Okay, what I didn't want to happen...happened. I have been going for weighted walks and to get the HR up, I would jog a distance to increase HR and then walk again. Once the HR dipped below 108 or so, I would jog again...and so on and so forth. Well, my left knee started to swell again. So I think I am relegated to walking/hiking and bike rides for cardio. That is until I get the rowing machine I want.