Progressions of Isometric Core Training - NSCA of Isometric Core Training Natasha Mendrin, MS, ......

Progressions of IsometricCore TrainingNatasha Mendrin, MS, Scott K. Lynn, PhD, Halecia K. Griffith-Merritt, MS, and Guillermo J. Noffal, PhDCenter for Sport Performance, Department of Kinesiology, California State University, Fullerton, California

A B S T R A C T

WITH THE GROWTH IN POPULAR-

ITY OF CORE TRAINING, IT IS

IMPORTANT THAT THERE IS A

CLEAR UNDERSTANDING OF HOW

TO BEST TAILOR THESE EXER-

CISES TO SAFELY MEET THE

NEEDS OF DIFFERENT INDIVIDU-

ALS. EXTENSIVE RESEARCH HAS

SHOWN THAT TRAINING THE

CORE MUSCLES ISOMETRICALLY,

THAT IS WITHOUT BENDING THE

SPINE, IS SAFE AND MAY HELP

REDUCE THE INCIDENCE OF BACK

INJURY. EXERCISE PROFESSIO-

NALS MUST HAVE THE ABILITY TO

MODIFY ISOMETRIC CORE EXER-

CISES AND ALTER THEIR DIFFI-

CULTY TO ENSURE THAT THEY

PROVIDE A SAFE AND APPROPRI-

ATE CHALLENGE FOR INDIVIDUALS

OF VARYING FITNESS LEVELS AND

TRAINING GOALS. THEREFORE,

THIS ARTICLE SUMMARIZES THE

CURRENT RESEARCH THAT OUT-

LINES THE POTENTIAL NEGATIVE

CONSEQUENCES OF CON-

STANTLY BENDING OR MOVING

THROUGH THE SPINE. THIS PRO-

VIDES THE RATIONALE FOR

TRAINING THE CORE ISOMETRI-

CALLY TO AVOID REPLICATING

THESE KNOWN MECHANISMS OF

INJURY DURING EXERCISE. EXAM-

PLES OF ISOMETRIC CORE EXER-

CISES OF VARYING DIFFICULTY

ARE ALSO PROVIDED, AS WELL

AS A MODEL OUTLINING HOW TO

IMPLEMENT THESEPROGRESSIONS

TO SAFELY MEET THE NEEDS OF

ANY INDIVIDUAL IN A GENERAL

FITNESS POPULATION.

INTRODUCTION

There is great interest among thegeneral population in core train-ing exercises. No matter what

the goal of this core training, it mustbe ensured that these exercises areperformed as safely as possible. Expos-ing the general population to poten-tially harmful exercises should beavoided at all costs. Since approxi-mately up to 85% of people will expe-rience low back pain (LBP) duringtheir lifetime (1), and it is the leadingcause of limited physical activity inpeople 45 years of age and younger(1), exercise professionals must havean understanding of the researchexamining how to safely and effec-tively train the core musculature.

Research has suggested that the coremusculature be trained differently thanthe muscles of the limbs (20). Limbmuscles (biceps brachii, hamstrings,etc.) are commonly used to move thesegments to which they are attached,so training them as prime movers maybe appropriate. However, McGill (20)suggests that most often during humanmovement, the function of the coremusculature is to co-contract, stiffen,and prevent motion rather than pro-duce it. Proficient human movementinvolves the limb muscles generatingpower that must be transferredthrough a stiffened core so that theentire body can be moved efficiently.It is believed that if proper core stabi-lization is not maintained, when poweris developed from the ball and socket

joints (hips and shoulders), the spinewill bend or lose its neutral alignment.This spinal movement is considered an“energy leak,” as the power generatedfrom the limbs is absorbed proximallyin the soft tissues of the spine and nottransferred distally as efficiently as pos-sible (20). The detrimental effects of anenergy leak such as a repeated spinalflexion during hip flexion movementshave been shown to lead to injuriessuch as posterior disc herniation (5).Therefore, to make core training assafe as possible for any population,the core muscles should be trainedas stabilizers rather than prime mov-ers (20). This concept is supported byresearch examining low back loadsduring different abdominal exercises(2) as well as by a recent trainingstudy comparing long-term isometriccore training to a more dynamic train-ing program (15).

Spinal posture has been found to bea key determinant in the amount ofcompressive load that the spine is ableto withstand before injury occurs, as ina flexed posture, the spine has a muchlower yield point and ultimate com-pressive strength (9). This means thatwhen there is flexion of the spine inaddition to the compression, the loadthat the spine can withstand decreasesand the risk of injury increases substan-tially (5,9). Therefore, the safest way totrain the core musculature is to ensurethat the spine remains in a neutral posi-tion when any load is introduced tothe body.

Address correspondence to Dr. Scott K. Lynn,[email protected].

KEY WORDS :

abdominal exercises; core stability; lowback pain; spinal posture

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PRACTICAL APPLICATIONS

LBP can be caused by an acute injuryor can be due to chronically poormovement patterns that buildup overtime (1). Although core training maynot be able to prevent LBP due to blunttraumas such as car accidents, certaintypes of LBP are preventable byimproving the quality of movement(12). A fundamental and effective wayto prevent LBP is to maintain a neutrallordotic curve in the lumbar spine(12,19,26) as the stresses and strainson the low back tissues are increasedin nonneutral postures (8). Strainapplied repeatedly or for a prolongedperiod of time to a tissue will eventuallyresult in tissue failure and pain (26);therefore, continually adopting animproper posture in any environment(i.e., workplace, gym, activities of dailyliving) may cause injury (19). However,identifying and correcting spinal pos-tures both statically and during move-ment may help relieve the pain andprevent further damage (19). Exerciseprofessionals can now quantify andtrack the movement of the lumbopel-vic complex easily in clients using inex-pensive and readily availabletechnologies (i.e., smartphone applica-tion) that have been shown to identifythose at risk of injury (6). Correctiveexercises can then be undertaken withthese individuals to avoid injury.

MOVEMENTS OF THE SPINE

The spine moves in 4 directions: flex-ion, extension, lateral flexion (rightand left), and axial rotation (rightand left). Research supporting theinjury risk from excessive movementof the spine in any one direction ispresented below.

FLEXION AND EXTENSION

Lumbar flexion and extension bothhave distinct mechanisms of differentinjuries. Repeated lumbar flexion andextension have been shown to causea stretching of the passive tissues(5,12) which can lead to small micro-traumas that can buildup over time tocause tissue damage (27). These con-ditions are worsened when high com-pressive loads are introduced to many

repetitions of flexions or extensions(5). Therefore, greater compressiveloads can lead to a greater risk ofinjury when combined with nonneu-tral sagittal plane positions of the lum-bar spine. Continued exposure tosuch movements and postures overtime may lead to the developmentof chronic conditions, where visco-elastic tissues begin to degenerate.

An intervertebral disc (IVD) injurymost commonly occurs posteriorlydue to a spinal flexion mechanism.This is due to the increased pressureon the posterior side of the disc as thespine goes into flexion (5,18). Anteriordisc herniations are not as commonbut have been known to occur amongpopulations such as gymnasts whoexperience extreme levels of extension(25,28). IVD injuries are progressiveconditions with a mechanism of injurythat commonly involves compressionwith the spinal flexion (posterior IVDherniation) or extension (anterior IVDherniation) (5). Callaghan and McGill(5) showed that, as the compressiveload increased, there was much greaterincidence of injury to the IVD duringrepeated flexion and extension move-ments. This indicates that the risk ofIVD injury increases during a move-ment that involves flexing or extendingthe spine when external loads areadded to the movement.

Spinal flexion not only creates a pos-terior shear force on the IVD, but italso increases the extensor muscleactivity and load (10). The increasedmuscle activity has been shown tocause compressive stresses on theIVD in the lumbar spine (10). In com-parison to an upright posture, ananteriorly positioned thorax resultedin significant increases in load andstress on the lumbar spine (10).McGill et al. (21) also assessedwhether changes in hip flexion angleor lumbar curvature affected lumbarextensor muscle fiber direction andthus its ability to support anteriorshear loads. Muscle angle orientationwas not affected with 308 of hip flex-ion if a neutral lumbar position wasmaintained; however, in a flexed

lumbar position, these angles werealtered. Full lumbar flexion compro-mised the ability of lumbar extensorsto support shear force, makingthe handling of heavy loads ina flexed lumbar position much moredangerous.

There are also spinal pathologies thatare believed to be caused by excessive,repeated extension of the lumbarspine. These include the spondyliticdisorders (spondylolisthesis and spon-dylolysis), which are a common causeof LBP in young athletes (25,28).Although this work is focused on a gen-eral fitness population, many formerathletes may have developed long-term injuries from these activities (3).Those who have been gymnasts,cricket bowlers, divers, weightlifters,wrestlers, and football linemen maybe at increased risk of developing thesedisorders as these activities can fre-quently require extension of the lumbarspine while in loaded positions (25).Spondylolisthesis is recognized as for-ward slippage of one vertebra onanother, whereas spondylolysis occurswhen there is a fracture to the posteriorpart of the vertebrae known as the parsinterarticularis (25,28). Therefore,avoiding overt and excessive extensionof the lumbar spine, while loaded, isimportant for preventing LBP.

ROTATION AND LATERAL FLEXION

Movements that involve twisting ofthe spine are common in work-related, athletic, and domestic tasks.Pure axial rotation has not been shownto be a direct cause of injury (18), butrarely do movements involve just rota-tion. Generally, there is a combinedloading that includes flexion-extension, static axial torque, or staticcompression (7). Axial torque, whichleads to axial rotation, has been shownto significantly increase the likelihoodof injury (7). Those who experienceaxial rotation repetitively with com-bined loading are at a high risk of sev-eral pathologies, including discherniation (7). Marshall and McGill(18) determined that pure axial torque(twist) did not lead to any damage to

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the disc; however, when axial torquewas combined with flexion-extension,there was a large increase in tissue de-formations that are known to lead todisc herniation. Therefore, compulsorymovements that involve combinedtwisting and bending of the spine cre-ate a risk for low back injury andshould be avoided.

Asymmetric loading of the spine withlateral lifting and lowering is alsobelieved to lead to LBP. Huang et al.(11) examined the pulling force duringlateral lifting and lowering from

a standing position and found that peakforce occurred in a laterally flexedposition in the opposite direction ofthe load, which may impose anincreased risk of injury to the spine.Marras et al. (17) identified the later-ally bent posture and lateral bendingvelocity as risks related to low backdisorders. Additionally, Kumar et al.(14) found that strength declines asan individual assumes a laterally flexedspinal posture. Research invariablyconcludes that lateral bending or fron-tal plane movement of the spine

compromises the integrity of thespine; therefore, it may be wise toavoid exercises that involve repeatedspinal lateral bending beyond that ofwhich is tolerable.

EXERCISE CONSIDERATIONS

PROGRESSION AND REGRESSION

Exercise modification is necessary sothat exercise professionals may tailorexercises to fit an individual’s specificneeds while still maintaining an appro-priate level of challenge. Exercise pro-gression increases the difficulty whenthe basic exercise no longer providesa challenge. Theoretically, exercisesthat are properly progressed will con-tinually improve the efficiency ofmovement patterns, while also increas-ing the margin of safety (the distancebetween applied loads and the failuretolerance of the tissues) (24). Con-versely, exercise regression decreasesthe difficulty so that an individual canlearn the appropriate muscular activa-tion strategies in a way that decreasesthe chances of developing compensa-tions in their movement patterns lead-ing to injury (16). It has been suggestedthat a safe and effective exercise planshould be of low risk and high demand(23); therefore, a trainer should have

Figure 1. Blanchard and Glasgow (4) exercise progression model.

Figure 2. Basic plank.

Progressions of Isometric Core Training

VOLUME 38 | NUMBER 4 | AUGUST 201652


the ability to make small variations inthe difficulty of an exercise to ensurethat the client can handle the increasesin demand without placing them at riskfor injury.

Blanchard and Glasgow (4) suggesteda model for exercise progression andregression (Figure 1). In Figure 1, hor-izontal axis represents time, and thevertical axis represents the level of

difficulty of the exercise. The most con-trolled level of any exercise is labeled“A” in Figure 1. At this level, the clientshould be focusing on only one funda-mental task, and other variables should

Figure 3. Wheel rollout.

Figure 4. Dead bug.



be limited. For core exercise, thisshould be training the core muscula-ture to stabilize the lumbar spine ina neutral lordotic position. Proprio-ceptive sense of this neutral lordoticposition would be the primary goal ofa core exercise at this level. Thiswould also be a fundamental goal ofevery progression of a core exercise asthe triangle labeled A is on top ofevery progression. The level “A” exer-cise can then be slowly progressedlinearly (moving up the triangle) byincreasing the duration of the hold,number of repetitions, etc. The nextstep “B” would be to add an extrinsiccomponent to the exercise to furthercomplicate the basic task. Furtherprogressions to the exercise couldthen be performed separately oradded to the previous progression(“C,” “D,” etc.). Once an exercise var-iation is mastered, a progression needsto be introduced to ensure constantchallenge and improvement. Theexercise progression model will be re-visited at the end of the article to givemore specific ideas for implementingthe exercises presented in this article.

DURATION OF STATIC POSTURE

Although increasing the duration ofa static hold is presented as a way toprogress within the basic exercise,there is some concern in regard tothe duration that isometric contrac-tions are held. Kell and Bhambhani(13) investigated muscle oxygenation(MOx) during prolonged static postureand found that maintaining a staticposture may lead to decreased MOxand increased fatigue—factors that canlead to injury and pain. It is believedthat there is a correlation betweenMOx levels and LBP, which makes itvital that MOx is maintained during anisometric contraction. It has beendetermined that a 30-second isometrichold will reduce lumbar extensor MOx(22). Thus, muscular rest after a 30-second isometric hold is recommendedto maintain adequate MOx levels andto ultimately reduce the risk of injury(13,22). Progressing isometric exercisesby simply increasing the duration ofthe hold may not be the best strategy.Progressions could instead be intro-duced by increasing the difficulty ofthe exercise or by increasing the

number of repetitions of shorter iso-metric holds.

MOVEMENT VERSUS MOMENT

Progressing isometric exercises re-quires an understanding of the differ-ence between a “movement” and“moment.” A flexion movement isa kinematic term and defines the actof bending the spine forward or of flex-ing the spine. A flexion moment isa kinetic term and is the act of creatinga moment or torque. Moments can becreated independent of whether or notmovement occurs. Pushing an immov-able object requires the spine to stiffenwith anterior muscle activation toavoid energy leaks or spine move-ments. Hence, these muscles shouldbe producing a flexion moment with-out actual movement. For those whowant to avoid back injury or pain,enhancing stiffness with flexionmoment training while avoiding flex-ion movements is essential to controland ultimately eliminate the microtrau-mas that lead to pain (20). With thisknowledge, it can be assumed that it issafest to progress core exercises with

Figure 6. Bodysaw.

Figure 5. Mountain climbers.




moments rather than movements. Thisarticle will provide examples of pro-gressions of isometric core exercisesthat challenge the core musculaturein each of the 3 principal planes: sag-ittal, frontal, and transverse.

The following figures show exerciseswith their corresponding progressionsand regressions. Note, all steps neededto perform an exercise are depictedwith letters (a, b, c), whereas romannumerals (i, ii, iii) indicate progressionswithin an exercise (difficulty increaseswith larger numbers).

ISOMETRIC CORE TRAININGEXAMPLES

SAGITTAL PLANE EXERCISES

One option for regressing the plank(figure 2) includes placing the forearmson a raised surface (i); the higher thesurface you use, the greater the regres-sion. The basic form of the plank isperformed with the feet on the floor,a level trunk, and the elbows directlyunder the shoulders (ii). There aremany ways to progress this exercise,

some of which include walking theforearms slightly forward from thetrunk (iii) to increase the momentarm distance or placing the feet ona raised surface (iv).

The starting position for the wheelrollout (figure 3) has the individualkneeling with their hands on the wheel(ia). The movement involves rollingout as far as possible while maintainingstability and a neutral lumbar spine asthe moment arm distance is increased(ib), and then returning to the startingposition by rolling back. Performingthis exercise on the feet rather thanthe knees will further increase themoment arm distance and the difficulty(iia–iib). If this exercise is too difficultto perform on the wheel, the same con-cept can be achieved in a more stableposition on the hands (not shown).

To perform the dead bug (figure 4),begin by laying supine on the BOSUwith the hips and knees flexed at 908and both arms positioned directlyupward (ii). Maintain an abdominalbrace and neutral lordotic curvatures

of the spine (including neck), and holdthis position. To increase the difficulty,slowly extend either one leg or onearm at a time and alternate (iii). Fur-ther progressing, this exercise is per-formed by extending the opposite armand leg simultaneously (iv). If an indi-vidual is not able to maintain stabilityon the BOSU, these same exercisescan be performed on the floor witha towel rolled under the lumbar spineto maintain a neutral lordotic curva-ture (i).

The mountain climber exercise shownin figure 5 is being performed on a sus-pension trainer, but it can also be per-formed on surfaces such as sliders ora slide board. The feet insert into thehandles of the suspension trainer, andthe body is level with the handsdirectly under the shoulders (a). Alter-nately driving one knee toward thechest and returning to the starting posi-tion (b–c). Options for progressing thismovement might include increasingthe speed, raising the height of the sus-pension trainer, or walking the hands

Figure 7. Sagittal plane body blade.



slightly forward away from the body. Itis important to ensure that the motionis coming entirely from the hip andthere is no spine flexion as the kneecomes toward the chest.

The starting position for the bodysaw(figure 6) is a basic plank but with thefeet positioned on a sliding surface (a).The movement involves pushingagainst the floor with the forearmsto slide the feet backward, going onlyas far as the abdominal brace is main-tained (b), and then sliding the feet for-ward to where the shoulders pass overthe elbows (c). To progress this exercise,decrease the speed of the movement orfurther increase the moment arm

distance by sliding the feet farther back.This exercise is being performed ona slide board, although it can also beperformed on sliders or even a towelon a tiled floor.

The sagittal plane body blade (figure 7)exercise can be performed by holdingthe blade either vertically or horizon-tally (not shown) and involves oscillat-ing the blade while maintainingabdominal bracing. This exercise canbe progressed by moving the arms fur-ther away from the trunk (ii) or by per-forming the same exercise unilaterallyto introduce some twisting forces thatwill require increased transverse planemuscle recruitment as well (not shown).

FRONTAL PLANE EXERCISES

The most regressed form of the sideplank (figure 8) shown is with theknees bent at 908 and stacked, withthe elbow directly under the shoulder(i). The elbow can also be placed ona raised surface to regress this exerciseusing the same principle as was shownin Figure 1 (basic plank). Extendingthe legs with the feet in a wide stance(ii) is the first progression and can belater followed by stacking the feet (iii)to reduce the base of support. Placingthe feet on a raised surface (iv) isanother option for progressing thismovement. Once higher levels of fron-tal plane stability are achieved, this

Figure 8. Side plank.




Figure 9. Suitcase carry.

Figure 10. Frontal plane body blade.



exercise can be performed with thesupporting arm extended (v) and laterwith the top leg lifted for the highestprogression shown here (vi). Addi-tional ways of progressing this exercisemight involve placing a weight on thehip or holding a weight with the toparm extended straight up.

To perform a suitcase carry (figure 9)hold a moderately heavy kettlebell inone hand, and walk with abdominalbracing to avoid any lateral trunkbending (i). For progression, holdthe kettlebell bottoms-up at shoulderlevel, making sure not to rest the armon the chest (ii). The last progression

shown is holding the kettlebell with anextended arm directly above the shoul-der (iii). Considerations for altering thisexercise include the degree of armabduction, the weight of the kettlebell,and the duration of walking.

To perform the frontal plane bodyblade (figure 10) hold the body bladedirectly in front of the chest and oscil-late the blade side to side (i), being sureto maintain abdominal bracing. Thisexercise can be progressed by movingthe arms further away from the trunk(ii) or by performing the same exerciseunilaterally as was discussed in Figure 6(not shown).

TRANSVERSE PLANE EXERCISES

The landmine exercise (figure 11) is gen-erally performed with a barbell that issecured at one end and freely movable atthe other. Hold the top end with bothhands and stand with the feet shoulder-width apart (ia). Apply abdominal braceand, in a controlled manner, rotate thebar from side to side. This exercise canbe performed in 2 forms: (i and ii) allow-ing the hips and shoulders to rotate andthe weight to shift or (iii and iv) keepingthe hips and shoulders facing forwardand only allowing the arms and bar torotate with noweight shift. One progres-sion (iib and ivb) would be to extend the

Figure 11. Landmines.




arms further from the body. In addition,

adding weight to the top end of thebarbell can increase the challenge ofthe exercise.

Figure 12 shows 3 levels of the bird dogexercise. The first level is performed on

the hands and knees (i–iii), the secondon the feet and elbows (iv–vi), and the

third on the feet and hands (vii–ix). Themost regressed form of each level starts

with alternately extending either one

arm or one leg out at a time, and the

final progression is to extend the oppo-site arm and leg at the same time.

To perform the cable press (figure 13)walk out laterally from a cablemachine holding a handle with bothhands close to the chest and the feet

Figure 12. Bird dog.

Figure 13. Cable press.



in a comfortable athletic stance (a).Without any movement of the trunk,slowly extend both arms away fromthe chest. You can begin by only ex-tending your arms slightly away fromyour chest (b) and progress to extend-ing them as far as possible (c), beingsure to maintain the abdominal brace,and then return back to the startingposition. This exercise can be furtherprogressed by increasing the weighton the cable machine or by narrowingthe stance (i.e., the base of support).

To perform the around the worldexercise (figure 14) hold a kettlebellwith both hands starting just abovethe shoulder (ia) and bring it backand around the head in a circular fash-ion (ib–id). This movement essentially

challenges the muscles of the trunkthat control motion in all 3 planesbut is only effective as long as theabdominal brace is maintained. Pro-gressing this exercise can be per-formed by extending the arms furtheraway from the body (iia–iid) or byincreasing the weight of the kettlebell.

To perform the push up shouldertouch exercise (figure 15) start withthe feet slightly wider than the shoul-der width and with the hands directlyunder the shoulders (ia). Keeping a levelpelvis, lift one hand to grab the oppo-site forearm (ib), and then slowly re-turn the hand back down. Forregression, widen the feet and bringthe hands closer together. Progressingthis exercise can be performed by

reaching the hand higher up the oppo-site arm (ii) or by narrowing the feet(not shown).

The chop (figure 16) is performed bykneeling on one knee (knee furthestfrom cable machine down) next to thecable machine and hold the bar withboth hands above the shoulder level(ia). With a neutral spine and abdominalbrace, bring the handle down in a diag-onal pattern toward the opposite hip(ib–ic); then return to the starting posi-tion. To gradually progress, incremen-tally narrow the stance in half-kneelinguntil both legs are inline (iia–iic). Per-forming this exercise in a lunge positionor standing will also make it more dif-ficult, as well as increasing the weighton the cable machine.

Figure 14. Around the world.




To perform the lift (figure 17) kneelon one knee next to the cablemachine (the knee closest to thecable machine is down), and holdthe bar with both hands at the hiplevel (ia). With a neutral spine and

abdominal brace, bring the handle

up in a diagonal pattern toward theopposite shoulder (ib–ic). To gradu-

ally progress, incrementally narrow

the stance in half-kneeling until bothlegs are in alignment (iia–iic). Per-

forming this exercise in a lunge posi-

tion or standing will make it more

difficult, as well as increasing theweight on the cable machine.

To perform the bear crawl (figure 18)start on your hands and feet with yourknees bent, hands directly under theshoulders and knees directly underthe hips. Walk forward on your handsand feet, moving your contralaterallimbs together (a–c). It is importantto maintain level hips and a neutrallordotic spine throughout the move-ment. This exercise is not limited tojust moving forward and backward,but can be performed in any direction.

To regress this exercise, take a smallcontralateral step forward, pause fora moment, and then return back.Lengthening the time hoveringbetween steps will help prepare anindividual for locomotive bear crawls.

EXERCISE PROGRESSION MODEL

As stated earlier, it is extremely impor-tant that exercise progressions are im-plemented properly to ensure that theclient is continuously moving towardtheir fitness goals as safely as possible.Figure 1 presents a model proposed by

Figure 15. Push-up shoulder touch.



Blanchard and Glasgow (4) for exerciseprogression that is very general. There-fore, this section will help the exerciseprofessional apply this model to safelyand appropriately progress the exer-cises presented in this article.

It is suggested that the section marked“A” in Figure 1 is the most controlledlevel of the exercise where the clienthas the goal of only focusing onintrinsic factors such as joint proprio-ception. For core training, the goal ofthis initial exercise could be to stabi-lize the lumbar spine in a neutral lor-dotic position under a sagittal plane

load such as that presented in thefront plank (Figure 2ii). This simpleexercise can then be regressed if theclient struggles to maintain a neutrallordotic curvature by putting them onan angle (Figure 2i), as this decreasesthe amount of moment that the coremuscles must match in order to main-tain spinal position. You can thenslowly progress linearly within thisexercise by increasing the momentarm distance. This can be performedby slowly decreasing the angle by get-ting a smaller box for the client to puttheir forearms on. It can then further

be progressed by increasing thatmoment arm distance by moving yourforearms further away from your feetor by elevating the feet. All of thesethings will linearly alter the core chal-lenge while still keeping the intrinsicfocus of this level “A” exercise.

Once the intrinsic factors of the basic“A” exercise are mastered, Blanchardand Glasgow (4) suggest that theseexercises could then be progressedby adding an extrinsic factor. Exam-ples of extrinsic factors are the wheelpresented in Figure 3, the BOSUball presented in Figure 4, the

Figure 16. Chops.




suspension trainer straps presented inFigure 5, or the sliders under the feetpresented in Figure 6. All of these ex-ercises present an extrinsic factor thatadds to the difficulty of the exercisewhile still maintaining the same basic

goal—stabilize the lumbar spine ina neutral lordotic position under a sag-ittal plane load. Any of these extrinsicfactors could be included under theprogressions marked “B,” “C,” or“D” in the model and then be

progressed/regressed linearly withinthe same extrinsic factor by alteringthe moment arm distance or theamount of sagittal plane torqueapplied to the core muscles. It shouldbe noted that the extrinsic factors

Figure 17. Lifts.

Figure 18. Bear crawl.



presented in Figures 3–6 (wheel, BO-SU ball, suspension strap, foot sliders)would most likely never be used incombination, as was suggested byBlanchard and Glasgow (4), as thefourth level of progression in Figure 1.However, all of these exercises areperformed in very nonfunctional po-sitions (prone or supine), so Blan-chard and Glasgow (4) suggesta further progression would be toadd multiple changes in stimulus/environment to the basic challenge.This could be performed in a standingposition and using something such asa body blade (Figure 7) to add furtherchallenge to the core. The momentarm distance can then also be alteredwithin this exercise by increasing thedistance of the body blade from thecore muscles.

After the client has become profi-cient in maintaining a neutral lor-dotic lumbar spine under sagittalplane loads and challenges, theycan be progressed to frontal planeexercises (Figures 8–10), followedby transverse plane exercise (Figures11–18). For each of these planes,a new progression model will beginwith the basic intrinsic goal “A” oftraining the proprioceptors to main-tain a neutral lumbar spine undera destabilizing load. These exercisescan then be progressed by first add-ing one extrinsic factor, followed bymultiple changes in the environ-ment/stimulus. Using the dead bugexercise (Figure 4), the goal of thebasic exercise “A” is to maintaina neutral lordotic curvature ina supine position on the floor (Figur-e 4i). This exercise could be pro-gressed by adding the extrinsicfactor “B” of the BOSU ball (ii). Add-ing limb movement would be modi-fication “C” and could be used whilelying on the floor “AC” (not shown)or in combination with the BOSUball “ABC” (Figure 4iii and iv). Thefinal progression “D” could addanother intrinsic factor by havingthem catch and toss a ball. If theycould do this while stabilizing theircore on the BOSU and moving their

limbs, this would be progression“ABCD.”

FINAL CONSIDERATIONS

The goal of this article was toenhance the understanding of howto progress isometric exercises de-signed to target the core muscula-ture. It should be noted that thefigures provide only limited exam-ples of these types of training exer-cises, but there are an infinite amountof additional variations and other posi-tions and movements that can accom-plish the same goal. Many of theexercises shown also involve unilateralloading of the spine, which can help theexercise professional to identify andcorrect any asymmetries that may bepresent in their clients. However, it isimportant that these exercises are per-formed bilaterally (on both sides) toensure even development of stabilizingmusculature. As mentioned prior, somevariations of the exercises may not beappropriate for all individuals. Forexample, the plank progression of walk-ing the forearms forward away from thetrunk places stress on the shoulder jointand may be aggravating to those withan existing shoulder pathology. Manyexercises which require static holdscan also be progressed by increasingthe time the exercise is held; however,performing several repetitions whileholding a position for no more than30 seconds is advised (13,22). It shouldalso be recognized that some of the ex-ercises presented in this article are per-formed in relatively nonfunctionalexercise positions, thus further progres-sion would involve weight bearing ex-ercises such as squats, lunges, andweightlifting; however, it is imperativethat a neutral lordosis is maintainedthroughout the course of every exer-cise. If an individual is unable to main-tain a desirable spine position duringany movement, it should be regresseduntil the client can develop the appro-priate muscular activation strategies.Once they have mastered the exercisein its regressed form, then it can beappropriately progressed and adaptedto the needs of the individual using

the model presented by Blanchardand Glasgow (4).

Conflicts of Interest and Source of Funding:The authors report no conflicts of interestand no source of funding.

Natasha

Mendrin Depart-ment of Kinesiol-ogy, CaliforniaState University,Fullerton, CA.

Scott K. Lynn isan AssociateProfessor in theDepartment ofKinesiology atCalifornia StateUniversity, Full-erton, CA.

Halecia K.

Griffith-Merritt

Department ofKinesiology, Cal-ifornia StateUniversity, Full-erton, CA.

Guillermo J.

Noffal is a Profes-sor in theDepartment ofKinesiology atCalifornia StateUniversity, Full-erton, CA.

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