Vigorous exercise will not impair your fertility at all if it's part of a healthy lifestyle. Some female athletes are extraordinarily thin however, which can cause a condition that prevents the hypothalamus from properly releasing gonadotropin-releasing hormone (GNRH).
In turn, this can completely stop ovulation as well as estrogen production. So an extremely underweight woman may be perfectly fertile, in that she has plenty of healthy eggs in her body. But she may be unable to release her eggs through ovulation because she's stopped producing certain hormones. As long as you continue to have your period (a sign that you are ovulating), your fertility should not be impaired.
Vigorous exercise is also fine for men, as long as they don't try to enhance their performance with anabolic steroids, some of which are legally and readily available in health food stores in the form of androstenedione. Androstenedione is a "natural" anabolic steroid, but that doesn't make it any less potent. Like any other anabolic steroid, it can increase muscle mass dramatically, but it can also shrink the testicles, lower the sperm count, and cause liver disease and early heart attacks.
yeah. i think it's ok to exercise vigourously as long as you don't use any drugs..