From everything that I have read, exercise is exercise. A bike, treadmill, running, elliptical, etc. Whatever is good for you . I have found that I can burn a lot of calories on the bike, but I find it boring. I used to run, but back, hip, and leg problems ended that about eight years ago. I now use an elliptical daily and I am sure I am getting at least an equal workout to when I ran. As long as you have a means of monitoring your workout you will be fine.