I know you said workout at home, but if you live close to some mountain biking trails, you could give it a try. I usually climb for 45 minutes to an hour as fast as I can...which for me is like doing several sprints. Then, as a reward for my self punishment, I get to fly down the hill with a huge adrenaline rush. And all with no lower back or knee pain. Of course, sometimes there is a little trail rash.