An Elliptical vs. a Treadmill for the Core Stomach & Waist. Part of the series: Developing a Fitness Plan. Ellipticals and treadmills are both great ways to tackle the core stomach and waist, but for different reasons. Find out about an elliptical versus a treadmill for the core stomach and waist with help from one of the leading health and fitness professionals in the state of Utah in this free video clip.