Contract and relax. Contract and relax. That’s what your muscles do every time you lift weights. Whenever you curl or crunch, your muscles work hard to complete the movement and help you finish your set. It’s a fascinating process that takes place not only in your arms and legs, but also in your abs and entire core. And by putting this powerful area through regular workouts, you can develop a strong, sturdy midsection.
Whether you know the term or not, you engage in concentric contractions every day. It’s the muscle movement that takes place when you contract a muscle and make it shorter, such as in a bicep curl. If you regularly lift weights, you do these powerful contractions every time you step in the gym. And it’s the kind of contraction you complete whenever you do abdominal crunches of any variety. The muscles get shorter as you put forth effort and relax as they lengthen.
The science behind concentric contractions is easy to understand. Every time a muscle is forced to do a contracting movement that challenges it, the fibers break down -- microscopically -- so that your body can build it back up stronger than before and do what you’ve just asked it to do. It’s a built-in response, and it’s what happens whenever you contract your abs. The healing of the fibers takes place during your recovery periods, the 24- to 48-hour break between strength-training sessions.
Meet the Muscles
It’s easy to think of standard crunches as the main ab contraction exercises. The truth, though, is that there are hundreds of contracting exercises that hit all of the muscles in the ab group: the internal and external obliques, the rectus abdominis and the transversus abdominis. The most noticeable of the bunch is the rectus abdominis, which is what you see when you look at a ripped "six pack." The rectus abdominis is the muscle just below the transverse, and the obliques make up the sides.
While there are almost endless options for abdominal contraction exercises, a few have become popular due to their ability to provide the biggest "bang for the buck" -- the best results for your time. If you want to maximize your time contracting and building your abs, try long-arm crunches, oblique crunches, bicycle crunches and compound crunches.
After graduating from the University of Kansas with a bachelor's degree in sports information, Jill Lee served for 10 years as a magazine editor for the Fellowship of Christian Athletes (FCA). Also a published author, Lee now works as a professional writer and editor focusing on fitness, sports and careers.