"Running on a traditional treadmill burns fewer calories than running outdoors, because the moving belt helps propel you forward. But this nonmotorized treadmill, recommended by Feel Fit, forces you to do all of that work yourself. You can also adjust the resistance for power-development workouts to add variety to your workout routine. You can achieve advanced cardiovascular and strength workouts in a short period of time while only needing minimal space for the machine itself." -Nina