I would suggest NOT doing this; it is not natural and you will cause more damage. (Dereck shakes his head) Instead I would suggest looking at "Stretching Scientifically" by Thomas Kurz.



While I have not done everything this book has suggested, what little I did help considerably for my flexibility when doing Taekwondo.

In all seriousness, DON'T even consider a stretching machine and especially not one you may try to design yourself. Leave that stuff for the movies where it belongs.
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"IF I COME ... I'M BRINGING THE PAIN WITH ME"