Worst Ab Exercises

Whether you want to lose belly fat or strengthen your abdominal muscles, many products and exercises promise to help you achieve those goals. However, a study by Dr. Peter Francis of San Diego State University reported that some abdominal exercises do nothing to strengthen or flatten your abs. Abdominal muscles work with other muscles to produce movement and protect your spine. They do not work in isolation, so they should not be trained in isolation.

Ab Rocker

The ab rocker places you in a slight trunk-flexion posture on the ground, and it helps you do crunches. According to a product infomerical, its simple rocking motion can be used to smooth the tummy and waistline, but that is impossible. Body fat cannot be reduced by exercising a particular area, and the exercise provide little stimulation to abdominal muscles. This exercise was ranked last by Francis' study. Stick with sit-ups.

Twisting Machine

You can find this device in many gyms; it allows you to flex the lumbar spine while twisting at the waist. According to fitness expert Phil Kaplan, this causes too much pressure upon the spinal ligaments, which can lead to chronic injury. Do other rotation exercises, such as medicine-ball rotations.

Resistance Ab Machines

These machines place you in a fixed position for trunk and hip flexion against resistance. That puts some people at risk for spine and hip injuries because of weak cores, excessive stress in the joints and poor posture. Jump-roping will improve your posture, strengthen your cardiovascular system and burn more calories.

Leg Raises

Although you feel the abdominal burn as you do this exercise (straight leg raises or upright leg lifts), you actually are working the hip flexors to your legs up to your ribs, according to Francis's study. You feel the burn because the hip flexors are pulling on their attachments to the lumbar spine. This can cause excessive tightness to the hip flexors--and low-back pain.

Side Bends

In this exercise, you hold a dumbbell in each hand and flex from side to side. Many people believe side bends will reduce the waistline, but without proper nutrition and total body exercises that burn more calories, side bends won't slim you. According to Juan Carlos Santana, director of the Institute of Human Performance, side bends mainly work the quadratus lumborum, which are at the pelvis and trunk to provide lateral flexion.