What is the core? Aren’t we just talking about the abs?
Before we dive into how to develop the core, let’s define what the core is and what it does. The anatomical core makes up the trunk region of the body, including skeletal structures such as the rib cage, vertebral column, pelvic girdle, and shoulder girdle (see pics below). The core also incorporates passive soft tissues (cartilage, ligaments) and active muscles surrounding the skeletal structures. When we think of what the core does, we focus on the active muscles because they cause, control, and prevent the movements that challenge the core. As we can see, there is a lot more to the core than just abs. There are several other muscles considered part of the core in addition to the abdominal muscles. Many of these muscles function to provide stability and stiffness and allow for dynamic movement.
We can classify the core muscles into three broad categories: global core stabilizers, local core stabilizers, and upper and lower extremity core-limb transfer muscles. The global and local core stabilizers work to stabilize the spine during movement. The global stabilizers encompass larger muscle groups (e.g., erector spinae and rectus abdominis) that span larger sections of the spine. The local stabilizers are deep, smaller muscles closest to the spine (e.g., multifidus and rotatores). The large, core-limb transfer muscles transfer torque between the arms and legs (e.g., latissimus dorsi and gluteus maximus).
One of the best ways to envision the core is as a bridge between the arms and legs. This bridge must provide stability for the actions of the limbs. But the bridge must also transfer torque and velocity to allow the limbs to perform various high-speed movements such as throwing a punch or kicking a ball. Proper core training involves using all the muscles of the core in conjunction to cause movement through concentric actions (muscle shortening), control movement through eccentric actions (muscle lengthening), and prevent movement through isometric actions (constant muscle length). Therefore, to train the core most effectively, we should use various exercises that challenge each core function.
Vertebral Column and Pelvic Girdle:
Global Stabilizers and Core-limb Transfer Muscles:
How do we train the core?
Now that we have a better understanding of the core, let’s discuss how to train it. Nearly all the functional movements of the trunk involved in daily activities and sport derive from four basic movement patterns: trunk flexion, trunk extension, trunk rotation, and trunk lateral flexion (see examples of these below). To optimally train the core, we must include exercises that demand stabilization against or action through the four basic movement patterns. By incorporating each of these movement patterns in our training, we establish a balanced strength development of the core. A balanced program will not only help prevent injury but will also enhance overall strength development and performance. An effective routine will include static (isometric) and dynamic (concentric and eccentric) exercises that include open and closed chain exercises in single and multiple planes of movement.
Core training should start simple and increase in complexity with experience. Since the core muscles are involved in so many movements of daily life and sport - constantly activated, it is best to initiate training with an emphasis on localized muscular endurance before advancing to strength and power training. This will enable the core to withstand the demands of daily life and sport.
We can achieve localized muscular endurance by using lighter external resistance and performing higher repetition and set counts or using longer times under tension. Once we establish a base of muscular endurance, we can begin loading the core with heavier resistance to increase core strength. After building core strength, core training can progress (if required by sport) to include power exercises that require resistance combined with quick, explosive movements. Core training is achieved by manipulating the body’s weight against itself and using external loads to increase resistance. Initially, core training should focus on exercises that target the core (such as crunches and reverse extensions) and then move on to more traditional compound lifts (such as the deadlift, back squat, or push press). If necessitated by sport, core training should eventually include explosive or ballistic movements (such as med ball slams/throws and Olympic lifts). An example of how to progress core training is as follows:
Train the four basic movement patterns using 1-3 sets of 15-20 repetitions (or 45-90 secs) for each exercise for several weeks before progressing; focus on core-specific exercises.
Train the four basic movement patterns with an increased external load using 1-3 sets of 10-12 repetitions (or 30-60 secs) for each exercise for several weeks before advancing; include core-specific and compound movements.
Train the four basic movement patterns with quick, explosive movements (if necessitated by sport) using 1-5 sets of 1-5 repetitions for each exercise; include exercises such as med ball slams/throws, tire flips, sledgehammer swings, and Olympic lifts.
Trunk Lateral Flexion:
Know this article is an overview of the core and core development and should not be considered exhaustive or comprehensive in its explanation. If you want a deeper dive into developing the core, I suggest reading Developing the Core from the National Strength and Conditioning Association’s (NSCA) “Sports Performance Series.”
Developing the Core, National Strength and Conditioning Association, 2014.