To Crunch or Not to Crunch: An Evidence-Based Examination of Spinal Flexion Exercises, Their Potential Risks, and Their Applicability to Program Design
The crunch and its many variations have long been considered a staple exercise in fitness programs. These exercises involve dynamic flexion of the spine in the sagittal plane and are performed to increase abdominal strength and development (124), particularly in the rectus abdominis and obliques musculature. Strength and conditioning coaches frequently include such exercises as a component of athletic routines designed to enhance sporting performance (45).
Recently, however, some fitness professionals have questioned the wisdom of performing flexion-based spinal exercises, such as the crunch (23,75,110). Concerns are usually predicated on the belief that the spine has a finite number of bending cycles and that exceeding this limit will hasten the onset of disc damage (75). Proponents of the theory claim that spinal flexion therefore should be saved for activities of daily living such as tying one's shoes rather than “wasted” on crunches and other flexion-based abdominal exercises. Opponents of the theory counter that an alarming discrepancy exists between laboratory results and what is occurring in gyms and athletic facilities around the world with respect to total flexion cycles and spinal injury and cite a lack of evidence showing any detriments. Therefore, the purpose of this article will be 3-fold: First, to review the relevant research pertaining to the risks of performing dynamic spinal flexion exercises; second, to explore the potential benefits associated with spinal flexion exercises; and third, to discuss the application of these findings to exercise program design.
Full paper here