I agree with Lisa. When I got Sherman, he was already 7 years old so we did not have to go through that training. But Sher is also 20lbs and a bit longer legged. Even at that he has problems keeping up. When I watch my daughter's yorkie she can barely keep up with me on the walks I take and I end up carrying the useless thing.
Sophie may never ever be a "running" partner for you just 'cause she is so little....