I walked ~16 miles on last Saturday morning to come back home with sore legs. I had pain in the most unusual of the places. At the back of the knee but in the lower portion just above the calf. I was expecting my shins to give up first but it didn't happen. Strangely rest of the things were just fine. Little pain in the Achilles tendon which is normal for me. My Achilles tendon is my Achilles heel. :)