Hey Vic, after you've been on this thread a while, you'll see that things don't always turn around real quickly here. Not all the people on the thread check into LRC that frequently. Your question is pretty specific, and it might be hard to get a reasonable response. I personally don't use orthotics and have relied mostly on some moderate posting available in stock shoes. A couple of guys I often run with love their Mizunos, so I got a pair of Elixirs when I won a gift certificate. After running in them a few times, I never warmed up to them, as they're too stiff and unyielding for my tastes. I have relinquished them to grass-only runs; I do like the upper though.
Rtype, after your success on that running backwards suggestion, I went online to see what there is on running backwards. I was pretty surprised at how established retro-running (or retro-locomotion), as it is commonly called, is in other parts of the world. Best academic link I found was Prof. Em. Bates at Oregon.
http://darkwing.uoregon.edu/~btbates/backward/backward1.htm
There are plenty of PT sites that suggest it works great for knee rehab or for tightness in the hamstrings...I haven't found definitive research though. Some elites (notably Sonya Richards) use retro-running in their regimen. I also found that Rod Dixon used retro-running very regularly.
Kiryea, regarding max heart rate, I went online again, and found this discussion from Runners World:
http://www.runnersworld.co.uk/general/heart-rate-training-find-your-maximum-heart-rate/181.html
I was happy to see that it agreed with my experience, but it also suggests to me that your 186 bpm is probably closer to your true reading; that's a nice upper level for a 50+ yo! Mines about 182-183 bpm, when I was 18 yo is was more like 235-240 bpm. :-/
Finally, returning to the strength discussion. I had always felt that I could do whatever strength exercises I needed with my own body weight. But with the knee issue that I had this summer, I couldn't discount the possibility that the lunges I'd been doing all spring contributed in some way to the knee going over the edge when I jarred it this summer. So to some degree, I'm thinking that maybe I can get the same benefit as lunges without jarring the knee by using weights. Thanks to everyone for their insights, perspectives, and routines regarding use of weights.