Some fitness professionals see the word “core” as gimmicky and replace it with words like “trunk,” “center” or “column.” Others resist the term because they feel it lacks a clear definition. Here’s an easy, if slightly disconcerting, way to visualize the core: “Unplug” the arms, legs and head, and the core is everything that’s left! In more technical terms, the lumbo-pelvic-hip complex, along with additional muscles that act on the spine, is often considered the “core of the core.” The LPHC includes the lumbar spine, pelvic girdle, abdomen and hip joints. The muscles of the core are, then, any muscles that cross over or directly act upon the LPHC (NASM 2018).
Whatever you call the core, or however you picture it, understanding its function and movements is essential for fitness professionals because this area of the body is the foundation for our ability to produce nearly all movements. If the core cannot support a particular exercise, then the arms and legs involved in it cannot produce the requisite force or speed. This is why fitness professionals often state that every exercise is a core exercise.
A Logical, Progressive Approach to Core Training
As with any good regimen, a core training program must be designed to progress exercise participants safely and logically, providing a strong foundation (literally) before introducing strength or power moves. Too often, trainers and clients skip the stabilization phase, opting for more exciting and dynamic movements.
Limits in core stabilization training can impede performance outcomes, as well as structural and movement efficiency, and may ultimately lead to injury or pain. In fact, a lack of core stability and proper mobility may lead to back pain in some people, and providing appropriate exercises to strengthen the core can mitigate such pain (Gomes-Neto et al. 2017). Our job as personal trainers is not to address or treat pain, but we are well within our limits to address stability and movement deficiencies.
NASM’s exclusive Optimum Performance Training™ (OPT™) model offers a pathway for progressing functional abilities, including flexibility, core stabilization, balance, strength, power and cardiorespiratory endurance (see “Sample: Progressive Core Workout”). In this article, we’ll look at stabilization, strength and power in NASM’s OPT model as it relates to core training.
Assessing a Client’s Core Stability
Understanding the movements of the spine is imperative to better understanding the core. The spine can be stabilized in all planes, flex and extend in the sagittal plane, flex laterally in the frontal plane (side bend), and perform a combination of these movements in and through multiple planes concurrently (as in a crunch with rotation). In a core training program, the client should begin at the highest level at which he or she can maintain stability while performing an exercise with proper form.
Various movement assessments can identify whether core stabilization is lacking. Here are some, but by no means all, of the options available:
- double-leg lowering test
- overhead squat assessment (OHSA)
- floor bridge (without arching or rounding the spine)
- quadruped opposite arm/leg raise (bird-dog)
Status and progress are evaluated through reassessments, when the trainer gauges whether the client is ready to progress to more dynamic core exercises.
Core Stability Essentials: Bracing and Drawing In
There are two main types of core stability: intervertebral stability and lumbo-pelvic stability.
Intervertebral stability is the ability to minimize movement between vertebrae. This can be done through activation/facilitation of smaller muscles like the transverse abdominis, diaphragm, pelvic-floor muscles and small paraspinal muscles (such as the multifidus). Exercises include Kegels and drawing in (pulling the navel toward the spine).
Lumbo-pelvic stability is the ability to minimize movement between the rib cage and pelvis. This can be done through abdominal bracing (isometric tightening of the core muscles).
Be sure to begin core training by cuing clients on how to perform the drawing-in maneuver and abdominal bracing, as both are essential for performing core exercises properly and safely.
Core Stabilization Exercises
Stabilization is the first phase of core training, according to the NASM OPT model. At this level, there is little to no movement of the spine. By applying this simple guideline, we can more easily provide a taxonomy for exercise. We can add anti-rotational exercises like these:
- plank (prone iso-abs)
- side plank (side iso-abs)
- floor prone cobra (without spinal extension)
- floor bridge (as long as the spine is not dipping or hyperextended)
- cable anti-rotation chest press (Pallof press) (standing or kneeling)
Other exercises that integrate the core are not necessarily core-focused, but they do require the core to remain strong and incredibly stable. For example:
- bent-over rows
- kettlebell swings
- asymmetrically loaded carries
Just because core stabilization exercises are the first part of a progressive program, that doesn’t mean they’re easy. They can be very difficult to perform and even more difficult to do well. These exercises can also be made increasingly difficult when a trainer adds unstable tools, perturbations and different force vectors.
Core Strength Exercises
Core strength exercises require movement of the spine through relatively large ranges of motion and integrate the full muscle-action spectrum (eccentric, isometric and concentric muscle actions). These movements include flexion, extension, lateral flexion, rotation and a combination of those joint actions.
Exercisers usually start in this phase and rarely leave it. Here are some of the common exercises:
- back extension
- side bends
- trunk rotations
These core-focused exercises can also integrate resistance through the use of bands, cables, medicine balls and free weights. A twist can be added, too, as in cable and medicine ball rotations and back extensions.
"Just because core stabilization exercises are the first part of a progressive program, that doesn’t mean they’re easy. They can be very difficult to perform and even more difficult to do well. "
Core Power Exercises
Core power exercises utilize little to no resistance and focus on the movement’s rate of force production (speed). For most clients and trainers, these exercises are fun, because they usually involve throwing things! Here are some examples, which are typically done with a medicine ball:
- rotation chest pass
- overhead crunch throw
- soccer throw
- medicine ball slam
Be sure to use the right type of ball (as in a wall-ball version of a medicine ball) and to throw against a surface that can take the beating (no drywall!). Even though power training focuses on the explosive concentric phase, we cannot achieve this without eccentrically lengthening, or stretching, the muscle. The idea is to spend as little time as possible transitioning from the stretching phase back into an explosive concentric movement.
With all parts of the muscle action spectrum supported by good core stability and balance, we can develop a high-functioning integrated performance paradigm and stretch-shortening cycle (NASM 2018).
A Workout With Science at Its Core
While some voices within and outside of the fitness industry have expressed concern over the potential negative impact of core exercises on the lower back, “numerous studies … support the role of core training in the prevention and rehabilitation of low back pain” (NASM 2018). So, you should not be afraid of core exercises, and neither should your clients.
Of course, any exercise that causes back pain should be avoided, be it a core stability exercise like a plank; a core strength exercise like a crunch; or a core power exercise like a rotation chest pass. Otherwise, placed within a well-designed progressive and systematic training protocol such as the NASM OPT model, these moves are fine. In fact, when clients follow this type of program, they can develop a core musculature that protects the spine during workouts as well as everyday activities.