I'm 49, been in perimenopause for a couple of years, haven't had a period since March.
I only started having hot flashes late this summer. After I was diagnosed with benign proliferative breast changes, I eliminated hydrolyzed soy protein from my diet, and cut way, way back on unfermented soy and alcohol. Ever since then I've been getting hot flashes that are very brief but also very frequent. On average I probably have 5-6 a day, lasting at most 2-3 minutes.
It's too early for me to be able to say whether they'll get "bad" or not. But the women I know who complain most bitterly about their hot flashes, are the same ones who might make a show of exercising but refuse to actually exert themselves, theatrically mopping their brows if they get the slightest flush in their cheeks. Right now I'm guessing that it comes down to whether you view sweat as something natural, healthy and even (sometimes) fun, or as something to be avoided at all costs. So far my hot flashes are at best a brief respite from being freezing all the time; at worst "Oh, I'm sweating again."
But I know that I've got a long way to go and I might not feel so superior a couple of years from now 
Edit: Oh, and I have yet to experience one while I'm doing cardio. Don't know if that's because my body's thermal regulation system works better when it's working hard, or whether I just don't notice it. I did have a flash during a Pilates workout last week. That was probably the most "interesting" one I've had so far
Last edited by OakLeaf; 11-17-2008 at 06:30 AM.
Speed comes from what you put behind you. - Judi Ketteler