Download What inside YOUR CORE

What’s inside YOUR CORE?
Jonathan N. Mike - MS, CSCS, USAW, NSCA-CPT
Doctorate Student: Exercise Physiology/ Strength and Conditioning
It is critically important to discuss differences between core strength and core stability.
Interestingly enough, individuals use them interchangeably. However in reality, they are
different. In addition, it is imperative to converse on the application of core training and
current research involved with this phenomenon. It is fascinating that trainers and
coaches implement these modalities into their program without knowing either historical
significance or current research and application initiatives.
The “core musculature” consists of the 29 pairs of muscles that support the lumbopelvic-hip complex in order to stabile the spine, pelvis, and kinetic chain during
functional movement (1). Stability is the ability of the body to control the whole
range of motion of a joint thereby not creating deformity, neurological deficits, or
incapacitating pain (2,3). In the proceeding paragraphs, there is evidence to support that
endurance is the better training variable when training core musculature. (4,5).
To differentiate between terms, the article from Faries (6) notes core ‘stability’ is being
made to the stability of the spine, not the stability of the muscle themselves. The
authors also mention there has been no reference to enhancing the stability of a muscle,
but rather the ability of the muscle to contract. Specifically, the muscles are contracting in
order to control that functional movement.
Core “strength” is used and reference is made to the ability of the musculature to
stabilize the spine through contractile forces and intra-abdominal pressure (6).
However, confusion exits on labeling an exercise core strength or stability. According to
Faries (6), core exercises do not aim to increase the stability of the musculature, but
enhance the muscles ability to stabilize the spine, specifically, the lumbar spine.
Recent research has promoted the Transverse Abdominis (TrA) and Multifidis or
Multifidi as the primary stabilizers of the spine (1,2,7), and thus when contracted they are
able to increase tension of the thora-columbar fascia and increase intra-abdominal
pressure, increasing spinal stiffness in order to resist forces acting on the lumbar spine.
So, in other words, this lends the fact that core stability is essential for resisting
forces on the spine such as in squatting, deadlifting, and overhead pressing. It is also
useful for upper body movements, and can aid in single arm or leg exercises. In
addition, since these muscles do not create movement of the spine, the internal oblique,
the medial fibers of the external oblique, and the quadratus lumborum also assist in
stabilizing the spine, but also FUNCTION, secondarily to MOVE the spine (2).
Faries (2007) stresses the importance of both local (i.e. TrA, Multifidis) and global
(rectus abdominus, erector spinae) musculature in terms of incorporating both into a
training program, although overall the whole ‘application’ to core training from a
‘research view’ is limited. Since those global muscles have long levers and force arms,
they are able to produce high outputs of torque with emphasis on speed, power, and a
large arc of multiplanar movements, while counteracting the external loads for transfer to
local systems (1,8). In regards to fiber typing, the local system consists of mainly type 1
and global is mainly type II (8,9).
It has been suggested that focus should move past the strength alone to understand the
speed with which the muscles contract in reaction to a force (2). Also, some individuals
might do well on a strength test of force but do poor on a performance test of endurance
(10). History and specificity of training are major influences. As with assessment,
measures of the core should include various performance measures of force, endurance,
and power (6).
There is also the possibility of too much stability as well as too little stability and what
the optimum dosage response should represent. “Sufficient stability” would be the
minimal level to assure spinal stability without imposing unnecessary loads on the
muscles and tissues (11). However, an ideal set of exercises for all individuals currently
does not exist, but general suggestions for exercises that emphasize trunk stabilization in
a neutral spine, while emphasizing mobility of the hip and knees (12, 13, 5). For a further
discussion in this area, please refer to McGill in the reference section.
In regards to performance enhancement, limited research has been conducted. However,
Hagins (14) showed that a 4 weeks lumbar stabilization exercise program improved the
ability to perform progressively difficult lumbar stabilization exercises. Six weeks of
swiss ball training specifically designed for core activation improved ability of core
musculature to stabilize the spine significantly, while also improving core endurance
(15).
Functional progression is the important aspect of core strengthening, which includes
performance goals, history of functional activities, variety of assessment, and training in
all 3 planes of motion (16,10). Interestingly, a brief statement made of the possibility of
overtraining the global system such as rectus abdominus, which seems to be the most
utilized part of core training. Consequently, the local system must compensate
Many coaches are big advocates of the whole ‘functional’ aspect because it works for
them and their athletes and clients, while others are not as convinced. Notwithstanding,
personal trainers, fitness professionals and coaches will continue to use what has worked
and what they are successfully with despite what ‘research’ says. This can be a good
thing as it opens more doors for new types of training, philosophies and principles.
References
1). Fredericson, M., and T. Moore. Core stabilization training for middle and
long-distance runners. New Stud. Athletics. 20:25–37. 2005
2). NORRIS, C.M. Functional load abdominal training: Part 1. J. Body Work
Mov. Ther. 3:150–158. 1999.
3). Panjabi, M.M. The stabilizing system of the spine. Part I. Function, dysfunction
adaptation and enhancement. J. Spinal Disord. 5:383–389. 1992.
4). McGill, S.M. Low back exercises: Evidence for improving exercise regimens.
Phys. Ther. 78:754–765. 1998.47.
5). McGill, S.M. Stability: From biomechanical concept to chiropractic practice.
J. Can. Chiropractic Assoc.43:75–88. 1999.
6). Faries, M, and Greenwood, M. Core Training: Stabilizing the Confusion. Strength and
Conditioning Journal. 29 (2). 2007
7). Moseley, G.L., P.W. Hodges, and S.C. Gandevia. Deep and superficial fibers of the
lumbar multifidus muscle are differentially active during voluntary arm movements.
Spine. 27:E29–
E36. 2002.
8). Standford, M.E. Effectiveness of specific lumbar stabilization exercises: A
single case study. J. Man. Manipulative Ther. 10:40–46. 2002.
9). Richardson, C., G. Jull, R. Toppenburg, and M. Comeford. Techniques for active
lumbar stabilization for spinal protection: A pilot study. Aust. J. Physiother. 38:105–112.
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10). Kroll, P.G., L. Machado, C. Happy,
S. Leong, and B. Chen. The relationship between five measures of trunk strength. J. Back
Musculoskeletal Rehabil. 14:89–97. 2000.
11). Vera-Garcia, F.J., S.H.M. Brown, J.R. Brown, and S.M. McGill. Effects of different
levels of torso coactivation on trunk muscular and kinematic responses to posteriorly
applied sudden loads. Clin. Biomech. 21:443– 455. 2006.
12). Axler CT, McGill SM. Low back loads over a variety of abdominal exercises:
searching for the safest abdominal challenge. Med Sci Sports Exerc. 1997 Jun;29(6):80411.
13). Barr KP, Griggs M, Cadby T. Lumbar stabilization: core concepts and current
literature, Part 1. Am J Phys Med Rehabil. 2005 Jun;84(6):473-80. Review.
14). Hagins, M., K. Adler, M. Cash, J. Daughtery, and G. Mitrani. Effects of practice on
the ability to perform lumbar stabilization exercises. Orthop. Sports Phys. Ther. 29:546–
555. 1999.
15). Stanton, R., P.R. Reaburn, and B. Humphries. The effect of short-term
Swiss ball training on core stability and running economy. J. Strength Cond.Res. 18:522–
528. 2004.
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