I am sorry I know there is a thread out, I am new to this forum. I have a 10 month old sheltie, that loves to run in the trails with me. I have no leash on her and she goes in circles, runs up waits, and starts all over again. One thing we started was hiking. I have been taking her on two hour hikes up a mountain. Some of it is rocky and she has to jump up and then come down and she has to jump down off the rocks. She is still full speed ahead. I have been going every weekend for the last few weekends. We do some jogging as well. Again she is off leash. She mostly stays right behind me when we are jogging. My question is - is this too much pounding on her legs climbing those rocks. It is not a really long section, but maybe I need to cut back.