Abdominal exercises are useful for building the abdominal muscles. This is useful for improving performance with certain sports, back pain, taking punches, but it has little effect on decreasing fat in that area of the body (belly fat), or on the body's distribution of body fat.

The anterior abdominal wall is made up of 4 muscles—the rectus abdominis muscle, the internal and external obliques, and the transversus abdominis.

The effectiveness of abdominal exercise is measured using electromyography (EMG) relative to the traditional crunch. The following ranks abdominal exercises from best to worst in terms of activity detected by the EMG measures:

1Compared to traditional crunch (100%)

Abdominal exercises also put some degree of compressive force on the lumbar spine, putting unwanted stress on the lower back. In addition, exaggerated abdominal exercise can cause respiratory problems. A study of twelve exercises concluded that no single exercise covered all abdominal muscles with high intensity and low compression.

The benefit of focused training on the "deep core" muscles such as the transversus abdominis has been disputed, with some experts advocating a more comprehensive training regimen.