For many years, much of our knowledge of the way muscles work was based on the study of human cadavers. By looking at the anatomy of corpses, modern scientists figured that the function of our abdominal muscles, especially the lower abs, must be to flex the spine.
Which is exactly what you do when you perform a crunch, a situp, or any other move that requires you to round your lower back. As a result, these exercises were popularized as the best way to work your lower abs, and included in every fitness training program or lower abs workout you’d find anywhere.
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