Have Positional Syncope But Sensation Of Passing Out Leaves As I Stand; Pressing In Chest. Explain Situation?

I have positional syncope but it is reverse positional syncope. In another words, if I stand up the symptom ( fainting or passing out) goes away. The worse time I get this symptom is when I position myself to do an angled leg press in the gym. I do not need to push the weight; I just need to put my feet up on the plate to get the feeling of passing out (which did occur one time). The other times I get the same feeling but less so is when I bend over or lay prone with a pad pressing on my stomach/chest. There are a few positional things I can do that help such as straightening my neck but does not preclude the feeling necessary. I am a 64 year old 210lb 7 % body fat bodybuilder.