Answer from Gail Akers: Both are excellent and effective machines for cardiovascular training. It really dpepends on the intensity level you are working at on either machines. When you are on the eliptical is the resistance and/or ramp at a level that is challenging, in other words are you in your target heart rate zone?And on the treadmill is the speed and/or incline at a challenging level, again are you in your target heart rate zone? A few common mistakes I see regarding the eliptical is that many individuals do not have the resistance high enough, and their legs are just "flopping" around. The mistakes I see with the treadmill is for one most people think to get a good workout you have to run, so not true, if you walk at an efficient speed and with a challenging incline you will be working just as hard ( I am a long distance runner and I personally find my walking portion of my treadmill workouts to be far more challenging!!!)The treadmill uitilizes more muscle groups and requires more impact vs. the eliptical. Use both and just mix it up!!!

Answer from Bonne Marano: I just posted a new article called The Cardio Comparison. It covers the elliptical machine, treadmill, stair climber and the stationary bike..