I love running with my dog but I wished I didn't have to hold a leash. I tried this system but the leash did not easily rotate around the belt so if my dog crossed sides I still had to fiddle with it.  And, although he is usually very good about running close to me, there are those times he sees something he wants to chase and he can't help himself and lunges.  This happened once while using this contraption and he jerked me right off my feet, luckily I wasn't hurt badly. He is a strong 75lb dog so I should have known better.