Flat Stomach Bicycle Crunches Muscles Worked. The standard bicycle crunch consists of lying on your back with your hands behind your head then lifting each knee up toward your chest in the direction of the opposite shoulder. Thus the rectus abdominis the front sheath of your abs that make up the six pack muscles are activated.
These muscles are more commonly called the obliques and the rectus abdominis like all muscle building exercises these may provide a toned look or more musculature but they do not necessarily rid the belly of belly fat. You should start to see visible improvements within a few weeks to a few months. They re good for building your abs muscles and obliques plus sculpting a six pack.
The rotation activates your obliques.
You will need to body fat from all over the body for that to happen. Keeping your legs flat on the other hand works the middle abs. The bicycle crunch lifts the torso and contracts the abdominal muscles in the same way as a standard crunch. It is an excellent way to help tone your tummy and lose weight but it will not necessarily make your tummy flat.