Today I’m fortunate enough to have my very first guest post by someone who I respect and admire in this industry – my brother, Brandon McCary. Brandon is a Rehab Specialist who holds certifications with NASM (PES), Functional Movement Systems (Level-2 FMS Expert), and ISSA (SSN) – just to name a few.
If you’re a trainer, than this is a great post for you. So with that, enjoy!
The Lumbo-Pelvic-Hip Complex, Part 1.
The core is comprised of two stabilization systems, the local and global core systems. The core is made up of muscles and connective tissues of the lumbar spine, pelvic girdle, and hip joint, which constitutes the Lumbo-Pelvic-Hip Complex. The core is where the body’s center of gravity is located and where all movement originates. Active individuals with a stable core can prevent abdominal tears, by activating the local core prior to extremity movement, such as during a soccer strike.
A neuromuscularly efficient core is needed in order to have optimal neuromuscular control of the human movement system. A stable, strong, and powerful firing core prevents injury and allows for acceleration, deceleration, and stabilization during dynamic movements.
The Local Stabilization System
The primary muscles that make up the local stabilization system are the diaphragm, transverse abdominis, internal obliques, multifidus, and pelvic floor musculature. The local core muscles attachdirectly to the vertebrae. These deep muscles of the spine are primarily slow twitch muscle fibers, fibers with optimal endurance for maintaining posture and respiration. Muscle spindles are abundant among the local core muscles, muscle spindles are sensory receptors which detect the rate of change in muscle length.
Intervertebral Stability (deep stiffness)
Intervertebral Stability (IVS) is only possible through training both types of intervertebral stiffness. The first type of stiffness is achieved by co-contraction of the transverse abdominus and multifidus by performing an exercise known as “Drawing-In”. Next up, performing exercises that increase intra-abdominal pressure, like “Belly Breathing” will also increase IVS. These exercises can be progressing through three different postures: Fundamental, Transitional, and Functional. A great example of transitional phase belly breathing is in the sphinx position (more on this cool stuff in part 2). By having both forms of core stiffness trained, you will have 100% local core stability achieved, which allows for optimal IVS, which then limits excessive compressive, shear, and rotational forces between spinal segments.
Core Stabilization Mechanisms
The core is also stabilized during functional movement by two core stabilization mechanisms, one being the fascial nextwork that acts as an auxiliary core stabilizer by dynamic engagement, the thoracolumbar fascia mechanism. The second auxiliary core stabilizing mechanism is the intra-abdominal pressure mechanism, which activates the diaphragm and pelvic floor.
Inspiration and Expiration
Inspiration and expiration is also achieved via local core activation. The muscles required for inspiration and elevation of the ribs are your “principal” and “accessory” muscles. The principal muscles are the diaphragm, external intercostals, and the accessory muscles are the scalene group, sternocleidomastoid and pectoralis minor. The muscles required for expiration and rib depression are your “active breathing” and “quiet breathing” muscles. The active breathing muscles are the internal intercostals, abdominals and quadratus lumborum. As for quiet breathing, the expiration results from passive, elastic recoil of the lungs, rib cage, and diaphragm.
Diaphragm, Intra-abdominal Pressure, Pelvo-
The “roof” of the local core, is the diaphragm. Since the diaphragm is located between the thoracic and abdominal cavities, learning to build intra-abdominal pressure will cause diaphragmatic elevation and pelvic floor contraction, which allows for decreased compressive forces across spinal segments. Simply being able to contract your diaphragm can help you prevent injury, and produce optimal movement! Learning to breathe with the diaphragm/abdomen rather than the chest/accessory musculature is extremely useful in pain relief and performance. Chest breathing can actually alter your head position due to the hypertonic/tight accessory neck muscles. The “pelvo-ocular reflex” theorized that one’s head position can have an effect on one’s pelvic position. If your head migrates forward, the pelvis reflexively rotates anteriorly to readjust one’s center of gravity, which will cause even further problems with thoracolumbar fascia pain of the low back. In part 2, exercises for diaphragmatic breathing and both the local, and global core will be discussed.
Thoracolumbar Fascia Mechanism
The thoracolumbar fascia (TLF) is a fascial network of noncontractile tissue that is engaged dynamically by contractile tissues that attach to it, such as the erector spinae, multifidus, transverse abdominis, internal oblique, gluteus maximus, latissimus dorsi, and quadratus lumborum. Training the local core achieves increased spinal stiffness/stability which decreases translational and rotational stress at the spine. The multifidus is the local core’s multisegmental “spinal glue”, and from the cervical region all the way down to the sacral region, the multifidus runs deep within each spinal segment, stabilizing each facet joint from the neck to the tailbone.
Pelvic Floor Mechanism, Stress Incontinence
The pelvic floor is considered the “floor” of the local core, and is activated when intra-abdominal pressure is present. Having weak pelvic floor musculature is common among adults, unfortunately, if it goes unnoticed for too long, pelvic floor dysfunction can set in. Also, common among females is stress incontinence, but the good news is, it can be easily treated with core stability exercises and functional movements. The deep squat exercise is actually great for recruiting the pelvic floor, and should be part of ones rehab program once local core stability has been worked on.
The Global Stabilization System
The global core muscles are the quadratus lumborum, psoas major, external/internal obliques, rectus abdominis, gluteus medius, and adductor musculature. These muscles transfer loads between the upper and lower extremity and provide stability between the pelvis and spine.
Lumbo-Pelvic Stability (superficial stiffness)
By simultaneously activating the abdominals (rectus abdominis), lower back (quadratus lumborum), buttock (gluteus medius) at the same time, you achieve what is called co-contraction of superficial musculature of the spine, which is known as an exercise called, “bracing”. Just like with drawing-in and belly breathing, there are also three different postures for core bracing: Fundamental, Transitional, and Functional. When the muscles are contracting, they are increasing stiffness between the spine and pelvis. A great example of a functional brace is when you stand up from squatting, and simultaneously brace the abs, low back and glutes in effort to stabilize the lumbar spine (the thoracolumbar fascia mechanism also has a role in this).
Optimal Movement Optimal neuromuscular control of movement is made up of several factors. We are already learned the local and global core systems role in movement, now it’s time to learn what other factors need to be considered for optimal movement.
1. Length-Tension Relationships
Having an optimal gamma efferent system, which is achieved by having optimal force generation in relation to a muscles “tone”. Neurologically, normal muscles aren’t hypertonic (overactive/tight) or hypotonic (underactive/weak+tight). For ex. When running, having the ability to generate force/tension in the hamstrings without spasticity (muscle spasm) occuring!
2. Force-Couple Relationships
Another necessary factor for having optimal neuromuscular control is having normal force-coupling relationships, or the ability to activate groups of muscles at once. A great example would be during a baseball pitcher’s throw, the upper and lower trapezius muscles have to activate together in order to stabilize scapular upward rotation.
3. Joint Arthokinematics (Joint Centration) Lastly, having normal joint arthokinematics is the ability to maintain joint position through all planes of motion, for ex. as seen in the photo below, the ball and socket joint-the shoulder joint should be able to move from flexion to extension without the humeral head gliding anteriorly.
4. Buttressing Your Truss (Spinal Stability)
As the eminent Biomechanist, Dr. Stuart McGill once said, “Create a truss”. Think of your core as a stable bridge, the deeper the truss, the more stable the bridge! How do we make our core “deep” in effort to become more stable? We train not only the global/superficial core, but also the local/deep core! When both core systems are stabilized, we then have….optimal Spinal Stability! Intervertebral Stability + Lumbo-Pelvic Stability = Spinal Stability
Finally…Optimal Neuromuscular Control!
All of these factors: spinal stability, length-tension relationships, force-couple relationships, and joint arthokinematics have to be normal in order for there to be symmetrical, powerful, and optimal movement!
In part 2, the local core, “drawing-in/belly breathing” exercise progressions, and static/dynamic global core “bracing” exercise progressions will be discussed, and demonstrated.