How to Flatten Your Stomach With a Core Ball
How to Flatten Your Stomach With a Core Ball. Part of the series: Let's Get to the Core!. Flattening your stomach with a core ball will require crunches done in just the right way. Flatten your stomach with a core ball with help from one of the leading health and fitness professionals in the state of Utah in this free video clip. Read more: http://www.livestrong.com/video/10043...