Simply put, "core muscles" lock down parts of our torsos to give us extra stability when our bodies need it, for example, when throwing a ball or picking up a toddler. The three most important core muscle groups are:
1. those in our backs,
2. those under our spines, and
3. our abdominals.
The word "core" became popular in the 90s when aerobics and yoga turned out to have not much effect on students' waists-lines. Today Amazon.com sells hundreds of titles that include the word "core." Some of these core workouts do a nice job at integrating muscle function so that the body processes actions more efficiently. Good core routines also work the body "functionally;" that is, while bearing its entire weight. Other, less thoughtfully designed programs have ratched down the concept of "core" to only one of its components, namely abs. Students of these systems miss out on neuro-muscular learning, since they use only small groups of muscles at a time. Examples of imbalanced core workouts that over-emphasize the abdominals are Pilates and exercise ball routines.
Such over-emphasis on ab-work results in bodies that lack athletic power and have insufficient protection against episodes of back pain. A strong balanced core requires support on both sides of our bodies. So glute strengthening needs to be a big part of any core workout. Glutes, however, are highly resistant to exercise. The reason for their pig-headedness goes back to our evolution when glutes needed to work long and hard. Now they're our largest, deepest muscles and come lacced with fat for extra endurance. It follows that we need to work them long and hard before they sit up and take notice. Any core workout worth its salt knows this and has something special cooked up to serve these particular core muscles.
Last but not least, for a strong core you need to work on upper back strength and alignment. Good posture and control over your shoulders will result, free your lower back from lots of needless stress and strain and protect your shoulders from injury.
The beauty of core muscles is their versatility. As I mentioned above, their principal job is to stiffen our torsos whenever our actions call for extra support around our spines. Our well-braced torso also gives our arms and legs more power by providing them with a stable base from which to perform, whenitting a tennis ball for example. What's impressive is that core muscles can freeze our torsos into just about any bend or twist. They can also stiffen only torso sections needed while leaving other parts free to maneuver.
With training, core muscles can become amazingly quick and deft at calculating the intersection of body-position and muscle power. Experienced athletes know to focus on developing both these components of core performance: namely, strength and coordination.
Consider a pitcher's throw of the ball. The core muscles allow her spine to twist but then lock, exerting tremendous holding power around the shoulder-blades. Without the support of these muscles a pitcher's arm would be in grave danger of flying off, ball still in hand.
Core muscles' last trick is their ability to let go when we need our torsos to become pliable, such as when we're lounging in an easy chair or strutting our stuff on the dance floor.
Now let's look at where the core muscles are in a tennis player's body as someone prepares to hit the ball:
–First, her abdominals stiffen her torso, preventing it from falling back as she swings.
–Second, her back muscles solidify into a base for her shoulders.
–Third, deep muscles in her upper back lock her shoulder blades firmly down giving power and stability to the arm holding the racquet.
–Fourth, her glutes weld her torso and legs into an immovable structure long enough for her to drive the ball over the net.
This stiffening-loosen dance characterizes core muscles at their best. Legs may allow us to run, arms to throw. Core muscles enable us to run and throw with our entire bodies.
Good core workouts, therefore, includes strength exercises for the shoulder stabilizers and the glutes as well as for the abs and back. Just as important, well-designed core training teachers muscles to interact with each other, and also with the rest of our bodies. This education for the abs can make the difference between "throwing like a girl" and throwing like an athlete.