Before you search on line for ab exercise machines, here is a synopsis of five ab exercisers to to flatten abs.

Ab King

The Ab King Pro ab exercise machine looks like a workout bench. It has a metal handle arching over it. The purpose of the handle is to grab it to help you do crunches. The upper part of the bench supports your neck and moves along with your upper body as you pull up during the crunch.

To use, you lie on the bench and place your legs on the floor or on the foot rest. You then grab the bar handle and do crunches. Really the only exercise that you can do with this machine is the basic crunch which you can do on the floor.

Ab Circle Pro

To use the Ab Circle Pro ab exercise machine, you get on your hands and knees. Your hands grab handle bars at the one end of the machine, and your knees are placed on knee pad on the other end of the machine.

There are two exercises which you can do with Ab Circle Pro. The first exercise, called the flexion movement, works your abs by rotating your body from side to side. If this exercise is done quickly enough, it is suppose to give you a cardio workout.

The second exercise is known as the thigh and bun movement. A special pin is adjusted to allow the machine to work for this exercise. This position also allows for the advanced flexion movement. In this exercise you rotate your body from side to side with both legs close together.

Ab Rocket

The Ab Rocket Abdominal Trainer ab exercise machine looks like a chaise lounger. To use it you sit down on it and hold the arms. You then slowly push backwards stretching yourself out. The ab rocket provides resistance to this movement and assists you to get back into a sitting position. The Ab Rocket supports the head
and neck while the rolling cushion action gently massages the back.

There are three resistance levels, and several crunch style exercises that you can do with it.

Ab Roller

The Ab Roller is generic term for a type of abdominal exerciser. Its exact shape and size depends upon the manufacturer, but conceptually, they all work the same way.

Basically an ab roller is a bent metal frame that is used to assist you in doing a crunch. You lay down on the floor and rest your head on the pad. This helps you to maintain a straight neck. You grab the handle and use the roll of the machine to guide you through the crunch. You can do both straight and sideways crunches.

Ab Coaster

There are two ways to work on your abs. You can do crunches which work the stomach from the top down. A more effective workout is to work the abs from the bottom up. Hanging leg raises are exercises which do this, but they are the hardest belly exercises to do, and takes a lot of upper body strength.

The Ab Coaster ab exercise machine helps you do leg raises without the strain on your upper body or putting pressure on your back. With the Ab Coaster, your knees come up to your chest in a natural crunching motion. The arcing movement simulates leg raises but is not as hard as traditional leg raises. You can also work the obliques by doing diagonal leg raises.

Searching online and following links is a good way to find more information about ab exercises and ab exercise machines.