The core comprises the torso muscles—the muscles governing the center, or core, of the body, usually with special emphasis on the front of the torso. Accordingly, the core includes several large muscle categories: abdominals, pectorals, pelvic muscles; the glutes, neck, back, and shoulder muscles are often involved in core movements and can also be thought of as part of the core. The diaphragm, the internal muscle that controls breathing, can also be thought of as a core muscle. (Therefore, deep breathing could be considered a core exercise.)
Because core muscles do not necessarily fit into sectional categories (front, back, side), it is no surprise that there are a multitude of possible core exercises and many of them work the same muscles in varying ways and to varying degrees. However, certain basic moves are essential to the core workout.
The abdominals are the primary muscles targeted in these exercises, but the back and chest typically get involved incidentally. The spine is supported by back muscles, so strengthening them is highly beneficial.
The most straightforward way to work the abs, along with the chest and back, is to get in plank position (as though to do a push-up) and hold position for about 30 seconds. An easier variation is to get down on elbows and/or knees in place of hands and feet.
Another simple exercise that puts more emphasis on the back is the bridge: Lie down on back with knees bent, feet flat on the floor. Keeping abs engaged, lift lower body until thighs and back form a straight line; you can then progress to pushing your core up into a slight upward arch for greater challenge. Hold about 30 seconds.
The side abdominals, or obliques, comprise layers of muscle that control sideways flexion and extension of the torso. Underneath both the internal and external obliques are the transverse abdominals, which span the entire front-side region of the waist; the transverse abdominals are involved in almost all core movements.
The most straightforward oblique/transverse abdominal exercise is the T-stand: Prop your body up sideways using one arm, keeping legs, back, and arms straight to form a T shape. A way to make this rigorous move a little easier is to get down on your elbow rather than palm—in effect shortening the top of the T. If that is still too difficult, try dropping the knee closest to the floor down for added support. Try to hold on each side for about 20 seconds.
The pelvic floor, especially important to women, it is gratuitously engaged in most core exercises—this is yet another included benefit.
Any gym apparatus or exercise move that targets any of the individual core muscles could be seen as core exercise. However, extensive interconnection between layers of core muscles suggests that less targeted movements that engage multiple muscle groups simultaneously are more effective at producing core exercise benefits.
A strong core provides a natural corset—both aesthetic and supportive. Women’s magazines tout the figure-enhancing benefits of core exercises (though these benefits certainly apply to men, as well). However, medical sources instead emphasize that a strong core reduces chance of injury and enhances ability to function physically, since almost all movements are in some way supported by the core. A stronger core usually means better posture, which is good for both personal appearance and for muscular support of bones and joints.