Functional Fitness: Posture and the Core Area

[Explor­ing Life] The word core means the cen­ter of an object. The Earth’s core, for exam­ple, is also referred to as the cen­ter of the Earth. The core area, or cen­tre, of the body is the site of the inter­nal organs. The core area includes the entire area from the diaphragm down to the base of the pelvis. Core devel­op­ment means the inte­grated and coor­di­nated devel­op­ment of mus­cles, inter­nal organs, pos­ture, and breath­ing. With respect to exer­cise, the core area of the body is the sin­gle most impor­tant con­sid­er­a­tion in any fit­ness pro­gram. In this arti­cle I will explore the basic mus­cu­la­ture of the core area, devel­op­ing body aware­ness of the core, and defin­ing prin­ci­ples for the cor­rect devel­op­ment of the core area.

Core Def­i­n­i­tion: The Site of the Inter­nal Organs

Peri­toneum: The inter­nal organs of the core, or vis­cera, are con­tained in a pro­tec­tive bag of fas­cia known as the peri­toneum. Fas­cia is a sheet or band of fibrous con­nec­tive tis­sue that serve the pur­pose of sep­a­rat­ing or bind­ing together mus­cles and organs. Our entire body is per­me­ated by a vast, con­nected matrix of fas­cia that sur­rounds and pen­e­trates our bones, mus­cles, organs, nerves and blood ves­sels. The peri­toneum is an area of fas­cia that plays an impor­tant role in pro­tect­ing the inter­nal organs:

The peri­toneum, cov­ers almost the entire intes­tine, and all the other inter­nal organs: it facil­i­tates move­ment, even if it keeps the organs in their orig­i­nal place; it pro­tects the abdom­i­nal cav­ity from path­o­genic agents, thanks to the secre­tive and absorbent char­ac­ter­is­tics of its epithe­lium. It is highly vas­cu­lar­ized and it allows amino acids, mono­sac­cha­rdes, glyc­erin, vit­a­mins, water and min­eral salts to enter the mesen­teric blood cir­cu­la­tion. [1]

The back of the peri­toneum is pro­tected and sup­ported by the spine and the pelvis. The front of the peri­toneum is pro­tected by two an inner and outer layer of abdom­i­nal mus­cles that form a gir­dle across the abdomen. One impor­tant func­tion of the core mus­cu­la­ture is to pro­vide sup­port and pro­tec­tion for the inter­nal organs. (See Gray’s Anatomy: The Abdomen)

Basic Mus­cu­la­ture

The core mus­cu­la­ture may be divided into two lay­ers, the inner core and the outer core.

The Inner Core: The deep­est layer of core sta­bil­ity mus­cles are the trans­verse abdo­minis, the mul­ti­fidus, the pelvic floor (or per­ineum), and the psoas mus­cle. While all mus­cles inter­act together and their devel­op­ment must be coor­di­nated and bal­anced, these mus­cles pro­vide the deep­est level of core stability.

1. Trans­verse Abdomi­nus: The cen­tral mus­cle of the inner core area is the trans­verse abdomi­nus (TA). It is the deep­est layer of abdom­i­nal mus­cle that wraps hor­i­zon­tally around the abdomen. It’s main role is to sta­bi­lize the trunk and main­tain abdom­i­nal pres­sure. The TA orig­i­nates in the spinal col­umn of the lum­bar region and wraps around the inner abdom­i­nal area hor­i­zon­tally. Since it is attached to the spine it is the most impor­tant mus­cle for sta­bi­liz­ing the lower back (lum­bar) area. The action of the TA is a squeez­ing motion. Through the lum­bar fas­cia, the TA con­nects to the mul­ti­fidi, which are tiny mus­cles that run between the lum­bar ver­te­brae. [See Mus­cles that Act on the Abdomen]
2. The Mul­ti­fidus: The mul­ti­fidus is a very thin mus­cle deep in the spinal col­umn. The pur­pose of it is to sta­bi­lize the spine and it works together with the TA and the mus­cles of the pelvic floor. When healthy, the mul­ti­fidus will antic­i­pate action and pre­pare the spine for move­ment; when unhealthy the mul­ti­fidus is slow to react lead­ing to pain and poten­tial injury. The main pur­pose of the mul­ti­fidi are to sta­bi­lize the seg­ments along the entire range of the spine. When the mul­ti­fidi con­tract they pro­vide sup­port for the spine and allow us to be in an upright posi­tion. The lum­bar mul­ti­fidi are located in the lower back region. Both the mul­ti­fidus and the trans­verse abdo­minis work in uni­son to pro­vide spinal sta­bil­ity and pro­tec­tion. In other words, the TA and the mul­ti­fidus are in con­stant com­mu­ni­ca­tion about the con­di­tion of the spinal col­umn. If the TA is weak then the action of the lum­bar mul­ti­fidi are strained. If the lum­bar mul­ti­fidi are weak the abil­ity to con­tract the seg­ments of our spine in the lower back are impaired. The TA and lum­bar mul­ti­fidi must work in bal­ance to sta­bi­lize the core. (See Gray’s Anatomy: 6. The Fas­ciæ and Mus­cles of the Trunk. a. The Deep Mus­cles of the Back)
3. The Pelvic Floor: The pelvic floor is a diamond-shaped area defined by the two sit bones, the tail­bone, and the pubic bone. It con­sists of a band of mus­cle extends approx­i­mately mid-way across the dia­mond divid­ing it into two tri­an­gles. The pelvic floor is the base of the core and fun­da­men­tal to pos­ture and core sta­bil­ity and sep­a­rates the inter­nal organs from the per­ineum. A weak TA cre­ates a feel­ing of con­stantly “bear­ing down” result­ing in a pro­tru­sion of the abdomen. This is turn weak­ens the nat­ural lift and mus­cu­lar sup­port of the per­ineum result­ing in a degra­da­tion of the core area. Both the TA and the mus­cles of the per­ineum need to work in bal­ance. (See Gray’s Anatomy: 6e. The Mus­cles and Fas­ciæ of the Pelvis)
4. The Psoas Mus­cle: The psoas mus­cle is the only mus­cle that links the lower (lum­bar) spine to the legs. This mus­cle is essen­tial for bal­ance, align­ment, joint rota­tion and range of motion. The psoas mus­cle also influ­ence the cir­cu­la­tory sys­tem, func­tion­ing of the inter­nal organs, as well as breath­ing. Though we often think of the core in terms or strength or sta­bil­ity, the core area is also crit­i­cal to pos­tural inte­gra­tion and align­ment. Pos­tural mis­align­ment, regard­less of the strength of our mus­cles, even­tu­ally leads to pain. The psoas mus­cle lies at the inter­sec­tion between our legs and our upper body. An under­de­vel­oped psoas mus­cle makes us feel heavy and imbal­anced on our feet. When our body is imbal­anced our mind nat­u­rally fol­lows and this can cre­ate a sense of emo­tional insta­bil­ity within. (See Mus­cles that act on ante­rior thigh: Psoas Major Mus­cle. [2]

The Outer Core: The group of mus­cles com­pris­ing the outer core are not attached to the spinal col­umn, and there­fore do not pro­vide the spine with direct sup­port. These mus­cles include the rec­tus abdomi­nus, and inter­nal and exter­nal obliques.

1. Rec­tus Abdo­minis: On the sur­face of the abdomen between the ribs and pubic bone. It’s main role is to move the body between the rib cage and the pelvis.
2. Exter­nal Oblique Mus­cles: On either side of the rec­tus abdomi­nus, the exter­nal oblique mus­cles allow the trunk to twist. Con­trac­tion of the right exter­nal oblique twists the body to the left.
3. Inter­nal Oblique Mus­cles: These flank the rec­tus abdomi­nus inside the hip­bones and func­tion in tan­dem with the exter­nal obliques. Twist­ing to the left requires the left inter­nal oblique to con­tract in tan­dem with the right exter­nal oblique. [See Mus­cles that Act on the Abdomen]

Core Devel­op­ment

Bal­anced Core Strength: The lower back has a nat­ural curve that is an impor­tant aspect of healthy pos­ture. Straight­en­ing the lower back, as called for in many exer­cises, acti­vates the outer abdom­i­nal mus­cles to push the lum­bar curve straight. The TA is not involved in this action. Squeez­ing in from all sides of the lower abdomen while main­tain­ing the nat­ural lum­bar curve in the lower back does engage the TA. Learn­ing to feel the dif­fer­ence between these two actions is one way to iso­late the action of the TA.

Research sug­gests that the secret to pre­ven­tion and elim­i­na­tion of low back pain is sus­tained con­trac­tion of the TA …outer corset empha­sis can actu­ally over­whelm the inner corset and make it weaker… If you have an under­ac­tive TA, stan­dard abdom­i­nal exer­cises will not engage it and will, in fact, over­ride it. Core strength­en­ing pro­grams are suc­cess­ful only if you can dis­tin­guish the sub­tle sen­sa­tion of TA activ­ity clearly enough to be sure you are using it. [3]

The sus­tained con­trac­tion of the TA refers to main­tain­ing a sense of gen­tly squeez­ing inward and upward in the lower abdom­i­nal region between the pelvic floor and navel. Learn­ing to main­tain an active TA changes the sen­sa­tions in the body due to the realign­ment of cen­tral sup­port. When our TA is inac­tive there is often a sense of bear­ing down as revealed by a pro­trud­ing stom­ach and a gen­eral slouch­ing over from the neck down to the hips. Prop­erly acti­vat­ing and sus­tain­ing the TA reverses these con­di­tions and sen­sa­tions by cre­at­ing a nat­ural inward and upward life between the pelvic floor and navel. This opens the abdom­i­nal area, pro­vides lower back sup­port, and cre­ates more space for the motion of the diaphragm.

Breath­ing and the TA: The diaphragm is a mus­cle that lies between the tho­rax and the abdomen and plays a key role in breath­ing. Dur­ing inhala­tion the diaphragm con­tracts increas­ing space in the chest area: when it relaxes air is exhaled. The diaphragm inter­acts with the mus­cles of the abdomen, which func­tion as an antag­o­nist to the motion of the diaphragm. A weak TA causes the body to slouch for­ward press­ing the tho­rax down on the abdomen. This in turn restricts the nor­mal func­tion­ing of the diaphragm and results in abnor­mal pat­terns of breath­ing, which has a range of neg­a­tive phys­i­o­log­i­cal and psy­cho­log­i­cal effects. If the outer core mus­cles are con­tracted, breath­ing becomes dif­fi­cult since the move­ment of the lower rib cage is restricted. Con­trac­tion of the TA mus­cle does not inter­fere with the move­ment of the lower rib cage dur­ing breathing.

Pres­sure on the Inter­nal Organs: A weak core area directly affects the oper­a­tion of the inter­nal organs. Clo­sure, or con­sis­tent down­ward pres­sure on the stom­ach, inhibits blood cir­cu­la­tion as well as the effec­tive exchange of oxy­gen and car­bon diox­ide in the blood­stream. This places the inter­nal organs in a con­stant state of stress and can result in a range of symp­toms includ­ing diges­tive prob­lems and incontinence.

Habit­u­al­iza­tion of Ten­sion in the Body and Mind: An imbal­anced core area affects both body and mind. Although we can become tol­er­ant of unhealthy states of stress, the sub­con­scious habit­u­al­iza­tion of ten­sion in the core area can lead to phys­i­cal and emo­tional dif­fi­cul­ties. In this sense, the mus­cles of the abdomen can directly con­tribute to our states of mind.

Notes

1. Lazzetti and Rigutti. The Atlas of Human Anatomy, 2002.

2. A good overview of the psoas mus­cle is Psoas: The For­got­ten Mus­cle.

3. Bond, Mary. The New Rules of Pos­ture, 2007.