Now that Lean Time Keto got worked the actual deep core muscles, now its fine to go on and work those outermost, rectus abdominis muscle group. Now go ahead and do some crunches. If you want the greatest crunch exercises do these for a swiss ball. This will give you extension and also flexion. A lot sit up all the way in order to incur maximum advantages of. Do a crunch flex and flex stretch about 20 times when.