Personally I have weak/damaged patellar tendons in my knees (AKA jumpers knee that vball and bball players get). If I'm riding a lot of rough terrain or repetatively hitting big jumps the lower part of my knees, mostly the right one gets really sore. Once its aggitated it can hurt pretty bad on hard carves but mostly it just throbs afterward and is sore for a couple of days. The pain is pretty focused on the patellar tendon so its the tendon/tissue at the bottom of the knee cap. I had to quit vball so that I could continue to snowboard, after vball games I could hardly walk, snowboarding doesn't aggitate it too bad.