Here is my situation...I run 5 to 7 miles a day, 4 days a week, on pavement. Recently, an old injury has been giving me foot/ankle pain, and my doctor has advised a lower-impact form of aerobic exercise. He specifically mentioned either running on a treadmill or using an elliptical machine. I was wondering if anyone here has experience with both types of machines, and if so, which do they prefer...especially with respect to effectiveness of the aerobic workout. Thanks in advance for any and all help. TroopSarge Wanna kill these ads? We can help!