Why should you care about muscles you can't even see? The answer is, among other reasons, to flatten abs, eliminate back pain - particularly lower back pain - and achieve core fitness.
By now you are probably familiar with "core training" or you have at least heard the term used on TV or in various fitness publications. Your "core" refers not just to the abdominals, but your entire trunk musculature, including those deep muscles you can't even see (like the Transversus Abdominis, or TVA).
Back pain is one of the biggest complaints of men of ALL ages, and many women suffer from it as well, especially during and after pregnancy. You see a weak core, combined with other problems such as tightness in certain muscle groups, lousy form and poor selection of exercises is one of the leading causes of lower back pain. The good news is that it's largely preventable with a few easy exercises.
There's more. Your core is also the seat of power for your entire body. If you're an athlete - recreational or competitive - core strength means better performance on the playing field. If you're a non-athlete, greater core strength means more efficient and safer performance of regular day to day activities. If you know anyone who blew out their back lifting boxes or simply doing work around the house you know what I'm talking about.
About 15 years ago, I was diagnosed with a herniated disk, and at one point a neurosurgeon told me I should be on the lookout for "foot flop". This is when the nerves in the leg go numb to the point where the foot literally drags on the ground and, he explained, that surgery was imminent and unavoidable. I was fairly freaked out. An alternative therapy was an epidural injection of steroids which, after just one treatment, did provide relief.
I knew that a lifestyle change was in order and fortunately, I was able to rehab my own back without ever going under the knife, thanks to a ton of flexibility work and some intelligent abdominal training. Once you rupture a disk you can rehab to a remarkable degree, but it's something you always have to be cautious about.
Anyway, in the last few years since I started to use core training methods, and not just the traditional "bodybuilding-style" routines, I've seen a greater improvement in my lower low back than ever before. If you haven't started doing any ball work or core training yourself, I would definitely urge you to look into it.
The reason I'm mentioning core training today is because of the availability of home core fitness programs that do not have to break the bank. In fact there are unique programs available that do not focus on traditional advise such as killing yourself with mind numbing sit ups and crunches.
Looks for programs that offer levels to progress through, as not all of us are ready for the more advanced core training techniques. Level progression from beginner up to "athlete" is ideal. Note that some of the exercises are a lot more challenging than they look in the pictures. You have to try them to appreciate them. Many of them can be done with just your body weight. Others require a stability ball (swiss ball), and a handful can be done with a cable apparatus you'd find in any gym.
So get started on a program that creates core fitness through a workout program that will flatten your abs and reduce lower back pain.
