According to Dr. Stuart M. McGill, author of Ultimate Back Fitness and Performance, spinal flexion (rounding the lower back) is a key contributor to disc herniations. Think about it. When do you “throw your back out”? Normally, when you are bending forward (spinal flexion). The exact same motion that is performed during crunches and sit-ups.
The common misconception is that your core is only the group of visible muscles that you see on models with 6 or 8 packs. Rather, your core is comprised of several muscles that work together to stabilize and protect the spine against external forces. Because the true function of the core is to brace the spine, planking exercises are far more effective at working your core and strengthening your back than crunches. In addition, planks are a low risk move when it comes to injury.
Do you sit for extended periods of time commuting to work or at your desk? The last thing you want to do if you spend large amounts of time sitting is to reinforce that poor posture with crunches. Planking will teach your core to stabilize your spine in the optimal position.
Do you golf? By tightening your six pack muscles, you are essentially shortening your abdominal wall. This shortening can limit your thoracic mobility and thus reduce your ability to rotate. Last time I checked, rotating was kind of important to your golf game!
I know what you are thinking. What if I just care about getting a washboard stomach? Fear not my faithful cruncher- your regular exercises like squats, lunges, push-ups, etc. will work your abs enough to make you proud this Summer. Throw in a few planking exercises for spinal health and you are good to go. Stick to crunches and you may have back injury to fear!
Take care of your spine. It is sacred and enables you to live that fit lifestyle that brings you to Ellipse. Consider foam rolling your upper back to release the lactic acid before and after your workout. Most of all, find your plank and challenge yourself to improve it day after day.