Vigg,
We are on the same page. I found a wonderful site where you can read about working out and heart rate. [url]http://www.babyfit.com/ 140 is just a guideline, the real heart rate max is different for everybody. You are not new to exercise, so keep on riding. They recommend women who did not do anything before pragnancy to subtract your age from 220 and then take 70% of that. This number would be your max heart rate. But if you are already fit and have done plenty of exercise, your target heart rate can be higher.