Hi Sylvie,
There is an exercise training program by Dr Leviene from Dallas that might be helpful for POTS.
http://www.sciencedirect.com/science...66070214002021
You can read about it in this blog -
http://potsgrrl.blogspot.co.il/2011/...-protocol.html
There is a lot of information about tests and treatments for POTS in that blog.

According to what you wrote here and on previous posts, if your blood pressure is falling when standing, I am not sure the diagnosis is POTS, as far as I know it seems NMH/OH.