I feel you on the SSOOOO much energy part. If my boy doesnt get enough energy he is harassing everyone with every squeaky toy he owns in a perpetual game of fetch...
When we go for walks they have to be enough to tucker out my Yorkie and my Doberman which isnt an easy feat. We usually do a daily 3mi walk and mix it up with brisk walking, jogging and short bursts of running. By the time we get home both are tired.
I would say the safety of it really depends on your dog. A 3mi jog may be a little too hard on her but if you incorporate some jogging to your regular routine I think she would probably love it.
Both my dogs are also treadmill trained. In the event that it rains my Yorkie will burn off steam on that. I just sit on the floor next to him reading a book (never leave a dog on a treadmill unsupervised). My boys actually LOVE their treadmill--if they could figure out a way to turn it on themselves they would!
