Gym Abdominal Exercises

Gyms offer an array of equipment you can use to train your abdominal muscles. Strong abs help you maintain proper form for other exercises in the gym. Strong abdominal muscles also reduce your risk of lower body injuries, according to the Corrective High-performance Exercise Kinesiology Institute. It's best to complete three sets of each exercise and vary the number of reps and the resistance you use with each set.

Roman Chair Knee Raises

The Roman chair machine allows you to use the weight of your lower body as resistance against your rectus abdominis or "six-pack" muscle. This is an upright machine with back and arm pads. Focus on your abs to draw your pelvis toward your chest. Do this exercise especially if you have a tendency to pull on your head and neck when you do crunches. Perform Roman chair knee-ups by placing your back and forearms on the pads. Hold your body upright in a secure position as you step off the foot supports and slowly curl your pelvis toward your chest, raising your knees. Place a 5-lb. medicine ball between your knees to increase the intensity of this exercise.

Seated Rope Crunches

Seated rope crunches stabilize the lower rectus abdominis as the upper portion curls the rib cage toward the pelvis. Use a lateral pull down machine with a double rope attachment to perform rope crunches. Sit backward at the edge of the lateral pull down chair. Hold the rope close to the left and right sides of the neck near your collar bones. Focus on your abdominal muscles, and draw the top of your rib cage toward your pelvis in a slow and controlled motion. Come back up slowly and repeat.

Oblique Crunches on Hyperextension Machine

The internal and external oblique muscles are responsible for rotating and bending your trunk laterally. Using a hyperextension machine for oblique crunches requires you to secure your lower body while you bend sideways toward the floor then toward the ceiling. Perform oblique crunches by placing your left hip on the hip pads. Cross your legs under the foot supports to secure and immobilize your lower body. Suck your navel toward your spine, and lightly place your fingers behind your ears with your elbows out toward the side. Bend at your waist, lowering your left side toward the floor. Move back toward the ceiling, squeezing the right side of your rib cage and pelvis together. Repeat after the desired number of reps, then switch sides.
Stop doing this exercise if it further increases any pain you may already feel on the sides of your knees. Instead, lay on the floor to do oblique crunches, bending your knees and placing your feet flat on the floor. Use the same hand position, draw the right side of your rib cage toward the right side of the pelvis. Reverse directions to a slightly bent position, and repeat the movement. Complete a full set, then switch to your left side.