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To Crunch or Not to CrunchCore / Torso training is the body’s center of gravity & is where all movement begins. All functional activities whether it be in sport or activities of daily living (ADL). Functional activities are multi-planar, even if they appear to be single plane dominant. As discussed in class, the muscles responsible for movements in other planes (synergists & acting stabilizers) need to be dynamically activated to allow for torso stabilization & optimal neuromuscular efficiency a specific plane of movement. Generally speaking it is considered prudent for all individuals looking to improve lifelong fitness & functionality & or optimal sports performance (ADL) to appropriately train the whole kinetic chain. Abdominal / core training which includes lumbar spine flexion has been scrutinized by authorities for the past few years. Leading the way in this movement Dr. Stuart McGill, PhD who has devoted years to lumbar spine health and research strongly suggests that the risk to benefit ratio of including any spinal flexion exercises in a strength training program is too high. McGill feels there are many safe & equally effective exercises that target the torso musculature, & that is not wise to use sit-ups & other flexion exercises. Proponents of this theory claim that the spine has a finite number of bending cycles and that exceeding that limit will hasten the onset of vertebral degeneration.(2) The belief is that it there are many other effective exercise options & it would be prudent to limit the amount of spinal flexion training (sit-ups –crunches), if not eliminate them altogether in a training program. While being widely accepted by many authorities in the fitness and sports enhancement field, it has also been met with skepticism. Opponents of this argument counter that an alarming amount of discrepancy exist between laboratory results and what is occurring in gyms and athletic facilities. They also feel that exercises that bend & extend the spine are ideal for aesthetically developing the abdominals & for sports performance. They also suggest that these flexion based exercises are actually beneficial to low back health. Most recently in an article To Crunch or Not to Crunch: an Examination of Spinal Flexion Exercises, Their Potential Risks, and Their Applicability to Program Design by Bret Conteras MA, CSCS.& Brad Schoenfeld MSc CSCS examines the relevant research and then presents recommendations of their own for program design.Brief Overview of degenerative disc diseaseOpponents to the research use the following bulleted points in the crux of their argument.Laboratory studiesUse porcine cervical (neck) vertebrae; (1), (2) This point suggest there may be flaws in the findings because the research was done using pig cervical vertebrae & not human lumbar vertebrae. The tissue used was not living therefore appropriate fluid supply was not available to help maintain the disc suppleness. Vertebrae were Mounted in special machines that apply continuous pressure loads coupled with repeated flexion and extension moments. (1) (2) The use of these special machines place much more stress on the spine that the actual exercises used & that the flexion cycles greatly exceed those that would happen in several training sessions.When done in vitro the supportive musculature was removed which does not replicate in vivo (real life) response in human spines during exercise (2)Living tissue has the ability to remodel after being subjected to stress, and adapt in order to accommodate the demands…cadaver tissue cannot (2)Absolute ranges of motion are smaller in porcine subjects than in humans Studies in question attempted to mimic loading patterns of occupational workers by subjecting them to thousands of continuous bending pattern cycles which is far beyond what is normally performed in the course of a dynamic exercise program. 2. Benefits Spinal Flexion Exercises Natural fluid flow to the disc is compromised, with flexion exercises which reduces disc height which interferers with normal disc biomechanics (2)Fluid flow in & out of the disc is vital for glucose & nutrient supply needed to maintain healthy discs. Flexion of the spine promotes fluid flow to the back (anterior disc tissue) while extension promotes fluid flow the front (anterior) thus increasing the amounts of the aforementioned metabolites to disc tissue.Spinal flexion promotes an increase in fluid exchange in the discs, which in turns increases nutrient flow. Disc degeneration has been linked to low metabolite flow to disc tissue. The crunch movement places a tensile stress by stretching / extending the height of the posterior annulus of the disc. This Flexion allows metabolites into the tissue and is also considered to have an anti catabolic (tissue breakdown) effect on discs.Spinal flexion exercise promotes flexibility of the spine. It has been suggested that improved flexibility that is gained resistance training has been attributed to increased connective tissue and muscular, strength along with improved motor learning / neuromuscular coordination.Greater neuromuscular activation of rectus abdominis thus making it ideal for hypertrophyMcGill’s rebuttalThere is no such thing as a bad exercise but poorly matched exercises with individuals based on their age, ability & training goal. Even though, McGill does strongly feel that based on evidence collected from research done by him & others that loaded spinal flexion does play a large role in disc degeneration & the onset of back pain. Some points of contention from McGill Based on the article.The use of pig spinesMcgill states that the use of pig spine tissue is very limited & that extensive work is done using living individuals & human cadaver spines in research. The cadaver spines may be from older cadavers & somewhat dried out spines but still provide valid & useful feedback regarding disc injuries. (3)A second point is the 3rd & 4th cervical spine structure of porcine cervical spine is so similar to the lumbar spine of humans that it is a logical substitute. McGill even says that skilled medical professionals can have difficulty recognizing the difference if it is not pointed out before observation. (3)The amount of compression applied in vitro (lab studies) is purposely set to be comparable to the amount elicited in a crunch exercise(1) (2) Motion posture & load are the main risks of back damage, It is clearly evident that repeated loaded flexion will eventually cause delaminating of the vertebral disc tissue in individuals who have healthy spines. If the spine has had injury the flexion will not aid in the reforming scar / collagenous tissue. Aesthetically speaking – do you have to flex the spine to get a ripped 6 pack abs?, Mcgill states he is solely interested in performance not aesthetics still feels that exercises that challenge flexion extension will improve both functionality & appearance of the abs.McGill States that genetics 1st will influence that by determine where the body deposits fat. Diet is the 2nd most important element in acquiring ripped abs. So it is not valid to think that one must do multiple flexion exercises to achieve good looking abs.Again …Based on patients seen (athletes & non athletes) of all ages, Research seems to continually support the theory that disc pathology can be directly related to repeated bouts of loaded lumbar flexion. With such variety of equally effective torso exercises available, why choose exercises directly linked to increasing the incident of injury. loaded spine flexion does not help rehab of damaged spine tissue but will continue to force hydraulic (fluid) push the nucleus out into the annulus. Unloaded flexion such as a Cat Camel exercises in the quadruped position is an example of unloaded spinal flexion is ideal for stimulating disc recovery. This has recommendation is considered controversial & is often disputed by some individuals Most recently a McGill – a spine must first be stable before moments & forces are produced to enhance performance. Ultimate Back Fitness and Performance McGill, S. HYPERLINK "" emory.edu/anatomymanual/back ................
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