Cardio exercise is good for your heart - the more you exercise the stronger your heart gets, so I seriously doubt it could cause trouble, probably quite the opposite. Sounds like more fun than going down the gym! And, by the way, where the heck did you find a man who could 'perform' that many times in one night? Sounds like one to hang on to ;)
I can't believe you would say that on a serious thread, Lil O'lady, I may be suffering a serious medical condition and it has only come to light as a result of this activity.
waspette when you said '3 times a night' I think you meant '3 times in a lifetime'. It's not my fault if I have enormous sexual stamina of the cardio-threatening variety, maybe you need to expand your horizons.