As a quick review, in the previous article we looked at the importance of tongue position for neck stabilization during the performance of exercise, specifically the crunch. Since the D.C. area is preparing for beach season, the crunch seems to be an exercise of choice, for better or worse. So let’s delve a little deeper into another aspect of the execution of this movement: training surface.
The surface on which perform our abdominal exercises is a vital aspect of the crunch’s efficacy. This is because the surface on which we crunch affects the range of motion (ROM) of the pattern. But how much motion should one allow for a particular crunch? Wow, you ask such relevant questions!
We know that the abdominal muscles on which we are focusing, specifically the rectus abdominus, have multiple functions. Along with the normal spinal flexion the this muscle performs, we must also remember that whatever a muscles does, it also prevents the opposite. So, even though this muscle flexes the spine (curling into a ball or the crunch motion), it also prevents the opposite motion, spinal hyperextension (back bending). And it is in this position that many Americans are stuck chronically, (i.e. lumber lordosis) and also a position in which injury often occurs in sport or in life in general .
So it is important to exercise the abdominal muscles into extension. Indeed, we would not do half of an arm curl, or a leg extension, or other exercise (unless we are bodybuilders). So why do we treat the abs differently?
It therefore seems reasonable that a Swiss ball is a much more effective tool for the performance of crunches then simply using the floor, as it allows for the spine to reach into extension, and therefore trains the abs in that range of motion. Indeed, the rectus abdominus (with the help of the internal and external obliques) are the only muscles capable of pulling a person out of a position of spinal extension.
Also, research studies seem to support the notion that overall abdominal muscle activity is greater while doing abdominal exercises on the ball.
So, in closing, we can see how a curved surface should be used for crunches, to allow for strengthening of the abdominals through a full range of spinal motion, and that exercises on the ball create a greater degree of muscle activation in the abdominal muscles. So, the next time you think about doing a few crunches, think about getting on the ball!
David Younkins, M.S., CES