Hve pots syndrome & have exercised for years & am not deconditioned.i have to lay down & sleep after exercise or i'll black out.will this ever improve?

Hydrate and nourish: If your fatigue mainly becomes an issue after an exercise, it may be related to a dehydration or low sugar following your exercise, so ensure you are plenty hydrated with salty beverage and a snack right after the workout. Also if not already ruled out, get a cardiac echo to ensure no mitral valve prolapse is present that can also cause fatigue. try the above and talk to a neurologist afterwards