much near the end of the race. Might just take some getting used.