Crunches and situps can be great core exercises to tone the abs when performed correctly. Learn how to do a crunch the right ...

With the exception of the plank, each exercise should be done for 10-15 repetitions. If an exercise alternates between sides, perform 10-15 repetitions on each side. Try holding the plank for 15-30 ...

The plank, that trusty isometric exercise that's been a staple in countless ab routines, has long been the undisputed queen ...