I have received a few questions about treadmills vs. elliptical trainers and so I thought I'd touch briefly on the subject. With the treadmill and the elliptical machine being probably two of the most popular pieces of exercise equipment I can see where some concern would come in to play as far as which is more effective. First and foremost I'd have to say it depends on the person. If you've had any joint problems, (knee's especially), I'd go for the elliptical. It is designed to put a lot less impact on your joints. With this said, I don't want you to think that the elliptical is the "easier option." With exercise you have to remember that it is or can be as hard as you make it.
Elliptical machines with handles can give you a full body workout, getting that upper body into motion which is great. It has the option of a forward pedal which targets the glutes and hamstrings more, and a backward motion which targets the quads more. In the past Elliptical machines have lacked variety, making them less desirable than a treadmill, but updated models have proved this wrong adding incline and resistance settings. The key here is using these different settings, and not keeping it on a stagnant pace.
Treadmills are great. They always have been and they always will be. From the walker to the marathon runner you really can vary your workout to fit YOU. You can change the incline and speed making your workout more cardiovascular or more fat burning, depending on your desired goals. I have always felt like running gives me a good workout!
With my clients I've seen that they've generally burned more calories on the elliptical machine vs. the treadmill due to the fact that it is easier to push yourself when on an elliptical machine. Running burns more calories than walking, and if you're comparing walking to using an elliptical, I'd pick the elliptical. You'll burn more calories overall.
If you're looking to purchase one or the other they are both great options, but I'd pick whatever it is you think you'll use. Running 5 miles a day on your treadmill is a great goal, but if you don't think you'll do it, don't buy an expensive piece of equipment just to let it collect dust.
If you're wondering what is the better option for your gym workouts I'd mix it up. Variety is the best thing for your body. Just make sure you're pushing yourself. Break a sweat. For the most part people underestimate their capabilities when it comes to exercise. Push yourself! THAT is when you'll see results.