WBFF World champion fitness model and competitor, Rob Riches, reveals his entire ab workout in full detail, showing the top exercises to strengthen and condition the entire core and abdominal region. Throughout these video shorts (9 in total), you'll learn how to do each exercise properly, and feel muscles that you've never felt worked before. In part 5 of this 9 part video short Rob demonstrates a few variations on one of the most effective and easiest exercises...