Sit-ups and crunches are two of the most overused ab exercises. Most people would have probably done hundreds of sit-ups, only to discover that they don’t burn belly fat. Those who train the rectus abdominis (six pack muscle) with excessive sit-ups can end up with a protruding belly.
Dangers of performing repeated sit-ups
Sit-ups involve full spinal flexion that compresses the spine. This can lead to disk bulging or herniation. If you are training your abs with sit-ups, you are only damaging your spine.
When performing sit-ups, the illiopsoas muscle is mainly responsible for flexing your torso towards your thigh. The illiopsoas is made up of 2 muscles: psoas and iliacus. The psoas originates from the lower back and the iliacus originates from the thigh bone. Both muscles end at the same point.
During repeated sit-ups, the illiopsoas pulls on the lower back while there is little or no ab engagement. This can cause lower back pain and poor posture. The constant flexing of your spine causes it to become weaker and prone to injury. In addition, your core muscles are not being trained to support and stabilise your spine.
The bottom line … Do sit-ups work as an ab exercise?
Sit-ups do not burn belly fat. Neither do they work for developing flat stomach or six pack abs. Instead of working your ab muscles in isolation, it is better to train them with functional exercises that mimic real life movements. You’ll build strong core muscles, lose belly fat and get good looking abs without sacrificing your back and poor posture.
See also: Ab Exercises That Really Work