What is core exercise?

 In physical fitness, the core is what we commonly call the torso. Core training is exercise that involves the movement of the torso. Unlike the appendicular muscles, the movement of the torso is not associated with a major joint, although the movement of the torso usually involves some hip action. 

Also unlike appendicular movement, there is a complex multi-layer host of stabilization muscles that work to protect the spine when the torso moves. So core training develops strength to move the torso, but also to develop the stabilization muscles that support the spine.

Core exercise focuses primarily on the muscles that are associated with the movement of the torso. Most common of these movements is the action of bending-over at the waist. This action is both a flexion and an extension of the dominant muscles. On the anterior (the front) of the torso, the dominant muscle is the rectus abdominis muscle which is commonly called the abs. On the posterior (the back) the dominant muscles are the sacrospinalis which are three groups of muscles: spinalis, longissimus and lliocostalis. 

Equally important to the core are a complex, multilayered group of stabilizer muscles. The function of these muscles is to stabilize the spine when the torso is moved. The deepest layers of muscles are the transverse abdominis and the multifidi. When these muscles are activated they increase in intra-abdominal pressure surrounding the spinal column making it rigid capable of resisting damaging forces. These muscles are the most important stabilizers and called the primary stabilizers. 

There is a second group of stabilizers that assist in protecting the spine. These are called the secondary stabilizers as they do not directly connect to the spinal column itself. The secondary stabilizers include the internal obliques, external obliques and the gluteal muscles. These muscles are also essential for the protection of the spine, especially the gluteal muscles. Without strong hips supporting the base of the spine, a healthy spine cannot exist. Unlike the core’s action muscles, the stabilizers activate automatically when the torso is moved. If we had to think about these muscles, they would be too late in protecting the spine.

The situps and crunches are good exemplifications of  core exercises. The prime mover is the rectus abdominis. The synergists include the external obliques, the iliopsoas, the tensors and the sartoris muscles. The stabilizers include the transversus abdominis, the multifidus and the quadratus lumborum which are the deepest core muscles. When we perform the basic core movement, all of these muscles come into play, but we are rarely aware of the host of muscles that are utilized in that movement. Thus it is difficult to pinpoint exercises the supporting muscles.

Core training develops both the muscles that move the torso and those muscles that stabilize the spine during that movement. For many years the dominant core exercise was the sit-up, but recently the exercise has fallen out of favor because of the potential of lower back problems. The sit-up does place torque on your spine especially if the exercise includes diagonal movement. The sit-up also develops the hip flexor muscles which can exert pressure on the lower spine resulting in lower back pain.