Iain,
I had weight-related BP problems anyway. The spike was because I overdid it on the treadmill and hyperventilated. It's really trippy, you should try it sometime.
I've probably experienced very short term high blood pressure spikes, heavy front squats will do that. Still don't fancy having the effect last any appreciable amount of time thanks.
Aside from the change in exercise and dietary habits - any stop and smell the daisies type after effects? I sort of wish my fathers brain bleed earlier this year had had that effect, but it just didn't. Not on him anyway, my mother now smells more daisies than she did before.