Hamstring Stretch Devices?

I've found that if my lower back is bothering me, the quickest way to relieve it is usually to stretch my hamstrings. I've been stretching by lying on my back and pulling on a nylon strap looped around my foot, as we practiced in GM 101. But using this method, I find it difficult to keep my leg locked straight, and hard to keep the strap at the correct angle (which would seem to be parallel to the floor). Hip hinging, of course, offers a good stretch, as I do when I brush my teeth, bend to help a student at a desk, etc. But I'm looking for a way to add more stretching while lying in bed or doing other exercises.

I ran across two products on the web that look promising:

1. IdealStretch: http://www.idealstretch.com/index.php.
I like the way it keeps the leg straight and aligned while stretching. It also looks like it gives the user good mechanical advantage to maximize the stretch.

2. HamstringStretch-Rx: http://www.abledata.com/abledata.cfm?pageid=113583&top=0&productid=114116&trail=0.
I like this one because instead of trying to pull a strap up towards the head, I find awkward, it lets the user pushes a bar down towards the feet. It also keeps the direction of the pull parallel to the floor.

Has anyone used either of these, or found other devices that work well? Esther, what are your thoughts?
Thanks, Eliot

1. You don't want to lock your leg when doing hamstring stretches because that tends to stretch, and sometimes tear, the muscle where it inserts on the bone. It's preferable to have some give at the knee so you feel the stretch in the belly of the muscle.

2. If you loop the strap close to your heel, it generally stays on the foot pretty well and stretches the hamstrings (the goal) more than the calf muscles (which you can more easily stretch in glidewalking by leaving your heel on the ground a long time.)

3. I consider this exercise to be a three-in-one: hamstirng stretch, rhomboid strengthener, and arm use patterner. If is awkward for most people to use their arms out ahead of them without the shoulders going forward, but this is really good practice for every day life. So I encourage you to practice this till it doesn't feel awkward.

4. I personally prefer less paraphernalia rather than more, but the second device seems to be provide okay forces if you are looking for a device.