Dude,
This proly won't interest you, but I'll mention it anyway, jic, as it's been something that I've been experimenting with for some time, and just recently have been doing "full" multi-minute sessions on this.
It turns out to be really *really* elegant, from many povs. And it is something doable by you, Fran, anyone, even athletes.
Running indoors, without a treadmill. And not in a circle.
How??
In as little as a 6' linear space by 3' wide (poss. even less), "run" (or walk) forward and backward, forward and backward, again and again and again. Def'ly start with walking, build up speed.
It initially seems stupid, but the physics/physiology are pretty irrefutable, and my sessions have been quite illuminating. It wasn't until I started my dorky treadmill that I really grokked the value of these.
I do this in a 10 foot line.
What is remarkable about this is:
It is *near-zero impact*, as there is not enough room to develop the vertical component in normal running, therefore no descending impact. It forces most of the exertion along the horizontal plane instead of the vertical.
It appears to use many more muscles, but differently, because of the constant accelerations/decelerations, including those of the torso, for balance/momentum.
Because you are going backwards, it recruits a whole different and full set of agonist muscles (agonist as in opposite, not agonizing, altho this may be true as well. ). Even when I run outside, I try to do a short lap backwards.
The horizontal forces are substantial (f = m ***a***, yo), and a carpet that is at all loose will show it.
Just a few minutes will have the heart pounding, bea, of course varying with intensity.
A very safe, controllable, efficient, effective workout. Add handweights (the HeavyHands method), and it becomes one of the great workouts.
Very good neuromuscularly as well, for balance, coordination, perception, etc.
And, afaict, much more resistive in nature, than pure running, but with a resistance quite pegged to the speed, which gives it a very versatile hybrid nature between the aerobic and anaerobic.
I have to still experiment more with this. Like a treadmill, you can actually watch TV while doing this, just as you can on a treadmill, BUT it's much quieter!
Need good sneakers, tho, for good grip, due to the substantial accel/decel.
Sprinters, iirc, actually do a version of this, but not in such a small space.
You should try this just to see how this motion impacts the body, might be something Fran can do. It is very controllable, with a slow walk making it all seem inconsequential, but with a sprint-speed making it seem like Holy Shit!!!
You may opt for faster "running" forward than backward, as the backward is more difficult. A two-speed "split" is not hard to coordinate at all. In fact, you can "run" very quickly forward, and very naturally just walk back, if you choose.
And, as hokey as this may sound, it may be something y'all can do together, possibly meeting at the center, like a spring. Don't crash!!
I'm off to do a session now -- a few minutes on the treadmill, followed by a few minutes of this. And V's, but of course of course of course.... :)
Oh, no foolin, keep this mum, as I will be patenting this... no foolin... If it somehow takes off, I suspect I will be off'ed by the treadmill peeple/mfr's.
Later, I'll tell you a story about an oil measuring device my buddy designed, that had his life threatened.
Later,
Kris.