Hi Jackie,
I have a stairmaster as well and I used it for 9 years as my predominant form of cardio. It translated well into running as far as aerobic fitness went. When I used it I made sure not to use the hand rails too much and always did some interval training during the workouts. I wasn't doing any strength work back then. When I was pregnant with my second baby I did the stairmaster 4 or 5 days a week for 50 minutes. I never let my heart rate get over 135, but I worked out until the day I delivered. I started again with the doctor's permission after a week off. When the baby was 4 weeks old I ran a 10K with my sisters who are runners.I did it in okay time for a non-runner, but I was so sore afterward! The crippled kind of sore that makes walking steps unbearable for about 4 days. Cardio-wise it is a great substitute for running, but I would never count on it to condition your running muscles. Now that I am older, (that baby turned 10 yesterday) wiser, and less obsessed, I wouldn't ever pull a stunt like that again, but I managed to stay in pretty good shape through four pregnancies using my stairmaster. I discovered Cathe 9 months ago and my workout life has never been more fun or varied, but I am still a big fan of the stairmaster, especially since you can get some reading done at the same time! It is a great machine to have when your kids are little. Have a great day.
