I’ve just finished presented a review paper on postural control at NTU – part of the presentation is about doing crunches effectively. Do allow me to share you with here.
It is more effective doing crunches on a fitball than on a flat surface.
While we can do regular crunches on flat surface, Garcia 2000 found that doing crunches on labile surfaces such as the fitball modifies the way that the muscles work together to stabilize the whole body and spine, it also involves improving muscle activity amplitude. The study found that performing such exercises on labile surfaces has a higher demand on the motor system. They also approximately doubled the abdominal muscle activity! Activity in the external oblique muscle increased approximately fourfold if one performs crunches over the gym ball with the feet on the floor. It also generally doubled activity in the rectus abdominis muscle.Cholewicki et al and Sarti et al, 2006 demonstrated the importance of the abdominal muscles in ensuring sufficient spine stability to prevent buckling and enhancing function. The optimal muscle recruitment schemes chosen by the motor control system determine the resultant stability together with the spine load that results from active muscle forces. In our view, clinical issues include the need to understand the effects of using labile surfaces to challenge the muscular system during rehabilitative exercise.
Doing push up exercises with hands on the gym ball and toes on the floor in prone position, resulted in the highest activity of all abdominal muscles, as researched by Mori A, 2004. Lifting up of the pelvis in a bridged position exercise, supporting the head with the gym ball and with the feet on the floor in supine position, resulted in higher muscle activity of the back extensor muscles than another exercise. Physical therapists need to clarify the purpose of the trunk stabilization exercise because “different kinds of exercises with the gym ball demand various levels of muscular activity and use of various parts of the trunk muscles”.
That being said, if you’re in a gym, do remember to use a fitball to do your crunches/push ups. Do note that doing thousands of crunches (spot reduction) will NOT result in a flat stomach – you will also need to do other types of exercises to burn off the fat that is on top of your abdominal muscles.
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